2 bike-related questions, por favor...

I can't help with the Crank length issue. 

But I have a Trek 5200 and it is a comfortable ride.  I'm 6'3" and 210 pds.  I used to have an aluminum bike and I wouldn't ride it because it was just too uncomfortable. The streets of Brooklyn are as chewed up as you can get. 

I also have a Cannondale carbon/ aluminum frame that is very comfortable. The amount of time you spend riding and being properly fitted will make a big difference in your comfort level. Or I should say It made a big difference in my comfort level.

I say buy as much bike as you can reasonably afford.

1stTimeTri - 2007-02-01 11:45 AM I'm going to be 42, 6'3", 165 lbs, inseam is around 35-5/8", and am starting to train for my 1st tri which is held in Sept. I have 2 questions: 1). I asked a Trek rep at a Trek store about road bikes and he was leading me to a 2006 clearance Trek 5000 (full carbon). I was asking about road "feel" on an aluminum vs. carbon since the road's are not that great here in Wisconsin (lots of cracks, bumps, etc.). The rep stated that the carbon would feel more "dead" when riding, indicating that the bike would "absorb" more of the impacts more than the aluminum. Question: A). Is that true? B). Justification to go with an aluminum vs. carbon (obviously, cost) bike? C). With my size, is there an "optimal" bike frame size, along with top tube length I should strive for? 2). My engineer friend, who has been doing tri's for almost 20 years, is speaking to me about crank lengths. The stock size is usually around 170 - 180 mm. My friend wants to test me within a couple of weeks and have me try different crank lengths (starting at 175/180 mm and move up to an "optimal" to see if there is better efficiency and power with me going with longer cranks (I don't know about all the other geometry features and sizing yet. I'm thinking that, with all things being equal on a bike, he'd adjust for my proper knee angle on the extension at least.) Yes, we'll be watching for foot/toe to front tire distance, turning angle, and length of ground to bottom bracket/frame distance, and if there will be any knee discomfort. I hope to report my findings after the test within 2 to 3 weeks, hopefully. Question: Thoughts about longer crank size? Thanks for your feedback, everyone, and keep training happily! I appreciate your comments.

honestly if you haven't ridden a lot of other frames, you won't be able to tell if the frame is 'alive' or 'dead'.  It would have to be at one extreme or the other for you to feel it.  In general, the carbon will be better for rougher roads, so yes, it will be more comfy.

Crank length is a weird issue and you will get as many different answers as there are riders.  Some claim that for taller people, longer cranks give better power economy.  Others counter that by saying you get the same power at a lower turnover, which is rougher on the legs and makes the run harder.  It will make a bigger difference in someone who has a lot of training in and is looking for an extra edge.

I'd ride the stock cranks for now.  The most important thing is to just get on the bike and ride.  After you put some time in, you can start making decisions as to what parts you want to swap to match your style.

As far as crank length and toe clearance from your front tire, I don't think that on a road bike, toe clearance won't necessarily be an issue. On my bike (a custom fitted Guru), I have A LOT of toe overlap on my tire if I crank my handlebars into a sharp turn. Rarely when I am making a sharp turn though, is my foot in the way of the tire - I just don't have my pedals anywhere near a 3 and 9 o'clock position, they're out of the way - closer to a 12 and 6 o'clock position.

Maybe if one is very new to riding a bike, it will become an issue, but for the most part, I think it is instinctual to NOT have your feet in the way of the tire.

Most of your riding will more than likely not require sharp turns. So with crank length, your foremost concern will be power development.

Regarding carbon and aluminum, I rode an aluminum frame on the crappy roads out here in the Boston suburbs for 2 years. Our roads SUCK. My 3rd year riding/training on the same pathetic roads was on a carbon frame and there was a substantial difference in the quality of the ride.  

The Trek 5200 is a different bike than the 5000. I think the 5000 is very entry level and possibly a lower end carbon too (though don't quote me on that). Anyway, I think you'd do better looking at the bike componets and fit than the bike material.

Good luck and post pics when you get the bike.

Jen

1. A) possibly, but other elements besides frame material impact the "feel" of the ride (e.g., fit, tire pressure, etc.) B) personally frame material would be low down on my list when choosing a bike (e.g. fit, cost, components all rank higher) C) you should get a professional fitting to figure out which bike and which size frame you should ride (this will have a much bigger impact on the "feel" of the ride than Al vs. carbon vs. steel...)

2.  Let the fitter select this for you (probably stay "standard" in the 170-175 range), but as others suggested it's not clear that crank size makes much difference at the end of the day for most riders.