What is the effect of changing length of crank arms? There are some length options for the crank arms - like 170mm, 175mm.
What is the difference for the rider? In which way does it effect the commute?

Tried looking at Selecting the right crank length, didn't get a comprehensive answer.

If you keep the rest of the bike the same a shorter crank gives more ground clearance at the bottom of the stroke, and that's going to be the main thing most people notice. You're unlikely to notice a change in power output unless you're shorter than, say, 1.7m, which would put you firmly on the down-slope of the power curve (ie, the part where longer = less power). You may notice a change in comfort or pain levels due to the increased joint articulation from the longer cranks. IMO most people would be better off switching from 170mm cranks to 160mm or 165mm cranks.

At the high performance end the power output varies in interesting ways. Since power = torque x speed, and torque = force x radius, a longer crank means more torque but also more leg movement to produce it. And vice versa for shorter cranks. In practice most athletes have a fairly flat relationship between average power and crank length in the range 150-170mm, but it's also something that is little studied.

A study by Martin (2001) suggests that it doesn't really matter:

  Power produced with the 145- and 170-mm cranks was significantly (P < 0.05) greater than that produced with the 120- and 220-mm cranks. The optimal pedaling rate decreased significantly with increasing crank length, from 136 rpm for the 120-mm cranks to 110 rpm for the 220-mm cranks. ... The optimal crank length was 20% of leg length or 41% of tibia length. ... Even though maximum cycling power was significantly affected by crank length, use of the standard 170-mm length cranks should not substantially compromise maximum power in most adults.

I found some thought experiments and this interesting summary/bibliography. (edit to add) Ian Sims at GreenSpeed has long had an interest but I can't access their site right now, so here's an A2B magazine post. It's worth noting that Ian has changed his position completely, based on evidence that he mentions in that article. Previously he was a fan of long cranks, now he's suggesting that short ones work better.

Edit by mattnz replacing Mσᶎ's link: PowerCranks have an interesting sales push with useful links and discussion.  They also provide test results showing advantages of short cranks. Apart from being benificial to people with poor flexibilty and knee problems, short cranks provide major racing benefit from improved aerodynamic position. They also discuss why its a myth you need long cranks for climbing.

(moz again) My experience is that shorter than conventional cranks work better than I expected and reduced my knee pain somewhat when riding hard (long tours or fast commuting for 40+ km/day). I'm 1.8m tall and ride 155mm cranks because those are the shortest I could get without paying a price premium. My partner is 1.5m tall and prefers 145mm cranks. Going up to the 165mm cranks on my load bike feels like a significant jump, but I haven't tested them because I don't have access to a power meter.


Front tire/disc brake question Is it normal my disc rubbing with no tightened QR and to stop when I tighten it? Or it should not rubbing both times...?(Because now when I tighten the QR the disc starts rubbing in one of the pads. It is not rubbing when QR is open) Also is it normal my front tyre to be closer to one of the legs of the fork(not centered) when wheel is all the way in the dropouts?

The QR system was designed before the advent of modern disc brakes, and as such there are a few peculiarities such as the one you are experiencing.  You should only  worry about rubbing after clamping the QR.

No fork or drop-out is perfectly set.  When you put the wheel in the dropout with the QR open, there likely be a bit of slack in how it fits in the dropout.  This goes away when you tighten the QR.   Depending on how your caliper is set this may make rubbing disappear or if you are unlucky, appear, depending on the final position of the hub relative to the dropout after clamping the QR.

Note that it is also important to properly center the hub in the dropout before closing the QR, otherwise the hub can get positioned off center.  As mentioned this can cause rubbing or worse if you set the caliper when the hub is not properly settled in the hub, you will likely experience rubbing the next time you open and close the QR.

These problems are inherent to combing the QR system with the tighter tolerances demanded by disc brakes.  I suspect this was one of the drivers  behind newer standards such as thru-axels, which should be more consistent when fixing the wheel to the dropout (although I can't confirm as I don't have practical experience with thru-axels yet).

The practical solution is to carefully center the hub before clamping the QR (e.g., by placing the bike on the ground then opening the QR,  allowing the wheel and hub to center, then clamping the QR).  if you get rubbing the you will likely need to reset the caliper position or back the pads off.   The goal is to set the caliper against a stable wheel position that you can recreate the next time you open and close the QR.


Big crack on my Schwalbe Marathon Plus tire Is it still safe to ride the below tire, or should I replace it?

you can carefully prize the crack apart and see if it is just the rubber that is damaged or if it goes through to the casing.  Your main focus should be where it extends to the sidewall as the tread area is protected by the thick rubber layer on a marathon plus.
If you conclude that it's only the outer rubber layer, i'd be happy running it as a rear tyre for shorter/local rides.  I'd replace it if i were going on a longer or more remote journey.
If there is any sign that the actual tyre carcass is damaged then it is not safe to ride and should be replaced.


Are there any sub $100 gps devices that can export a gpx file I am looking to ride with strava, however as a teenager I receive very little to no money regularly and I do not have a smart phone. I would like a device that tracks my ride via gps and exports a gpx file so I may upload it to strava. It must cost less than $100 AUD.

Instead of an actual GPS device, I would recommend buying a used smart phone, (The Strava app itself only works on either iPhones or Androids). A "Nothing Special" used smart phone you can usually find for maybe 40 bucks, depending on the model and brand.

Download the app and just take the phone with you wherever you ride. It's not a fancy system, but it works. This is the method I use now.


Bolts for Fox Float RP2 I saw my bolt was loose on my mountain bike, so I turned back home, but ended up losing it along the road. I had to walk the bike home because my rear shock (Fox Float RP2) to my bike (Gary Fisher HiFi Deluxe 29er). The shock is connected by two bolts to the bike. I am missing the bottom one. Does anyone know where I can look up this part for purchase or if it is a common part that I don't need a specific one? I've learned lots about this bike just from breaking it so many times, but I can see I have plenty to learn!

Shock bolt size and threading can vary a fair bit. At least they also tend to be easy to find. I believe that takes an M6 x 1.0mm bolt. Probably about a centimeter long. If a 5mm allen wrench is the right size, I'm probably right. It could also be an M8 x 1.25mm, or even M8 x 1.00mm. All of these can be found in any bicycle shop and most hardware stores. I'd recommend dealing with it in person though because online shopping / shipping is slow and you'll get very frustrated if you get it wrong.


Cracked chainstay weld -- now what? Yesterday while riding my Surly Ogre around town I noticed that it was making a weird metallic popping noise on the left downstroke. When I got home to take a look I was rather surprised to find that the right chainstay had broken completely free of the dropout at the weld (see pic at bottom).

The frame is out of warranty, so my options seem to be a) buy a new frame or b) try to weld it back. I know nothing about welding, and there is no frame builder in town, but a local machine shop said they could sandblast and TIG weld it back together for $120. My question is a) is this safe and b) is it worth it? The frame set me back ~$440 when I bought it new 5 years ago. So the repair option saves money, but I'd want to be sure the same problem will not arise again in a few years. Also I'm unsure whether it can be rewelded sufficiently strongly.

More generally, what I can do to prevent this from reoccurring? I weigh 175lbs, I've never crashed the bike and have used it exclusively for commuting and ferrying groceries. Back when I built it I sprayed the inside with cosmoline, and it's been kept in a dry climate, so frame rust also doesn't seem like an explanation. I'm puzzled as to how such a beefy bike (to quote Surly's own marketing copy) could fail so catastrophically in a fairly short amount of time.

Get in touch with Surly even if it out of warranty. The worst they can do is say no, and even if they won't fix it, they should be able to offer advise on the the best way to proceed. They live or die based on peoples perception of the brand, so have a vested interest in helping you resolve this kind of problem.

Any competent engineering shop should be able to make a reliable repair on Cromo. frames.


Fat or Skinny Tires for Winter Riding? Fat or Skinny?
I think the arguments are as follows:

Fat: You can float on top of the snow and you don-t have to go through it.  You have a larger contact patch with the ground.
Skinny: Will find it's way through the snow to find some pavement to grab onto.
Studded: Works great on ice but has no effect on snow/slush/other stuff.  (Note never tried studded tires so just speculating).

Conditions of Interest
I am interested in traction on:

Cleared city streets
Uncleared city streets

Uncleared city streets where cars have gone through and made deep ruts

Slush

Slush that has re-frozen into deep ruts
Ice patches

Note: All pictures are take from google images.
Background
I have a short commute through part of Ottawa and run lots of erands on my bike.  When it is snowing and when the roads don't look good I have several routes that are only slow residential streets so I can stay away from people yacking on their phones.
I would also like to start doing some winter trail riding.
Here is the historical weather data for Ottawa.

I live in a country which doesn't have snow, but have recently gone to Europe (Czech Republic), where I could "understand" a bit how these things work. Also, my background is with mountainbike on any sort of offroad terrain, including mud and beach sand.

That being said, I think your most concern would be the grooves/ruts from refrozen snow on roads, much similar to sun-baked mud on some fire-road tracks, but much more slippery, and flotation, much similar to riding on loose gravel or sand (I am speculating a bit).

I can see a lot of studded tires are also slightly pending to the knobby-fatty end of spectrum. With wider tires (no need to be super-wide), you can use lower tire pressures to float better and yet don't get pinch flats. Also, with wide AND knobby tires, you can much more safely ride diagonally through ruts without the danger of your front wheel getting caught and you fall.

So, that's my (also a bit speculative) impressions about effects of tire width, tread-pattern and inflation pressure.

Hope it helps!


Switching to touring bicycle: Performance considerations I'm using a road bike more than 2 years for holiday tours and commuting.

Merida Scultura 903
Shimano Tiagra groupset (50-34, 12-28)
8-9 kg
700x23 tyres

Now i have plans to switch to touring bike. Expected:

VSF TX-Randonneur
Shimano 105 groupset (50-39-30, 11-43)
14-15 kg (with tubus etc)
700-43 tyres

I am really wondering about performance / speed change? Does anyone experienced this kind of process? Typically my speed is 30/32 km/h in flat roads.

There are a lot of factors that go into your speed and efficiency, and this switch touches several of them:

Rider Position: Typically, a bike with touring geometry will have a slightly longer wheelbase, and lower bottom bracket. Along with other geometry tweeks, the result is that on a touring bike you are likely to be in a slightly more upright position, increasing your wind resistance.
Weight: As in your example, touring bikes can be 2x heavier or more. This doesn't make as much difference when you are already up to speed and on a flat road. Weight makes a huge difference in acceleration and climbing.
Rotating Mass: Some portion of that additional weight is located in your wider and heavier tires. This increases the rotating mass of your wheels and will also have a negative impact on your acceleration.
Racks, Bags, etc: Having panniers, handlebar bags, and other equipment attached to the bike, in addition to increasing the weight, will act like small parachutes and slow you down.

With all of those factors it's difficult to give you any kind of narrow estimate. I can tell you my experience, switching between riding a carbon-fiber racing bike with a small backpack, and a steel touring bike with one or two panniers attached. I find that over a 13 mile urban commute (relatively flat, but with a large number of potential stops) I am 15-25% slower on the touring bike. For me, much of that is a result of starts and stops (the acceleration effect mentioned above.)


Outboard bearing bottoms bracket (hollowtech II) - assessment of wear and lateral play, lifespans & when to replace? I have a road-version hollowtech II bottom bracket (shimano 105 model - BB-R60). over the last couple of days i noticed a very slight clicking feeling as i pedalled.

removing the crankset i find that the left-hand side of the BB cup feels smooth and snug with no play. however the right sided cup has a very small amount of lateral play.

i last replaced the bottom bracket less than six months ago (at which point the old one had developed a significant amount of play after around 1000miles) and i would estimate that the new one has only done around 400miles since. These bottom brackets are non-serviceable, sealed units.

Googling suggests that it's not uncommon to get through these pretty quickly,  although this does seem odd to me as i thought that outboard bearings were supposed to be more durable and I have hardly ever had to service, never mind replace, the older BBs on my older bikes.

i'm about to leave in tour again  (around 3000 miles) and I'm wondering how to interpret this small amount of lateral play

will it definitely get worse, and if so how quickly?
should i just replace it now, or should i take another one with me and replace it when it has developed more play?

i'm also worried that this relatively new bottom bracket is already showing signs of wear.

is this indicative of me doing something wrong during installation and/or usage?

it's worth noting that although the first bottom bracket came with the bike, i did replace the crankset a few hundred miles before  before it started to show play so feasibly i could have done something wrong then; i could have possibly overtightened the plastic pre-load screw on the crank. the second BB didn't have an ideal installation as i did it at the side of the road on tour and there was a tiny tiny amount of drizzle, but i don't think i overtightened the pre load and if any water got into the shell it was only a minute amount.

as it's a touring bike it  has also had a fair amount of use in the rain and with heavy rear panniers and the occasional rough road.

is this a normal lifespan for these BBs? i.e do i need to be thinking replacing the current BB and taking another one or two spares with me for a 3000 mile trip? so far my BBs are looking like their average lifespan is going to be around 1000 miles and i'm planning on cycling 3000 over 3 months...

That there's some amount of play you can feel through the black plastic shield in one of the bearings with the cranks out isn't necessarily a big deal. What you're looking for is the quality of the adjustment you can get out of it with the cranks on. If you're forced to either have it grindy/frictiony or have play or both at the same time, that's a BB that needs replaced.

Broadly speaking, yes you seem to be wearing them out on the fast side. Your description of the issues you're having somewhat suggests not enough care given to keeping the bearing adjusted. You shouldn't have to mess with it all the time, but every once in a while on a Shimano outboard BB to be sure. You're trying to always keep it slightly preloaded. Another way of saying it is as loose as possible but with no play. Too little or too much preload will trash the bearings.

Chronically running through these BBs, especially despite ones best efforts with adjustment, can also suggest a shell that needs facing and chasing to get better bearing alignment.

Outboard BBs, the cheaper ones in particular, really aren't all that durable compared to high quality square taper cartridge BBs. I have a BB-UN72, Shimano's nice but modestly priced upper end square taper unit, with thousands of miles on it in all weather conditions and over 10 years old that's still utterly perfect. No outboard BBs do that that I'm aware of.

If you're doing high mileage touring then just getting a King or Phil along with making sure the shell is well-prepped would probably make some sense. What kind of mileage you get still depends on you and the conditions you ride in, but they are more robust. I'm also a big fan of the Enduro replacement bearing kits for Shimano outboard BBs, because they replace the bearing with a larger and more durable cartridge by getting rid of the black top hat seal and putting a different kind of seal in its place, but the catch with them is you more or less need a special tool to install them into the cups. I've observed them be a good solution for folks having trouble with tearing through BBs though.


How to wash a hydration pack (not resevoir)? What's the best way to wash the pack part of a hydration pack (not the resevoir/hose)? Is it just like a back pack: cold water and a little detergent with air/tumble dry low?

Here's what I found from Dakine (brand I have), guess I should've trusted Google first!

  DAKINE Pack Washing Instructions

  We recommend washing your DAKINE backpack by hand in cold water with a mild detergent and soft bristled
  brush. If hand washing is not going to do the trick, the second option
  is to use a "front loader" washing machine. This is better because it
  has no center post for straps to catch on. There is still a chance the
  straps could catch so place your pack inside a pillowcase or mesh bag
  before washing. Wash your pack in cold water with a mild detergent on
  gentle cycle, Do not bleach your pack. Hang to dry in a warm but shady
  place, the sun could change the color of your pack. Switching the pack
  from inside out to right side out throughout the drying process is the
  best way prevent mildew. Damage caused by washing packs or bags will
  not be covered by warranty.


Multiple flat tires on front My new bike is a Giant LaFree (electric pedal assist) with 26 x 2.35 tires. The tires are CST Metropolitan Palmbay.
I have had multiple flats on the front. The leak is always on the inside of the tube in the same place, where the ribs are.
My bike shop sells me Sunlite 26 x 1.95 - 2.125 tubes. I have changed the inner rim strips to cloth ones, I run the tires at 60 psi (recommended on the sidewall is 22 - 60 psi).
I'm not sure what to try next.
Thanks very much,
Robert

The Sunlight tubes I was using have a "ribbed" area near the valve stem. Patches just did not hold in that ribbed area.
Inside the rim no sharp areas or spokes protruding, but I added an additional cloth rim strip and a Continental brand tube purchased from a different shop.
It is holding for now, although this problem sometimes doesn't show up immediately.
Here's hoping it is a good fix.

(later) I am happy to report that changing to a different brand of tube (continental) and adding a second rim strip has solved my problem of multiple flat tires.


Useful and accurate mapping websites: United Kingdom What are your favourite regional online websites or blogs relating to mapping or routing that you find useful and accurate.

See also: What are the most useful or interesting cycling-related websites or blogs?

Please vote up or down based on the accuracy/usability of these services and post one website link at a time.

CycleStreets
CycleStreets is a UK-wide cycle journey planner system, which lets you plan routes from A to B by bike. It is designed by cyclists, for cyclists, and caters for the needs of both confident and less confident cyclists.
The service looks to be free, however, funding issues are causing the site's development to be slow, and they accept donations.
The site is currently in beta, and has gaps in coverage. There's an iPhone app for the site, and an Android app was in development last year.
The most useful feature, the Journey planner provides information you would normally get from any free mapping service, turn-by-turn directions, journey time and distance.
It also gauges the quietness of the route based on how much of the journey is based on cycle paths and roads, provides an elevation profile and the ability to import your journey to Google Earth or export it to a GPS device


Switching from straight handle bar to drop down - which dual control lever would fit? I am currently looking for ways to modify my bike.

I do have a straight handlebar equipped and I‘d like to switch to a drop down road bike handlebar. My drivetrain is built mostly from Shimano SLX parts

MT600 36/26 Crank (2S)
SLX M7020 Front Derailleur (2S)
SLX M7000 11-42 (11S)
Deore XT M8000 GS Rear Derailleur (11S)
BR-MT200 Disc Brake
SLX M7000 Shift Levers

I'm  having troubles figuring out which drop down brake shift Levers (aka dual control lever) from the Tiagra or Sora series could work with those parts (2x11 and disc brake). Is there any possibility at all upgrading the shift levers without changing anything else in the drivetrain? I‘d like to stay with Shimano parts, if possible.

Kind regards

What you are proposing to do is basically impossible. There is no documented compatibility between Shimano mountain and road groupset components.

The derailleurs have different actuation ratios (how far the cage moves for a given length of cable pull). MTB and road cassettes have different sprocket spacings. I've not read about anyone experimenting with Shimano road levers and MTB hydraulic brake calipers but I'd bet they are not compatible either.

You cannot  replace the entire drivetrain and brakes. An 11 speed cassette may not fit on a MTB freehub body and a road crank won't fit in a wider MTB bottom bracket shell, and if you are contemplating buying a whole now groupset, just buy a whole new bike!

Another reason to not attempt this is that flat bar bike frames typically have a longer reach, as the distance from the head tube to the flat bar grips is shorter the the distance from the headtube to the hood or drop hand positions on a drop bar. Flat to drop bar conversions typically need a very short stem which can negatively affect the steering.


What types of mountain bike handle bar grips are available and how to they affect comfort and handling? This question has been floating around in my head for a while, mainly because I don't know anything about grips (edit to resolve confusion:covers for the part of the handlebar you hold on to).

Are there different types of grips available for mountain bikes?

Do different types of grip affect handling or comfort?

Which grips you get for a mountain bike is mostly a matter of comfort and personal taste.

In terms of how they attach to the bike, there are grips that glue on and grips that screw on. They're exactly what they sound like. Locking grips (that tighten onto the bars with an allen key or a screwdriver) will avoid the grips twisting over time.

You can also get "ergonomic" locking grips. I had a pair of these and found them quite comfortable, and again, this is a matter of personal preference. (I also found that they reduced fine control just a little bit.) Some even come with smaller barends built-in.


Looking for a first race worthy road bike - What should I look for? I am a runner and have been getting into biking just to add some additional flavor to my workout schedule and racing.  I am wondering what I should look for when purchasing a new road bike.

Is the bike manufacturer the largest determiner?
Are the components what I should worry about?  If so should I only buy SRAM or is Shimano just as good? Are there other brands to consider?
Is there anything about the wheels that could set one road bike apart from another?
Other than a carbon frame is there anything else I should look for in the frame? (Yes, I understand that it should fit my body.)
What else should I consider when looking at buying a race worthy road bike?

Budget:  I plan on spending about US$3k or less.

Edit-  Just as additional information I bought a Specialized Tri-Cross that I use for commuting, rougher roads, pulling kids and joy rides.  I am looking at doing some 50/100 milers and a 550 mile relay so although unexperienced I want a good racing bike.  Also due to the spouse factor it is easier to buy one $2500 dollar bike then get a starter and upgrade latter especially since I already have an all around bike.

My recommendation is to buy a used bike on Craigslist or eBay first. Many people will vehemently disagree on the best manufacturer, component group, frame material, etc., but the best advice I can give is to buy a cheaper bike that you can use until you decide upon what you actually want. This is doubly important because the things you think are important to you in a bike right now will likely change within a month or two of actually riding.

With that said, my advice is to ignore the manufacturer. Go with a Shimano 105-level or equivalent groupset. SRAM Rival/Apex or Campagnolo Veloce are similar. Campagnolo parts are harder to find (in the U.S. at least), so I'd lean slightly more towards SRAM or Shimano. Try both systems out, and decide which you prefer. Regardless, go with an entry-level groupset. There's little advantage to an expensive one for a novice rider.

Ignore the wheels. Whatever wheels come on the bike will be good enough to get you started and they can always be upgraded later. And don't get caught up on carbon versus aluminum versus steel. Whichever happens to be on the bike you like best that's in your price range will suit you fine. You're just starting out; buy expensive things only after you've been on the bike awhile. Chasing performance with expensive parts is a fool's game. The engine matters much more than the bike does.

Last, get fitted and make sure you're buying a bike that's well suited towards your body. A bike that doesn't fit will make you uncomfortable and hurt your performance.

And don't feel like you need to spend the full $3,000 right out of the gate. $1,500 now leaves $1,500 left over when you decide cycling isn't for you. Or $1,500 for upgrades when you decide you'd rather do nothing but ride and know exactly what you want. The difference between a $1,500 bike and a $3,000 one is probably less than you think. Again, the engine is what matters.


Shimano rear hub body compatibility My free hub body has cracked and im looking to replace it. I have discovered it uses a 14mm hex key to remove. I cannot find a freehub body for sale that matches m785.

Will a "m760-m765" body fit my "m785" hub?

This Shimano tech doc has the relevant part numbers for you.

Y3CZ98040, I think. You may want just part of it though.

It also has a handy interchangeability table, that tells me a freehub body from an M985 or M775 would work too, but might be the wrong colour.

You can look up more here.


How to install geneticbikes.com's chain tug to horizontal dropout with anti-rotational washer and hub gears? I have 8 speed Shimano hub-geared bike. When I place the chain tug by geneticbikes.com, the black tud does not fit into the dropout. According to the thread, here, I can use one chain tug to the right without serrated anti-rotational washer and one anti-rotational washer to the left.

The tud does not fit the dropout. I cannot understand where it should be in some hole but cannot understand the mechanics. What is the tud for?

You can see there the anti-rotational washer, being not round while the chain tug is round.

I am unable to find the right position to the chain tug, apparently the black tud behind in the way. I tested and the tug is of the right size to fit the line but it is very hard to find the right position without tilting the chain tug, not found any position yet (not sure whether I need to round the tud to fit it.

[Update] After filing, how to protect the frame from the tug's screws? Tug on the right (chain's side) and the anti-rotational washer on the other side (recommend on the link below, not sure whether it is enough to stop the hub rolling).

You can see how the screws make bad to the frame, how to protect it?

...and here is the picture on the right side, the anti-rotational washer is on the left side. The right side has no anti-rotational washer -- a problem? The fender screw is on the way to put the tug on a very good position, could the fender be placed on the same screw as the rack?

Further information

same question but with incomplete answers here
moz explaining chain tug here, to protect the soft aluminium frame
chain tug to solve a chain slippage problem here

The extra stud would usually sit in the dropout slot and help align everything, but your dropout runs the wrong way for that so the stud is just an annoyance. File it off and things will work much better.

If the raised/recessed circle on the front of the tug is not big enough to accept the nut on the hub you may have to file that as well. It's visible in the bottom photo above.

update: you will probably be ok with only one antirotation washer, but ideally if you can get the tug in between the frame and hub so you can put the washer on the outside that would be better. Remember that the tug is now taking the force from the chain so the nuts don't need to be done up especially tightly. So you don't need full thread coverage on the nut.


Leaving lock on the parking rack - is this rude? We have a bicycle parking rack near the office building. It's rather large: for about 30-35 bikes.

Someone has left their lock (chain or whatever) locked around one part of the rack.

So, I've got two questions:

is this rude, or it's just me thinking this way?
can I park my bike on such a place if there are no other options?

Whether it's rude is a matter of local custom. Whether you're offended by it depends on your flexibility and sensitivity

Often, we cyclists can become a little over sensitive, after having to defend ourselves from car doors, pedestrians, cars, trucks, laws that don't take us into account, police who have a ticket quota, and even other cyclists.

Relax.

The person who left it there is just trying to save themselves the trouble of carrying it every day.

And yes, you can still park your bike there. Of course they may think you're rude then, so I'd only park there if it was the last position available.


Making panniers out of canvas map bags -- how to seal after the build? I'm planning to make my own panniers out of a set of army map bags -- these are small bags, about as large as a small front pannier, with a rigid back.

The hooks I'm planning to use attach to the bag with two screws and nuts. I'll have to drill or punch a hole in the canvas and packing to get them to stay. How can I seal the holes so that the bags will stay fairly water resistant?

(This is a bit of a test question -- will the board cover DIY-style topics like this? It is a real project I have going, though.)

I assuming you are going to put some washers on the inside of the bug so the bolt/net holds well.

I would expect silicone sealant under the washers (on the inside of the bug) and the clips combined with a rubber washers between the head of the bolts and clip and the inside washer and net would do the job.

End of bolt
Rubber Washer
Pannier clip
Silicone Sealant
Bag
Silicon Sealant
Metal Washer
Rubber Washer
Net

However after saying the above, as the clips will be on the inside of the bugs, you will have to be in very strong rain before they leak, you may well find you have other leaks.   A simple small waterproof rucksack liner inside of the bag may be the best option.


Can I use an 11-32 cassette promoted for MTBs on my trekking bike with Shimano Acera rear derailleur? I need to replace my cassette but assortment is restricted atm.
Can I use the following cassette on my bike?
https://www.sram.com/en/sram/models/cs-pg-950-a1
It's an SRAM PG-950, 9 speed, 11-32T. With regard to those numbers it should be fine on my trekking bike. But what confuses me is that it is explicitely promoted for MTBs. Is that a deal-breaker or irrelevant?

All common 9 speed cassettes use the same freehub body. Also, trekking bikes normally use MTB parts, so there is no problem there. The Acera line is an MTB line. The manufacturers normally only distinguish (with some exceptions) road/MTB/urban and other bikes like hybrid, trekking, gravel, cyclocross take many components from those lines with only a few specifics.
Just check that your Acera rear derailleur actually allows this 11/32 range, but it should. All should be OK.


Road Fork: Curved vs Straight? I found a frame I'm interested in building up, but it doesn't include a fork.  So I've been looking for carbon 700cc forks... with disc tabs.  I've found a few, but ran into a new dilemma - curved vs straight?

The frames I'm looking at are cyclocross/touring.  I wouldn't think 29ers are into rigid front ends.

Any reason to choose one over the other - brake chatter, bump suppression?

For a carbon-fiber disc fork the difference is almost certainly purely aesthetic. Both curved and straight forks will be designed around equivalent rake values, so the direct handling and performance will be identical.  The only other difference between curved and straight blades - mostly discussed in terms of standard steel forks - is a minimal amount of shock absorption, and much of the distinction there will be excised by the additional reinforcement required to handle the stresses of a disc brake.


What's the quickest "boost food" whilst riding in a fast bunch? I am starting to ride with a bunch of cyclists doing on average 40 to 50k.
My personal average is around mid 30s to 45k/hr.
Aside from proper training, exercise and leg muscles, what food do you recommend to give you a quick energy boost to be able to keep up with the bunch?
I was told Mars Bars are quick energy sources, but high in the bad stuff. Any other more natural recommendations?
Thanks

Some personal thoughts/opinions:

If you're not riding much longer than an hour or so, you might not need much. Perhaps a sports/electrolyte drink that contains sugars will suffice and be convenient.
I use mainly cheap gel bars for a sugar hit, but they get quite boring and eat away at your teeth. Flapjack, oats, etc are good for a bit of variety but perhaps more appropriate for longer rides as they release energy slower.
Cereal bars can be quite dry and difficult to get down especially if you're a bit dehydrated.
Something with caffeine may be of benefit (caffeine on its own doesn't have energy, but it can give you a boost). I'd drink some strong coffee before the ride. Caffeine has a half-life of approximately 5 to 6 hours.
Trial and error is key!


Hydraulic Brake Loud Noise and Vibration I have a shimano br-m446 installed in my MTB, i recently replaced it with new pads, my problem is that it is squealing so bad, with a mild to moderate vibration during braking in downhills. and it's really really annoying.

I haven't placed anything on them, i clean my rotors with water and laundry detergent i don't know if that causes the problem.

if so what should i do?

thanks.

As suggested in the comments, follow the burn in procedure. If that fails, then you can try to reset the caliper alignment (follow the installation instructions or one of the many sites on the internet). Also clean the disc with a volatile oil solvent such as alcohol or methylated spirits.

If that fails, it may be your pads - what did you have and what did you replace them with? Organics tend to make less noise but don't perform as well or last as long, metallic compounds tend to be better performing material and last longer but are more prone to noise.


Why do I have to keep changing positions? Despite riding seriously -- about 6,000 miles/yr -- for over 20 years, I apparently have some kind of obsessive-compulsion thing about always fooling with my bike fit.  (95 changes -- NOT a typo! -- last year alone.)  Seems to get worse every year.  Before resigning myself to this being a "mental" thing, anyone know if it's possible there may be a physical reason for this?  For instance, I use the "hands-off" test to determine the seat's fore/aft; I find it very hard to believe that some "mental condition" could result in me being able to pass the test with a 6 cm -- tip behind BB -- setback one day, then a few days later, I can't pass it unless the seat is 9 cm back!!!  And, yes, I've had several bike fittings.  (It's soon after those that I REALLY went nuts changing things due to the resulting loss in efficiency and/or pain.)  The fitters seem to be confused, too!  The range of their fits includes:

seat height (BB-seat): 81-82 cm

seat setback (BB-tip): 5.5-9 cm

bar reach (tip-bar): 53-56 cm

bar drop: 5-8 cm

After changing positions, it feels much better for a few rides.  Then, on one ride, the fit suddenly feels so screwed up, its as if I'm on someone else's bike!  I then recheck things, discover something has to be changed by a centimeter or 3.  Then it feels WAY better -- and is usually WAY faster -- until a few days later, when something is obviously wrong . . . and so on, and so on.

So, any ideas as to why -- besides the mental thing?  Anything to try? If it helps, I'm 6'2" with an inseam of about 36".  My torso is pretty short, relative to my legs, and I think my thighs are on the short side relative to my lower legs. (Guess I could average out all the fittings, and see how that works.)  I realize I may need a sports psychologist more than a bike fit expert, but I don't have the time or money for that!

Fit is a dynamic thing, but it's not so dynamic that it needs to be changed as often as you're changing it. I'm no psychologist, but I think it's safe to say it's a mental thing. Making adjustments feels better and faster because it feels new for a few rides and then you get used to it. Split the difference of all the measurements you listed and leave it that way for awhile. Be honest with yourself when you feel the need to make an adjustment and realize that once you're within the range of fit that works for your body, no small change is going to make a night and day difference.
If you've been making that many changes for years, you've basically conditioned your mind to react the way that it does and you'll never be happy because of it unless you just leave the fit of your bike alone, unless of course it truly needs to be adjusted. The challenge for you will be determining the difference.
This is not all that uncommon of a condition. I've seen people who do it with bike fit, bikes/components, diet, etc, always expecting the next change to be the one that makes the difference. Just remember that most of it comes down to the rider, especially his/her fitness and skill level, and those things only come with time.


Can I legally use front facing blue light in the UK? I have a white front-facing light and a red light at the back. However, I was wondering if I could add the blue light at the front as well from a legal standpoint. Whether it is flashing or constant doesn't matter to me, I was just wondering if it was okay to have another type of colour at the front to get noticed, and this is the only other colour I have available.

Regulation 16 of the Road Vehicles Lighting Regulations (1989) states:

  Restrictions on fitting blue warning beacons, special warning lamps and similar devices

  No vehicle, other than an emergency vehicle, shall be fitted with–

  (a) a blue warning beacon or special warning lamp, or

  (b) a device which resembles a blue warning beacon or a special warning lamp, whether the same is in working order or not.

The Regulations have been updated multiple times since 1989, but Regulation 16 has not changed.

A warning beacon is defined by the Regulation to be "A lamp that is capable of emitting a flashing or rotating beam of light throughout 360° in the horizontal plane" and a special warning lamp is "A lamp, fitted to the front or rear of a vehicle, capable of emitting a blue flashing light and not any other kind of light".  A blue flashing lamp would surely "resemble... a special warning lamp"; it's unclear whether a solid blue lamp does, but please just don't. Blue lights on emergency vehicles are useful mostly because blue uniquely means "emergency vehicle." People who see a blue light will be distracted trying to figure out if it is an emergency vehicle.

Stick to white lights on the front and red ones on the back. Note that the human eye is not very sensitive to blue (only about 20% as sensitive as to red and green), so blue is a poor choice anyway. See also Should unconventional colors be avoided for lighting?


painting a machined rim I have purchased a handbuilt rear wheel that will be used with a disc brake and never with a rim brake (it has a 6 bolt hub). The rim is a mavic a719.

The rim is anodized black but the machined part (rim brake surfact) is silver. Ideally I'd like it to be black for aesthetic purposes and was thinking about giving it a light coat of spray paint.

Is there any reason that this is a bad idea? Is there any other way of easily making it black?

NB: I'm aware that there are non machined rims available. I'm aware that some my see it as ugly or poor etiquette to run a disc hub and machined rim. After a lot of research, I concluded that this was the rim I wanted.

I've had many sets of painted rims.  All of them were painted by a professional whose day job was cars.  I have no idea what the prep and such involved was, but all of them looked great until I cracked the rims, had large rocks take chunks out, whichever.

Paint is certainly not going to hurt your metal rim, and it may offer it some protection.  Whether or not the paint stays on (which doesn't actually seem to be your question) is a matter involving far too many variables (prep, materials, care, conditions) to answer.  Unless you are planning to use some frightening type of paint I haven't heard of, you won't damage the rim by painting it.


Inline Barrel Adjusters with Shimano 105 R7020? I'm upgrading my Shimano 105 5800 shifters to newer 7020 shifters in order to equip my bike with hydraulic brakes. I'm not changing any other components as part of this upgrade. The kit shipped with the necessary cables but without inline barrel adjusters. I did some reading and the 7000 front derailleur has "integrated cable tension adjustment" so it appears that it doesn't need barrel adjusters. I am not sure if the derailleur manages this on its own, or is a combination of shifter + derailleur, etc.

Considering I will continue using my existing derailleur, I want to confirm that I should cut the new cable housings and add my old barrel adjusters to this setup.

If you have the newer FD-5801 you don’t need the dedicated inline barrel adjusters. The derailleur itself has a built-in tension adjustment hex screw. It rotates the cable clamping point around which effectively shortens or lengthens the cable.

See page 18 in the manual: https://si.shimano.com/pdfs/dm/DM-RAFD001-05-ENG.pdf

  Adjust the cable tension with the cable adjustment barrel (C) or cable
  adjuster on the frame so that the bracket indicator (B) or (E) is
  aligned with the input link indicator (A) or (D).

Of course you can still install inline barrel adjusters. They allow for an increased adjustment range, can be adjusted while riding and don’t require a hex key.

The FD-5800 doesn't have the integrated cable tension adjustment.


Hydraulic disc pads binding on disc I took the front wheel off my mountain bike and the hydraulic disc pads closed. I’ve opened them back up and replaced the wheel. However, the pads seem to now be closing up all the time and binding on the disc.

Why is this happening, and how can I resolve it?

You may not have opened up (manually reset) the brake pistons sufficiently.  Typically, I remove the brake pads and use a plastic tire lever to push pistons back as far as possible. If do not push hard enough you will not fully reset the pistons and the pads will still rub.

Aside - for those new to hydraulic brakes, most systems automatically set the pad rotor distance to accommodate for wear whenever you activate the brakes.  If remove your wheel and squeeze your brake lever, the pistons reset for a closer distance because the rotor is no longer there to stop the pads.  As a result, you cannot get your wheel and rotor back in.  You fix this by resetting the pistons as described above. Also if you change your brake pads you will also need manually reset the pistons.

You may also find this Shimano tech document on resetting Shimano hydraulic brakes useful.  Most other hydraulics will operate in a similar manner.

http://bike.shimano.com.sg/publish/content/global_cycle/en/sg/index/tech_support/tech_tips.download.-Par50rparsys-0005-downloadFile.html/Resetting%20Disc%20Brake%20Pistons.pdf


Help me understand my 8-speed uniglide compatibility issue I have a Dura Ace 8-speed uniglide rear hub/freewheel marked 'Integrated 8 SIS' and an 8 speed uniglide 14-21T cassette.

Two issues - the first being that the smallest cog needs to be a special 32mm Dura Ace thread, I think this issue unrelated but include the info in case it is. (32mm 14T Dura Ace cog on its way)

The actual issue I'd like to clarify appears to be the size of either the cassette or the freewheel on the hub is incorrect.

If I stack 8 speeds I run out of splines and the second to smallest cog (15T) would just spin if I were to apply torque:

If I try 7 speeds, I cant thread on the smallest cog as it'll hit the splines:

If I add a spacer to the 7 then it appears to all fit. But it's hardly correct, this is meant to be an 8 speed system right?? :

Measuring the pitch I see that it is indeed 8-speed (4.8mm), yet the stack height appears slightly larger at 35.85mm (it should be 35.4mm) - probably due to the smallest cog and the black spacer (0.3mm thicker than the others).

The only way I can see to maybe get it working would be to turn off some of the uniglide splines on a lathe and use two Dura Ace threaded cogs (14T and 15T) - the 15T one wouldn't have as much thread to work on in this case. Or perhaps running pins through the 3 holes that run through the cogs and spacers?? I am yet to check if doing that would leave enough room between the smallest cog with chain on and the frame..

Edit: Another option is buying another 32mm threaded Dura Ace cog in 15T and turn/file/mill out the uniglide teeth on it for use as the second smallest cog (14T would be another 32mm threaded Dura Ace cog)

Hopefully this is something basic I'm overlooking? ;)

This is not my area of expertise, but at first glance you have a 6/7 speed freehub body, not an 8 speed as you thought.

I see the threads on the 8 speed are cut into the splines, whereas yours has a continuous thread all the way around, but its lower than the highest part of the splines.

Some photos thanks to google images:

Images from https://www.bikeforums.net/classic-vintage/626072-dura-ace-freehub-id-7400-7402-7403-101-a.html and theres more info there.


Momentum of rear derailleur wheels? I have new derailleur and I am somewhat surprised that when I try to spin it with hand (no chain is mounted yet) it basically has no momentum, it almost immediately stops. Almost any other spinning part of the bicycle has much more momentum and spins for a while.

Granted, the wheels in derailleur are the lightest ones, but shouldn't they at least make a one full turn?

The screws are not too tightened because out of curiosity I loosened them already. No change.

The derailleur wheels are small and light weight, so have very small moment of angular inertia. The bearings they run on need to withstand a significant force due to the action of the chain, not just the weight of the wheel. So the bearings are fairly robust and lubricated. As a result there is a little "greasy sliding resistance friction" (for want of a better word) in the bearing. The resistance is small and its effect on riding resistance virtually imperceptible, but as the wheel's angular momentum is also very small, it spins down rapidly if spun by hand.

If the wheel was engineered like a fidgit spinner then it would spin for ages, but its bearings would fail within minutes.


Pedals and cleats compatibility I started riding road bikes seriously a couple of years ago at which point I acquired Exustar pedals and shoes. The pedals have kept up well, but my shoes are getting a bit tired and I'm wanting to get new ones. Seeing as I've ever only had one pair of shoes/pedals I don't really know how pedals and cleats compatibility works? Is there a standard shape for cleats? If I buy, Shimano shoes for example, will I be able to use them with my pedals? Or do I take the cleats off of my old shoes and put them on my new ones? How does it all work?!

I would appreciate it if someone could enlighten me!

Exustar road pedals are compatible with Look cleats, so you need to make sure any new shoes you consider are also compatible with Look cleats. Luckily, shoes w/ Look compatibility are very common, but you will want to check specifically when downselecting which ones you want to buy.

Generally, when you buy new shoes, you should buy new cleats; old cleats which are worn or stressed may crack and cause, at best, an unhappy ride home or, at worst, a crash. If this is not your style (for philosophical or monetary reasons), be sure to inspect the old cleats very carefully or, better, have your Local Bike Shop (LBS) mechanics check'em out.

One consideration when buying new cleats is float; this is how much your heels can move side-to-side without unclipping, and is designed to reduce stress on / fatigue of your knees. Look cleats come with three levels of float: none; 4.5 deg. or 9 deg. Non-Look cleats may have different float ranges. Which is best for you is a personal decision, based on riding style, experience, fitness, physical structure, etc.

Another consideration is the type of Look cleat: the "old" / non-Keo version (Delta?) or the Keo-version. These are not compatible, so be sure to understand which you need. If you are not sure which you have, take your old shoes with you when shopping for new cleats.

The last issue you'll have to deal with is installation; mounting the cleats is easy, but positioning can be very touchy. Here again, unless you have a lot of experience, I would recommend asking your LBS to assist in this; it may cost a little bit, but it should make your riding experience much better.

A few resources which may help in your efforts:

Exustar cleats at http://www.exustar.com/product.php?t1s=13&level=1
The authorized Exustar importer in the US is QCycle (qcycle.com)
Look cleats can be found on their website (lookcycle.com)
Sheldon Brown (the font of all cycling knowledge) on knee pain at http://www.sheldonbrown.com/pain.html#knees

Hope this helps.


Chain derailment from front crank. Fine on large ring won't hold on smaller inner ring Second hand bike. GTZR3000

Shimano 105 9 speedshifter
9 speed rear group shimano
9 speed tiagra rear derailleur

The bike runs fine on large front ring, shifting is perfect.

When I change for an incline to the smaller front ring and apply pedal presure the chain comes straignt off. On a stand without pressure resistance on the drive train, everything moves perfectly. Back on the road and again and pedal pressure sends the chain off.

Can anyone advise if they are aware of potential reason why?

I could be caused because the chain is not running a straight line from the rear cogs to the front chain rings. If you put the bike on the stand and follow the chain from the top of the cogs to the chainrings. You will see if it follows a straight line. It might be slight off so that it won't jump off when on the stand but it does when there is pressure.

Another reason could the rear cogs wable. If it so, you will need to change the cogs.


How do I best clean the cog wheels? Would it be best to take it off first then soak it in soap, or should I use petrol to get the grease off first?

You don't need to take the cassette (cogs) off to clean it.

Use a citrus degreaser fluid. Clean the chain and chainrings at the same time. You can use a rag pulled taut to get between the cogs, or there are a number of specialized cassette and chain cleaning tools available.

There are many instructional videos out there with tips on cassette and chain cleaning also.


How to prevent breathing issues during extreme cold Yesterday I rode to work in -2°F / -19°C temps.  When I got to my destination (only about 3.5 miles), my lungs felt terrible.  My voice was hoarse and I was coughing a lot. All this despite the fact that I was wearing several wool and fleece layers, a thick balaclava and was completely toasty the whole ride.

The ride may have triggered some exercise induced asthma due to the extreme cold. I tried to cover my face with the balaclava, but there was not enough ventilation and was getting short of breath trying to breath through the fleece, especially when climbing hills.

This sort of thing is something that should not be repeated for the health of my lungs.  What gear or techniques can I use to prevent this kind of lung irritation during extreme cold?

A scientific Journal, Chest Journal, published an article about the efficiency of heat exchange masks on asthmatic subjects during cold weather exercise.  They found that the heat exchanger masks were at least as effective as pre-treatment with albuterol in preventing decline in lung function.

I found several commercial heat exchange masks which could potentially be used for cycling:
Airtrim AirTrim Heat/Moisture Exchange Masks - seems to be the most athlete focused product and would likely be effective.

N-Ferno 6970 Extreme Balaclava with Hot Rox

Polarwrap, The Exchanger Mask

Talus Outdoor Technologies ColdAvenger Pro Soft Shell Mask or  ColdAvenger Expedition Balaclava

AirGuard Medical CT Mask for COPD or Asthma - May not be designed for high levels of activity

However, for less extreme temperatures, simply breathing through some medium, like fleece, which captures the moisture you exhale and passes inhaled air back over it may work as a less efficient, but still potentially effective heat exchange in warmer temps. For me, breathing through the balaclava helps a bit in temps over 15F, but is less effective at lower temps.

Anti-Pollution masks may provide a similar effect as well, but may not capture as much heat if they use exhalation valves which remove some of the exhaled air without capturing the heat.


What modern wheel and tire size could be replaced from 32-630 ( 27 x 1 ¼ ) wheels Referring from the question, specifically, what is the closest modern wheel size for my old 32-630 ( 27 x 1 ¼ ) wheels. It's hard to find rims and tires for that size now a days. I'm looking for the closest size in terms of wheel diameter. It should not go any bigger but close to exact size or smaller.
I'm also converting my bike with disc brake, so rim size won't be any issue with rim brakes.

I have read this guide and mostly I found closest to mine is the 700C or 622mm ISO version for road bikes.

https://bike.bikegremlin.com/285/bicycle-tyre-dimensions/

After measuring the outside diameter of my ETRTO 630 sized rim and tire with a modern ETRTO-622 sized tyre, (ie a "700c") I notice they have a slight difference which my fork and frame can tolerate.

The 622 rim is 8 mm smaller diameter (4mm smaller radius) than a 630 rim and is a good fit.   So therefore I will go with a more modern 700c wheelset.

Thank you for those who have comment and helped me decide better.


Cheap energy sources for electronics during touring with low amount of sun energy? My goal is to find a cheap energy sources for touring.

I cannot use solar all the time so I am planning to get Reelights outlined here, for lights, because they are cheaper than installing a hub generator. But the next problem is my laptop because it needs much more energy and I don't have much solar radiation at my latitude. I included the description about solar panel installation because I may need to use it with other energy sources which I am not aware of, perhaps gas, oil or something like that but they are expensive. So to the question:

Which cheap energy sources would you use during touring with low amount of sun energy?

One possible implementation to store energy

  The ten-watt solar panel (which weighs
  about a pound) lies on top of my
  panniers on the back of the bicycle (I
  carry my tent and sleeping bags in the
  front bags). As I ride, mostly in the
  sun, the panel produces current which
  runs through 12 5.7AH nicad cells,
  charging them during the day. After I
  stop for the night, I unplug the
  panel, and use the same plug to
  connect the battery to the computer
  via a Targus auto/air adapter.

  This setup requires me to carry the
  computer, an AC charger and the Targus
  DC charger, the solar panel, nicad
  cells and connector cord, a
  multimeter, and various nylon and
  plastic bags plus the computer case,
  with a total weight of seven pounds or
  less. (source)

Suggestions, some of which may be a solution

hub dynamo recommendations here for lighting
solar panels for electronics projects
moz suggests here to carry a solar panel but not diamond-framed
Amon suggests here a particularly interesting home-brew stuff that may lead to some kind of solution but with USB.
Darkcanuck outlines the situation with different choices here: sun, AA/etc charger and dynamo charger.
solar-powered Laptop during touring, more here.

Assuming you add the robust stand you were talking about here it should be possible to pedal the bike on the stand. Even pedalling gently will give you 50-100W of mechanical power that you can use to spin a small generator. I suggest looking for a dead RC toy and using the motor from that, since they often use that level of power. Ideally drive it from the chain rather than the tyre, but focus on making it work to start with. A little work on voltage conversion should give you enough power to charge the laptop fairly quickly, and with a little work you could even use it while pedalling.

Otherwise a hub dyno. A decent bottle dyno will not be much cheaper but will need more maintenance.


High to low gear shifter on derailleur gear bike? Inherited this bike and it's got this strange gear shifter that I don't understand. The one on the right is one to five with six spaced a little further away. It's got a 3 and 6 cog derailleur as you'd expect but I can't work out how this works. It's also all really stiff and hard to move which makes it a pain to test out.

Looks like the left-hand front shifter has multiple positions to allow you to adjust the front derailleur to avoid chain rub when shifting through the rear sprockets.

The shifter is probably corroded inside which is making the action very stiff - notice the rust on the central screw. The cable and front derailleur may also be contributing to the stiffness.

If you can get some light oil inside then work the shift action repeatedly you may get it to free up some. You can disassemble it, clean the internal components, lube with grease and re-assemble. If you are unsure about getting it back together properly, taking frequent pictures or even making a video of the disassembly process can help you remember where all the components are supposed to go.


Replacement for 52 tooth chainring Ultegra triple ( 6503 ) 9 speed Hello It seems that the stock 52t chainring for a road triple ultegra 9 speed is on  back-order or has been discontinued. Is there a replacement that will fit and shift?
This is for my wifes Trek and she is not one to be told " Just baby it a little on the up shift "  Thanks in advance for any and all help in this matter.

You should be able to replace your chainring this with any 9 or 10 speed chainring that is 110 BCD (which is the Bolt Circle Diameter for the spider on an ultegra triple crankset).

Tiagra/105/ultegra replacement rings should all fit, as well as most 3rd party manufacturers replacement rings.  Make sure the ring you want to use as a replacement has ramps and pins so that it will work as well as the original.  Stick with shimano parts to be sure of the best performance with the ultegra drivetrain.


Help me identify this specific Giant XTC I bought this bike a couple of years ago and I'm looking to sell it. I don't know what year it was, nor the frame size, but it's in really good shape. I pulled the serial number from the bottom of the frame but it hasn't helped me look up anything online.
Any extra information would be really appreciated
The guy I bought it from mentioned it being originally from Europe, possibly Germany if I remember right.
It's labeled XTC 1.5 performance series, but everything I looked up online shows either 1 or 2 as the options

I'm going with some generation of their ATX mountain bike.  The 890 ATX comes to mind. One aspect that will likely give us the best idea is those cool lugged frame accents where the top and down tubes meet the headtube.


Shimano Gears won't shift Basically when pushing the button to shift gear I can only get one speed up and one speed down. I tried adjusting derailer and the tightness on cables but it makes no difference.

Figured I'd make a video to explain it better
here you go.

thanks and  ask questions if needed

Can't really tell much by your video. We see you clicking up & clicking down, but you don't appear to be turning the cranks. The gears will not shift unless the drive train is in motion.


A long, straight, stiff mudguard? I saw a bike with such a mudguard the other day. It was mounted on the seat tube and stuck straight out horizontally, between the two seat stays, over the brake and then over the rear wheel.

I liked the mount point because it means that the top of the seat tube is protected from crud, unlike seat post mounted mudguards.

Does anyone know where I can buy such a mudguard? Or who makes one like it?

I think of three kind of mud guards that fit the description: musguard, quickfix, and fender bender.

An other solution is the ass saver, but this is not what you are looking for.


Most Crucial Gear/ Accessories for a (Road) Cycling Beginner? Some background information on myself before I get to the question:

I've decided to get in to cycling both as a hobby and because I need the activity. (Though I'm honestly driven more by the former - I've always enjoyed riding since I was a kid.) I already have a bike that seems decent to me (for someone in my position), but I'm also a newcomer and don't know that much. It's a 2004 Cannondale R800. When I was about 15, my dad and I each got one to start together. Long story short, we had some demotivating initial experiences with the clipless pedals, moved shortly after, and soon the bikes were (sadly) forgotten.

Now (~6 years later), I'm looking to actually get into it, and it seems that there is a lot of "essential" gear I should buy. I have somewhat limited funds (as a student), and can't do it all at once, so was hoping for some guidance in both what I absolutely need to get, and what would be more ancillary. Also, recommendations on around how much I should be spending on different items would be helpful. For example, I know headlights can run anywhere from $10-$1000+, but I don't know what the sweet spots between performance and value are.

I live in a fairly rural environment in a university town of ~21k people. There is a decent bike shop in town considering the size, however their focus is much more casual/ kid-oriented.

What I do have:

Jersey (longsleeve + shortsleeve)
Cycling Shorts
Cycling Shoes
Helmet
(Small) Saddle Bag
Pump
Emergency Patch Kit

Things I don't have, but are on my radar to acquire (at some point):

Headlights / Taillights
Cycling computer / heart monitor (I do have an Android phone that I know can facilitate this point.)
Additional clothing, though nothing particular at the moment
Gloves
Tool kit

I'd like to be fairly serious about it, though training for self-improvement, not competition. I'm planning to gear up to riding my first century this September.

Tell me if there's any more information I need to add, and, thanks!

Sounds like you have the basics covered pretty well.... If you're turning in some serious mileage, you want to be able to handle flats and minor repairs on the road.
Minimum is a good frame pump ( a lot of the mini pumps have trouble getting past 50 pounds or so...) spare tube, tire tools, etc.  Some of the handy little hand-cleaning wipes are a good idea as well.
A multi-tool that will take care of most emergencies is a good investment; it should include a chain breaker, allen wrenches to fit the fasteners on your bike, etc.
Some money is never a bad idea.  You may just HAVE to have a donut....


Commuting on flat terrain/handle bar For my new job I'll have to commute about 10 - 20km (6 - 12mi) each day (one trip) in flat terrain. Right now, I'm commuting 6km/4mi each day, with an elevation gain of 160m uphill to work.

I'm riding a hybrid bicycle with a gear hub (only one gear lever) and a straight handle bar.

I assume that for my new route, a more aerodynamic position would be nice and I'm pondering about a better handlebar choice -- drop handlebars or tri bars as addition to my straight handlebar? Is it just a matter of personal preference, or are there general pros and cons?

The route will be mostly on a seperate bike lane next to a road with little traffic.

When spending more time on your bike, it's good to be able to vary your position. For that reason alone I would advice a drop bar or butterfly bar. It'll prevent all kind of small complaints about wrists, shoulders and back.

Getting in better shape because of the extra daily exercise, you'll gradually feel more comfortable in a more sportive (aerodynamic) position.


average cycling speed 12km/h I am now in training for cycling. Long time didn't got into bike. I am using a 21 gear mountain bike with highest gear, and around 70 - 80rpm. What's surprise me is my average speed only 12km/h(recorded from strava) and 14km/h(recorded from mapmyride).

I was wondering whether i am using the wrong gear? I thought that the higher with the same rpm will move faster than a lower gear with same rpm.

12km/h is much slower than my expectation. I expect 70rpm would be 20km/h or more.

You can calculate your speed vs cadence using this online calculator. You want your cadence to be roughly 80 rpm (60 being the lower bound).

With a 42t chainring and 14t cog in the back (not uncommon for a 26" mtb -- this is big ring in front, small in back), you should be doing around 31 kph at 80 RPM, so chances are you're either spinning too fast in a too low gear or spinning too slow in a too high gear.


Oversized tyres and teaching my son to measure! So my son has been trying to customize his bike and seems to have never heard of a tape measure!! I need some help to get him on the road! He has purchased 2 oversized tyres with a size 26 x 2.50. The exsisting tyres are 27.5 x 2.10 so will these tyres fit onto that size rim?
The tyres that are currently on the rims are a brand called kenda and seem to be stuck to the rim somehow, I cant seem to take them off the rim? If anyone can help me I would be so grateful cause at the moment I'm getting grief from all angles and it's not even my fault!!!!

Regarding diameter: You can't put 26" tires on a 27.5" rim, which it sounds like your son wants to do. I can guarantee with absolute certainty that the new tires will not work because they're the wrong diameter.

Regarding width: We don't know the width of the rims on your son's bike.
Also, rims can handle tires across a range of widths. It is possible that the 2.1" tires on the rims now are at the outer limit of the rims' range, but we have no way of knowing. I'd look at the rim and look up the manufacturer's guidelines online.
Regarding removing the existing tires: do you have tire levers? There are numerous videos showing how to remove a tire. Here's one.


Why are tandem pedals mounted with the same position? I have noticed that on all the tandems I have seen the pedals are mounted in the same position. i.e. while the front right one is up, so is the rear right one, and not front right up and rear right down.

Is there a specific reason for this?

Sheldon goes into some detail on this.

Having the pedals 180° out of sync would lead to a couple of problems:

Starting off, as most people have one foot on the pedal and lean towards the other foot on the ground, including both people on a tandem.
Foot overlap.  There's often not enough room for the captain's foot to be at the back of the stroke and the stoker's to be at the front without them colliding.
You couldn't corner with the outside foot down, as the other person would have the inside foot down and strike the ground.

A phase difference of 90° is used sometimes.  The power is more even through the stroke but handling is worse at low speeds among other downsides.

Another post dicusses 90° out of phase and also slightly out of phase

The second article suggests that most people ride exactly in phase because that's how tandems are set up by default.  Changing takes some getting used to and a little fiddling so people need a good reason to mess with it.


Is an e-bike more of a bicycle or more of a scooter? With new battery technologies a new kind of "bicycle" has emerged - so-called e-bike.

It usually has an electric motor on one of its wheels. The motor is powered by a rather huge (size of a small bag) battery. Pedals, star wheels and the chain are still in place, so the user can

use it as a normal bicycle or
use pedals to assist the vehicle or
just rely on the motor and use it as a scooter.

Speeds like 20 kmph witout using pedals are typically promised.

What I don't get is in which scenario and how I use such vehicle.

Do I use is as a scooter with ability to be driven by pedals once it runs out of the battery or do I use it as a bicycle with the motor assisting me and letting go faster without too much of activity?

There are different electric bikes with different experiences.

Some are heavy and powerful, and move with a push of a button. Their pedals are more about legal status than about human power. I'd call them "scooters".

Some are designed to supply power only when the pedals are turning. In that case you have to do a little work for the electric motor to kick in. These are usually called pedelec (from "pedal electric cycle").

Some use sensors in the drivetrain to decide when to apply the power. Those often have a switch so you can get them to drive the motor without pedaling, giving them a "scooter mode".

Some (like the StokeMonkey) apply the power directly to the drivetrain, so you always have to pedal to get them to work. If you're looking for exercise this is a good idea - no temptation to just cruise under power alone.


Can my relative still ride a bike despite having RSI My relative has RSI, and encounters wrist pain from fairly minor activities involving use of hands. Is there anything that could be recommended so they could still enjoy cycling despite having RSI?
Thanks a lot.

I'll note that health and medical advice is generally off-topic here, but the bicycle configuration could have a strong bearing on how your relative manages.
Generally speaking an upright posture, on a "city bike", will place less stress on the hands and arms than a racier road bike or mountain bike.
And some recumbent configurations, especially of the tricycle variety, are also less stressful to the hands and arms.
But it's up to your relative, in consultation with his doctor and a knowledgeable bike fitter, to decide what is suitable.


Why are hub shells such different diameters? I'm curious: why are some hub shells much larger diameter than others?  Is it an aesthetic consideration? Or are there cost/functionality tradeoffs?  Take for example this Dura-Ace hub -- pretty skinny.  Same for a classic Campy record hub.  Compare to this much fatter Tiagra hub, or a Phil Wood front hub.  I'm just talking standard hubs, not internal gears, powertaps, dynamos, etc.  [Addition after DR Hicks answer: nor I am I talking about hub flanges, but rather the barrel of the hub shell.]

A smaller diameter hub is lighter (and likely cheaper).

A larger diameter hub has several advantages:

The bearings can be larger
Since the spoke flange has a larger diameter, it also has a larger circumference, meaning that spoke holes are farther apart.  This reduces the stress on the spoke flange with heavily-loaded bikes, and also makes higher spoke counts practical.
Related to 2, the spokes, for a given "cross", leave the hub at a more oblique angle, meaning that the force of the spoke is pulling more tangentially and less radially.  This again reduces stress on the spoke flange and also increases the rigidity of the wheel against torque.

A non-obvious disadvantage of the larger hub, when it gets MUCH larger, is that, for 3 or 4 cross, the spoke arrives at the rim at a definite angle.  Unless the rim had been drilled at a matching angle, this increases the stress on the spoke where it enters the nipple, increasing the chance of spoke failure.  But this is mostly a problem with geared hubs.

It's pretty much tradition to have larger diameter hubs on touring bikes and tandems.  Not sure to what extent this is a practical measure vs "expectations" -- the larger flange looks like its built to be rugged, while the small flange looks "light on its feet".


Can't inflate my bike tires Received an old bike from a family member and I've tried to inflate the tires but whenever I attach the pump to the tire it seems that I can't inflate it. All I hear is a hissing and it feels like all the air is escaping out the back of the pump. Both the bike and the pump haven't been used in several years so it's possible one or both is broken. I believe the bike has Schrader valves and the pump works for any type of valve but I'm not completely sure. Does anyone know a way to test if either is broken or a way to make sure there is a good connection between the valve and pump? Thanks x

Even easier tests:

hold your thumb over the end of the hose and pump.  You should feel pressure build.
visit your local bike shop - many of them have a self-service air pump somewhere outside for the convenience of customers.
visit a bike repair stand in your city, if you have one
visit a bike cooperative
ask a fellow cyclist if they can loan you a pump because yours isn't working
visit your local service station/gas station/petrol station.   With care, you can use a car tyre inflater.   It will only take a second so don't overdo it.


How does the geometry of cross bikes affect on-road handling? I'm planning on getting a cyclocross bike for commuting because my road bike is suboptimal for riding in rain and snow. A bike shop employee told me that cross bikes have worse geometry for riding on the road. He said that if you forget you're riding a cross bike and lean through a corner, you'll wipe out. He credited this problem to the geometry, rims, and tires of cross bikes. Is the assertion of the bike shop employee true, or was he full of it?

What are the practical differences in handling between a cross bike and a road bike? What are the noticeable effects of cyclocross frame geometry?

Related questions: Can I use a cyclocross bike for regular road-biking purposes?, What is the difference between race/road and cx bikes?, Explaining the effects of frame geometries

A lot of people commute on cross bikes just fine (and even prefer them to conventional road bikes). He's full of it - the amount you'd need to forget to have issues is roughly being confused enough to think you're an onion (and if you're this confused, well, you're screwed anyway!), especially at commuting speeds. There are different bicycles for different purposes - for example, you're not going to take a touring bike like the Trek 520 and compare it to a racy road bike like the Specialized Allez. You probably wouldn't want to enter a road race with a cross bike, but commuting is a fine purpose for a lot of them.

There are 2 sorts of cross bikes - ones meant for racing , and ones meant for regular use (e.g. Trek Crossrip). These aren't necessarily disjoint (e.g. Kona Jake the Snake is used for both, to some extent), but you can tell roughly what they are for by looking at the components spec'd (example description for the Trek crossrip).

Obviously, you want slick tires for your commuter (if you're on the road) since the slightly knobby cross tires that come with them increase noise and can lower cornering speeds (For example, cornering quickly with a mountain bike on knobby tires does lead to washouts sometimes due to the knobs squirming). But things like the Kenda Small Block Eight are fine for commuting.

Typically, cross bikes have higher bottom brackets, larger tire clearances, cantilever/disc brakes, longer wheelbases , cables routed so that you can shoulder the bike easily and more relaxed geometries than road racers. This serves to give more shock absorbance and stability for the bike. The more commuter oriented variants also have easy fender mounting, rack mounts, etc.

I think the other parts of your question are answered in your related questions and the Wikipedia article.

Not really an answer to the question: Since rain, snow and grit do tend to damage drivetrain, you may just want to use an old cheap rigid mountain bike (e.g. 80s-90s Specialized Hardrock/Rockhopper, etc.). Great tire clearance, very stable, cheap to replace parts on, discrete (so they don't attract attention in the bike rack), etc.


Drop Handlebars on an Old Bike I'm shopping around for a vintage bike (maybe an old Raleigh or Schwinn), but I'm looking for two things:

Fenders and a Chain Guard
Drop Handlebars

I'm starting to think that drop handlebars are newer than most of the vintage bikes I'm looking at.  Is it realistic to expect a 50s-70s bike with drop handlebars?

You can have mudguards and a chainguard, mudguards and drop bars, but not drop bars and a chainguard:

http://sheldonbrown.com/retroraleighs/

To use an automotive analogy, you are looking for the station-wagon version of a two-seater sports car.

That said, why not put drops on an old Raleigh 3-speed? The 3-speed Sturmey Archer lever will be simple enough to mount, you will just need new bars, levers, all-important bar-end plugs and tape. Obviously the bars will need to be the older 25.4mm clamp size, but you should be able to acquire these bits and bobs second hand for not much money. The alternative option of getting a chainguard to put on a retro Raleigh is a bit harder - those were a bit model specific whereas handlebars are not.

Personally I have a 12 speed Raleigh Gran Sport with the drop bars and a Raleigh Sports 3 Speed with the 'Northroad' bars. I would not swap the bars over on either because they are well thought out and go with the frame geometry. The 'Northroads' bars are a real treat and, if I did not already have a 3-speed with them, I would look for a bike with them.


Switching from MTB to road handlebars I have a gravel bike with an MTB setup. SRAM GX rear mech, SRAM XO shifter, 1x11 system, Shimano disc brakes. How would I go about replacing my flat handlebars with road bars?

Alternative 1
Get a hold of a Shimano 11-speed shifter, a brake lever and a Jtek Shiftmate to convert from Shimano ratio to SRAM.

Alternative 2
Get a hold of SRAM 11-speed road shifter and brake lever. Also need new hydraulic brakes which are not compatible.

Alternative 3
Get new mechanical disc brakes. Get SRAM shifters with mechanical levers.

So what is the best alternative? Or do I have more options?

And can I use SRAM GX rear mech with SRAM Apex or Rival shifters without a ratio adapter like Jtek Shiftmate?

Much appreciated. Cheers!

You absolutely need SRAM shift/brake lever units. SRAM road shift/brake levers are compatible with their MTB derailleurs and come in a 1x11 version.

Trying to mix Shimano and SRAM will just be a huge headache. I'm not even sure there is a shift cable pull converter for that.

Hydraulic vs mechanical calipers is up to you and your budget.

Something you should be aware of is that flat bar bike frames are typically longer than drop bar frames, because flat bars place the rider's hands closer to the head-tube than drop bar hoods or drops hand positions do. Check your bike's geometry to make sure you wont end up with too much reach.


Which traffic light do I have to follow? There is one situation in Bonn, Germany, where the buses have their own lane (right one) and the cars are separate (left lane). The cars have a regular traffic light (red, yellow, green) and the buses have their special kind (white bars, — and |). It looks like this:

The interesting thing is that the cyclist are supposed to take the bus lane, so they are on the right lane. One can see that right after the traffic light there is a dashed line parallel to the road that marks the bike area on the road.

The traffic light obviously aids the buses and cars merge again to a single lane. As a cyclist, I am not really sure what to do:

I could abide the car traffic light. It is the traffic light that I have been taught to read in school (elementary school, actually) and is the official one for car drivers as well. However, when the car traffic light is green, I have a harder time merging with the cars.
Use the bus traffic light because it is in my lane. It make also most sense since the traffic light is for merging the two lanes. But I cannot really read the traffic light, I just assume that the three lights correspond to red, yellow, and green. If a bus was right behind me, he would have to pass me if I waited for the car traffic light to switch to green again. This doesn't make any sense, I should just free up the bus/bike lane.
Ignore both lights. In every case I can just slowly merge with the car lane as I see fit. Usually one of the lights is on “Go”.

Every time I pass this place, I am a bit uneasy whether I am doing the right thing. I just carefully watch for traffic and merge with the car lane when there aren't any cars around. I'd like to know what the correct behavior for this situation would be.

I received an answer from the traffic guidance department of the city. They told that I can either ride on the car lane (left) and then use the regular car traffic lane. If I take the bus lane (right), I do not have to stop at any light at all.

There is no cycle traffic light on the right post because cyclists on the car lane then might interpret that as their light for the left lane as well and get in conflict with a bus on the bus lane.


What is this device attached to the seat-tube? I dug out my late Dad's bicycle. Dad used the bicycle during his medical school days in the late 1940s ... or so. The bicycle has accumulated sufficient rust that it is impossible to identify the manufacturer.

What is this device attached to the seat-tube? It's upper portion appears to be spring-loaded..

It appears to be a clamp-on pump peg that got moved down out of the way either intentionally or from coming loose.


Crank extractor not screwing in properly I'm trying to insert my crank extractor into the crank of a square taper (Shimano Tourney). It won't really screw in properly. On several attempts it will go in a little bit (about 1 or 2 mm) and quite abruptly won't turn anymore, as if it didn't go in properly. It doesn't feel right. I've tried it enough times that I'm fairly sure it's not the angle I'm using causing the problem.

I am starting with the inner part of the extractor fully inside the outer part, so it isn't that the inner part is simply already pushing into the spindle or anything.

The crank extractor is the Birzman universal crank extractor.

What am I doing wrong here?

It's at this point that the extractor will 'stick', only going in a very small amount. Shouldn't it go further?

If you want to save the cranks, consider taking this to a shop.

Wonder if this bike was run without a plastic cover over the hole?

I suspect the threads in the crank are slightly damaged.  You might be lucky and force the extractor in correctly, or you might screw-up the threads completely if it on the wrong angle

An LBS will have taps that will chase the threads back to smoothness.  Taps like this are quite expensive and generally unnecessary for the home mechanic.  I don't own any this size.

You can try another crank-extractor - I own two and they have subtly different tolerances.  Not sure how that works but one goes in where the other doesn't, and its not always the same one that works.

If the cranks are trash already, then slap a lot of lube in  and have your best effort at lining up the extractor.  Your last resort is to carefully cut the crank off by grinding through the eye, without going into the BB.

If the BB needs replacing AND its the left side, you might be able to grind through the BB axle between crank arm and BB, and then use a drift to push the stubby bit out of the crankarm eye.  This should save the crank arm but it will still have damaged threads.  If its the right-side then the spider and chainrings will be in the way.


Eco friendly Bike cleaning What is the most eco friendly way to clean your bike? I want to use a degreaser and other cleaning solutions that are biodegradable.

For most things, you can just wipe the bike down with a wet towel or sponge and it will be about as green as you can get and adequate (well, as green as you get would be to leave it dirty). Some dish soap and a hose (on shower setting, not jet or super soaker or whatever) if its really dirty. Don't use a pressure washer or something since you might get dirt into bearings or crevices.

If you want to use degreasers, citrus degreaser should be biodegradable depending on what brand you get for the chain. Park Tool among others make a convenient little thing you clamp onto the chain to clean it.

One link to look at is Park Tool's guide.


What kind of overshoes can I use with a large touring SPD cycling shoe such as the Giro Rumble VR? I got myself a Giro Rumble VR size EU 46/UK 11/US 12 and it has been a good shoe.
However, since they are very breathable, my feet are getting too cold at around 5 deg C, and I tried to get a regular road shoe cover for them, such as the dhb Extreme Weather Neoprene Overshoe.
But as can be seen from the photos, the Giro is basically as large as regular sneakers, and it was impossible to make the L-sized covers fit it, and I don't think XL would have been large enough either.
Is there any other cover I could get that would work better? Or do I have to just buy warmer/more standard sized MTB shoes?
Related: Waterproof overshoes on Platform Pedals with pins
Edit
I'm not in the mood for DIY (doing enough of that already), so I just got myself a standard sized dhb Dorica MTB Shoe and that worked with the cover. I got the non-extreme one though. This was an improvement, but it is still a bit cold when nearing zero. I might get a toe warmer as well at some point. The Giro will be reserved for 10 degrees +. One advantage of the Dorica is that it is easier to clean due to leather-like cover, especially when you can jus wash the cover separately.

You need overshoes specifically designed for MTB shoes. Note that most of them would say Road Compatible: Yes, MTB Compatible: Yes but they are typically optimised for road shoes. I have the Shimano S3000X NPU + overshoes which are marketed as MTB overshoes and they are great, although it looks like they are hard to find nowadays in reasonable sizes.


Are flat handlebars stable at high speed? I live in a mountainous area, and so there are lots of opportunities for descending at high speed. I currently have a bike with drop bars, and when in the drops, I feel very stable doing this.

I am now in the market for a new bike, and I'm thinking I might like to switch to flat bars. However, on my current bike, I feel quite unstable on the tops at speed. Can the new bike (it is a custom frame) be designed to feel and be stable at high speed (say, over 40 MPH) with flat bars?

First off, understand that the geometry of the bike affects stability, especially the "marriage" between head angle and fork rake.  Adjusting these parameters (which can really only be "adjusted" by the frame builder) has a very dramatic effect on stability.

Beyond that, the hand position has an effect in a couple of ways.  First, if the hand position is more forward, it tends to "pull" the steering tube straight, reducing "responsiveness" and making it easier to hold the front wheel straight, while a more rearward position will make the steering more responsive and maybe "twitchy".  Similarly, an outboard hand position will allow the arms to brace the bar more, while an inboard position allows less torque to be applied to the steering tube.  Finally, when riding on the drops one can (with a bar of a certain geometry) brace the lower arm against the corner of the top of the bar, adding more rigidity than would be present with just the hands on the drops.

(Note that weight distribution (eg, how forward/aft and high/low the rider's center of gravity is) also has an effect.  Riding on the drops or not affects this to a degree.)

But remember that rigidity does not equal control.  A "stable" bike will take a bump and re-balance itself more or less automatically, due to steering tube geometry, et al, somewhat independent of hand position.  It's good to have a bar that allows you to apply the "desired" amount of torque to the steering tube (based on your preference for responsiveness vs stability), but if all that's doing is letting you fight poor inherent bike stability that's not a good trade-off.


Is the shifter really broken? My high shifter isn't shifting in gears 1-4 (5-8 are fine). I took it to a shop and they said I need a new shifter because it's in "really bad shape". No details or anything. Does it seem like they're pulling a fast one on me?

Thanks.

Normally, a shop will not lie on their customers, as they do want you to come back again. But if you don't know whether to trust them or not, you can try to show your bike to another shop.


Differences between Biopace and Rotor cranks On mountain bikes of a certain age, "Biopace" chainrings are ubiquitous. These chainrings are (purposely) not circular.  It seems that most people today agree that Biopace rings didn't live up to the hype.  They were a fad, and they're no longer popular.

Despite this, a new type of non-circular chainrings, "Rotor cranks", are currently in vogue. Professional road riders use them.  What are the key differences between rotor cranks and Biopace?  In other words, how can Biopace be bad and Rotor cranks be good? Or are they both bad or both good?

If you are looking at the Biopace/Rotor/O-Symmetric relationship as similar due purely to aesthetics, or their similarity due to their lack of similarity to round chainrings then, yes, they are similar products.

But, that said, from the RotoR website "The Q-Rings are elliptical; the Biopace and O.SYMETRIC chainrings are asymmetrical.". And Sheldon Brown points out that Shimano called Biopace "point-symmetric egg curve". Which really only gives them the similarity of being different from the norm which in this case, is a round chainring, but if you go a step further, they are quite different.

So, to try and answer the question posed above.

The first difference between RotoR and Biopace is elliptical vs. asymetrical.
The second is the inherent purpose which, as previously stated, is that the Biopace chainrings placed the maximum tooth size at the dead spot while Q-Rings (RotoR) have the minimum tooth size at the dead spot. RotoR claims this is to increase your ability to get through the inefficient spot of your pedal stroke. Biopace is supposed to speed your way through the power portion (less teeth) and use 'stored' energy to power through the dead spot (more teeth)
Which leads to the third difference which is the adjustable nature of Q-rings (RotoR). Since my dead spot could be different from your dead spot (and would ideally be analyzed with some sort of spin scan) you can adjust where the minimum tooth size sits in relation to the crank arm.

So, to simplify it (perhaps too much) RotoR claims that it is more efficient and better for your knees etc. to minimize the tooth size at the dead spot and maximize the tooth size where you generate the most power and are the most efficient.

Having installed a set and seen the power file from a MTB powertap I can vouch for the fact that it appears to 'smooth' the application of torque while mountain biking. The thought behind this is that by smoothing out your application of torque you will be able to ascend technical climbs ... better. That is one coaches take on the Q-rings and why he sees benefit.

So, that all said. Have a gander at Sheldon Browns take on the issue of Biopace. Essentially, to try and summarize his thoughts, Biopace is striving to achieve the exact things that RotoR is trying just by going about it in what appears to be the completely opposite way.
In fact, he even mentions the application of Biopace to mountain biking and how it evens out the application of power to the cranks.

IMO it is all very confusing. RotoR does trot out some scientific studies and I can attest to a difference in torque application on the mountain bike. In my experience, what is universal with RotoR and O-Symmetric is that the shifting is ABSOLUTELY terrible. Add mud to the mix (MTB) and it goes from terrible to non-existant so whatever perceived benefit there is ... I think you might lose with poor shifting performance.

What is helpful from Sheldon's take is that it seems Biopace failed more due to clumsy marketing and poor communication than it did from being a poor design.

Lastly, I don't think any of them are 'GOOD' or 'BAD'. They are different and might work very well in some applications and poorly in others (Ie. RotoR and mud). But the Biopace choice is pretty much a moot point because ... you can't buy them new anyways.


Vintage bike - help with chainring replacement I recently broke the large chainring on my vintage bike, and need to replace it, but am having trouble determining what size I need. I lost the chainring on the ride home, so am measuring the bolt circle diameter on the crankset to determine the size.

In this picture, you can see that the distance between adjacent bolt holes is roughly 109.5mm (4.3125 inches):

According to the Sheldon Brown site...

  "Multiplying this dimension by 1.701 will give you the actual BCD for
  a 5-bolt chainring"

...making my BCD 186.2595mm.

However, I'm not finding anything online with a size anywhere near that big. Can someone confirm my method of measuring is correct, and if so, any tips on sourcing a new chainring of this size? Or is my chainring size just obsolete at this point? I'm hoping to just replace the chainring, and not the whole crankset, if possible.

The crank arm is branded as Silstar, but I'm not finding any chainrings of that size under that brand either. The bike was a hobby project for the previous owner, who built it from scratch, and I no longer am able to contact him for any info on the parts.

Thank you for any info.

I believe I have that same crank on a roughly 1983 Schwinn World Sport (see image). I got it used, so I don't know if it was the original, but in any case, mine has 40 teeth on the small ring and 52 on the big ring, so that's likely the size you're looking for.

That said, it might be easier to find a replacement for the entire crank+chain rings rather than match that chainring. Mine is a standard square taper spindle, and many vintage cranks that would fit are available on eBay etc.

If you live in a city with a co-op that salvages old bikes, they often have loads of cranks from that era that would fit.

Furthermore, since the square taper spindle was a standard for so long, a more recently made crank is also an option.

UPDATE: Images online seem to indicate this crank was standard on early 80's World Sports. Given how many of those bikes are still around, which means the cranks should be relatively easy to find, or you could easily find a whole bike and take the crank off if it's really important to you to match your original.