Baby seat for stoker's seat post on tandem My wife and I used to both commute by bike, and now that our child is old enough to go on a bike, we'd like to do so again. She has already installed a front-mounted baby seat on her dutch-style bike, the kid loves to ride in it!

However, it seems silly to adapt my road bike for a child seat when we already have a tandem bike made for two adults that would offer a much smoother ride for the child in the stoker's position. Is there such a thing as a seat-post adapter to carry a child seat instead of a saddle, or a baby seat that could replace the saddle?

I don't know of a child seat which replaces the seat-post and I think it's unlikely that it exists as a product as this would be such an unusual case. The normal Hamax seats which attach to the seat tube will work fine and the design shown here provides some suspension.

I've ridden the bike like this, without a stoker and it does take some extra care due to the weight high up, especially at low speed and when pushing/parking the bike. In this photo I have the rear brake locked on with a strap, to stop the bike slipping. If you were certain you'd never have a stoker riding then, depending on the frame design, you could probably attach it to the captain's seat tube, but on a tandem it can be helpful to have a bit of weight over the back wheel for traction.

I know that doesn't exactly answer your question, but hopefully it's some help.


Which kind of electric-assist bike would be appropriate? I have a regular bike that I wanted to use to commute to my work (~12km/7mi) and back. In practice it turned out that while it was OK for one way, at my current level of fitness, I felt rather too tired after work to get back on bike and drive all the way back, so I only did this a couple of times. Plus, of course, it took approximately 30% more time than going by car (but that's generally OK).

So, I have started to look if maybe electric-assist bikes would be a help there. My  idea was that I would use muscle power as much as possible to give myself a decent workout, but the electric power could help when I felt too tired or when I needed to go faster.

I looked at Hybrid electric bikes, how do they work? and Why would I use an electric bike?, but I kind of feel they assume plenty of things already known.

Do I understand it right that there are several kinds of electrical bikes(hybrid? others?), and which kind would be best suited for the use as I described? How about the fact that electrical bikes are (as far as I can see here) around +10kg to my existing bike?

I am in Eastern Europe.  There are no equivalents to the UK's Bike-To-Work scheme available here.

The choice of whether to ride an electric-assist bike or regular bike involves a lot of different factors, including just your own personal wants and desires. E-bikes add an extra dimension to the riding that can make it more enjoyable for some, especially those that don't already have an affinity for bike riding to start with.

So any answer will necessarily involve a healthy dose of opinion, and you'll have to see which of those opinions seem to mirror your own approach to riding best.

That said, it's worth focusing on your specific scenario, as prep for your broader research into what electric bike specifically would work best for you…

IMHO an electric bike is most useful if you have one of a few different goals as a priority:

Reducing time riding. Even on a flat, an electric bike will let an average cyclist go faster. Note however that an experienced, fit cyclist can easily ride at the same pace on flat terrain as a regular pedal-assist bike will operate (in the US, e-bikes treated as regular bikes are limited to 20 mph for assist, while outside the US, I believe the limit is 25 kph…faster than that, and the bikes become subject to at least some of the motor vehicle regulations, including prohibitions for use on bike/shared-use trails).
Reduced effort. For some, this is as much about practicality as it is laziness. While an experienced, fit cyclist can maintain 20 mph on a flat, this still requires effort, which at the very least will likely involve sweating, and may call for specific clothing. With an e-bike, one can ride at higher speeds with relatively little effort, in street clothes and arrive at your destination ready to work, play, whatever.
Flattening the hills. This is a corollary to the previous two points. In some locales, the riding is already very flat and comfortable, speed is not important (and may not be even possible, depending on congestion on the bike trails), and an e-bike would be superfluous. But in a hilly place, the presence of hills might significantly slow you down, and using an e-bike might turn an impractical ride (due to time or effort constraints) into a practical one.

As a case-in-point: I currently commute using an electric bike. I have for decades used a regular bike for commuting, but my longest ride had been about 10 miles, and for much of that time I was riding less than 5 miles each way. Even with moderate hills, this was fine for my level of fitness and time availability. But my commute has recently increased to about 25 miles, over very steep hills, amounting to about 1800 feet of vertical gain over the ride. Without an electric bike, this would probably be about 2.5 hours of riding each way, but with the electric bike, it's only 1.5 hours.

In your own example, the distance is clearly within the range I found comfortable on a regular bike, even with hills. So I'll point out the first obvious fact:

While you may be getting tired now, you will find that over time, it gets easier. Probably a lot easier depending on your current fitness level. This depends a bit on how hilly it is, but even with hills you'll find you're able to climb them faster, or with less effort, or both. If you keep the travel time constant, you'll expend less effort as you get stronger. If you are willing to expend the same amount of perceived effort as you get stronger, you'll find that the ride goes more and more quickly. The bulk of the gains will come early in the process, and with such a short ride, you may not find much improvement after that, but the ride will stop feeling like a chore regardless.

In other words, don't judge the ride by how you feel now. I have found that a short 20-minute ride home after work is just what I need to unwind. One thing I've always valued about biking is that it's one of the few places I get any real exercise, and so I don't mind spending the time doing it. I quite enjoy it,  actually. (That said, if your job involves a lot of heavy lifting or other exhausting work all day, maybe you'll never find biking home to be something you look forward to.)

On a ride of the length you're proposing, an electric bike is going to be more about transportation than fitness. Even without an electric motor, it's just barely long enough to improve your fitness, but with an electric motor, the ride will be shortened so much that even the aerobic benefit will be minimal, and you probably won't get much if any strength benefit.

If you do decide to get an electric bike, all of the information that's already out there should be all you need. That is, there are a myriad of choices, and most of them relate more to how the bike feels to you than the ride itself. Any electric bike you find would probably work fine on that commute.

That said…I did wind up forming my own opinions of electric bike configurations before I bought mine, through lots of test rides, so I'll share those:

Most important: I really didn't like the bikes that didn't use torque sensors to govern the motor. Instead, they use pedal cadence sensors, and the motors are generally just "on" or "off". You can get used to that scheme, but I found that it made the bike seem more like an uncoordinated partner than part of the team. The motor would kick in hard immediately, instead of moderating its assist to match my pedal stroke, and it wasn't possible to smoothly adjust my speed with pedal force, because if I kept pedaling at all, the motor kept at its set boost. This gave the impression of the motor actually working harder as I pedaled more lightly and vice a versa, which is IMHO the opposite of what you want.So I strongly recommend considering only bikes that use a torque sensor to control the assist level.
The other big configuration choice to look at is a hub-mounted motor vs a mid-drive motor. The former drives the wheel directly, the latter drives via the pedal crank. This is largely a subjective choice, partly driven by economics (the latter are generally more expensive). There are pros and cons to each, covered adequately by any number of other resources. The biggest differences come down to weight distribution (hub drive puts the weight rear-ward, which can affect bike handling more) and gearing (mid-drive takes advantage of the bike's gearing, and so can provide more torque over a wider range). IMHO, the weight distribution is the more important of these two, but this may only be an issue if you also tend to ride with a rear rack loaded down with gear (I do, but many people won't), and is in any case mitigated by the fact that the electric bikes tend to be significantly heavier than a regular bike, so the center of gravity (balance) of the bike doesn't actually shift that far rearward even with a heavy motor on the hub.

Other options mostly involve things like where the battery is mounted (again, rear-mounted batteries mess with the bike balance in ways that frame-mounted batteries don't), how big the battery is, whether it can be charged on or off the bike (but your short ride means this is probably not that important), manufacturer (I found that Brose, Yamaha, and Bosch systems all seemed to work better than the other manufacturers I found and tried, but this is far from an objective, educated observation), how much capacity the battery has (again, your short ride means that pretty much any e-bike should suffice), and of course all the other components on the bike.

Regarding components, mainly I mean the brand and quality level. But one other characteristic that could affect your choice is the drive-train. Specifically, internally-geared-hub vs derailleur (the former available only with mid-drive bikes, as far as I know), and if IGH, then whether the bike is belt-drive or chain-drive. I ride in all weather except heavy snow, so I opted for a belt-drive bike. But honestly, the best riding bike (in terms of just how the bike handled and fit me) I found was from Haibike, available only with a chain drive. It was really a difficult choice to make, but ultimately I knew I didn't want to spend all the extra time and mess dealing with cleaning the chain and gears after every ride in the rain.

If you only plan to ride in good weather, chain drive is great, costs significantly less, and is universally available (limiting yourself to belt drive means reducing the available options significantly).


Traveling road bikes that disassemble I did a ride with a guy who had a bike like this http://www.sandsmachine.com/a_rod_r2.htm

It was a regular road bike (Allow) that you could disassemble and fit in a case slightly larger than the wheels.

He said he used his bike for Triathlons and other riding events.

I am interested in configuring my own bike to work this way (Regular road bike, steel)

The mechanism that allows disassembling the frame is called an S&S Coupling, Bicycle Torque Coupling or BTC.  Searching for bikes with this mechanism should allow you find other models of bikes that can be disassembled in the same manner.


What is cheaper, to walk or to cycle? I recently started cycling to work, after having been walking the same distance for a couple of years. I used to have to replace my shoes about every six months, because they were too worn. This weekend I replaced my chain, because it was too worn and earlier this year I replaced my tyres, but more because I wanted better tyres than because they were too worn.

After learning about the prices of bike components and how long they last, I started to compare the maintenance cost of cycling versus walking. Most bike parts are cheaper and last longer than my shoes. So is it possible that cycling is actually cheaper than walking?

Cycling is cheaper than walking.

I asked a few people what they think is cheaper, walking or cycling, and everyone answered that walking is cheaper. It seems logical, because to walk, all you need is shoes, while to cycle, you still need shoes, but you also need a bike and arguably a helmet and gloves.

There's a wide range of prices for both shoes and bikes, and it's up to everyone to decide how much they want to spend on each, but to make this a fair comparison I will use lower midrange UK prices in my calculation.

One pair of shoes is obviously cheaper than a pair of shoes, a bike, a helmet and a pair of gloves, so if you are comparing the cost of going 10 miles, walking is definitely cheaper:

However, at 10,000 miles, the numbers look very different:

The cost of walking 10,000 miles is 20 times higher, while the cost of cycling didn't even double. Already after 10,000 miles, the bike has payed for itself and is saving you money, even compared to walking.

I know that there are other components that you will need to replace, such as brake pads and cables, but these could last 10,000 miles depending on your riding conditions, and even if they don't, they are so cheap that they will barely make a difference to final cost. I also didn't include the cost of labour and the tools needed to perform the maintenance. Most maintenance tasks are easy enough that you can perform them yourself and the tools needed are generally pretty cheap. Again, it wouldn't make much difference to the final cost.

Now, there are a few things that would make a huge difference to the calculation. If you put a price on the time spent traveling, cycling is several times more cost efficient than walking. However, over short distances, you might find yourself spending all the time you saved, by going faster, on parking and locking your bike. Theft and accidents, can completely ruin the numbers for cycling, but you can also get mugged or have an accident, while walking, so it's not completely one sided. I left these things out, because they are too situational and hard to predict.

Cycling is also more energy efficient, but I don't think most people would notice any difference in their food consumption, so I don't think it's worth trying to estimate how much money that would save.

I think my calculation is fair and even if my estimates are a bit off, I think it's quite clear that, given a long enough distance, cycling is cheaper than walking. Any feedback is welcome and I really don't mind to be proven wrong.


Pedals no longer increase speed after a relatively low speed So i have this bike:
MENS PRO MOTIVE DS400 DUAL SUSPENSION MOUNTAIN BIKE

Bought it 2nd hand quite recently and had this thing that after reaching a certain speed no matter how hard i pedal speed doesnt increase. The pedals feel as if nothing is attached to them at that point. any help?

BTW am completely new to bikes :)

The gear ratio you're using is determined by the ratio of the number of teeth of the chainring (gear in the front) and cog on the cassette (gear in the back). For a fixed cadence (number of times you turn the pedals per minute), the higher the gear ratio, the faster you go.

So, you need to either shift into a higher gear (move to a bigger chainring and/or a smaller cog on the cassette), or pedal faster.

Note that most bicycles have the ability to freewheel, which means that if you're not turning the pedals fast enough, the bicycle basically coasts. Contrast this with a fixed gear bicycle, which so long as the rear wheel is turning, the pedals will be turning. If you're not pedaling fast enough with a bicycle that can freewheel (like yours), you're basically coasting. So, if you want to use that gear, you need to pedal faster in order to get power through. And if you're maxing out the highest gear, you may want to change the cassette/freewheel to get a smaller smallest cog in the back.

If your cadence is below 60 rpm, chances are it's too slow -- you should probably aim for around 80 rpm.


How often should I clean my BMX bike? I recently got my bike and rode it for a good 4 hours yesterday.

I'm pretty new to BMX riding, and really want to maintain my bike well.

I hear people clean their bike every time they finish, but was wondering if that is necessary.

A clean bike is a happy bike. No, cleaning every speck.of sort off the frame after each ride isn't necessary.

However, wiping down the frame, and wiping any extra dirt or crud from the hubs, brakes and chain can only help keep your bike in good shape for as long as possible.

Make sure to lightly lube the chain once a week or so. And every couple of weeks, take a set of Allen keys and check that none of the bolts on your bike are coming loose.

Take it in for a tune every 6 months to a year, and you should be good to go. :)


Converting from MTB style levers to STI This is my city bike:
https://www.giant-bicycles.com/en-us/bikes/model/escape.3/18736/76133/#specifications

Currently I use trekking bars and the MTB style shifter/brake set that came with it. If I wanted to convert it to STI brifters as far as I know all I have to swap are the bars, levers and brakes. Is that correct? I'll leave it as a 7 speed and use the tourney brifters, I'm just trying to see if I need to swap any other parts.

Shimano road and mountain shifters use a different cable pull ratio for the front derailer. It can be made to kinda sorta work, but it won't perform right. If you buy any of the currently made Shimano road triple FDs, you will run into the problem that their minimum tooth difference between the middle and large ring spec is 11 or more, whereas you need 10, and also the profile of the cage won't be ideally matched to your chainrings. The best solution is getting an IRD Alpina FD, presuming you definitely want to stay with your current crank. You may also get acceptable performance with an older 7/8s road triple FD such as FD-3303. Older ones have a min difference spec of 10.

Other than that, no issues. Note also that you can use an 8-speed STI if you want, such as Claris.


Tire Change Compatibility I'm trying road bikes for the first time, and I'm rather unfamiliar with tires and how things are intercompatible.
I'm thinking of getting a cheap Merax 608XC, and plan on taking it on trails such as the C&O Canal towpath. I've heard of cyclocross and touring bikes, but simply don't have the budget to afford any. I'm currently planning to get the merax and swap out the tires, but I don't really know if switching out the 700x23c tire for a 700x28c with knobs is possible?

Save your money and get a used bike instead (look for bike shops in your area that sell used bikes, or craigslist or something). 230 dollars should net you something decent from the 80s or 90s, along with some accessories (helmet, locks, lights, etc.). It'll be much higher quality than what you're looking at (the bike you've linked is bso-ish), and older road bikes have much larger tire clearance normally than newer bikes.

One of the big problems with buying your first bike online is sizing -- not everyone fits the sizing charts bike manufacturers may publish. And you don't get a test ride online to know if it will fit you well.

The C&O canal towpath just has a bit of gravel on it, not much terrain toughness. I'd not worry about knobs, just 28c+ tires. As for sizing, you have to try the tires with the particular bike, especially with a road bike. Normally with modern road bikes, you can maybe go 1 tire size up with a smooth tire compared to whats originally spec'd. You've gotta check the tire clearance to see if the tire will fit (also note that two new tires will run 40+ dollars on the low end). So, I'd conjecture that the 28c tire won't fit.


Fork replacement for SR Suntour 29er I ride pretty aggressively cross country and trail in colorado, and occasionally will go to the bike park and do some jumps.

I recently bought a specialized hardrock 29er for my wife, who's a novice rider.  The price was right, and the bike is great for her.  The problem is I want to ride it sometimes, but the fork sketches me out.  First: it sucks compared to my fox fork on my 26" bike and second: I'm afraid it's going to break on me.

The fork is an 80mm SR suntour.  Does anybody have any suggestions for reasonably priced replacements? I don't want to change the geometry too much.  I think the idea is if i put some money into the fork, we could put it on her next bike if/when she decides to upgrade.

Been there and not done that. The only option I found was to go used, but even then, its hard to get a reasonably prices upgrade. A better option for me was replace the bike. For the price of upgrading the shock (at least $400) I sold my old bike ($300) and got an 'as new' bike that was much better all round.

Accept that you are choosing to ride her cheap bike. Even if you upgrade the shocks, you will be still be riding a cheap bike..... before you know it it will be Grandfathers Axe (3 new heads and 4 new handles, but its the same axe my grandad used).


What are the rules about take a bike on the London Tube? Can I take a bike on the Tube (underground) in London, if so how much does it cost?

Transport for London page on Bikes on Public Transport

On the tube, folding bikes are good anywhere at any time.  Non-folders are restricted to only certain lines - in most cases these are lines that have no deep below ground tracks - and certain times.

To a certain extent it is going to be up to the station/train staff.  I've travelled on the DLR with my bike in the past, before I realised they have a total ban (I was dismissed from the train, which sucked because I'd had a few to drink and was trying to avoid cycling home).  If in any doubt, or trying to wing it, its always worth asking before you enter the station.


What tyre widths I can use? Just yesterday I noticed that my tyres soon need to be changed but my tyre size is  27.5 x 2.8 But the closest sizes I can find are 2.35, 2.4, 2.1. Those were the closest sizes I could find in store (because I don't buy stuff overseas). What should I do or which size will fit?

'27.5' refers to the rim diameter, It is the same diameter as '650b' or ISO 584. The inch measurement tends to be used for MTB wheels, '650b' for road wheels. You obviously have to fit tires for the correct rim diameter.

'2.8' is the approximate tire width when mounted on a suitable width rim.

The inner width of your rims (distance between flanges) determines what range of tire width you can use. There are a few tables available on the internet that give general tire width ranges for different inner rim widths, but none I found cover the plus size range.

You can probably use tires that are narrower than 2.8". To make sure, measure the inner width of your rims in millimeters (a ruler is accurate enough), You should be able to find the rim width range that any model of tire is compatible with on the manufacturer's website.

An approximate rule for minimum tire width is no narrower than the outer width of the rim, preferably a little wider.


How to improve my performance on a commute? I commute to work on a Trek 7100e hybrid bike. It's about 15 miles (24km) each way, along flattish suburban roads and a (fairly smooth) canal towpath. It takes me about an hour. Due to the distance (and extra time compared to driving), I only do this about once a week. I'm a medium-height, slightly built guy, reasonable fitness level. What is the best way to improve my speed and reduce my time, without spending much money?

Pedals - I don't really want to go clipless due to the expense, but I'd consider it if it's the best way. Are toe clips and straps likely to make much difference?
Reducing 'luggage weight'. My standard pack for work is a change of clothes and some basic bike maintenance stuff (tube, pump, tools, and a cable lock). It's currently in a double pannier that's probably overkill. Should I consider going to a rack trunk, a handlebar bag (no rack required), or something else? I don't like cycling that far with a backpack.
Tyres - change to slicks? Or narrower tyres? Would that mean I'd need to change the wheels too?
I'd assumed (and read somewhere here) that changing to drop handlebars would be more trouble than it's worth.
Something I haven't thought of?

EDIT - just a quick update. A work colleague had some spare LOOK clipless pedals and shoes, so I gave them a try. And I'm a convert! I see a definite improvement in performance, especially in acceleration - I can get up to speed a lot quicker than I could before. Thanks to everyone who answered. I'll probably try skinnier tyres too, but not until I actually need to change them.

EDIT three years on. I upgraded to a road bike (Pinnacle Dolomite 4, 2016) and that's been the biggest improvement in speed. I still have a rack on the back (just a rack top bag now, no panniers), clipless pedals, and 25mm tyres inflated to 100psi. I usually try to leave some clothes in work to reduce weight. Record time is now 51 minutes!

I posted a comment

  Slick tires would make a difference, if you're not using them. Maintaining 24 kph on a hybrid that you ride one day a week is pretty good. The next two increments after slick tires would be clipless pedals, riding more frequently, and then a road bike.

... but decided a full answer was needed.

Given that the trip is 24 km, doing it in 60 minutes is 24 kph. Not bad for a lightly built guy riding a hybrid that is reported to be heavy, one day per week. By my figures, you're putting about 150 watts into the pedals to do that. This assumes you're using wide, non-slick tires.

Switching to thinner, slick road tires would gain you 2 kph for the same effort, possibly 3 kph. That gets you there 5 minutes quicker.

But to put 150 watts into the pedals, you have to produce more, because without your feet being clipped in, they will slide a little, and you have to use energy to keep them in place. Lets guess that's 10% of your effort - 15 watts. So you're really producing 165 watts. That translates to about 1 kph faster if you were clipped in. But as the late night TV ads say, but wait there's more. With your feet clipped in, you can produce more power because you can pull the pedals up as well as push down. How much more? The experts argue. Some claim 15%, others 40%. If it's 15%, that's another 24 watts (15% of 165). So after your aerobic system has adapted to delivering that much extra oxygen, you'll be up to about 29 kph. But I think you'd need to be riding three times a week to develop that sustained pace.

Extra training can take you faster, if you are riding regularly. How much is up to your innate abilities and dedication.

And how to go even faster? A road bike. For the same power that drives you at 29 kph on the hybrid, you'll go at 31 kph on a road bike, getting you there in 47 minutes.

So, you said you didn't want to spend much money. I'm arguing that clipless pedals will give you good return. They also support you as you work to increase your strength and fitness.


Which derailler hanger? Which derailler hanger should work on saracen raw 3 with sram sx4 rear derailer? The old derailler snapped off rhe frame

These claim to fit the Saracen Raw 2, which appears to be the same frame with slightly different components. It looks right based on what I can find on the internet.

The compatibility of a hanger is between it and the frame, in general, standard rear derailleurs are compatible with all hangers.

https://www.ebay.co.uk/itm/SARACEN-Mantra-Raw-2-MONGOOSE-Tyax-Comp-Super-Rear-Gear-Mech-Hanger-CC003-/301758510575


Replacement bottom bracket for Shimano XT FC-M785 crankset I ride a BMC FS-02 mountain bike which came with a Shimano XT group, including a FC-M785 XT Crankset (2X10).  The bottom bracket is apparently included in that and mine is showing some signs of wear.

I'm new to the press-fit bottom bracket and am trying to figure out what a good replacement is and what exact dimensions, if any, I need to be aware of.

TL;DNR - I recently had exactly the same problem with my 3x10 XT MTB and handed the job to the LBS.

You need to be aware the great thing about standards is when you can't find one that suits you make a a new one. The Cycle industry took this to new extremes since the early 2000's with regards to Bottom Brackets. The BB matches the crank set to the frame, so you half of the equation knowing the crank set. The manufacturer and all my normal goto references for bike specs are silent on the BB standard of the frame.

If the BB is press fit, its probably BB30. Have a look on the lower seat tube - some manufacturers helpfully print use information on BB.

If press fit, this is one job that might be better left to your LBS - you probably won't have the correct tools to do it yourself, correct tools are expensive and DIY cobbled together tools can easily stuff a frame. With the correct tools the LBS has, it is a 30 minute job, and that 30 minutes comes with years of experience.


How can I tell if I have properly patched a tube? (specifically a 2" mt. bike tube) I normally swap out a the tube on the trail if I get a flat and then patch at home. So that leaves me with a patched tube ready to put in a tire and I'd like to test it without having to swap out a tube ('cause I'm lazy :).

I thought that perhaps I could just inflate it but I'm concerned that without the opposing pressure of the tire it might blow an otherwise solid patch.

I do like you do when riding, and I usually save up my tubes with holes and patch a bunch of them all at once. That way I can use a tub of water to both find the holes, and can go back through them after patching and test to see if they are holding air.

If I have any doubt after patching a tube, I give it a little time to cure and then I pump it up and hang it from a hook in my garage overnight to see if it loses air.


Is it worth wearing a headlamp when cycling as well as having a bar mounted light? Most bike lights seem to be the bar / seatpost mounted variety. Is it worth also having a headlamp for riding?

I go cycle touring, ride in the city and do mountain bike xc trail riding.

I've got a budget enough to buy something decent.

This is always going to be a matter of opinion but here are some reasons why I think the answer is "yes":

Cornering: you don't have to be cornering hard for a bar-mounted light to point the wrong way, and cornering is a time when you really don't want to hit a pothole.

Signaling to others: if a bus starts indicating out while you're alongside, lifting your head to flash their mirror is quite effective.

If you come off in the dark: you don't want someone to swerve round the bike towards your head. (my head torch has a rear light as well, thanks to my modifications).

I also like the fact that when riding with my bar light quite dipped (e.g. on a busy, two-way but unlit bike path), I have hands-free control of how far in front the road is illuminated, and can avoid dazzling people coming the other way while still illuminating the road ahead.  I use a head torch with a narrow beam.


Velodrome atmospheric conditions During the Olympics the commentators made a big deal about the need to maintain very specific atmospheric conditions in the velodrome, including having airlocks to enter and exit the building.

They stated that the atmosphere is very warm, and humid.

Why are those precise conditions needed for velodrome events?

My suspicion is the high temperature lowers the air density and thus lowers wind resistance but that's purely a guess.  I've no idea what the humidity levels would do to help, surely that would increase the air density again!

Also, with such high temperatures, is there a danger of athletes overheating?

The equation for total aerodynamic drag force on a bicycle is well-understood and, you're right, air density has a role in it: the higher the density, the greater the drag. As you guessed, density decreases with increasing temperature so warm air is less dense than cold air. It's also probably no surprise that density decreases with pressure. However, evidently counter-intuitively, humid air is less dense than dry air. The simplest explanation is that water molecules contain two hydrogen atoms and one oxygen atom so they have a molecular mass of 18 g/mol, while dry air has a molecular mass of around 29 g/mol. You can check the wikipedia page on air density for more details.


Can we use a 9 speed rear derailleur on a 8 speed bike? I have a Rockrider 5.2 with a Shimano Altus 8 speed rear derailleur. After an accident it started to malfunction. I planned on replacing it with a Shimano Acera M3000 but then it is marketed as 9 speed.

Is it fine if I use a 9 speed rear derailleur on a 8 speed bike?

The pull ratio, which is the important bit, is the same for nearly all Shimano 6,7,8 and 9 speed derailleurs.

Other things to look for when changing derailleurs are the capacity, minimum and maximum cog size. These will be fine for the swap you are proposing.


Convert fixed side of flip flop hub to freewheel I have a flip flop hub and I'd like to convert the fixed side to be free wheel. Is this possible? If so how much might it cost?

My motivation for this is that:

I never ride fixie
I'm running a 46/16 and would like to have a lower gear ratio (46/17 or
46/18). It would be really nice if I could keep the 46/16 and just flip the hub to have a different gear ratio.

You can just use the freewheel on the large thread on the fixed side. It's the same size, and just as durable as the freewheel side, for normal people.

So just unscrew the lockring and cog, and put on a standard freewheel of your choice. Did it as a bike messenger, and it still holds to this day.

Happy riding!


change derailleur and shifter in an old road bike reconverted to hybrid I have an old road bike, that I converted to a hybrid bike, I just use it for small tourings. Some time ago I changed the handlebar, the brake levers and the tires.

Recently the derailleur broke up, it was in bad shape and there's no way to repair it, so I just want to get a new one, also I would like to replace the shifters, as they are the old ones that are on the frame, and put triggers like an MTB.

The bike has a 6 speed cassette, I was thinking in a cheap Shimano Tourney derailleur but I can't happen to find trigger shifters of 6 speed on online stores. My idea would be to put a 7 speed shifter with just 6 speeds and someday change the cassette.

What you think? Would be possible to put a 7 speed cassette? Any other suggestions?

It's best to have chain, shifters that match your cassette, both in terms of number of speeds and make (and to a lesser extent model).

In a non-matching configuration, your chain will try to sit slightly between gears in certain settings, which is actually rather annoying.

Having said that, what you propose will work for locomotion, and depending on how much annoyance you're cool with bearing in a given day it may work well enough for your desires.

I tell you these things as someone who has piecemeal upgraged from 7 to 9 speeds; it isn't an ideal solution.


How can bum / testicle / inner thigh pain from a saddle be prevented? I occasionally commute a 50miles round trip and by the end of it, things are usually not feeling very good down below.

I've tried a couple of different saddles, but they both gave me problems. One chaffed my inner thigh, and the other one seemed to not do my privates any good!

I'm wondering what tips have you got for getting comfy?

First, do you have cycling shorts w/ a chamois? If not, I would highly recommend them. As a note, they are your underwear (ex: do not wear undergarments and then put on the shorts).

Second, how did you choose your saddle? Was it fitted through some type of measurement system ala bontragers inform system or specializeds BG system? How much did you spend on the saddle and was it appropriate for the style of riding you are partaking in?

Third, does your bicycle fit you properly? Have you had it fitted?

So, there are a few points that you could answer to give me some help. I cannot recommend a saddle because everyone is different but I can recommend a brand that provides some type of measurement system for choosing your saddle.
As well, if you are wearing cycling shorts a nice chamois butter might help with the chafing.


Tried to replace bicycle brake housing. Broken cable? I was attempting to replace my stock front v brake to a better aftermarket v brake everything went ok until I tried to test it and the brake cable end, the one that connects to the brake lever, will not stay in place.

As you can see, the cable gets clamped at the brake lever entrance. On my bicycle the clamp or  ferrule will not stay in place. In other words, the cable does not tighten because it will not clamp into the brake lever, it slides.

My question is.. Can this be fixed? Perhaps I can glue it in somehow? Perhaps there is something that gets clamped in a different way?

Apologies for the vague explanation.

There are two types of brake anchor (one is plum-shaped, the other is barrel-shaped or cylindrical). If you have the wrong one at the brake end, it won't fit properly and will slide around.
To solve this, some brake cable vendors sell their cables with both types of end anchors attached. You just use the end that you need and cut off (with a proper brake line cutter, not a pair of pliers) the end you don't need:

Be sure to put a ferrule on the cut end of the cable because it will unravel. DIY options include shrink wrap, a cork, an electrical crimp connector, tape (not personally recommended), string, wire, hot glue, etc.


New puncture resistant tires punctured after 2 min ride So, because I do ultra-light touring I bought new puncture resistant tires for my road bike (Continental Grand Prix 4-Season, 28c), I installed them and after two minutes I had a puncture. First I thought I had punctured the tube when mounting the tires, but then I looked and not one, but TWO pieces of glass had gone through the tire. Is this just extremely unlucky or are these tires worthless?

While we don't do product reviews, note that puncture resistant doesn't mean puncture proof -- with any air based system, you're going to run the risk of cutting the tire and tube and getting a flat. Some tires are better than others in terms of puncture protection, using things like kevlar belts. The tires you bought trade off for some more the weight and handling performance versus durability to road hazards (by fitting a kevlar belt rather than whatever lighter thing they put in there) so that you have less protection from road hazards than say, a Schwalbe Marathon Plus.

Don't ride through glass and in general avoid road hazards is the best thing to do.


Securing a bike on a car rack against theft I sometimes find the need to leave my bike on my bike rack while I'm away from my car.  It's a simple strapped-on rack, so locking the bike to the rack doesn't help.  (My car doesn't have a towing hitch.)

What can I do to secure the bike to the car in a way that will deter theft?

The Simplest Option - Passive Lock Strap

By far the simplest and easiest way to do this is to use a "trunk lock strap" or "passive lock strap". Searching in Google for either of those phases should turn up suitable products.

The idea with these is that they are a flexible cable that you loop around your bike and then close a thicker stubbed end inside your vehicle either in your trunk if you use a rear rack, or inside a passenger door if you use a roof rack.

You should note that no product is completely theft-proof, and you will ideally want to use more than one locking/security mechanism. At a minimum, if leaving the bike on the rack, I would remove the front tire and put it in the car as well as using this strap. That way they can't just cut the strap and ride away with the bike.

More Complicated - Tow Loop

A more complicated and likely far more expensive option is to look into the installation of an external Tow Loop. Many modern cars that are not equipped with a towing package, still have some kind of loop or bracket either directly under the bumper, or beneath some removable cover in the bumper. You can have an externally accessible tow loop retrofitted to the car and then you could lock the bike with a cable through that loop.

Google your vehicle make and model and add the words "tow hooks" or "tow points" for ideas, or talk to a qualified auto mechanic/dealer.


Price difference between buying a bike in Europe (Austria) vs USA? I am moving to Vienna, Austria in two weeks.

My wife and I want to buy bikes before we leave, but I'm wondering if the hassle of trying to find great bikes on such short notice would be greater than just buying some when we get there.

My wife is looking for a town bike for

Thanks,

Eric

I would be in favor of waiting until you move. There is the possible problem of needing service work under warranty and the nearest dealer being some distance away. You must also factor in the shipping cost  along with the expense of disassembly and reassembly if you can't do it yourself. There is also no better way to start a good relationship with your local shop than by buying two bikes. The other advantage is being able to check out the terrain and see what type of bike you need.


Crank arm snapped: what could have caused it? Recently, on my single-speed bike, the right crank arm just snapped. Was slowly going up a hill, and all of a sudden it broke in two pieces.

I have now exchanged the entire crank & chain set (sadly had to give away my beloved spider crank!)

Afaik this is not a very usual thing to happen.
What could have caused it?

Edit: It looked pretty much exactly like this.

Crank arms snap all the time. Odds are pretty good that it was an older crank and the fatigue in the metal built up enough that it was no longer structurally sound. Metals are a lot like crystals on the atomic scale, but when you repeatedly put a load on them tiny cracks begin to form and grow, until the metal is warn out and cracks.

Fatigued metal is also more likely to snap when subjected to above average forces, so it makes sense that this happened when you were hammering up a hill.

Airlines around the world are required to have their aircraft x-rayed periodically for signs of fatigue. When they see microscopic cracks they replace the part.

If it wasn't an old part it's likely that there was a flaw in metal.


How did cyclists get over curbs before BMX era? There were curbs before 1970s, right? I wonder whether everyone had to dismount or dramatically slow down before curbs until bunny hop and wheel lift became popular, I guess, in 1970s among first BMXers. Same with cyclocross: for decades, from its beginnings, riders always dismounted before barriers. But suddenly, inspired by BMX, they realized it's possible to simply jump over?

EDIT: changed wording to underline that CX is much older than BMX.

EDIT2: I don't want to make you think that you need BMX bike to hop curbs. What I'm pointing to is that before BMX there was little mainstream attention to techniques like bunny hop (at least I got such impression), and after BMX got popular they spread throughout all cycling world. Though not many of us are skilled in jumping curbs, virtually everyone knows that can be done at ease by other riders.

People were doing tricks on bicycles almost as soon as they were invented. While I couldn't find references about curb hopping in particular, I'm pretty sure that these tricksters from the late 1800s wouldn't have had a problem pulling it off.

Cyclocross has roots that go almost as far back. The first organized cyclocross races were around the end of the 19th century and the first French National Championship was in 1902.

I would guess that prior to BMX most people got over curbs the same way that most people get over curbs today. They slowed down a bit, lifted the front wheel over the curb, and leaned forward to get the weight off the rear wheel. Keep in mind, most cycling commuters can't pull off a decent bunny hop and many commuter bikes aren't designed to do so.


To what extent should I insulate an electric bike battery during winter? For temperatures between 0 F and 32 F, to what extent, if at all, should I insulate electric bicycle batteries?  I have read that they do not like temperature extremes.  Should I wrap a battery in 1 layer of bubble wrap during weather like this?  Multiple layers?  What about other types of insulation?  What amount of insulation will cause the battery to heat itself to optimum temperatures without overheating?  I realize that this depends on the temperature range, speed, and reliance on the battery when riding, so some sort of algorithm that takes all of these factors into account would be ideal, or at least some safe minimum amount, assuming the temperature is below freezing.

For clarification: I am talking about when the bike is being used outside during the winter.  I intend to store it inside all the time when it is not in use.

General advice is to store the battery at room temperature and install it in on the bike just before the ride. If the ride is under about 30 minutes the battery will stay warm enough not to be badly affected by the cold. For longer rides, a layer or two of insulation would not hurt (as long as it is not so  much the battery over heats).  Bubble wrap would be a great way to experiment and work out how much was needed and if it made a difference for your rides, but I would look at something a bit more durable in the form of an insulated zip up or Velcro cover for a long term solution.

When charging lithium batteries in cold climates you need to be careful. Never charge Lithium below about +5C.
 Ideally bring them up to room temperature before charging. Note this is the internal temperature of the battery - don't bring a battery that's been on a bike at -10C inside  and start charging after a few minutes when the case feels warm, I would give it a couple of hours.


Checking 'plumb' when mounting bike on trainer From my former questions, y'all might be aware that I prefer to ride indoors  - for various reasons

no hordes of people of median IQ in 1500kg death machines waiting to smoosh me;
no need to wear lycra or Kardashian-shoes or helmets;
no 'free travel' by not pedalling on downhills.

My Wahoo KickR is currently at a mate's place, so I've had to go back to an old "dumb" trainer; that's fine, because I've got a built-in power meter on my bike now, so I can still calibrate my workouts to power and HR zones.

One thing I've noticed on the dumb trainer is that I am very sensitive if the bike's not "plumb" (worse, if it 'shifts' during a session). What I mean by that is that it's very slightly tilted from vertical along its long axis, or if, having felt relatively 'plumb' it moves out of plumb during the ride (oddly, it tends to tilt left more often than chance would indicate).

I can compensate by turning the front wheel in the opposite direction to the 'tilt', but that puts significant strain on shoulders and arms if I'm training remotely hard.

It's not 'Princess and the Pea'-levels of sensitivity, but it's noticeable; by the 50 minute mark of a ride, if the bike's 'leaning' I get preoccupied by it, which screws with concentration and nek minnit my scranus is killing me and it's easier to just get off the bike.

Since the top tube on the bike is wider than the down tube (see? I know all the words now), to measure 'plumb' would seem to require taking a plumb-line down both sides of the top tube and ensuring that the gap is even on both sides. That's a gigantic pfaff, and I'm sick of it already and I've only one it twice.

I had thought perhaps that I could try to run a single line from a loose loop attached to the top tube (hoping that it intersects the down tube centrally), but that doesn't seem to work.

Has anybody ever bothered to actually do this, or do people not care much?

If I was 70kg or thereabouts I would not be that concerned if the bike felt like it was listing like a drunken galleon; it would be unlikely that the entire thing would come adrift.

As it is, I'm ~104kg - if I can notice that the bike's not 'vertical', I'm betting that there will come a day when gravity will notice as well (and given Sod's Law, it'll probably happen when I'm sprinting).

There are several options, ranging from low tech kludges to actually solving the problem. So, starting from low end:

Loop a string around your top tube and tie so that loop is loose and the string can move. Tie the weight to the other end of the string. Now you have a plumb that hangs at the center of the tube.
Get a spirit level. If the solution needs to be free and you have a smart phone, there are also apps for it.
Higher tech variation: Get a laser spirit level and fix it to the frame so that the line shows at down tube. Now you can check the bike position by just looking down.
Actually solving the problem, option 1: Forget the trainer and use rollers instead. You will now maintain the bike upright automatically.
Actually solving the problem, option 2: It sounds like you thorougly dislike cycling. Try some other kind of exercise.


How do I keep wrinkles out of tubeless rim tape? I just set up my Surly My Other Brother Daryl rims to run tubeless.  They are 80mm rims and this is my first time setting up tubeless.  I used Surly's official tubeless kit for those rims.  I believe it uses Whiskey Parts tape.  My first comment is that it's really hard to wrap the tape without wrinkles.  The tape is flat, stiff and non-pliable.  It doesn't want to mold in to a concave shape.  I pulled hard and took my time, but there are definitely wrinkles.  I tried to make sure that the tape is as wrinkle free as possible on the edges.

Got the tires mounted with a compressor.  The front holds fine, but the rear loses pressure quickly as I ride (10 psi down to 6 is a few minutes).  I must admit that there was a bit of a wrinkle at the valve.  I assumed that the sealant would take care of it.  No sealant is escaping anywhere (I think used 4oz per 5" tire).

I guess I have a few questions here:

Why is tubeless rim tape so stiff?  I feel like I'd get easier results from Gorilla tape.
If there's a wrinkle at the sidewall or by the valve, is that the kiss of death?
If a tubeless setup is losing pressure while riding, will it most likely seal up after a few rides or do I need to pull everything off and start again?

I don't know why it's so stiff, but other brands of tubeless tape are also stiff.  Many riders do choose to use Gorilla tape.
If the wrinkle only creates a small air bubble, but is sealed at both edges of the tape you are probably ok.  If the wrinkle reaches the edge of the tape, i'd redo it.  I found keeping the tape taught, but not with too much tension, and coming behind and really pressing it onto the rim an inch at a time works well for me.
It really depends what the problem is.  I've had tubeless setups seal immediately, i've had one that took a full week of the 'shake and turn' technique and i've had one that did indeed finally seal after 2 weeks of riding.

If you are losing pressure that quickly (4psi in a few mins) there is definitely something wrong with your setup - generally even without any sealant the losses are in the region of 0.5-1psi/hour if things are setup right.
Take the wheel and either stand it upright in the bath and slowly rotate to find leaks (don't dunk the hub!), or liberally coat it in soapy water and look for bubbles


Symptoms of handlebars that are too narrow? Triceps pain? Recently I went down from 42cm handlebars to 40cm ones, but I've been getting really tight/sore triceps whilst on the bike. I've read that usually the symptom of running bars that are too narrow is usually that you have breathing difficulties, but that aspect is fine for me. After about 20 minutes or so, my triceps start getting really sore, towards the elbow end of the muscle. Is this a sign that the bars are too narrow?

I went from 42cm to 40cm bars on a road bike and experienced the same symptoms.  The switch to narrower bars can definitely cause tricep pain at the elbow.  So, yes, tricep pain can be a symptom of narrow bars (it could be from other things too).  Whether it is a temporary or a permanent symptom can be gleaned by how you feel after you've had some time to adjust to your new setup.

It sounds trivial, but make sure when you are riding in this new cockpit, that you keep your elbows bent and use your arms as suspension/dampening/etc.  If you aren't able to ride comfortably with your elbows not locked out, this is a problem.  If this is the case, I'd first add some rise to the stem to bring the bars up a bit.  If you still can't get a comfortable position, then I'd recommend getting another set of 42's and riding what you know is comfortable and works for you.


Saddle height for toddler's balance bike My toddler (two and a half years old) has just started scooting around on her balance bike. I'd like to ensure that the saddle is at the best height for her to learn to balance. I know the rules of thumb for adjusting this on an adult bike with pedals, but they obviously don't apply here!

What is the ideal height, probably expressed in terms of how straight her legs should be when sitting on the saddle?

They grow so fast it really doesn't matter, but if the kid looks too low then they are, so go up a bit.

Rider should be able to stand over the seat with both feet on the ground.

While some balance bikes have bike seats with clamps like this, they're in the minority for cost and weight reasons.

This wooden frame is far more common and much lighter for the child to manage.

Notice the seat-pole (plank?) only has two visible holes, for a total of only three seat positions.

Don't overthink this, just be an encouraging parent :)


My square taper crank was partially extracted in accident. What to do? I was trying to learn how to track stand and I had a strap on my left foot.  I failed miserably and I tilled over then since my foot was in the strap my left crank got pulled out.  What do I do to fix it.

Hope you're ok!

Agree with the first comment on the Q. It's hard to discern what's going on from the picture.

Your crank is held on to the bottom bracket (the axle/bearing combination to which the crank arms bolt) by being jammed up on the wedge shaped tapered spindle  (axle) of the bottom bracket. This is done by placing the crank arms onto the spindle and tightening down the bolts that hold them in place until the crank is forced up onto the spindle.

For the crank arm to come off, it either has to break badly (altho it's hard to imagine how this could happen) or the arm has to slide off the spindle. For THIS to happen, though, the crank arm bolt that forces the crank arm up onto the spindle and holds it there needs to be missing.

Perhaps your crank arm bolt had fallen out previously and the cran arm was just hanging on due to being wedged on? If this is the case,.consider yourself lucky -- you found out about the missing bolt in an easy manner (assuming your crash didn't hurt too badly) -- if your crank came off in traffic, it could have been catastrophic.

Check to see if there's a missing bolt that holds the crank arm in place. It would match the other side. (There's a few different styles.) If you need a new bolt, you can get them from a shop. Crank arm bolts need quite a bit of force to push crank arms onto the spindle (but not too much!) -- they're often out on with a torque wrench. Your shop could probably do that for you for a few bucks.

Also, and this is important, make sure the metal around the hole didn't crack in the crash (or previously). Cracked cranks do happen and are a cause for crank arm bolts to come loose. Maybe take the loose arm to the shop with you to get a 2nd pair of eyes on it.

Good luck!


What are the ISCG05 bolt dimensions? What are the dimensions for bolts meant to be used with ISCG05 chain devices?

Here is the official standard.
It says M6×1 for the mounting holes.


Do tyre savers made of a chain catch debris as effectively as tyre savers made of a wire? Are they practical? I get a lot of slow punctures in my rear wheel (I think mainly from glass), so have been looking into installing a cheap tyre saver there. They are meant to catch the debris before it gets pushed into the inner tube in the course of several revolutions.
They seem to throw off a lot of spray in wet weather (see Andrew R Stewart's post on https://www.bikeforums.net/classic-vintage/1102564-flint-catchers-diy.html ), and to avoid spray/mud going into my chain (positioning illustrated in image 1 - not my bike) I want to fix the tyre saver at the trailing edge of my fixed rear mudguard (also for easy access to remove any larger debris which gets stuck; image 2 illustrates positioning).
A wire tyre saver fixed to the rear mudguard seems likely to struggle maintaining contact with the tyre as it vibrates with the mudguard (see Andrew R Stewart's post on https://www.bikeforums.net/classic-vintage/1102564-flint-catchers-diy.html ), so I want to try a flexible tyre saver made of chain instead (see image 3). (To give the tyre saver enough clearance that it won't bang against the rear mudguard, I would bend the rear mudguard upwards and let the tyre saver hang downwards).
However, first I want to check whether there are any disadvantages of a flexible tyre saver made of a chain vs made of a wire in your experience. Does a chain tyre saver make any irritating rattling sound compared to a wire tyre saver? Does a chain tyre saver pick debris of a tyre as effectively as one made of wire? If rattling is an issue, what is the best (non-rattly) material from which to make a flexible tyre-saver?
(NB I am considering alternative solutions to frequent punctures as well, but treat puncture-resistant tyres, injecting tubes with sealant etc as off-topic for the purpose of this question. They have already been discussed a lot on this site and are not without their disadvantages, eg increased weight/inertia/cost, so I want this page to be focussed on tyre savers in their own right. Do share tips on any installations which might shield the drivetrain from tyre saver spray in image 1 though.)

Just by looking at these, my first guess is that that the main difference between the chains and traditional wire ones is that the chain will bounce against the tire and not touch it for the most of the time. It will make a rattling or tingling sound, and add much less rolling resistance than the type that constantly drags against tires. I'm not sure if it makes any difference in puncture protection, because the effectiveness of the wire contraption is questionable to begin with.


How does lubricating your chain help protect your cassette and chainrings from wearing too? I just got my mountain bike back from the shop after a frame warranty, and they replaced my chain as it was apparently worn (2x11). They recommended changing the cassette and chainrings while I was at it, but I wanted to inspect those myself before making those relatively expensive changes.
That got me to think: how does lubricating the chain stop the cassette and chainrings from wearing? You’re not supposed to cover the cassette nor chainrings in lube, so what is preventing them from wearing?
In my case, I noticed that some of my favorite cogs had their contact faces deformed. There was a slight burr where the chain contacts the cog. On the other hand, the big chainring (my favorite) showed significant wear. I’m not surprised by this, considering the occurrence of chainring strikes and shifts under big power, but in some spots I’m pretty sure there’s shavings of metal missing. This corroborates to the fact that I now experience chain slippage every so often when using the new chain. This surely can’t be normal, what am I doing wrong?
I’ve only had the bike for 900km too, and I’m pretty good when it comes to cleaning and lubing. My drivetrain is Shimano SLX M7000 if it matters.

In the ideal case, the chain will not actually be rubbing significantly against the chainrings under load. As the chain wears, the spacing between the chain links becomes different from the tooth spacing, and this difference in spacing means that there is sliding contact as the teeth engage the chain.
The rollers inside the chain help to convert some of this sliding motion into rolling friction (transferring the actual sliding contact to the more protected and better lubricated internal joints of the chain), but any binding of these rollers against the pins again leads to sliding contact between the tooth and the chain.
Keeping the chain lubricated (and, as noted in the question comments, clean) will both minimize the wear that stretches the chain and prevent roller binding, thus reducing the wear on the teeth.


Front brake won't respond until fully engaged A bit new to cycling so please pardon my ignorance. All was fine on my bike up until the other day when I engaged the front brake and nothing happened. I had to fully squeeze the brake until it was touching the handlebar before the pads would close. This had never happened before, and the rear brake only needs a small squeeze for the pads to engage. I did squeeze hard on the brake as I was about to miss my turn, but nothing broke or snapped as far as I can see. Please see pictures for the front and rear brakes engaged. Any idea on what has happened?

Work the lever and check that that the caliper is moving - that will tell you that the cable is attached and has not broken.
Make sure the little lever on the caliper that spreads the pads to let the wheel come out of the bike isn't engaged
Inspect the cable run from lever to caliper, make sure the housing is properly inserted into the lever and all frame stops.
If that all checks out the cable may have slipped through the pinch bolt on the caliper. Undo the pinch bolt to free the cable, verify the lever is pulling cable by pulling on the cable and and working the lever, reattach the cable. You can refer to this Park Tool video for installing and adjusting calipers.


Bicycle Trailer pulls back wheel sideways I have 2 bikes. A touring bike and a mountain bike. The touring bike pulls my 40 lb daughter, snacks, and water just fine (with a Burley classic hitch). The mountain bike on the other hand pulls for about a mile then the front of the tire starts to cant to the right, eventually rubbing on the frame. This used to happen on my old univega mountain bike when pulling my son.
Anyone have any ideas on how to fix this or why it is happening? Is it because my touring bike is designed to pull a heavier load? Thanks in advance!

It is possible that you put not enough torque on axle nuts. The axle moves in the fork.
 If there is enough space, add some extra, broad spacers and then screw it back to the frame.

Use this kind of spacer (it's from Sram I-3, might require some drilling)


Please help me find the brand of bike on the pictures Saw him in the movie "Greta", but I can't recognise what brand it is(

The frame looks very much like a generic Chinese singer speed frame. They are sold by countless brands.

I have a very similar bike which was sold as Leader, I think (I bought used). I replaced the rubbish brakes and finishing kit.

The sticker with the brand on the down tube is above the clear coat and peels off. It's quite flimsy. That indicates that the brands are an afterthought by the local distributors.

However, I suspect the bike in the original question was not made for the European market. There are no braze ons for the rear brake cable. It is attached with pipe- or p-clamps. Three finishing kit is probably custom added for the film.


best ride to burn tummy fat what type of ride should I choose? I own kross k10 bike. Currently I am doing 7.7 km lap with combination of slow-fast-slow (40%-20%-40%) of total path.

Am I doing it correct?

You can't really burn "tummy fat."  Your body has an order that it will store fat in and it will lose fat in the reverse order.  You can lose bodyfat, but it goes away in the reverse order that you put it on.  You can make it appear that you've proportionally lost more weight in your tummy by building up the muscles there.


Hydraulic Brake lever becoming stiffer What are the factor(s) that would make the brake lever of a hydraulic brake become stiffer over time?

By stiffer, I mean that the lever becomes more difficult to pull, it offers more resistance and I need to exert more force in order to apply the brake.

By time, I am thinking a month or so following a service, with only moderate riding in the meantime.

Brake fluids are more viscous when cold
Water absorption can increase the viscosity

But only until heat causes the water to become gas, which is compressible. When this happens, the lever feels a lot less stiff and pressure at the pad is drastically reduced.

Your system may have originally been poorly bled.

Tilting and vibration of the bike during use can encourage bubbles to travel upwards. Assuming you have an "open" hydraulic brake system, pressing the lever opens and closes a valve between the pressurised volume in the hose and the free fluid in the lever reservoir. Bubbles at the top are displaced into the reservoir through the valve until it closes, fixing the volume and allowing lever pressure to be transmitted to the caliper. When the lever is released, the valve has another open phase during which (hopefully) fluid is drawn into the volume. This behaviour is easy to observe in designs like Shimano's XTR BL-M975.


Crankset identification Does anyone know, which exact crankset is pictured below? It came shipped with a Bike Friday NWT (New World Tourist)

The logo is for brand Origin8. It is not a current production model listed on their web site, but you search search for "origin8 crank", you'll find similar looking cranksets sold simply as "Origin8 alloy crankset".


Protecting carbon bike frame after a small chip? My bike frame is carbon and it recently got a small chip. It's about the size of a pinky fingernail in size. Should I do anything to treat the chip to help prevent it from getting worse?

Here's a photo of the chip, hopefully this helps narrow things down.

The effects of the chip depend a bit on "how much" was chipped away. Generally it is always better to seal the chip. I have seen water getting under the protective paint/carbon layer and the area slowly expanding.

If the chip is small I've heard people using nailpolish with good success. For anything a bit bigger, I would probably bring it into a carbon repair place and have them check that the carbon is still structurally sound. They can also repair the chip more professionally.


Can I put a Tortec Epic rear rack on a 27" frame? I'm reviewing racks for my newly re-built vintage tour bike. I have 126mm drops.   I'm guessing I can just use spacers/washers to get the width lined up,  but the it's listed as 26", so if there isn't clearance for the tire,  is there some simple way to raise the mount,  like some steel thingy with two holes in it and a little gap?  I don't have a lot of tools or shop space, so I need something ready made.  *I am in Hiroshima and there are not a lot of rack options I've been able to find locally.

I want this rack as it is well priced,  people seem to have good luck with them, it's steel and has a nice payload capacity.  I haven't seen anything that hits all of these points so I will make it work if I can.

Thanks!

Do you mean this rack? On the linked page it says that the rack will fit a 700c bike. Also I see that there are two holes at the bottom (dropout) mount, that would make it easy to use something like a repair strap to raise the rack if that proves necessary. Use a bolt through both holes so that the repair strap and rack can't move under load.

If you're handy with tools you might find it just as easy to get a short piece of stainless flat bar (or aluminum) and cut and drill it yourself.


Why such a dramatic drop in power when the handlebars are lower than the seat? I have done long rides with the bar 10+ cm below the saddle without getting a sore back, or anything.  Thing is, when I do, my average speed is 2 - 4 km/h SLOWER than when I have the bar higher up.

I do know you lose power as you get lower.  Weird thing with me, is that if the bar is lower than about 4 cm below the seat -- and I mean by just 5-10 mm -- my speed/power drops like a freakin' rock!  (I'm talking as much as 3+ km/h slower up a 10% grade!)  Any idea why such a dramatic drop in power?

My bar is only 53 cm from the seat, which seems awfully short to me, for someone who is 186 cm tall.  (If I increase that reach just another 5-10 mm, I also have that same sharp power drop.)  I do know my torso is shorter than normal, given my 91 cm inseam, but still.  I think I have reasonable flexibility -- I can touch the floor with my fingers while bending over.  I do know when I had the seat lower and/or further forward, that caused additional power loss when getting low, but I think I have the seat figured out now.

UPDATE:  Today I fooled around -- yet, again!!! -- some more.  Discovered that if I concentrate on flattening my back while leaning forward, I can actually go FASTER than the more "relaxed" position (when the sudden power loss occurred).  (Sorry, not too familiar with anatomy . . . that's the best I can describe it.)  As noted in one of the responses, this "leaning forward" motion did require moving the seat 5-10 mm forward to get to what seems to be optimal.  I'll see how the "new and improved" position works tomorrow.

I agree with the biomechanical hypothesis already mentioned by @DanielRHicks.

Every joint/muscle-group has an optimal range of motion and an optimal max-force/max-power position.

I am the same height as you, and the distance you mention is pretty short indeed, as measured on the bikes I ride.

There seems to be necessary to analyze the "cockpit triangle" of your bike: bottom-bracket/saddle/handlebars: in the hypothesis that, lowering your bar, you get an angle between torso and thighs that is too acute, then the correction of the problem would be opening that angle.

That could be made in two ways:

Rise the handlebar (which apparently is the opposite of what you want to do);
Move all your upper body front by putting a longer stem AND moving the saddle forward a bit, so that you feel the pedals "more behind" than in the current position.

As observations:

High power output (a.k.a FAST) bikes, with aggressive riding position, tend to throw the rider over the bars, so that the torso weight can counter-act the torque on the pedals, and also be more aerodynamic. It is common to see such bikes with high, forwarded and sloped seats (extreme example: time trial bikes);
If you just put a longer stem without bringing the saddle forward, you get in a more "superman" position, actually DECREASING the torso-thigh angle that we would want to increase.

Finally, there are mysteries in finding the perfect position on a bike. Perhaps even sub-conscious factors of varied nature might contribute for a sensation of "not-right". Unfortunately, only self-analysis and trial-and-error are the guaranteed key to salvation in this case, although some professional advice would be always welcome (a.k.a. bike-fit).

Hope this helps!


Will extra teeth on a chainring work? The current chainring im using has 32 teeth but I need to buy a new one. The reason is because the chainring I'm using is actually from a 3x set so the teeth does not have narrow wide teeth which is why my chain keeps falling off. So I searched online, I found a 34 tooth chainring and I want to know if 2 extra teeth will affect anything on my bike. I haven't bought it yet, I want to know if it is okay to buy it.

Two extra teeth will increase your gear ratios by 6% (34/32 = 1.06). What it will not do is help retain you chain any better.

Did you shorten the chain when you removed the inner and outer rings? (Assuming that's what you did.) If you didn't that may be why you are dropping the chain - it's too slack. BTW, you can re-install the front derailleur to act as a chain guide.

If you did shorten the chain you may have to replace it to accommodate the new larger chainring.


Dakota 20 - How do you show remaining route distance on dashboard? The Dakota 20 is pretty awesome, but I can't figure out how to get the remaining route distance to show up on the trip dashboard?

the official Manual from Garmin doesn't mention anything about this.

Thanks in advance!

Page 19 of the manual states:

  The Trip Computer displays your current speed, average speed, maximum speed, trip odometer, and other helpful statistics. Touch a field to change what is shown in that field.

If you've touched each field and remaining route distance is not an option, then I think it's safe to say that including this information on the dashboard is not possible. That said, the compass mode and possibly the navigation mode seem to be able to include this information, though they may leave off other data that you care about.


Vintage 70's Bike info? I was given a vintage touring bike recently. It's steer tube badge says D-114 made in Japan. I can't find any info on it and was hoping someone may have some info on the brand or bike.

Looks like a Nishiki Arrow Speed

I had one of those while in college in the early 90s.


How do I know if the tandem bicycle I've inherited is worth repairing? It has a serial # 459310 on it, no other identifiers I've inherited a vintage tandem. It looks as if it has been spray painted, and has no identifiers, etc remaining on the frame. The serial # on the bottom reads -459310. Any ideas on a make or model, and whether this is worth reparing? It needs a total re-work from the shredded tires up through the rusty chain and the dry-rotted seats and rusted handlebars...not a pretty picture if you get the drift.

The issues you've identified aren't terribly serious--however if they aren't a comprehensive listing of the issues (such as bad bearings, etc) then they may be understating the amount of work required.

The question of whether the make and model is "worth" repairing is largely up to you to decide.  Being an unknown bike you should evaluate it on the value it has for you, rather than a broader market value.

The specific issues you've cited aren't terribly costly to resolve.  You can purchase replacement tires, handlebars, and saddles from any good used parts shop for a fairly low price.  A new chain is a small investment, and is a regular component to replace.

Overall though I presume your question is omitting some details.  Photos and a more comprehensive listing of known issues will help better evaluate the potential to return the bike to a functional state.


Can I install a rack if I install plugin mudguards? I bought a Cube Cross Pro https://www.cube.eu/2019/bikes/trekking/tour/cross/cube-cross-pro-bluenorange-2019/

I want to install a rack and mudguards. I found these nice plugin mudguards https://www.bike-discount.de/en/buy/sks-germany-x-blade-shockblade-dark-set-29-617315 .... however I'm not sure if I bought them I will be able to install a rack or not. Why? because the rear mudgaurds will probably take the entire space on back above the tire. Here is a rack I'm thinking to buy https://www.bike-discount.de/en/buy/cube-porter-heavy-duty-28-29-528212

So what do you think? I haven't done something like that before.

I doubt that will work. If you are going to install the mudguard between rack and tire the “arm” of the SKS X-Blade mudguard is likely to collide with the two stays of the rack. There is a chance that you are lucky and the spacing is just right to fit it through.

If you are going to install mudguards, why not get some proper ones like the SKS Bluemels?

As a sidenote: Why get such a heavy and ugly rack for such a nice and relatively light bike? Something like the Tubus Fly (Vega if you need more tire clearance) would fit much more nicely.


Slipping chain from lowest (largest diameter) cassette sprockets I have a Decathlon RC500 road bike. It has 34/50 compact crankset in front and the rear cassette is 11/34 (11/13/15/17/19/21/24/28/32).

When I want to go into lowest gear, especially on uphill riding, the chain does not reach the 32 tooth sprocket at the back, from the 28 tooth sprocket, it keeps slipping down to the 24 tooth sprocket.

How do I fix this?

This does not sound like a basic derailleur indexing issue, nor a bent derailleur hanger problem.

Possibilities that I can think of:

You have a broken or malfunctioning shifter. As you try to change to the larger sprocket the shifter is pulling the cable, the ratchet mechanism is not catching and is slipping back two places.
Your derailleur low limit is set too far in. As the shifter pulls cable it hits the limit, does not complete the shift and again slips back two places.
B-screw is badly adjusted to the top jockey wheel hits the 32 tooth cog and has the same effect as the low limit set to far in.
You are hitting the upshift lever while working the downshift lever somehow.
I suppose it might also possible that your indexing is off by one gear to the high side, so when you try to shift to the lowest ratio the shifter is already in it's lowest position, resulting in an upshift instead.

What I'd do to troubleshoot this is disconnect the cable from the derailleur, With the bike is a stand make sure the derailleur can shift onto all sprockets by pushing it inwards while manually pedaling (be real careful not to catch you fingers in the chain). Adjust limits or b-screw if you find and issue.

Grab the cable with some pliers, apply tension, work the shifter. Can you make the shifter slip on the last downshift position? If this is the case it's very likely the shifter is malfunctioning.

If you don't find a problem try reconnecting the cable and working through the Park Tool rear derailleur adjustment procedure to ensure correct limits and indexing.


Advantages with longer seatpost in the seat tube? I am about to buy a new seatpost and I am wondering what's the ideal length. The one I have now is 33cm long, even though it only sticks out of 10cm from the frame (measured from the seat collar to the saddle rail).

Because of that, I thought a 25cm seatpost would be a better match and I would save in weight. The question is:

  Is there any advantage in having a longer seatpost?

Notice I am assuming the size of the frame and height of the rider is fixed here, so I am only talking about the lenght of the seatpost that's hidden inside the frame. The only thing I could think about is that a longer seatpost is subject to less torque.

Frames have a minimum insert requirement - 100mm-120mm for carbon is not uncommon. Seat posts also have a minimum, which is usually marked on the post - typically 75-100mm.  Both these limits should be adhered to. A long seat post may be too long to lower the seat to the correct position.  The difference between the minimum insertion and maximum will vary based on the frame, however it can be quite a small range especially on some more exotic shaped frames (e.g. Softtail MTB's)

The only advantage of going to the minimum insertion is weight savings. However going short adds stress to the seat tube.

The only significant disadvantages of a longer post is weight.

What length post to use between these minimum and maximum insertion depths will depend largely on your own preference for weight saving over strength and your weight and riding style.  My lightweight XC MTB  has 100mm inserted (100mm minimum), but I am 66kg, and don't do jumps. If I was 120kg and loved big air, it would have 200mm or more.

You can cut the end of the current seat post. Find the minimum insert for the frame and post, measure that much below the current posts location in the seat tube and rip into it with a hacksaw. When I have done this in the past, I also sand off the minimum insertion mark put a new one on the post.


Pulsating feedback on brake levers When on the I brake I get a pulsating feedback on my rear brake lever. I checked to make sure the wheel is true, and also the dish, which is ok.I re-checked the torque on the caliper bolt and adjusted it to 9Nm. The tire also has no bumps that I can see or feel. Any ideas?

After the discussion in the comments, I suspect that the rim is deformed.

This can happen if you hit a pothole or kerb too hard, especially if the tires are not pumped up hard.

If the rim is deformed then you may be able to see patches where the brakes have worn the rim more. It's the brakes grabbing on these that create the feedback you are feeling.

There is not much to be done about it. Some people try to straighten them using a wooden mallet, but the success rate is low. Often the wheel is worse rather than better.

To avoid this kind of damage in future try to get your weight off the wheel as it hits the bump, by getting out of the saddle and moving back as the front wheel hits, then moving forward before the back wheel hits.


How much axle space for the cap nuts and chain tugs? I am investigating whether I can insert cap nuts with too short axle attaching area. The image below is exaggerated but the attaching areas are about 1.2cm and 0.95cm. The difference 0.45cm meant in 6 months that the left cap nut became broken, metal spaghetti. I squeezed about 0.2cm from the past configuration due to the wrong conf, now the difference is about 0.25cm, but suppose I place there a chain tug, it will take away about 0.2cm and the problem may re-emerge: again metal spaghetti and broken cap nuts. So how much space should be reserved for cap nuts in axles?

The cap nut is about 2.1 cm deep.

1.23cm with the right cap nut, no problem, the nut in good condition. After placing there a chain tug, the space is about 1.0cm. 1.04cm with the left cap nut. With chain tug, the space is about 0.8cm. Even with 0.9, I got metal spaghetting and broken cap nut after 6 months. A problem?

Related

question about naming of cap-nuts here

I would first try a standard nut on the axle because often the cap nuts have a nice rounded entry to the threaded area which means the trhead doesn't start for a millimetre or so. From the photo it looks as though you should have enough axle for a standard nut to work.

The next step is to grind off some of the antirotation washer so your nut gets more space. Those washers are made of a nice hard steel so they're hard to file. Much better to use a power tool if you can. If not, get the finest, sharpest file you can. And try very hard to keep the surfaces of the washer parallel - if they're not you are much more likely to strip the nut.

And Neil Finn, the cable attachment shown above is the less problematic of the Shimano 8 speed ones that I've seen, but it's still prone to sticking bits of broken gear cable into your fingertips. Note that hhh has a broken strand and there's no end cap on that cable. Unless it's soldered it will eventually fray and then grabbing hold of it to fit it back into the hub gets ugly.


Marrakesh w/ Sora STI shifters & Alivio Trekking FD + Crankset 48T https://salsacycles.com/bikes/marrakesh/2020_marrakesh_sora
This seems to have managed to somehow got around difference between MTB & Road STI triple problem that many reported. Is it because these are Trekking components?
Want to convert from double to triple 48T or 46T. I already have a triple Sora STI being used as double.

If you look at the Shimano compatibility docs, the Alivio shift levers SL-M4000 are compatible with both the MTB RD/FD-M4000 and trekking RD/FD-T4000 versions of the derailleurs, so there is functionally no difference between the M and T versions.

Compatibility charts are here: https://productinfo.shimano.com/#/com?cid=C-432&acid=C-445

Shimano used a common derailleur actuation ratio for MTB up to 9 speed and road up to 10 speed, so I'm not surprised that the Sora drop bar shifters work with Alivio derailleurs.

if you want to fit Alivio cranks and derailleurs to a frame that is nominally a road bike you have to be aware of crank spacing, bottom bracket shell width and chainline (and what bottom bracket type you have.) The Alivio cranks want a MTB style Hollowtech BB that fits 73mm (or 68mm with spacers) shells, and provides a 50mm chainline.

Specs are here: https://productinfo.shimano.com/#/spec/TREKKING/Front%20Chainwheel


brake lever will not return My friend has a mountain bike that survived last years Queensland's floods (Australia, that is), but is all battered and bruised after not being ridden for a year. With my beginner's repair skills, I managed to make it almost roadworthy. The main problem now is the front brake lever: It will activate the brakes when pulled (and they work just fine) but the lever won't spring back into place when releasing it.

Any ideas as to why that might be? Is there some spring that has can be replaced or does the lever have to go altogether? I have applied some WD40 inside the lever as I noticed some rusty parts there, but it didn't do the trick.

Edit: I got some new cables and cable outers (cost me an arm and a leg here in Australia!), but it didn't do the trick. I dismantled the brake lever, only to see there is a spring inside the lever. (The spring resembles 2 circles of 5mm diameter with two 1mm vertical tips on either side. I presume that the tips serve to "hook" the lever & possible return it to position.)

This spring was rusty and fell apart when I tried to squeeze it. To conclude, since everything else is new, the issue is either: - This rusty spring that needs replacing, or - The 90o cable guide that was also rusty.

Some things to check and I'm assuming you're running V-brakes:

My first guess is that the brake cable inside the brake cable housing is sticking. Some light oil on the cable could help. (WD40 is a solvent, do not use it on cabling or chains and do not use it where you want to maintain lubrication on parts. Look for some light oil like TriFlow, or whatever your LBS sells.) If the brake cable does not travel smoothly, I would suggest a new brake cable.
If you unhook the brake cable at the front brake arms, the arms should travel smoothly and you should feel some spring action that will resist squeezing. If the brake arms have no spring to them, that's a problem.
With the brake cable unhooked, the brake hand lever should move freely. If it doesn't then oil it. Light oil should penetrate any rust, and that might take 20 minutes of sitting before it works in.

Keeping the brakes in good condition is worthwhile and important. If you don't feel confident about how they feel, seek some help. Having a front wheel misbehave can be quite dangerous. Best of luck!


Bottom Bracket Height I am just wondering if BB height from the ground is the same for all bikes or for all mountain bikes, all road bikes, etc? Or does every brand have its own design for that dimension?

No, it is not. Different bikes in the same class (mountain, cross, road, etc.) may even have different bottom bracket heights even among comparably sized bikes. It is a per manufacturer design decision where to place the bottom bracket.

Mountain bikes need higher bottom brackets to clear obstacles vs road bikes or cross bikes, for example.


Can Someone Help Me ID This Marzocchi Fork? I know it’s a Marzocchi, maybe a Dirt Jumper 3? but I’m trying to ID it so I can do a service and also would like to know the proper air pressure, which I can’t figure out without knowing what model it is.
There are no stickers on it, and there is an 05 stamp on the crown as well as the lowers, so I assume it is a 2005, but holy cow did Marzocchi make a ton of models that year. There are also the following stamps on the crown also.
3114A0209
T05D1223
They have quick releases, and the M shaped lowers crossbar and a slight M shape on the crown as well. Air valve in one side, and a rebound damper on that same side near the wheel.  On the left side of the fork there’s a knob with an adjuster that I assume locks out the fork or something.

The chromed crown in your photo doesn't have the prominent M-shaped lip, the diamond-shape in the middle looks more like the Marathon range.
Marzocchi "2005" (sold from mid-2004) OEM product catalogue, start at page 12: http://www.bartonicek.cz/marzocchi/servis/prehled_marzocchi_2005.pdf


Shimano 105 freehub FH-5800 - pawls not engaging, repair or replace? After a thorough clean and (over) oiling with WD40, my Shimano 105 FH-5800 freehub stopped engaging. Sounds like a common fail: I had previously thought that more oil = better. Live and learn!

Bike is just over 10 years old but in good condition otherwise. I don't know if:

This can be dismantled, cleaned out, re-greased and put back
If the bit with the pawls in it can be replaced?
Or if the whole freehub should be replaced and wheel rebuilt around it?
Any other options?

I've looked at countless guides online to do with all three, but I just can't work out what applies to me  and my kit and what doesn't.

I'm also not sure what I'd attempt myself and what I'd need a shop for. I certainly wouldn't attempt (3), but would considering (1) and (2) with solid advice. I would need to buy the Shimano tool and a chain whip first though - until this happened I'd never heard of freehub, cassette, pawl or Sheldon Brown for that matter - I'm getting a good education here!

Here's the back wheel when going wrong:
https://photos.app.goo.gl/8p3vnYAyxyndNtoz5

https://photos.app.goo.gl/CYjnuzZFZSuhisDM6

(apologies for the poor backing track )

Update: https://photos.app.goo.gl/oBSpGwfBUpxfyxDJA (additional photo of hub model)

Happy to send more images, but as far as I'm aware, unless I get the tools I can't currently get the cassette off to see more.

Thanks all

It should be possible to do one of 1. or 2. but the way Shimano hubs are, the pawls are contained in the freehub body, which is pictured below.

So that means option 2. is that bit more achievable than option 1 (but costs more in parts). You'd take the cassette off with tool and chainwhip, then disassemble the cup and cone hub using a cone spanner and regular 17mm, before the freehub body is removed with a big Allen key. You could always investigate inside the freehub body first and see if it just needs degunking. I doubt that WD40 penetrates all the way inside, it might just need it's overdue 10-year clean (jks that's not a thing).

Here is an image of a random Shimano rear hub exploded diagram, that I stole off of eBay. Part number 15 is a large bolt that you have to access to remove the freehub (Part Y3BL03000 for many hubs incl FH5800). I believe from Q&A on a retailer's website that it is a 10mm hex.

Doing 3. is a possibility, don't be afraid of giving it a go, but that might be 'running' whereas option 2. is 'walking'. Arguably.

Option 4. is buying a new wheel. Doesn't have to be that expensive, but would be more costly than option 2 and less fun.

Your next questions might include:

"how do I turn the 10mm Allen key with force now the long end is in the hub?" (Use a spanner)

"help, I took apart my hub and can't get it back together!" (see diagram, see How do I reassemble this Quando rear hub?)

and, "something, something, Darkside" (see a counsellor).

You should check the rim wear and overall health of the wheel before spending any money on spare parts, or even tools. If the rim is old and worn down near its limits then replacement parts wouldn't be the most economical way to go, you could put that money towards a new wheel. Tools are fun and useful going forwards though.


Will this crankset fit my bottom bracket? I've got a 2004 Trek 4300 that I need to replace the crankset on. I was able to look up the bottom bracket size here and see that it's a 73x122.5.

I'd like to buy this crankset but I'm not exactly sure how to know if it will fit or not? The specs say:

Square taper crank accepts 68x122.5 mm spindle

Does that mean it will not fit mine which has a shell size of 73?

It will fit.

If you need references: If you look at the Shimano Tech Doc, it suggests the Shimano BB-UN26 (which you can find that you can fit it in that version).


What kind of spokes for Giant PSL0 wheelset What specific spokes do I need for Giant PSL0s wheelset. I know they are DT Swiss but what kind and maybe where to get them.

Are you building this wheel yourself? There's a bit of planning that goes into building a wheel. As Daniel mentioned, length and gauge are important, but even before that you must have a hub that will accommodate the same number of spokes that the wheel will. Afterward, the number of spokes you will need will dictate what lacing pattern you should use.

As always, Sheldon has the answers.


Can I use my standard quick-release rear hub with a frame with 142x12mm rear end? I'm wanting to buy a Commencal VIP JR frame which has the 142mm x 12mm rear end. I'd like to keep my same wheelset however. My current rear hub is just the standard quick-release (which I assume is 135mm correct?). Is this possible? Perhaps with an adapter?

The answer to this depends on your hub -- we don't know what wheel set you are running. Some manufacturers (Hope, Chris King, etc.) have released adapter kits for some their hubs to be used as 12x142 mm, however other wheel sets don't have compatible hubs. If your hub manufacturer hasn't released told you that you can do the conversion, you're out of luck and need to get new wheels.


Skinny 26" tires? Giveing a small fixie a “faster” look I'm a very short woman and, since I wanted a triangle-frame fixie, I used 26" tires and a 49cm frame so it would fit me perfectly. The trouble is my tires are the wider variety. I want to have the slim fixie look, so I want skinny tires, but I can't find them in 26" size.

Are there any solutions?

I mostly want the slim tires for cosmetic reasons. The current tires function perfectly. (Used to to be a messenger, now I just commute) so maybe there are some tires that just have a more "speedy" look to them?

When my bike looks nice I feel good about riding. So, I'm hoping someone can help.

If your LBS doesn't stock speedier/skinnier 26" tires, you might have to order them (either through the shop or online somewhere).

They are a bit less common, but here's four options I found looking at some major tire manufacturer's websites:

Specialized All Condition Elite (26x1.0 available)
Schwalbe Durano 399 (26x1.10 and 26x1.35 available)
Continental Sport Contact (26x1.3 available)
Schwalbe Kojak (26x1.35 available)

Keep in mind:
There's limits to how narrow a tire you can reasonably put on a given rim.  If you go too narrow for a given rim, you'll get pinch flats and possibly even rim damage. Sheldon Brown's site has a helpful chart of tire width and rim width compatibility.  What is the (interior) width of your rims?  Or at the very least, what size tire do you have now?


Is it OK to use a crankset with partially stripped pedal threads? The threads on the right side of my crankset have been stripped and now only about half the threads remain (see picture below).

I can still insert my pedal all the way into the crank. Would it be OK to ride the bike like this whilst I wait for a new crank? Will it damage the pedal, or is there any chance the pedal could fall out?

Also is there a particular reason this would have happened in the first place? Under load, the pedal just popped off and took the missing threads with it. (The pedal is definitely the right sided pedal.)

I would not ride with that crank as photographed, for anything more than a slow and careful "get home" temporary ride, with myself not rising from the saddle at all.

The pedal thread is only 2/3 to 5/8 there, and the thread that is missing is the side nearest your pedal, which is the fulcrum of the lever.

Stresses on the remaining threads would be much higher, making it more likely to fail quickly with no warning.

While replacement of the crankset is a valid fix, its not cheap and you may have compatibility issues.  That looks like a Shimano RSX crank from the 90s through to some of the 8 speed sora cranks.  Also depends whether you value the originality and period-correctness.

Instead, I'd look at a pedal thread repair, often called a Helicoil.  A bike shop will have the special tools for this, which look like this  :

Its a replacement steel thread which gets permanently installed inside your bore, and the pedal goes into that.  IMO it leaves a better connection than a steel thread inside an aluminium threadded bore.

Good instructions are at https://www.parktool.com/blog/repair-help/pedal-bushing-repair-kit-procedure


What does the label on a tire mean? I went to a bike shop for new tires. I did not know which tires fit on my bike, so I just showed them my bike.

When I took a look at the new tires, there was a label at the side, which says:

  40-622 (700x38C-28x1 5/8 x 1 1/2)

What do all these numbers mean? I am asking for two reasons:

I would like to find the right tires for my bike in the future myself
When buying another bike, I would like to buy one where I can use this tires as well

The 40 is the inflated width in mm and the 622 is the internal diameter in mm. It's the international standard ISO-5775 for tire sizes. In brackets are the French size (700mm outer diameter x 38mm width) and the Inch size (28 outer diameter x 1 5/8 height x 1 1/2 width)

Wikipedia has a very detailed explanation of tire sizes and designations, I confirmed my answer on this page.


Trying to identify my Armstrong bicycle Can anyone tell me what model Armstrong this bicycle is and possibly what year thank you

It looks a lot like this Armstrong

The seat stay bolted to the seat tube may be one difference.
Based on the conversation in the thread...

this model is a 1953 so the rear hub tells me

If your bike does have a Sturmey Archer three speed hub you may be able to date the bike by the markings on the hub.
Hub Date Marks – How Old Is Your Sturmey Archer Hub?

Hubs after World War 2
From 1947 to 2000 Sturmey Archer clearly marked their hubs with a date. This hub date marking will show the last two figures of the year and the month.

The article goes on to explain how to date older SA hubs.
Here is the 1950 Armstrong catalog.
This picture looked to me like a good match

Three speeds and dynamo hubs were offered as an option
Other Armstrong catalogs