Planning for Colorado Mountainous Riding. - Page 2

Levi is a shrimp. Seriously, he looks like I could carry him around in my pocket. I don't know what size cranks any of them use, or whether they're using them because of a formula, or because the off-the-shelf bike geometries (in which crank lengths are factored) are made to generally fit riders of that size.

If I had to guess at the most important factors in deciding the size of the pedal circle, I'd guess 1) femur length, 2) foot size, and 3) changes in foot angle through the pedal stroke. Certainly femur length is roughly related to body height and (to a greater extent) inseam, but even a crank difference of 10mm would seem to make a small difference in the ranges of either knee or hip angles as they progress through the stroke.

In any case, I'm not seeing a justification for "longer cranks are better" as related to cycling. Assuming a straight leg at the bottom of the stroke, a longer crank closes the hip and knee angles at the start of the power stroke, which decreases mechanical advantage, is the typical complaint for losing power on TT setups and presents the greatest risk for knee injuries. Your calculations show a increase in power in this case, however, so I'm not sure I'm going to "get it" without a little more explanation.

There's even a whole school of thought on the triathlon forums about going to shorter cranks as a way to open the hips and knees for better performace. I don't know that it's ever been shown to provide a measurable advantage (across a spectrum of riders) in either case, however.

OMG. Does this mean you secretly want to buy one of my 170mm or 172.5mm DA 7700 cranks?!? Or, were you looking for a shorter pair?

Seriously, I know that parts of the KC area are hilly, so I guess I can understand your reservation at any benefit to having longer crankarms when riding on mountain roads. And, I suspect that if I lived in your neck of the woods that I wouldn't care which crank length my bike had ...

However, the crank length really can make a difference in more than just my mind once you're confronted with a lot of climbing ... incessant climbing.

And, I suspect that the lower oxygen level at altitude amplifies the differences ...

So, while I can't say that I can-or-do actually go faster with the longer cranks since I'm not racing/riding against a clock, the lack of increased speed would only be due to the choice to take advantage of the easier (that's relative ... it still isn't easy) pedaling that the longer cranks provide ... the other side of the coin suggests that if I am willing to endure the same level of lactic acid build up for a given speed with shorter cranks that I will be going faster with the longer cranks.

As I said, my riding position is now more COPPI than KOPS ...

I don't know what the maximum crank length would be if I used either a KOPS or a Tri riding position, but with the former it is doubtful that it could ever be 180mm.

And so, it doesn't surprise me that some Triathletes are considering shorter cranks ... because, IMO, the Tri posture is KOPS (a bad idea that has spread like a virus over the years) taken to the extreme ...

Although it seems as though you are trying to convince me of something, I'm NOT trying to convert ANYONE toward using longer cranks ... I was only stating my observation ...

So, if you want to continue to use the crank length which came on your bike, please do so!


BTW. I hope you realize you are seemingly contradicting your early reply within this thread wherein you all-but-endorse longer cranks when you stated:

For that kind of climb I wouldn't be surprised, as the longer cranks effectively gives you a slightly smaller gear by increasing leverage and footspeed. If you were overgeared initially, then longer cranks would push you back towards the typical range.

I presume you actually meant having a longer crank "gives you a slightly lower gear" (i.e., slightly bigger cog).

Honestly, I have no idea what you're talking about anymore.

Actually, that's exactly what you *did* say in post #5, and what I've been trying to understand this whole time. What is it about longer cranks that would cause one to "ultimately improve their speed?"

Quote:

Originally Posted by alfeng As I said, my riding position is now more COPPI than KOPS ...

No idea what that means. If it's relevant then perhaps you could explain?

Quote:

Originally Posted by alfeng Although it seems as though you are trying to convince me of something, I'm NOT trying to convert ANYONE toward using longer cranks ... I was only stating my observation ...

I'm not trying to convince you of anything. I'm trying to understand your statement in post #5 that we should use longer cranks if we ultimately want to improve our speed (which I do). You later said that your calculations show that going from a 170mm crank to 175mm would produce a 2.5% increase in something (power maybe or speed?). Maybe you could explain how that would happen, according to your calculations.

I don't see any contradiction there. Swampy said he did his testing on a fecking steep and long hill and found that the longer cranks performed better. I said that I could see performance improving on a hill where the bike was originally overgeared for the climb, but then longer cranks were used (instead of more appropriate gearing) to shorten the overall drive ratio. Swampy is notorious for prescribing huge gear work, so it doesn't surprise me that he would test his ideas in an overgeared situation. That's hardly an endorsement (on my part) for using longer cranks in the majority of cases where the range of available gearing is typically suitable. It makes a lot more sense to me to adjust the drive ratio by changing the cassette or chainrings than the cranks, but I like to do things the easy way whenever possible.

Okay. I'll admit/declare that 'I' think 'I' can climb faster with 177.5mm cranks than with 175mm cranks ...

And, without equivocation, I know I can climb faster with 177.5mm cranks than with 170mm cranks.

I can say, too, that I could probably climb/ride faster with 170mm cranks 30 years ago than I can now with 177.5mm cranks!

The calculations are only meaningful if a person's riding position allows him/her to use longer cranks. The Forum's brain trust can come up with their calculations if one of them thinks that my calculation is in error.

So, if you don't believe that longer cranks allow a person to climb faster, then you're just going to have to try it, yourself ...

And, because shorter cranks are easier to access, YOU could just put some shorter (i.e., 170mm ... heck, find some that are 165mm) cranks on your bike and ride one of your normal rides & then ascertain if you can cover the course in the same speed with the same effort OR if it takes you more effort (with the shorter cranks) to maintain the same speed ... doing the test back-to-back would be better, of course.

With the same riding conditions (temp, humidty, wind) you may-or-may-not see any difference ...

Is THAT what you wanted me to say/write?!?

MORE COPPI THAN KOPS. Well, go and study Fausto Coppi's riding position, and extrapolate.

BTW. I don't think "smaller gear" and "lower gear" mean the same thing, but maybe they do to everyone else (as to you), too.

I'm pretty sure smaller, shorter, and lower all mean the same thing, namely that the gear ratio is smaller than before. Using size to mean the physical size of the gears themselves is a little ambiguous since it would means one thing when talking about the drive gear, and the opposite if talking about the driven gear.

It's a little clearer if size refers to the gear ratio itself, which is the convention I'm most familiar with. A "smaller gear" could mean switching to the small chainring, using a larger cog, or a combination of the two which results in a lower overall gear ratio.

I test where I need to see results of where I'd like to improve. I also test to see what allows me to go faster for a given situation. IF I end up time trialing at 80 to 85 rpm it's because I tested several times at that part of the season to see what allowed me to go fastest for my state of training. Thankfully my coach was openminded as well as being very, very good.

On that occaison the testing was on a steep hill but the results seem to correlate fairly well when looking at time trial results on the flat where I posted a few personal bests. I'm not sure that I would have topped 29mph for 10 miles on the shorter cranks... Maybe I would, maybe I wouldn't, maybe I'll never know. Over geared? Not really. I could have used smaller gears on the flat and back then I could quite easily get up 12+% hills on 39x21 let alone the 25 I probably had on the block back then.

Thanks for the info. I'll look into sweet spot training, sustainable power, and doing some short intervals for bursts of power. I don't want to tinker with my crank length because my bike is fit to accommodate a past injury. Luckily I live in Colorado at 5600 feet and have access to some serious climbs and altitude for training. I'm stoked to get serious and organized about training for the first time. However, it sounds like two years ago when I had my best season ever I was doing something like sweet spot training by riding at 85% max HR almost all the time, even on mountainous 50 mile rides.

It's quite likely that you were doing SST work whether you had a name for it or not. I remember a discussion between coaches on another board where someone suggested that one reason Colorado has always had such a strong racing community could be because of the abundance of long steady climbs where the terrain gets folks riding long unbroken stretches of Tempo and above on a regular basis. Flatlanders and folks in cities with frequent traffic interruptions typically have to make efforts and stay very focused to ride 20 minute to hour or longer intervals sustained at those levels.

I moved to Seattle this spring and have found only a couple of good roads for 20 to 30 minute SST/L4 intervals and even then they get disrupted fairly often by traffic, folks pulling out of driveways, etc. I miss the open roads of Wyoming for sustained long efforts but just got back from a long weekend of riding in Aspen, gotta love the long unbroken training roads right out of that town.

-Dave