What is this metal bar parallel to the frame? I saw this at work the other day and I was completely baffled. This bicycle has an additional, adjustable metal bar that runs parallel to the upper part of the frame, between the seat and the handlebar mounts. It looks like a finished product including labels and whatnot. I didn't see any damage to the frame that I could tell.

Can someone identify this device and its function?

It's used for attaching a child seat similar to this one.

The above site shows a clearer image of the part in question which might be useful to future visitors.


What are the potential causes of my fingers going numb when riding? My fingers get numb quite quickly when riding. I'm a novice and not sure to what this can be due. I've tried gloves but they didn't help. I've tried added different handles to be able to switch positions more often; it helped a bit but it wasn't sufficient. I have an hybrid bike, a Minelli Revolution, if that changes anything. Currently looking to invest on a better bike though I'm afraid the issue will stick...

Are there specific adjustments on my bike that I should be tweaking to resolve this problem? It's really killing the joy of going for longer rides and I wish I could enjoy myself!

I'd suggest a change of gloves, but it seems that you already did so. If you haven't already, give a try to padded gloves.

You could try to check your grips and upgrade to ergonomic ones or changing the handlebar tape. Adjusting the saddle height might be a good idea too.

If the issue persists, perhaps the size of the handlebars or bike aren't adequate for your build, in which case you probably would benefit from getting a bike that fits you. See this question for additional suggestions.

As a last resort, and if you try all the possible adjustments, have a fitted bike, and still the numbness persists, I'd suggest you go to your doctor and discuss the issue.


What type of cleat is this? Should I save it or get new cleats? Can someone tell me what kind of cleat this is? circa 1993. I believe I got it  Someone told me that I can just get new shoes (the shoes are completely shot) and reuse the cleat.  Is that a good idea or should I get new cleats?  I think it's the shoes that are really expensive.  I am a very casual rider (go with kids) but I'm now used to the clip in style.

Here's a photo of the actual pedal.  Naturally, when I get new shoes (and cleats?) I want to make sure they fit pedal.

It's a Shimano SPD cleat. There are a few different models, but they are all cross compatible. You can reuse the old ones if you can unscrew it, but new pair should be under 20€, too.

EDIT: Looks like this is an old Shimano cleat, like this one: http://www.fixedgeargallery.com/reviews/dzr/ovis/10.jpg. Modern ones and most copies have a sharp angled "shoulder" on the middle section.


Is it possible to charge an ebike from a 12V solar powered battery? I would like to use an electric bike while doing wild camping with my camper van. So I won't have a 220v source for days, possible weeks at a time. I am wondering if I could add a battery in my camper, add a 150W solar panel, and then have an converter to 220v to charge the bike. Question is, can a 100 Ah battery (standard for campers) charge a 500WH ebike ? With the losses from the converter. 150W solar will charge that battery, so I am good on that side.
I guess what I don't understand with a 500Wh battery, is for how many hours the battery can output 500W, or does it meant it can ouptut a max of 500W for one hour, or for instance 250W for two hours ?
If it's 500 W for one hour, then a 100 Ah 12 V battery would have 1,200 Wh of energy stored, so I can easily charge that ebike once daily..am I on the right track here ?

You can charge it, but you probably won't do as well as you think. You're on the right track but you're missing a couple of things:

Solar panel ratings: These are optimistic and assume full sun hitting the panel at a good angle. Here's the maths.  You won't get that all day, so don't expect to get as much as you would by multiplying the number of hours sunlight by the panel wattage.  12 Hours full sunlight would naively give 1800Wh, but hopefully you're out riding and not adjusting the panel every few hours, and anyway as the sun gets lower in the sky it gives you less power because the atmosphere absorbs some.
Solar regulator: For a panel that big you really should have a regulator.  Some (linear) are quite wasteful.  Switching regulators are better, and can load the panel at its maximum power point for best efficiency.
12V battery behaviour: a lead-acid battery, even a deep discharge one,  won't last for long if you drain it regularly.  You've probably got about 600Wh accessible without shortening the life.  However that means you don't need to produce 1200Wh/day.
Round trip efficiency:  Every step is inefficient - charging the 12V battery, discharging the 12V battery, converting  12V DC to 220V AC, converting 220V AC to 36VDC (or similar) for the battery, and charging the bike battery (also discharging the bike battery but that's not specific to this case of limited solar power).
Other uses: I mostly plug my campervan in to the mains on a big campsite, but occasionally use a solar-charged battery for the fridge and lights.  If you do the same, you'll be eating in to your battery capacity, and (slightly more efficiently) diverting some of your panel's output from charging the battery.  You may of course have a dedicated panel and battery for the bike.

You'd need to choose an inverter based on the input specifications of the bike battery charger, with a little margin.  Don't over-spec it too much though as efficiency will suffer - unless of course you want to run higher-powered things off it occasionally.

As for the bike battery capacity, 500Wh means 500W for 1h, 250W for 2h, 100W for 5h etc.  In practice though, it will be more efficient at lower power outputs.  Most e-bikes are rated to 250W because that's a legal limit in many countries (e.g. all of the EU for standard road-legal e-bikes) so you could run flat out for only 2h, but run with a little motor assistance for much longer.  Hopefully you won't drain that completely, though it's not as bad for Li-ion batteries as it is for lead-acid.  If you were camping at the top of a hill you'd certainly regret using too much as the available assistance reduces as the battery gets low.

There are too many unknowns to calculate properly, but I reckon you'd be close to getting a charge of the bike battery per fully sunny day, but not quite there.  You'd want to monitor the state of charge of your 12V battery.  If you move the camper every few days, as I do, you may be able to charge your 12V battery from the engine to ensure it's fully topped up on a day when you're driving and not riding.  You should also make sure it's full before you leave home (if you're  in the van for months on end that won't make much difference).

Think about how much you rely on the bike - how stuck would you be if you had a few consecutive days of bad weather?


What Brand of Bicycle do I have? I was thinking about restoring an old bike I bought years ago, but I don't know what kind it is, to the best I could see, here are the numbers that was on the bottom: MOTSX (the 0 is a maybe) then 45 402 these were slanted beside the MOSTX, then these below were under them.
Mod 702 (almost sure it was a 7) then the numbers under Mod 12  12      86 (and spaced like that).
I know it's a 26" boys, but I have never seem 2 small bars for top on a boys bike, plus they are not welded on frame under seat, but sit in special cups like a U that are welded on. I just wanted to make sure it was worth restoring. It looks to me like it's from the 50s or 60s. It has Schwinn on hand grips, but anyone could have switched those. Its in great shape, and won't take a lot to fix. Here a picture Thanks Tom Barnes

I was searching for bikes and I found one identical to this one: it was a VINTAGE 1959 MURRAY SEARS FLIGHTLINER, all it was missing is the little silver bar that goes above the front fender that clips into that little silver clip on the bottom of the headtube. Some may have had headlight tanks, the one I found  didn't. So it could be a 59-60?


Roof-top bike rack crash Over the week-end my bike suffered a bike crash while on a roof-top rack. On a whim, the driver decided to go through an underground parking lot, everything happened so fast, I did not have time to stop him. Anyway, what happened happened. Two cervélo R3 got caught in a chain, and both bike fell off the rack, breaking the rack and some bike components, e.g. shifters, wheels and forks.

Here are some pictures of the damage on the bikes: images

We brought the bikes at our local bike shop, also a cervélo dealer. Their verdict was that my bike only needed minor repairs such as changing one shifter whereas the other bike has a cracked frame and would need a new frame.

Here is where I would like you opinion, since both bikes where involved in similar tensions and impacts, I do not feel comfortable keeping the frame. The specialist at the bike shop assured me it was "ok", although I am not sure he would go downhill at 80 km/h on it. Since my personal insurance is covering the cost, can I suggest that the frame be changed?

The problem here is that with a carbon or aluminum frame it will be hard to assess the damage accurately (at least with the tools that we or a LBS is likely to have). The best tool that you've got is evidence of stress on the frame – like the cracked paint in the photos of bike 1.

Add to this the likelihood that aluminum or carbon will fail dramatically and suddenly if they are damaged and it just seems prudent to replace the frame.


Aluminum (6061) frame dropout squeeze I have a bicycle with a 6061 aluminum frame. I had to replace the rear wheel, and I bought a wheel with an axle length that is a few mm short for the dropout spacing.
In order to fit the axle into the frame I would have to "squeeze" the dropout about 4mm. Currently the outer dropout of the frame is 144mm, and everything seems to fit if I squeeze it down to 140mm.
I have already ordered a longer hub axle, but it will be at least 2 weeks until I get it, and I would like to ride my bike with the squeezed frame until then. I know that in general, it is not a good idea to bend or even squeeze aluminum frames, but I am not sure those measly 4mm will make that much of a difference.
So, my question is:
Considering this is an aluminum frame, will the 4mm dropout squeeze cause damage in the long-term or maybe breakage? How safe is this?

It will damage the frame long term, or rather shorten the life expectancy for the rear triangle. Short term… it depends how short the term is.
Wheels are typically have standardized widths, as are frame's inner distances between the dropouts made to match them. Unless the frame is already damaged and bent or has a manufacturing defect, as the comments above suggest, you are likely trying to squeeze a 130 mm road hub wheel into a 135 mm MTB-frame (or maybe a 135 mm MTB wheel into 147 mm Boost-QR? does not matter, really)
Note that you may also have problems with adjusting the rear derailleur, as the cassette will also be off its intended position. It may not be possible to shift into the biggest rear cog.
If I were stranded somewhere far from proper components with only a 130 mm wheel to have, I would rather have attempted to add some sort of spacers taking up 2.5 + 2.5 mm at either side of the wheel, rather than compressing and stressing the dropouts.


Is there a lightweight electric assist braking system that can be applied to a bicycle trailer? I am building a bicycle trailer that i would like to have its own braking system due to its weight. I'm wondering what the best way to accomplish that would be.

People have come up with their own inertial/surge trailer hacks. Google is your friend here. On stackexchange is a related question: How to build surge brakes on bike trailer?

As far as I know, there's no commercial solutions. Part of this is the technical difficulty of braking both trailer wheels equally and in proportion to the main braking force. It's conceivably easier with BoB style single wheel trailers but most trailers are dual wheel with single-sided hubs, which adds further complexity.

Then there's the liability issue. Any time you add new technology, the manufacturer has to assume some liability on its use. Trailers in the USA are most often used to carry children and no manufacturer is going to go near there on that at a price point consumers are going to swallow (i.e., the only way you could upsell a $200 feature like trailer braking is to say it's safer but your lawyers won't allow you to say that).

The DIY solutions are quite ingenious so I'd suggest exploring them. The increase in the number of tandem hubs with disk brake mounts is making it easier to do this. See related question above.

As far as electronic solutions using ehubs. This is non-trivial. Cars can do this as the motor controller can read both steering input, brake input, wheel ABS sensors, and gyro sensors to apply the right amount of deceleration torque to each wheel for maximum stability. Doing this on an ebike or e-trailer isn't impossible but hard to do reliably at a reasonable price point. If using an ebike, note each hub motor alone is $150+.

Many of us who pull trailers use ebikes and as long as your ebike motor is sufficient and you have good brakes on the ebike, and you follow reasonable speed and load precautions, motors and brakes on the trailer seem like just another point of failure (and place we have to recharge).


How to mount Ohlins TTX22M to a 2018 Yeti SB 5.5 How do you mount a Ohlins TTX22M (17.87 x 2.25" - 16mm eyelet) shock to a 2018 Yeti SB 5.5?
I previously removed a Fox DPX2 which had vastly different mounting hardware (it turns out).
The Ohlins shock came with two 16mm DU bushings and two spherical bearings (not sure the size)
The shock bolts in my Yeti manual are listing:
Front Mount Bolt: BOLT TI FEMALE 8.0X31.0MM GEN2 (Figure 5.11)
Rear Mount Collet: COLLET AXLE 10X30.5X9.0 M10X1.0 (Figure 5.6)

All I can deduce from this is I probably need one with a bolt size of 8mm and another with a bolt size of 10mm
Which of these parts do I need to mount this shock? (Also, should I buy some tools?)

Here's the debacle of how I mounted an Ohlins shock to a Yeti SB 5.5. There is practically no information on the internet explaining how to do this; therefore, I wrote my experience to give back to the MTB community.
For Starters
Ohlins documentation is atrocious. It was not clear at all how I was supposed to mount my shock. You'd think they'd have some guide, but there was hardly anything useful.
There wasn't even a label on what I now know are called the "DU Bushings" and "Spherical Bearings". It's hard to Google when you don't even have a starting point.
What if a have a different bike?
This guide should still be useful. Your frame might be different, but it's likely the mounting hardware is similar between different bikes. Reference the manual for specifics.
Fair Warning
If you're not an experienced bike mechanic just take it to an Ohlins dealer. This was surprisingly difficult; both Yeti and Ohlins are very proprietary. It also takes forever for Ohlins to ship things to you.
Overview
To mount an aftermarket shock you need to first understand how shock mounts work.

A female metal rod going through the shock (Figure 5.11)
A bolt that threads into the female metal rod from the other side (Figure 5.13)
Washers between the rod and the bolt (Figure 5.12 / 5.14)
A spacer that goes into the eyelet of your shock. The female metal rod goes through the middle of this spacer. It's purpose is to fill the open gap in your frame and provide support.
Last, there's a DU bushing in the eyelet of the shock. This prevents damage to the eyelet and is replaceable if it get's damaged.

#1,#2,#3 is Yeti parts
#4,#5 is Ohlins / Fox parts
You cannot use Fox mounting hardware for Ohlins. It will not work... I tried.
The DU bushing comes in the Ohlins shock box. You'll also see "Spherical Bearings" which is an alternative to the DU bushing.
But what about the spacer?
Yes indeed, the spacer is not included with the Ohlins shock. This is because they couldn't possibly know what bike you're trying to mount to. Every frame has different measurements. Therefore, they leave it up to you to figure out what spacer you need. Consequently, this is where it gets confusing.
Step 1 - Shock Spacer Measurements
Let me start off with a note on being accurate with your measurements. The less accurate your measurements, the worse fit your shock will have. You should buy one of these. When measuring for shock mounts, you need to be accurate +- 0.1mm. Don't just go out there with a measuring tape and eyeball it.
Measure the inner width between the mounting points of the shock. In other words, don't include any of the bike frame in the measurement, you only want the open distance between the two mounting points. Ohlins needs this measurement so they can craft a custom spacer for that area.
A cheater way to measure this is to use your old shock as a reference. Just make sure you didn't lose any parts or spacers when you removed it or your measurement will be incorrect.
Also measure the diameter of the  metal rod that goes through the middle of the shock(Figure 5.11) - do this for the front and rear mount. Ohlins needs this to determine how wide the hole in the spacer is. The metal rod will have to slide into the middle of the spacer.
Step 2 - Eyelets
You have two options. DU bushing or the Ohlins "Spherical Bearing". I wanted to use the "Spherical Bearing", but never figured out how. If someone knows please let me know.
So, DU bushing is what I chose.
Step 3 - Installing DU bushing into eyelets
The proper way to do this is to buy a DU bushing installer tool, which is like $100.
Or you can be really careful and use a vice to squeeze the bushing in there.
The basic method of how I did this
Note 1: It's pretty hard to center the DU bushing
Note 2: It's really easy to scratch the paint on the Ohlins shock while doing this; be careful. Accept it if you damage it. It's not up to Ohlins to warranty damage from you installing it incorrectly.
I did leave a little mark, but barely noticeable.
Step 4 - Call Ohlins w/ measurements in hand
Take a quick measurement of the eyelet hole size with the DU bushing installed. Ohlins will need this to determine the diameter of the spacer. It has to fit in the eyelet hole perfectly.
Call Ohlins customer support with the measurements on hand. Tell them you installed the DU bushing that came with your shock. They should now be able to custom order spacers for your shock.
Step 5 - How to install it
Once you have the spacers you should have everything needed to install the shock.
Before installing them on your bike, you need to first test that the spacers are crafted correctly. You can test by pushing the metal rod through the spacer. It should be snug. If it's excessively hard to push in, or excessively loose, you need to return it. If you're handy with a drill, you could try that.
My Experience
I was unable to push the metal rod through the rear mount spacer. So I tried to force it through with a vice; this proved to be a very dumb idea. I destroyed both the metal rod and the spacer; I was unable to ride my bike because of it... a $160 mistake.
Don't do what I did. I broke the golden rule: "Don't force anything". I was too stoked to get my shock installed. If it doesn't fit, send it back or drill it to be wider. Do not force it like I did.
If I had to do this all again
I probably would have crafted my own spacer using a bench grinder and a drill. It would have been more accurate and a lot cheaper. I'm sure any strong plastic from the hardware store would suffice. Just make sure it doesn't damage your frame. You'll notice that it leaves marks on the inside of the frame if the spacer isn't perfect.
Still Unknowns
I still to this day don't know how to use those spherical bearings they provided. I have not been able to find a tutorial for how they're installed. If anyone has information about how to use these, I'm all ears.
Overall Impressions of the Shock
I was quite unhappy at how little documentation there was for installing the shock. The whole process took me about 3 months from when I received my actual shock to installing it on my bike.
However, once the shock is installed properly, it's a great upgrade from the Fox DPX. The coil is rad.
Lastly, here's video of me enjoying my new shock


Can't get over 50psi in bike wheel I've just replaced my mountain bike tyres/tubes with new 26x1.50 city slicks.
Max psi is 80 but my foot pump won't push more than 50 in.
Is this because it's a schrader valve, or do you think my foot pump is past it.
If it's the valve type is there any work around apart from bying presta tubes.

The valve isn't the limiting factor for the pressure -- you can go well above 80 psi with a Schrader valve.

If you're holding 50 PSI in the tire (the tire should feel a bit firm, but you can likely push it in a bit with your fingers), you shouldn't be leaking. I'd try depressing the core (pin in the center of the valve) a bit with a key/small screwdriver/finger nail to make sure its free and try pumping it up again.

If you're not holding the air in the tire, you either have a bad valve or a leak in the tube (in which case, get a new valve core/tube in the former case, and patch/get a new tube in the latter case and check the tire for damage).

Failing that, I'd try a different pump -- not all pumps are able to reach high enough pressures, but 50 psi is on the low end for the limit of a bicycle pump not specifically intended for low pressure situations like fat bikes (then again, a pump designed to do sports balls only needs to pump about 8-10 psi, so its possible). I'd try a floor pump like this one.


Pros and cons of gears in bottom bracket vs. rear hub? Since 6 years, I am the happy user of a bicycle with a Rohloff internal hub gear.  German quality squeezing 14 gears and a 526% gear range into the rear hub.  Less known is the newer and equally German Pinion gear, which reportedly has 18 maintenance-free gears and a 636% gear range — all squeezed into the bottom bracket.  Wow.  The Pinion website features the logos of many high-end touring brands like Santos, Idworx, and Koga.

What are the advantages and disadvantages of squeezing the gears into the bottom bracket, as opposed to into the rear hub?

The advantages of the Pinion are that the weight and complexity are in the middle of the bike and not being bounced around in the hub of the rear wheel, especially for a bike with suspension (the unsprung weight is lower). Also, because it sits in a custom housing it can be whatever size and shape they want, rather than being constrained by the width of the rear hub and needing to be both circular and balanced.

As David says, it's easier to switch the rear wheel out either when you are fixing a puncture or because you have several rear wheels (different tyres or whatever). You could take this to the extreme with a fat tyre bike and have a skinny standard 700c rear wheel for around town and a 4" fat wheel for off road. I am considering this for my recumbent touring tandem, as the extra weight of a pair of spare wheels might be compensated for by the ability to switch from skinny road tyres to proper offroad tyres and wheels.

One more subtle advantage of the Pinion is that ground speed doesn't matter. Rohloff hubs become noticeably less efficient at high speed, but one of the places they're most desirable is in velomobiles and other speedy bikes. This is compounded by those bikes often using smaller rear wheels (406 is common, 355 is about as common as 622) which further increases the rotation speed of the hub. With a Pinion that doesn't matter, the gearbox always rotates at your pedalling speed.

The advantage of the Rohloff is that it's proven technology, parts are fairly widely available and the wheel will fit into a standard bike frame. Especially for long distance touring, the thought of being stuck somewhere remote with a broken Pinion is horrifying, because the only option is wait for a new gearbox or bike to be shipped to you, or give up and go home. The Rohloff alternative is both less likely (because we have seen Rohloff hubs do 100Mm trips quite often already), and less terrible (because you can convert back to derailleur gears or even single speed using standard bike parts). I'll hit 100Mm on my Rohloff in sometime the next couple of years, it's one of the early-ish ones (4 digit serial) and it's been trouble-free despite regular use in load bikes as well as touring bikes.

The bottom bracket gearbox has to deal with much greater torque than the hub does. Rohloff require a 2.5x gearing down between the cranks and the hub, so all the parts can be correspondingly smaller and lighter. A fit cyclist can put a surprising amount of torque into a bottom bracket, akin to a decent car engine (but at much lower rpm). Schlumpf had a problem at one stage with their sintered gears shattering in use (I experienced that), largely because they underestimated just how much force was involved. This makes the Pinion more complex to design and build for a given weight target, and probably more expensive as a result. That it can be bigger and irregularly shaped counters this to some degree.

Finally, the Pinion really can't be sold as an after-market part because you need a framebuilder to cut your bike up and fit the gearbox. It's quite possible to fit a Rohloff to almost any bike whenever you have the money available to buy one. And if the Rohloff doesn't work for you, you can take it out and sell it second hand.


Di2 left shifter not working I got myself a bike with Shimano di2, but I am new electric gearing. I have a problem, that Front derailleur (left shifter) is not working. Clicking any of the buttons on the left shifter, does nothing. There is no sound of gear change attempt, no lights come up on the junction box.

Right shifter (back derailleur) is working fine, I've already done ~100km on my new bike using only gears at the back. If I longer press right shifter, junction box indicates green battery light, so I assume that the battery is fine.

Seller forgot to bring me a charger, so I will not have it for at least couple days more.

I tried checking if any of the cables are unplugged, but:

Cable on the left shifter hoods (under the rubber) seems to be plugged in
3 cables going into junction box under the stem are plugged in

I took a short video that shows what happens when I try to interact with my left shifter, it is hosted on dropbox. Sorry for the mud, it has been raining.

I've heard of loose connections between the shifters and their cables causing this sort of issue. In one case in particular, the connector didn't latch properly and the bar tape pulled it out, so it would seem OK when tested but not when riding.

In general if you've got battery and part of the system works, the connections are one of the first things to check - the front derailleur connector as well as the shifter connector. Here the lack of an LED on the controller suggests the shifter cable is at fault.


Does the age of brake pads make any difference? I recently changed my brake pads with some new ones that have been in my shed for years. They are not packaged, but as I am in the UK, which has a very variable climate. The shed gets very hot and humid in the day, and cools down at night.

Does this have an effect on the brake pads, with V brakes?

Almost any rubber product will degrade over time, loosing its properties. Different rubber compounds will degrade differently, depending on the formula and method of fabrication and, of course, environmental factors. This applies to brake pads, tires, grips, valve seals, inner tubes and more.

Usually brake pads tend to "dry" over time, turning less flexible and prone to cracks. A less flexible pad is less capable of creating friction. I know of some rubber (or rubber-like) products that when degraded turn to a thick paste that will stain fabrics, skin, etc. but never seen a brake pad degrade this way, if that where the case, it would not last eve one braking.

To test a V-Brake pad press hard with your fingernail on its working surface. You should be able to sink the fingernail just a little bit, leaving a pressure mark that will shortly disappear. If it feels hard, wood-like, almost sure you are better discarding it.

However, pad age is not the only factor that can degrade braking performance. Dirt and grease on pad or rim for example. I recommend washing them with liquid dish washing soap. Another factor is calibration. Brake pads not properly aligned may will not perform as designed.

Finally, there are different rubber formulas for aluminum or steel rims, (And for carbon fiber I guess) and I have tested pads that work wonders on steel are worthless on aluminum. Also have observed that the same pad can perform differently on aluminum rims made of different alloys.

<< End of answer and begin of anecdote >>

Recently I committed the mistake of trying to slowly descend a long pronounciated slope with a road bike from 1984 that still had the original pads (The ones it was originally sold with). The result was the friction generated was so poor that they only caused the rims to heat up to the point that both inner tubes were blown out. One rim was steel and the other a single wall aluminum.


Cycling fast - and brakes don't work - what to do? I hope this doesn't occur to any of us, but it can.

What must the cyclist do when he/she is cycling (too) fast and needs to stop or slow down immediately, but neither the front and rear brakes work at that moment (for whatever reason), and there is almost no way to avoid collision without stopping/slowing down?

Are there any recommended actions/maneuvers to try in order to stop the bike and/or avoid/minimize the potential dangers?

Well, a possible action is to try stopping the bike with one or two feet. What if they cannot reach the ground (i.e. the saddle is high)?

First, I'm sure you've already considered this, but for future visitors: don't get into this situation. If you're at all unsure of your brakes, stop riding until you can get them fixed. Brakes don't just stop working for no reason. Most cyclists should never experience this.

Second, are you sure you have to stop right now? If you're on the flat, you can come to a gentle halt just by sitting up in the saddle (to make yourself less aerodynamic) and waiting a minute. This is certainly preferable except in an emergency. If it really is an emergency, and you must stop in the next few seconds to avoid a brick wall, cliff edge, boiling lava, &c., do the following:

Manoeuvre to somewhere it is safe to do so, and then put your weight on one side so that you fall over sideways. You need an empty space a few metres long (depending on surface conditions and speed) to be sure you won't hit anything. If you're on a road, hitting a high kerb at an angle should help you land on the footpath. If you're in parkland or countryside, a hedge or bush is a much better option than a drainage ditch.

Be careful that even though you know a fall is coming you don't tense up: keep your joints loose and tucked in. Even at a fast cycling speed, if you stay frosty and alert you should be able to walk away from a deliberate fall like this with some bruises, no broken bones or head injuries.


Traning for 2x250km in 4,5 months Is this possible? The goal is to do this in 3 days - ride 250km one day, then take one day off, and ride 250km again the next day, all on a road bike, with about 2500m of total elevation gain, in 30C temperature, on a rented road bike (not saving money here).

Maximum distance I've done the last season was 200km on a trekking bike in one day, and that was after 1-2 months of training. 100km was my record on a road bike.

There's winter in my country, so I'll be able to ride hopefully in March, which means 2-3 months in a gym/running/swimming, and then just about 2 months of actual riding.

You don't say how young and foolish you are.  Many years ago, at age 17, I rode a double century (a little over 300 km) with about that much climbing with no training at all.  I had never ridden more than 50 km in a day.  The weather was much cooler than 30C.  The hard part about the second trip would have been psychological-I found the double to be much more than was fun.  I rode a number of centuries, 160 km, afterward and found them fun, but the double took 16 hours.  I was on a decent 1960's road bike. If you have done 200 km already, you have a good idea what it takes.  You can get a lot stronger in 2-3 months of training.  Go for it.


Are bike saddles always removable from the saddle post? I want to buy a mountain bike soon and I’ve been doing a bunch or research. I noticed that some bike saddles can detach from the top of the saddle post, while others get removed with the whole post. There are a couple of things I want to know. Can all saddles be detached from the top of the saddle post? Are saddles that detach with the post of cheaper quality?
that’s it, thank you

Saddles are always removable from the seatpost or, in some cases, the seat mast. I am not aware of any arrangements where the saddle is made in one piece with a seatpost or equivalent part. Because saddles are extremely personal, and even a rider's own saddle preference can change over time, it seems unlikely that there are such construction arrangements - I suppose a weight weenie cyclist might be willing and able to make or commission a saddle without rails bonded to a carbon seatpost or seat mast topper, but that would be very niche application. It would also be pointless, because most high end stock rim brake bikes and even a number of disc brake bikes can be brought under the UCI weight limit.
That said, a very small number of bikes have a seat tube that extends up from the top tube, which I believe is called a seat mast. You would clamp your saddle in a seat mast topper, then mount that on the mast. You would cut the seat tube to the correct length, and the mast topper offers a small range of height adjustment in case you need to change your saddle height. Probably the most prominent example is the Giant TCR, pictured below.

The picture is from this Velonews Q&A session with Lennard Zinn, where he fields a couple of letters from readers who are trying to extend a mast that had been cut, or else to just get a bit more saddle height than their cut mast allowed for. This neatly illustrates the potential downside of the seatmast design.
To the original question: in this arrangement, I suppose you could just remove the seatmast topper along with the saddle. However, the saddle is manufactured separately from the topper - or else how would you change your saddle horizontal position?
Why on earth would anyone make such an item? It could be lighter than seat tube and seat post arrangement, although remember that the impact of small amounts of weight on cycling performance are negligible. Open Cycles uses a seat mast arrangement on its Open MIND bike, and their webpage says that it allows them to make the seat tube very thin, at about 25mm - recall that a thinner tube should have more compliance than a thicker one, which should increase comfort. Alternatively, Speedvagen is a small batch steel frame builder, and as best as I can determine, the seat mast arrangement is an aesthetic choice only, and it's one of their signature design elements.
A 2008 article from Road Bike Action discusses some of the potential advantages of seatmasts, but I believe some of the arguments are incorrect (e.g. aerodynamic seat tubes and posts are more widely available today, although the post tends to be proprietary to each frame). If my memory is correct, seatmasts may have had a brief bloom in popularity in the late 2000s and early 2010s, but clearly they have not become widely accepted.


Electric Bike (eBike): Freewheel or Regenerative braking? Not asking for opinion which one is better, so please do not state without some reasons why one is better than another on eBike.

Question is: Freewheel or Regenerative braking is more efficient in Electric Bicycle?

So far I got:

Freewheel:

When battery go flat you can use it as a normal bicycle, while with
RB it feels like riding with a flat wheel (or even worse).
It is lighter than hub with RB, and cheaper
Similar to a bike

Regenerative Braking (RB)

You can charge your battery up whenever you need to stop, albeit minimal.
It helps you brake the bikes gradually, especially on downhill section, just like how motorised vehicles work.
Akin to motorised vehicle

Freewheeling is almost always better.

If a freewheel ebike control system fails, it reverts to being a regular bicycle and you can pedal home. Otherwise, you might find that you cannot even push it home if the motor is stuck on heavy regen.

Furthermore, there is very little energy that you can regenerate from a bicycle. There just isn't enough mass or significant enough velocity to make it worthwhile. The regen also makes braking more complicated than it has to be as you need to swap out your brakes/brifters with ones that have brake-switches in them.

On a vigorous discussion on the EndlessSphere forum, Justin Le pulled out data from his cross-country trip. While he did get 18% regen going down mountains passes, he also only got 1-2% regen touring over rolling terrain. His urban regen data was 11% which is close to the 10% figure that is used as the rough estimate of range extension possible.

  So, although this is a just from a single run, you could easily conclude that we'd expect about 5% regen for city riding in mostly flat terrain, 10% regen for city riding with lots of moderate hills, and probably more like 12-14% regen if there are really steep hills.

Since e-bikers tend to recharge every day and each recharge is only 1-2 cents of electricity, increasing range and efficiency  a modest 10% just isn't  as important as it would be with a hybrid or electric car.


Do indexed 3x downtube/barend front mech shifters exist? I'd like to use a 3x chainset and wonder if indexed 3x downtube/barend front mech shifters exist?

The front mech shifters were generally not indexed.
The front gear change is agricultural compared to the rear derailleur. With so many gears (up to 13 now) so close together, getting the shifting right is critical, but on the front, the gear spacing hasn't changed forever, so the degree of accuracy is not the same.
Basically it's still in the days of change and trim until it is quiet


What is what appears to be electrical conductive tape beneath the "water-proof cap" inside the Ultegra 6600 STI assembly? While performing some work on my Ultegra 6600 STI shifters I was curious to remove part no. 13, designated "water-proof cap" in Shimano's part fiche. To my surprise there was something that resembled conductive tape beneath it with (I think) 3 terminating metal pads. I didn't take a pic, unfortunately. Does anyone have any idea what that's for?

Flight Deck was a system where information on gear selection and cadence can be sent to a head unit to display to the rider, and combined with the wheel diameter, also speed. So electrical contacts to connect up to this. A bit superseded by GPS units now.


Will this electric air pump suit my tires and work for me? I have to buy air pump for bicycle, I saw this one online on Walmart.
My bicycle tires have a pressure range between 30 and 50 psi.  Will this pump work, or should I buy mechanical one?
What are it's drawbacks?

In my experience, batteries are frequently flat when you need them.   This unit has the likelyhood of sitting unused for months, going flat, and then being useless when you really need it.
I strongly suggest you get a manual mini-pump instead.  Sure it'll be slow, but its more likely to work when you need it.   High tech is not always appropriate.

Based on the cost, you could easily buy a nice minipump for in your pocket/bag while riding, AND have the luxury of a floor pump (aka a track pump) to leave at home for maintenance.
I personally carry a mini-floor pump on one bike.  Though I use the floor pump weekly for top-ups, I only use the mini pumps when something goes wrong (for me or someone else who didn't bring one! )
Adding USB doesn't make things better.

Here's a review of two electric air pumps.  https://cyclingtips.com/2020/03/xiaomi-mijia-vs-fumpa-electric-tire-inflators-reviewed/  Neither are the one you suggested, but the general points are still relevant.

Neither are intended for riding with.

noise and vibration

1 minute and 24 seconds to inflate a 700×25 mm tire to 80 psi,

had me questioning why I don’t just reach for my floor pump

recorded the Mi at 85 dB, while the Fumpa has a wake-the-neighbours 99 dB output. In both cases, you’ll want to reinflate your tires the night before you sneak out for your early-morning ride.

Upshot Buy a minipump for your pocket for emergencies, and a floor pump to keep at home.


'1 1/8' vs '1/2 1/8' chain/chainring Some 1/8 chains and chainrings are sold as "1/2 1/8" and some as "1 1/8". What is the first number describing?

My understanding is that practically all modern chains have a 1/2 inch pitch.

There are two measurements, given as pitch x width. The pitch is the distance between rollers and width is the width that the sprockets have to fit through. The pitch is generally 1/2" on modern chains, but some old bicycles (esp. old track bicycles) use 1" pitch chains (skip link or block chains).

The width changes depending on number of speeds (so you'll have a lower width for higher number of speeds). So single speeds will often use 1/8" (some have sprockets designed for 3/32" though, so you should check), 8 speed will use 3/32" , higher number of speeds will use 11/128" (11 speed), etc. [possibly different between manufacturers].


What is a good method for constructing dirt jumps? What is a good method for constructing dirt jumps? Not massive jumps, just something more than a simple mound of dirt for a bit of fun. It's one thing to pile up the dirt, but there seems to be a bit of an art form to getting the surface smooth.

Jumps takes time and effort to do right.   If you're going to rush or do a half-arse job then don't even bother starting.

Design is important - you need to consider run up space before and run out space afterwards.   Make the jump wide enough to give options - a metre would be a fair width unless you're making it difficult on purpose.

Bailing-out options - riders will ride around if it looks too hard, you may make the jump really wide to reduce this, or make it longer to go around.

Try to avoid digging a moat around your jump.  Source the dirt from metres further away, you want to avoid having water collect on your track, because wheels and water means erosion.

You're aiming for a smooth curve on the face, so build up your jump a few inches then stomp or compact it.  Damp soil will compact better than dry.

Deeper inside the mound you can use big rocks for bulk, but still pack the soil around them.   Trees and wood is not so good, it will rot.   Tanalised timber is okay for surfacing.

As your jump rises, keep tamping it down.  Use water to dampen it.

Remember it doesn't all have to be built in one sitting.

You can use shingle/stones to help reinforce the surface, but don't put sharp edges facing up.  Big flat river stones are okay in moderation.

The top - I'm not so sure on this.  You want to curve it back down quicker than you went up, but you must not have a lip or a sharp edge.... it won't last.   Jury is still out on timber at the top.... if you were building a jump with a wall on the far side (ie you have to get off the ground) then timber supports will be required.

The danger of timber is wear over time may create a tyre-grabbing rut right before the edge, where it's too late to stop.

Finishing - use a watering can or hose with a shower spray to smooth off the surface.  A flat spade or rake may be useful for smoothing, or you could even use a garden roller.   Also you might want to use some matting or concrete pavers to minimise erosion and to assist traction.

Final thought - do get permission to do what you want to.   Or do it on your own land.   Don't go damaging trees or wrecking other things to make your jump.

Edit: I forgot to add maintenance.   Do periodic work on your jumps, to fill erosion or ruts, or just generally clean up.  Rubbish laying about attracts other rubbish so keep it pleasant.


How should I finish the dynamo cable connection from SON coax to an SP connector? Connecting a SON coax cable to an SP (Shutter Precision) Dynamo "lego brick" results in exposed wire. How should I protect this and tidy it up?
Second question: how do I know the wires have been put the correct way round?

You don't have a choice about needing to cover the bare strands. So you are going to need to get a piece of heat shrink for the outer that when shrunk will be able to play nice with the hole in the connector. The connectors are only a few dollars if you screw one up (aside from the hassle of getting a new one) so I think the answer is don't be shy about using a teeny drill to enlarge the hole as needed. Before shrinking on that piece of heat shrink, you're going to take a larger piece and put it up on the full-section wire to cover the split part. Put it out of the way, shrink on your piece that covers the bare strands, then bring the bigger piece down and shrink that on in the area where it splits. The clear part is fine to be out in the world.
For the polarity question, presumably you are asking because this is a piece of Schmidt coax that's integral with one of their lights. In that case the outer is the ground.
Edit: I didn't think of this earlier, but another way you could do it without having to do anything "weird" would be get some normal one or two strand wire and then a matched set of spade connectors, 2x each male and female, then install the wires into the connector as it intended and put the male spade connectors on the other end, then prep the Schmidt wire the same way you would as for a Schmidt hub. There are B&M male and female spade sets that have a double crimp that prevent stress at the wire crimp that would be ideal for this.


My stem keeps moving side to side even thought I tighten it I just got a new Demolition Stem.I tight it with all my force And It keeps slipping side to side Like it doesnt match with the fork lined up And whenever I check it its fine but after a while it is always not lined up with the fork..Please help me

Is it possible you tightened the pinch bolts before tightening the bolt that runs vertically and holds the top cap down?  If you do that, the entire assembly won't be fixed tightly on the vertical and will allow side-to-side play.  I did that once and the symptoms were exactly as you describe.  To check this, loosen the pinch bolts and the bolt in the top cap.  Now tighten the top cap bolt first, then the pinch bolts.
Be very carefully while tightening the top cap. If tightened to much, it can overload and ruin the headset bearings.

Here's an image from Sheldon's site showing the bolts I mean:


Tires Not Taking in Air But Will Let Air Out Have tried a number of times to inflate mountain bike tires with schrader valves using a pump but it never inflates.  Tires already inflated but feel a little low on air, so I go to pump them and the valves are not accepting air, just feels like I'm compressing the air in the pump.  It doesn't appear that the valve is blocked or anything because when I first put the pump on the valve it lets air out.

What is going wrong?

You may simply not pushing the pump onto the value body enough, and the internal valve is not being opened.

Most pumps have a plastic insert behind the valve hole that is reversible for Schrader or Presta value use.

[Schrader left Presta right.]

This insert may be the wrong way around, or (as has often happened to me) the small peg that opens the Schrader valve has been bent so it no longer pushes on the valve.


Better solution for uncomfortably low bars: a stem riser, or taller stem? I've got my (threaded) stem at the maximum height, but I'd be more comfortable if the bars were higher relative to the seat. It would be uncomfortable to lower the seat any further.

I was intrigued by the idea of a stem riser as a cheaper solution than a taller stem, or a larger frame.

Stem risers do work but have limitations. They increase the amount of force you can put on the headset (as does anything else that gets the handlebars further up), they can break (unlikely but possible), they add a little slop and they often creak (a consequence of the slop). If you're a strong guy with wide handlebars and you're prone to really grunting on the bars you're more likely to break a riser (or anything else), and will probably find the small amount of extra slop makes the bars feel loose (or as though they're about to break).

threadless:  quill:

I've generally suggested them as an interim solution for someone playing with bike fit, or for someone who wants a bigger frame but can't afford a new bike.

Right now I have a back injury that means I need a more upright riding position, and I've obtained that via a set of upright bars that have a bit of rise as well as the sweep back, and a stem with more rise (that I swapped off my old commuter bike).


How to compare an IGH (Shimano Alfine 11) with a 10 speed cassette and 3x chainwheel? I'm try to compare the gear ratio of a IGH (Shimano Alfine 11) with a 10 speed cassette + 3 chainring setup.

I read Sheldon Brown's gain ratio definition.

I went to Sheldon Brown's gear calculator

I entered all the numbers from my bike and got this result

Here is my interpretation:

The first column group with heading 0.53 (low) shows the gear ratio of the 10x cassette and 3x chainwheel. Example: The number circled green is 34 / 11 = 3.1 Which to me is the gear ratio (correct me if I'm wrong). That first column group tells me the highest gear ratio is 3.8 (e.g. when going downhill), and the lowest gear ratio is 0.7 (not on the screenshot, e.g. when going steep uphill). The IGH has highest ratio 2.15 (not on the screenshot) and lowest ratio 0.53. To me that means on uphills I'll have an easier time with the IGH than with the cassette. However downhills I won't be able to go as fast with the IGH than with the cassette. Is my interpretation correct?

What do the other column groups mean? Consider the column group with heading 0.68 ? Where does the number circled in red come from (because 34 / 11 not equal 4.0) ?

Also where do the numbers 0.53, 0.68, 0.77 etc come from. I know they are from the Shimano specs. Are they really the gear ratios? Aren't the sizes of the single rear sprocket and the front chainwheel (that are installed on the bicycle) required to calculate the gear ratio of the IGH setup?

I think you’ve told it to do an Alfine hub with all 3 chainrings and all 10 cassette sprockets, so the computer is obliging.

Just include one chainring and one sprocket value to get the Alfine table.

Then calculate another table with all 3chainrings and 10 sprockets but no Alfine

You’ll get things more like this:

You’ll need to pick your own chainring and sprocket values for the Alfine, point being you can customise these to get the gearing you want. I put in random values (32,17) which give the Alfine something like the range of the 3x10 setup

Edit: a gain ratio of 1.9 may/will feel nothing like a gain ratio of 1.2 when you're climbing, so keep playing around with numbers for the IGH chainwheel and sprocket


Is there a specific grease for titanium frames? I have recently rebuilt my road bike on a second-hand Seven Cycles Alaris titanium frame.

I used a fairly standard hydrophobic grease throughout but I have been told I should use a titanium-specific grease. The bottom bracket is the only place that I can think of with threading in the frame.

Is there such a thing as a titanium-specific grease? Any advice on this?

For titanium frames, it is best to use a copper paste grease. You need to do so anywhere there is metal on metal contact, especially if it is aluminum to titanium contact.

Normal grease is not enough to prevent the accelerated oxidation and bonding that occurs between totanium and other metals.


Shimano Nexus 8 internal hub skip/clacking noise when under torque Hello fellow cycling enthusiasts.
Intro
I have bought, just 2 months ago, a new Cube Hyde Pro 2020 bicycle with belt drive (Gates, rear cassette out of metal, CDC with 22 teeth) Shimano Nexus 8 internal hub (model SG-C6001-8D). I mostly ride in the city and sometimes for fitness purposes.
Bicycle link with specs: cube.eu
Problem
Overall I am happy with the bike. It rides quiet and comfortable but I have noticed that under high torque situations like short steep inclines or fast take offs a single sharp and unpleasant clunking noise can be heard from the gear hub. This happens in all the gears. I have tried to catch this noise on camera and took a video of it on my daily commute on a short steep incline and gearbox in 1st gear: Youtube video
What I tried

First I made sure that the tension on the gear shifting cable was correct and that 2 yellow marks on the hub line up when the 4th gear is selected (see the picture)

Second step was that I checked the belt tension with the Gates frequency measurement app on the phone and it shows ~35HZ tension which is within the range recommended by the manufacturer

3rd step was research and it seems that few other users have noticed such behaviour even on this website. I actually found 2 threads with similar problem but with no clear solution:

The crank arm slips when pressing hard on pedals with Shimano Nexus

How to prevent Alfine 8 from “skipping”/"slipping under load?

I would greatly appreciate any help or input from you. Even if you don't have the solution but have observed the same behaviour please reach out and maybe we can find the solution together.
Thanks!

There are some Nexus and Alfine bikes that have made it out into the world with a spec mismatch between the over and under style cassette joints and the shifter.
The cable pull sequence works in reverse order between the two shifter types. Because the cable pull for this system varies with each click, everything gets screwed up if you then use the setup marks. Something like what you're experiencing can result.
To check this, get your exact cassette joint and shifter models and make sure they're listed as compatible on si.shimano.com.
If that checks out, test it with less belt tension.
If that's not it, get oil dunk gear and the Nexus/Alfine notchy tool, pull the core, wipe, inspect for anything out of place or prematurely damaged or worn, dunk, grease, reassemble, and see if that fixes it.
One perfectly likely explanation is that the pawls that drive the shell are having engagement problems. If one or more is under-lubricated, deformed, or out of place, it could cause a partial engagement problem, which also fits the symptoms. This can lead to a situation where the tips of the pawl(s) get damaged and the problem gets worse. This is easy to inspect for once the core is removed. Note that despite the ostensible complexity of the hub, the pawl system in question is the most exposed part of the whole deal, being the interface between the drive ring inside the hub shell and everything else. If it does the same behavior with the cable disconnected completely, I think this pretty likely is what's happening.
It is true that everything about this should be covered under warranty. Between parts shortages and the usual awkwardness of getting warrant support to happen for mail order bikes, it may get hairy at the moment.
Also check dropout alignment slash sync up slider fore/aft if applicable, all of which can in theory cause hub badness.


Road bike disc wheel interchangability This may be a duplicate, but I didn't find an answer:

Are road bike disc wheelsets interchangable? For example my cx bike has DT Swiss R24 wheels, could I buy a set of Mavic Ksyrium wheels and fit them onto my bike? Thinking about it, the calliper is fixed onto the frame at a certain position, so I imagine this is possible, or is there something to watch out for?

Calliper and disc positions are standard, as are hub widths and fork spacings for disk wheels. Minor adjustments of the calliper's position could be required.
There are however several methods for locking the wheels in the fork that will require your attention: traditional quick release or different types of through axles!


I have an 8-speed GT Aggressor Pro and I want to upgrade it to have 12 rear cogs I found a really cheap 12-speed SRAM groupset, and I want to know if I can just get a new rear wheel or if I need a new frame.

Your frame most likely has rear hub width of 135 mm for 10 mm QR-axles. 12-speed groupsets are likely to only be compatible with through-axle hubs of widths 148 mm (boost), and 142 mm (non-boost) and diameter 12 mm.

However, some of 142 mm hubs can be converted to accept 135 mm QR-axles by means of end caps swap. And cheaper 12-speed groupsets such as Sram NX Eagle are made to work with older Shimano freehub splined bodies that are used by 8- to 11-speed cassettes. So there seems to be a possibility to achieve what you want.

See also this discussion on the topic: https://forums.mtbr.com/wheels-tires/12-speed-9mm-qr-hubs-do-they-exist-1113587.html where some people report success of such a conversion to 12-speed. Good luck!


Single to double chainset conversion Can I change a single chain ring to a double?

I have an old steel frame with a narrow bottom bracket shell 66mm and a single 50 tooth chain ring. I would like to add a 36/40 inner and want to know what is needed and how to go about this.

Many thanks

You need a bunch of things.

left hand shifter, or a left hand replacement brifter if your bike has integrated shifters
front derailleur mechanism with a band-on (aka bolt-on) clamp mechanism and diameter of the same size as your seat tube
new inner gear cable and cable housing for the front mech
a pair of cranks that have the same length, and same size pedal mount hole as your existing pedals
the right hand crank should have chainrings sized to suit your need.  Since it takes a 50T now, smaller toothcounts should fit fine. Cranks should have the same BB interface as your current BB axle (probably square taper but others are possible)

Depending on the details you may also need

new bottom bracket axle with more length
bolt-on frame cable stop for the seatpost.  May need to be angled, OR
an "under-BB" cable guide.  Generally it is a piece of plastic, and is screwed into a hole in your BB
bolt on downtube cablestops or holders (if cable zip-ties aren't to your taste)
new grips/bartape.

Sourcing parts

If you have to buy all this new, it may be cheaper to buy another bike.

If you have access to a donor bike, something that has been crash damaged could be good.

Or start exploring your local bike cooperative or ebay/CL/gumtree etc.


What is the "3 foot law" and which US states have it? Some states seem to have something called the 3 foot law to keep cars away from cyclists.  Why 3 feet?  Which states in the USA have it?

The 3 foot law is an example of a law that exists mostly to create awareness rather than having some direct practical function.

This law is rarely enforced by itself. Can anyone cite an instance where a motorist was ticketed for passing in under three feet (and not ticketed for anything else)? The 3-foot law is, AFAIK, typically enforced as a supplement to some other violation such as failure to yield or reckless driving.

But more than anything else, the intent is to create some level of awareness in motorists about how to deal with cyclists. If motorists know it is a law, most will make an effort to abide by the law.

A quick google search reveals that, as of this year, 20 states in the USA have this law.  You can view a map depicting the status of this law in the United States here: http://www.3feetplease.com/important-stuff

It seems to me that in the last 10 years or so, motorists have been getting much better than in the past about getting along with bikes. It could be the marked lanes/signage, or perhaps things like the 3-foot law, but I have noticed a LOT LESS "entitlement-to-the-road" behavior from motorists than in the 1990's and earlier.


Should a new rear shock be building oil in the shaft? I've ridden my new bike (first full suspension I own) for about 150km now and I'm seeing some oil building over the O-ring in the shaft. It's a lot more oil than what you normally see on a front suspension, so I'm starting to worry about it, but it can be just my ignorance :p

Is this normal or should I send it back to the manufacturer? it's still on warranty.

There is no dripping while stored, so it's maybe only about wiping out the excess after every ride. Or the few first rides?

The shock is a RockShox Monarch RT

That is definitely not right. Send it back for repair.

Similar to front shocks, a good shock will have a very light film of oil you can just feel on the surface. A wipe with a clean cloth will show no visible sign of oil on the cloth (maybe smudge of dirt).  In this case, its clear an oil seal has gone.

Side note: It looks like you could do with lower air pressure for the riding you are doing. You have no used anywhere near the full travel of the rear suspension.


Original fork 1'', new fork 1 1/8'' I put a picture of my original frame. The internal diameter of the straight cylinder is 31mm.
In this frame was installed an original fork of diameter 1''.
I would like to buy this fork : https://www.bike-components.de/fr/Surly/Fourche-Rigide-Straggler-Disc-28-700c-p38261/
but the diameter is 1 1/8''.
I wonder, since there is some space between the frame and the 1'' fork, if I can installed this 1 1/8'' fork ?
I will need also to buy a new stem, but it's ok, my problem is more about the compatibility frame/fork.

Your frame seems to have a non-standard head tube diameter or you mis-measured it.
Here you can see a list of headset standards: https://www.parktool.com/blog/repair-help/headset-standards
There is no headset standard where head tube internal diameter would be 31mm.
For 1+1/8" forks and bicycles with external headset cups, the inner diameter of head tube should be 33.8-33.9 mm.
Only if you can find a headset that is compatible both with your frame and with the 1+1/8" fork, you can install it.
I would measure the head tube internal diameter again. The external pressed-in headset cups might be affecting your measurement.
Do note that 1" fork has 1" = 25.4mm outer diameter. The inner diameter is 22.2mm
A 1+1/8" fork has 28.6mm outer diameter and 25.4mm inner diameter.
So if your fork had 25.4mm inner diameter, it's a 1+1/8" fork.


Is it important to have a road bike shoes and pedals or it won't make a difference? I bought a Giant TCR Composite road bike yesterday and since it comes without a pedals i bought a MTB clipless pedals but i don't feel comfortable with this pedals, so should i buy a road bike specific pedals and shoes -as it is a clip pedals- or it is just a matter of time then i will be used to it ?

First, note that if you're new to clip/clipless systems, it takes a while to get used to it.

A lot of non-racers prefer mountain bike clipless pedals (e.g. Shimano SPD) since you can clip in on both sides of the pedal and the shoes often allow the cleats to be recessed (so you can walk around). Mountain marketed shoes generally tend to be more comfortable as well.
An example SPD pedal is:

Note that some SPD pedals also double as platform pedals, so you can use regular shoes.

Road pedals (e.g. Look/ Shimano SPD-SL) have larger support for the shoe but only allow you to clip in on one side of the pedal. An example of SPD-SL is:

However, at the end of the day, the pedal-shoe combination is completely up to you. You could use road platforms, toe clips, mountain bike clipless, road clipless, etc. - do what makes you most happy.

See this excellent question as well for comparison of pedal-shoe systems.


rebuilding/frankenbike query My son (teenager) has a second-hand Zombie bmx style bike - it's designed for kids, but as far as I can see the frame size is the same as any bmx. It needed a bit of messing around with, I've already replaced the wheels, which were fairly nasty pretend mags whose rims deformed whenever the tyres were inflated. What I'm now wondering is - the frame, like a lot of kids' bikes, is bulky and heavy. Is there a any reason why I couldn't transpose everything onto a different frame? Or am I missing an obvious incompatibility?

I love bikes, but as you can probably tell, bmx-s are foreign territory for me!

Unequivocally, yes, you can - it's just a matter of whether or not it's worth it to you.

Without seeing pictures or details: to avoid unnecessary added expense, you'll want to stick with frames that have:

The same head tube diameter, so you don't have to replace the headset
The same bottom bracket shell width (usually 68mm or 73mm), so you don't have to replace it and/or the crankset
The same rear brake mounts, so you don't have to replace that too (V-Brake/Braze-ons lower than the rim, U-Brake/Braze-ons higher than the rim, or cantilever/a hole in the center, disk brakes/two holes on the non-drive side near the hub). However, I'd probably go with V-Brake mounts and replace the rear brake if it has anything but disk.
The same seat tube diameter, so you can re-use the seatpost and clamp


Minimal effort chain cleaning One of the main reasons I eventually give up my bicycle commute in winter is that keeping my bike -mainly the drivetrain- clean despite all the rain/dirt/salt/hail/snow becomes too much of a time suck.

The weather means I feel I have to clean my chain at least every two or three days. But days are short and I have no shed. So on weekdays that means working in the dark under a streetlight in the cold. I know the cleaning is worth it, but after a few sessions with freezing fingers, eyes straining to find my tools I usually give up.

What I am looking for is a minimal routine that will keep my chain clean enough despite the weather.

[edited to add:]
I'm currently trying the following, but I'm not sure how well it will work in the long run:

At the end of each leg of my commute I use my waterbottle to spray the worst of the dirt and (hopefully) all the salt of my drivetrain.
In the morning before I leave I check my chain and, if I feel there is not enough oil on it, I add a drop to each chain roller, turn the crank a few times, and wipe of the excess.

No cleaning (other than the waterbottle) no resting to let the oil seep in.

[edit2, to answer some questions:]

I have full fenders on my bike.
I currently use this lube: http://www.cyclon.nl/index.php?m1=2&m2=9&m3=11&m4=19&lang_id=4 which is supposed to be a wet lube.

[Edit3: what I've done:]

I have switched to an even wetter lube. (this one: http://www.cyclon.nl/?m1=2&m2=9&m3=11&m4=22&lang_id=1)
I got myself a chain cleaner (this one from BBB: http://www.chainreactioncycles.com/Models.aspx?ModelID=4671)
I found a non-automatic car wash. (they are rare here, the first two google maps hits were no longer in business) There I can hose my bike down to remove the worst of the dirt/salt.
I have accepted that I will probably buy a new chain come spring.

I think I'll ride to the car wash every weekend or every other weekend depending on conditions. This takes me, including cleaning my chain and re-oiling everything after the hosedown, about 35 minutes including the 5k one-way ride to the car-wash. Pretty good!

Rain, hail, and snow don't hurt a chain. Salt makes it rust, and dirt wears it out.

Salt: You won't get all the salt out without removing the chain from the bike. The chain is doomed. You can, however, easily delay this till spring with regular application of wet chain lube. A bit of rust won't hurt if you ride regularly.

Dirt: Given that the chain only has to last till spring, a quick clean with a chain cleaner (as suggested by @meager) once every few hundred miles will be fine. 1 minute of cleaning, 1 of re-oiling is enough.

Come spring, splurge on a shiny new chain. If your budget is really tight and you don't want to buy a new chain every year, keep the old one for next winter. When you take it off, give it a really good clean (off the bike), soak it in oil and store it over summer.

However, there are a lot of reasons why a new chain every year is a good thing.


Recommendation for panniers to carry a laptop for daily commute That's available in the UK I've seen this question about Panniers, but as far as I can tell, the Arkel Panniers aren't available in the UK.

Does anyone have any recommendations for a good laptop holding pannier that converts into a backpack or a messenger bag style (I only don't want to wear it as a messenger bag while cycling), and is also readily available in the UK?

I don't want to wear a messenger bag while I'm cycling, as my issue is that my current bag is making my back sweat like crazy.

You could always get a laptop sleeve and slide that into a big enough pannier.

Timbuk2 has a couple pannier options that both have an included laptop sleeve and are designed to be easily carried off the bike. One converts to a messenger bag, the other more of a "shoulder bag". Looks like Timbuk2 has some of their stuff sold retail in the UK, and they also do direct orders with international shipping. I don't have either bag, but I do have a laptop messenger and a couple regular messenger bags from them that I've been happy with.

Their site is a bit of a pain to provide links to, but looks like Basil has a similar kind of laptop messenger pannier. Their site shows plenty of distribution in the UK.

Ortlieb's rear/larger panniers have an "Office" and "Downtown" line that both seem to be designed to accomodate a 15 inch laptop (via a sleeve/insert you purchase separately). Two different mounting options.

What I actually do when carrying the laptop on my bike is either bungee a laptop messenger to the top of the rack or stick a (well-padded) sleeve into a pannier


Shimano Alivio with Sora compatibility I have Giant Defy 3 2012 and I want change handlebar from drop down to straight.
I wonder if I can use Shimano Alivio M430 3-9 shifters with my front and rear Sora derailler. Thanks for advice

Don't know if it helps,... but I use Sora shifters for Alivio rear derailleur (switched bars from straight to drops).

So I would think they are compatible.


My Supercycle chain keeps breaking randomly I have an almost brand new Supercycle bike and for some reason, the chain keeps breaking on it. What could I be doing wrong

You have a low quality bike. The low quality shows as failures in various parts, in your case the chain. An immediate solution would be to replace it (either chain or the entire bike) with a decent quality one. No need to go fancy and expensive, anything that is sold in a bike shop should do the job.


At what speed does Aerodynamics of a bike come into play? Is a more aero bike more efficient than less aero bike at 10mph? At what speed does Aerodynamics affect your speed significantly.

update: "The question is dealing with the minimum speed that a cyclist will notice the effects of a modern aero frame vs a non-aero frame. via @user"

As long as you are moving through the air, aerodynamic drag will account for some portion of total drag. Here is a plot that shows the relative contribution of aerodynamic drag vs. rolling drag on total drag for a rider at constant speed on a flat surface with the given CdA (drag area) and Crr (coefficient of rolling resistance). There is no magic threshold speed at which aerodynamic drag suddenly appears. Whether the amount of drag is important or significant to you will depend on your power and riding goal, but for this example roughly 25% of total power will be consumed by aerodynamic drag at about 10 km/h (or about 6 mph).


LASER bicycle lights Is there any reason there are not yet LASER bicycle lights, given some cars already have them?

It makes more sense in bicycles, has they have not a 12V bulky battery like a car, and are more energy efficient than LED lights.

I am speaking about lights which directly illuminate to the front or rear, not things that project a straight line, or a bicycle or a lane on the floor?

The most important part of a vehicle light is the optics because you want a beam with a precise shape and distribution in order to illuminate the road evenly, without wasting light into the sky or blinding people coming in the other direction.

These optics are very difficult and expensive to design. It is easy to make a circular lens which will throw half the light into the sky and blind people coming towards you. A proper beam, which results in even illumination of the road regardless of distance, has to distribute light in a special way which is very un-even: low power at close distances, high power at long distances, a sharp cutoff to avoid blinding other riders, and it has to have the proper pattern in the horizontal direction also:

This lamp costs € 189 which is quite expensive. These beam shots tell the rest of story. It is very difficult to do a sharp cutoff without wasting light.

Important: beam accuracy depends on the ratio between optics size and light source size. The smaller the light source the better. A tiny point light source would be ideal, and it has to be positioned accurately at the focal point of the optics. A larger light source can work, but the size of the entire optics assembly has to be scaled up proportional to the size of the light source. If the optics size is constrained (ie, you're not riding with a 8 meter wide telescope) then the larger the light source, the more inaccurate the result.

Now, you mention laser lights. The reason these are interesting for car lights is not the efficiency. No-one cares about the efficiency of headlights when the car burns tens of kilowatts just to move. Besides, I found a 160lm/W efficacy figure for laser headlights. LEDs can do that already. The interesting bit is that laser-excited phosphor lights can create a really tiny point source, which is what makes these excellent optics possible.

But do you need that on a bicycle?

If you travel at 250 km/h in a fancy sports car, you'll need a light that illuminates the road very far away, at least several hundred meters. But a bicycle is a bit slower, so most people will be happy with a light that allows them to see, say 50m ahead, maybe 100m going downhill, and that can already be done with LEDs at a much cheaper price than laser.

There is also the fact that an optic that can aim a beam at long distances has to be aimed where the beam needs to be, which means a computer and several precision actuators. Since a bicycle leans in turns there would have to be extra actuators to compensate for that. It gets silly very quick.

Conclusion: even if laser-excited phosphor lights get cheap in the future, their advantage is enabling fancy optics you don't need on a bike, not efficiency. LED efficiency is driven by very strong economic factors (ie, the lighting industry) so LEDs will get more efficient. I don't think you'll get laser bike lights anytime soon.


Is there any builder site for bicycle? Say you want to build entirely your own bike, from frame to ring bell. Is there a site that can help you with compatibility among all parts? Or maybe you just want to upgrade your crank set but you don't know what else you must upgrade (BB? Pedals? Front derailleur?)

I'm thinking something like PC Part Picker or Logical Increments for pc's.

Is there a site that can help you with compatibility among all parts?

Yes

There are sites that will let you pick all of the compatible components for a bicycle.

The following are sites built by people who want to make money selling you a custom bike (these are examples of bike builder apps, not recommendations).

Fanatic.com has a bike builder feature on their website for mountain bikes for a specific set of brands.

Wrenchscience.com also has a bike builder on their website for a variety of bike types and brands.

You can build a bike on these sites and then use the list of parts to purchase from whomever you like.

For an example of a bike builder that does not appear to be tied to a store.
Bike Config is a 3D app that custom builds a bicycle. It appears to be all mountain bikes with a limited list of parts but they hope to grow.

Searching "build a bicycle online" will deliver these and other options.


Can road bumps excite frame eigen frequencies? During my last bike holiday I have happened to ride downwhill on roads which had transversal stripes to mark the approaching of a turn.

The stripes were made with road paint, and were slightly higher than the road plane, so that passing on them makes you feel the bump.

At the speed one can reach while on downhill the repeated "ta-ta-pum" is non comfortable, so I was induced to slow down.

However I was wondering: could it happen that, for some particular speed of the bike, the bump frequency resonates with the frame Eigen frequency leading to potential catastrophic frame failure?

A resonant frequency encountered on a road surface would be for the whole bike system, i.e. frame, wheels, rider etc. The rider is effectively attached to the frame via elements with spring, damping and active control properties (arms and legs). Bumps encountered at a specific frequency might buck the rider off.

Bicycle frames are pretty stiff so any undamped resonant frequencies they have would be relatively high. Certain not at 10 or so Hertz you may get from riding on regularly spaced road bumps.

You assume that all structures fail when excited at resonant frequencies. This is plainly not true, otherwise acoustic musical instruments would self destruct when played. There certainly are structures where resonances can contribute to damaging oscillations of course, but I don't think bicycle frames suffer from this.


Can a climbing helmet be used for biking safely? I have a Black Diamond HalfDome helmet I use for rock climbing.

Is it safe for me to bike with it or should I wear a regular helmet?

They are designed for different things: climbing helmets have more protection against sharp object penetrating the shell from directly above, while bicycle helmets have more protection for a high force hit with a blunt object (the ground, car bonnets etc) from the sides, front and back.

If helmets are required where you live, unless the climbing helmet meets the standards (EN 1078, CPSC etc) required by your country for cycling helmets, (some might, I don't know) you are not riding legally.

Even the safety benefit of wearing a helmet is hotly debated (refer What are the reasons for and against wearing a bicycle helmet?; wearing the wrong type of helmet is an unproductive debate that will have no useful outcome. Probably what will not be debated too hotly is "If you are in an accident, wearing a climbing helmet is safer than not wearing a helmet" and "It's best to wear a bicycle helmet that meets a recognized standard".

I suggest you refer to discussions in related questions such as are ski helmets safe and Would a military helmet make a safe alternative to a bicycle helmet?.


1994 Giant Iguana front sprocket I have a 1994 Giant Iguana.  The teeth on the front sprocket are significantly worn and the middle sprocket is cracked.  Are there replacement sprockets for this bike?

Without more info about the specifics of your crank set it's hard to answer exactly what size you need, but yes, they can be replaced. You will want to know the bolt pattern and bolt circle diameter. What brand is the crank set? Shimano? Maybe add a picture. Depending on the condition of the chain and cassette, it may be wise to consider replacing those too.


Very sloppy shifting on smaller cogs (BSO) I have very few complaints with my BSO, but this is one of them.

My rear derailleur seems to hold the same 'up and down' tension across all the cogs. So when I'm on the first couple of cogs (32 and 26 teeth), the shifting is precise and efficient. But when I move out towards the end of the freewheel, I have to push the lever a long way to make the jump to the next cog, and then pull it back to keep it from making noise.

Basically, the top jockey wheel stays at the same height all the way across the freewheel, which means that when it's on the small cogs, it's hanging well below them, and has to move a long way to get the chain to hop to the next cog.

Is there a way to adjust this, or is it simply a consequence of having BSO-level components?

OK Based on comments - your BSO rear derailler is not following the contour of your cassette, and is ending up a long way from the smaller cog.

It should be like this stylised image:

Doubtless you have some wear on the cassette, and the RD position is limiting the number of teeth that are actively engaged in the chain.

I bet on the big cog you've got 5/8 of the teeth meshed with the chain (~20 teeth) and on the little 14 you might have as few as 3/8 (~5 teeth)  so this accelerates wear, and fewer teeth meshed means skipping errors earlier.

You could try a new cassette and chain, if the cassette appears worn.

The other option would be check the rear derailler and see if you can make it move more diagonally

Another possibility is that your B-tension screw is too loose, or isn't even there.


Road Bike Bending Rear Skewers I'm pretty handy with bicycles, but I'm a little stumped on this one. Have a 90s Cannondale SR800 which is solid other than the back wheel was angled to the left side of the chainstays. Ridable, but you can tell if you try to ride it without any hands. Pulled everything apart back there and discovered that the drive side (right) end of the skewer was bent.

I also double checked and when the axle sits properly all the way in the dropouts that the wheel is aligned as it should be so I'm pretty sure the frame isn't bent.

So I assume the bad behavior was due to the bent skewer. Ordered a new one. Clamped everything down, and realized that the issue is actually that the axle will shift when enough force is applied to the chain when pedaling hard.

I assumed I just needed to clamp the skewer down harder, but the same issue happened and you can hear a pop from the back of the bike when it shifts. I clamped it down a little harder and the axle movement happened again and this time bent the end of the new skewer on the right side.

The dropouts are a slightly weird design where they are angled down and forward at roughly 130 degrees.

My guess is that the bike is missing a washer or something similar on the axle that's causing it not to clamp down properly. Currently the axle is just sitting in the dropouts with no extra hardware and it seems pretty snug in there. The same amount of axle is protruding on both sides of the back hub as well and I'd say each end is covering about 75% of the dropout.

Any thoughts?

I think there's more wrong than you've spotted. Unless there's a chunk missing from the end of the axle or the dropout you shouldn't get any  movement under power or not. Bending a QR skewer is not easy to do, which suggests that there's a lot of force being applied, and it's obviously being applied where it shouldn't be.
Here's a picture of that model, and the rear dropouts don't look unusual at all IMO. I'm not a fan of the 5cm long unsupported rear extension, but it can be made to work (obviously enough):

I suggest looking for cracks in the frame, ideally by getting someone else who can sit on the bike and hold the brakes while pushing on the cranks. Wipe it clean, then get down and look for cracks opening up as they put pressure on the cranks and lean back and forth. The dropouts moving will definitely bend a QR skewer. And shortly dump you on the road, BTW, when the frame breaks. Look especially around both dropouts, but also the whole rear triangle. A seatstay breaking loose at the top could possibly cause this problem too (very unlikely but possible). The fix is, obviously, a new frame.
The other thing to look for is a chunk knocked off the front inside corner of the dropout. If the axle can grind into there under power that could also produce the problem you see. The half-arse "fix" for that is to move the axle right in the wheel so there's more poking out on that side. Which will work after a fashion for a while. The real solution is to replace the frame, and on a bike that old, that really means replacing the bike.

Edit: bringing discussion from comments up into the answer.
Matt says

the drive side dropout is definitely more chewed up (axle can move horizontally about 1mm) than the left side is which doesn't move at all. I checked to see if the frame was bent at all with the string method and it was exactly correct. Couldn't find any cracks either.
How insane would it be to have someone add some aluminum (fill in a little bit of the dropout) and then grind it back out to spec?

The issue is that the frame was heat treated after it was welded together. So when you weld it again you're changing both the alloy and the heat treatment. As a rule what you get is both softer in some places and more brittle in others (Murphy's Law says it will be soft where it's vulnerable to abrasion and brittle where it flexes). Even so, that is definitely worth trying when the alternative is throwing away the bike.
The worst failure mode is likely that dropout breaking off the frame, which will probably shove the wheel into the frame and you'll skid to a halt. So it's relatively survivable as such things go.

A buddy who I would trust on this said that JB Weld there is worth trying

Any kind of epoxy or filler is worth a try because it's cheap and reversible. But those fillers will be softer than even the original aluminium, so they will be ground away faster then ideal.
Another approach would be filing a little off the inside surface of the dropout to make space and gluing a steel plate in place, just because steel is harder than JBWeld. If you have access to basic metalworking tools and advice that's probably a better idea. Gluing steel to aluminium can be done, but use a specialist adhesive rather than generic "superglue".
I think your best bet is the aluminium welding solution. Remember that the seat stays are thin-wall hollow tubes and discourage the guy from welding to them, maybe focus just on bulking up the dropout. I'm not an aluminium-working guy, so I'm just suggesting that because I've seen some pretty ugly "add lots of metal" fixes that break because they're transferring stress to places that are not designed for it.


How to remove play in cantilever pivot point? I have been working my way through issues with noisy front cantilever brakes. After running through many different ways to solve the issue including new pads (Kool Stop Dura2 Duel Compound), setting the toe in and cleaning the rims.
I now believe the noise is being generated by the play in the pivot point of the cantilever arm. It is not possible to tighten the bolt any further so there will need to be a washer or shim placed in here.

Has anyone had any success in removing the play from the pivot point?

The bike is a cyclocross Kona Jake 2012.

Before I add my two cents here I'll mention that this post is rather old to be unanswered.  If you figured this out already write an answer and choose it as "the answer" so it doesn't show up as unanswered and others can learn from it.

So, by "play" you could mean front to back (as in the length of the post/bolt) or around the bushing (as in a difference in the diameter of the post and hole in the brake arm).

I just checked the oldest canti-brake bike I've got (from the 1980s) and there is no play in either sense described above. So I would attempt to solve that problem next as the things you've already tried are all good, especially your choice of pads.  You might want to try the salmon colored rather than the dual compound though. They are the better of the two compounds for braking but they wear out faster.

If it is the former type of play I agree with the advice of @Daniel R Hicks.  If it is the other and you don't have replaceable canti-studs you ought to replace the brakes (arms) themselves. If there is play when they are at rest they will shimmy and shudder when braking. If there is play due to the strength of fork then you need a brake booster as suggested by @armb.

Another question for you - are both the brakes and levers original to the bike or have you replaced either? Mixing canti and v-brake components will cause problems but I haven't heard of noise being one of them.

A final note - take heart! I have a friend who is a fanatic about bike maintenance.  He was a bike mechanic, but now is an engineer in aerospace and his bike stuff is rather high end.  Last year he adjusted and replaced everything and never found the source of the noise.  He replaced the bike instead!


Is it a good idea to get a narrower front tire and a wider rear tire on a road bike? I am currently running Continental Grand Prix S 4000 in 23-622 / 700x23C front and rear. I am about to buy a new set of tires for my road bike and am fancying a smaller tire for the front and a wider tire for the rear. Actually Continental offers such tires as a set (GP attack and GP Force). Also note, that Motorcycles usually have a wider rear tire to support quick acceleration but still have dual disk brakes in the front to maximize brake force.

I tend to ride fast in a traffic situation where the majority of bikes travels slower. So I am often underestimated and have to brake sharply. While panic braking my bike tends to pulling, which I have learned to manage. I suspect a wider tire to reduce pulling, by developing more grip in low load situations. The weight balance gets shifted to the front, when breaking sharply and therefore the front tire does not skid even with much break pressure. The back tire on the other hand does only carry little weight and skid with the same brake pressure applied.

I am also facing periodical flat tires with a frequency of 1 per 10 weeks or so on the rear tire. I suspect a wider tire to pick up fewer glass splinters, by reducing the pressure. The rear tire carries the main load while non-braked riding and a wider one distributes the force to a bigger surface area thus reducing the pressure.

Update

Thanks for all the input. Your answers have helped me a lot in finding my decision.

I'm currently running the Conti Attack/Force combo on my road bike. I have previously run both the GP 4000, and the Schwalbe Ultremo ZX on the same bike.

The concept behind the Attack/Force is that the slightly wider (24mm) rear tire will allow just a bit more comfort, and the slightly narrower front tire (22mm) will be a touch lighter with more reactive handling.

I feel a difference in comfort, but I can't say the handling was noticeably different. Of course, the GP 4000 was pretty stable to begin with, so maybe that's a good thing that I don't notice a change.

They do feel a bit more stable in a corner, and I feel like the rubber compound is a bit stickier. They say it's the same Black Chili compound used on the current GP 4000, so maybe that's psychological.

I can say that the comfort aspect is worthwhile, and there is nothing I have bad to say, so why not try them. A set (here, at least) is the same price as a set of GP 4000's. No loss, at least, and a bit of gain on the comfort side.

@DanielRHicks commented that you might need to worry about braking power or traction. I've had no issues with braking performance, and these are a pro peleton tire. I don't see any issue there. I've also had no issues with flats on the tires, but then, I didn't have with the GP 4000 either.


How do you deal with flats in the winter? I was lucky last winter I went the entire winter without getting a flat.  I attribute it mostly to:

sharp items on the road being hidden under snow and ice
less agressive riding resulting in no blow out flats

I am curious how other people deal with flats in the winter.  Although I always carry a spare tube and CO2 I don't think I would be able to change a tire with bulky winter gloves on.  Changing a tire gloveless is also not really an option.

How do you deal with flats in the winter?

Prevention (good tyres, good inflation, regular checks).

For most rides, walking isn't an option, while I do sometimes run my commute, I use the bike because generally I want to get home. So a spare tube and CO2 is obligatory - with practice and a decent place to work (which can't always be guaranteed at the side of the road) I can change a tyre in less than five minutes.

In colder weather (at or around freezing) I ride with thin liner gloves inside cold weather gloves and I find I can change a tyre with them still on; this both keeps the fingers slightly less cold, but also a little cleaner.

If you're operating in a climate that regularly sees weather that's cold enough that five minutes without gloves is not an option, chapeau. But I think I would be looking for run-flat options (e.g. goo) and some way to get me home quicker than on foot!


How to fix a seized V-Brake arm? I was checking the brake pads on my bicycle and I noticed one of the arms seems to be seized:

It's this arm (I hope that's the right technical term). It will move but it's very stiff and when I use the brakes the other arm is doing all the work.

I did a search of the site and this seems a common problem but I couldn't find a simple explanation of how to fix it. Do I just undo the hex bolt at the end, apply grease and hope I can put it all back together? If so are there any I wish I hadn't done that pitfalls to avoid?

If it's relevant this is a town bike, a hybrid, rather than a true mountain bike so it's not a performance machine.

V-brakes aren't too complicated but there are a few things to watch out for:

you need quite a lot of torque to undo the bolt
the spring may make it fall apart sooner than you expect - hold on as you undo
make sure all the parts go back in the right order - take care as you dismantle.  Work with a tray underneath to catch anything that falls.

Once you've taken it to bits, clean all the muck and loose rust off the parts, the grease and reassemble. The bolt should be tight. You'll probably need to do the other arm as well, and may need to adjust the return spring screws. Obviously don't get grease or greasy hands on the pads.


How do tire pumps work? How does a pump push air into the tire and take in air from somewhere else? Why doesn't air spill out from the edges of the hole where the long thing goes in and out of the tube? I'm a complete noob to pumps.

Someone made a nice video.

There is a rubber seal around the piston which makes it air-tight with the inside of the cylinder. Then there are two check valves which only let the air flow in one direction: one to allow outside air in when you pull (but not let is out when you push), and one to let the high pressure air inside your tyre (but not let it out).


Snapping master links I have a 3x9 gearing installed and I've noticed that the chain broke, by failure of master link, twice within 25 km. Interestingly, the failure was perpendicular to the direction of motion:

What am I doing wrong?

Given the fact that the outer plates are deformed in the same direction, I believe you're probably cranking on the pedals way too hard when you're shifting.

Are you waiting too long to downshift in the front when starting up an incline? Are you standing while shifting? Are your forcing the front derailleur by putting excessive pressure on the shift lever? Any one of these factors are going to increase your chances of busting a chain. The bigger person you are weight wise, the more you have to be careful of these things, although you can weigh under a buck and still trash chains if you don't give them some love.

Keep in mind that when shifting you're putting side load on the chain links and really torquing them in a way they don't appreciate. You need to let off a little when you make any shift, up or down, front or rear. Beyond saving your chain from breakage, it will also save your drivetrain from premature and excessive wear.