Fixed gear/SS crankset question

[GD2002]

I need the forumites opinion(s) on the appropriate crankset length and why.
Should I use the same crankset size (currently using 172.5s for 2 road bikes) for a 'future' fixed gear bike?

Thanks y'all..

[KevinK]

The crank needs for a fixed gear is somewhat different than SS. Since you won't be able to coast through corners with a fixed gear, you should think about shorter cranks (170mm or less). For SS, I'd just use what you are used to.

Kevin

[GD2002]

Thanks.

[Fixed]

bro 165 are what most cats use
cheers
I have 170's on my work bike but is's a fixed gear mt.bike
cheers

[old_school]

1+
I run 170s on my road bike & 165s on my fixed.

If you plan on using toe clips, the extra clearance that you will gain in the corners from the shorter cranks is of particular importance. Also, shorter cranks will keep your spin up on hills.

[Smiley]

GD what is the BB drop on the bike u plan to use , if its 8 cm go shorter if its 7 cm you'll be OK with a longer crank , my 2 cents

[Smiley]

As a side note , Rapid Tourist on her Kirk fixee is turning 175 mm cranks and on her road bike she spins 170's. She's kinda of nuts :) in a good way :)

[FierteTi52]

I ride 170's and use 170's on fixed. I tried 165's and didn't like them, although my goal was a fixie to feel like my road bike.
Jeff.

[11.4]

So what's the point in riding a fixie? If you just want a one-speed road bike that feels exactly like a multi-speed road bike, you just don't need an extra bike. Just getting a fixed gear on your standard road bike isn't hard, and there's no acclimatization involved, and you are already familiar with the risk of pedal strike while pedaling through turns.

The point about a fixie is that you can't take crank length in isolation.
Specifically, you ideally want to be riding a lower gear (except in certain specific circumstances) with a shorter crankarm, and potentially a slightly different position. And you aren't riding slower -- rather, you are riding at a higher cadence and with greater aerobic output. You want to be applying the same kind of wattage you'd apply in summer in a bigger gear, but you want to be doing so while training your legs to handle higher cadence (higher leg speed), training neuromuscular systems as well as aerobic capacity. This translates into higher comfortable cadence plus greater "snap" and makes you a faster rider with better acceleration, while building your leg agility, pedaling smoothness, and aerobic capacity. You don't accomplish this as readily if you are riding bigger gears or longer cranks. With both a lower gear and shorter cranks, you can train very efficiently to achieve these goals. In addition, the shorter cranks/lower gears combination protects your joints and also allows you to warm up quicker, so you are able to do a more effective and lower risk winter workout. The point is to be training hard in the off-season, in a way that results in faster speed during your in-season (and faster speed is the ultimate purpose behind training, right?).

Riding shorter cranks than you are used to can take getting used to. That's why several people have commented that they didn't like the shorter cranks. (I'd have the same thing to say about going to longer cranks as well, by the way.)

And just for the record, you should be aware of the downside of fixed gear training. The big one is that on a fixie your pedals will carry your feet through weak or awkward points in your pedal stroke. This way you train in bad pedal stroke habits or weaknesses. Ride a fixie one-legged and you'll see it can be much easier than riding a road bike one-legged. It's important to combine fixed and freewheel riding to deal with this issue.

I mentioned certain circumstances where bigger gears may be appropriate. If you've been riding for a thousand miles in a 66 inch gear, and then moved to a 72 inch gear for another thousand, you are ready to ride a 79-81 inch gear with a lot of telephone-pole sprints and the like. Remember that just spinning in a low gear doesn't train you to spin the same speed in a big gear (which is what fast riding is all about). It feels good, but you do need to train the application of power to your pedals and very low gear spinning doesn't do that much for power. But if you combine the benefits of fixed-gear spinning with lots of larger-gear fixed-gear high-cadence sprints, you'll be transforming the neuromuscular control that you've developed (to produce high cadence) into pedaling that actually delivers more power (by introducing the same cadence in sprints at higher gearing). Then you'll be ready to ride faster in the spring.

[Ti Designs]

The point about a fixie is that you can't take crank length in isolation.
Specifically, you ideally want to be riding a lower gear (except in certain specific circumstances) with a shorter crankarm, and potentially a slightly different position. And you aren't riding slower -- rather, you are riding at a higher cadence and with greater aerobic output.

So why the shorter cranks and different position? The common answer will be shorter cranks and pedalling smaller circles allow for higher cadence. But if the goal of training on a fixed gear in the off-season is to have snap and leg speed next season, wouldn't using the same position and crank length eliminate a hard transition come spring time?

[dirtdigger88]

why do I always seem to throw a wrench into things- :rolleyes:

I run 175 cranks on my fixed- that has an 8 cm bb drop- ;)

but I have brakes on my fixed too- so whadda I know

Jason

[11.4]

So why the shorter cranks and different position? The common answer will be shorter cranks and pedalling smaller circles allow for higher cadence. But if the goal of training on a fixed gear in the off-season is to have snap and leg speed next season, wouldn't using the same position and crank length eliminate a hard transition come spring time?

The reason for a potentially slightly different position is that this is simply the best time to adjust your position on the bike (not in competition, lower gears, etc.). Most people set their position to the limit of their flexibility and neuromuscular training. That doesn't mean that it's a preferred position. If you can work yourself into a better position during the winter, that's a desired goal, right? It's a rare rider that's already in your ideal position.

The point about shorter cranks is that on longer cranks, you are having to make larger circles that somewhat limit your cadence (and we're talking about cadence applied with power, not just mad spinning on a downhill, since it's the former that builds your ability to ride faster in all conditions during the racing season). You are specifically trying to teach your legs to go through a complete rotation at, say, 135 rpm. Then you can go back to your road bike and be comfortable doing tempo at 115-120 rpm, which is likely a big improvement. At the extreme, consider track sprinters -- men in world cup events tend to race at speeds and with gearing that has them riding 155-165 rpm, so unless they are training to ride 175-180 rpm, they simply won't have the ability to turn the pedals over fast enough. Trying to turn those high cadences on long cranks is something that 12-year-old BMXers can excel at, but it's typically hard for adults to adapt that easily (but this is why the Australians and Brits have looked for their national team track talent among successful BMXers). You're specifically trying to coach your legs to rotate at high speed. Nearly every rider I've ever seen that tries long crankarms on a fixie at high cadence ends up applying fast acceleration on the downward stroke but can't manage the full range of motion and actually develops a proportionately weaker upstroke, which is counterproductive. You don't have to be as strong on your upstroke as your downstroke (that's a tri fallacy that gets perpetuated in ideas like Powercranks); you simply have to make sure your upstroke doesn't get in the way and hopefully contributes somewhat. There is no way that the human lower extremity anatomy will ever allow you to develop as much upstroke power as you can produce on the downstroke. You might be one of the rare riders who can do what that 12-year-old BMXer does on longer cranks, but most riders can't do so. And one result of this training may be that you find you can actually produce better power on shorter cranks. I've watched a number of riders using 177.5's and the like go through a winter on significantly shorter fixed-gear cranks and find that their SRM-optimized power comes at 170 or 172.5 mm rather than the 177.5's that they were optimized for previously. (And it's not just the optimum crank arm length; it's also significantly more power than they generated on 177.5's. Note that among European road pros, the ones that tend to use the really long cranks either are some of the sprinters who get paced to the finish and just have to wind up at the end, or those few gifted individuals with huge legpower who exploit it at lower cadence. You see people comment about 177.5's on Boonen's bike, or Ulrich's, but most riders are on much shorter cranks and the trend is to go slightly shorter from year to year as well. Some track riders are going a bit longer, but mostly to exploit more radical track designs (a la Theo Bos' new 200m record in Moscow) where gears can be a lot higher.

This isn't the only way to train in the winter. I never want to claim to know the only way to nirvana. It's just one of a variety of alternatives I offer to those I coach and train with, and the one that seems to be of use more often than others. People are different. You can easily be a rider who doesn't benefit from fixie use and should stay on a road bike all winter. Your unique neuromuscular abilities determine how you train, and my comments on this forum shouldn't supplant your self-examination and experience with your own training success.

[znfdl]

I ride 172.5s on my road bikes and my fixed gear bike. If you will not hit pedals while cornering and will not race the fixie, why change cranks lengths?

[old_school]

THIS ...

Is the sound of my jaw hitting the floor every time 11.4 posts on this board - definitely one of our most insightful and articulate members.

Thank you for hanging around these parts :beer: