Compact Cranks on a TT Bike?

[Extremelee]

Okay guys I am new to the site so go easy on me. I am a 52 year old male and ride about 200 miles per week. I have short legs (30" inseam and long torso). I currently ride compact cranks on my road bike (50x36, 11-23), 170mm. For some reason I feel like I can "turn" the cranks" more consistently on my road bike. When I am on my TT bike with standard 53x39, 11-23, 172.5 mm cranks, I always feel like I struggle to get on top of the gear. I have been given advice that the longer cranks give me leverage but if I cannot turn a 53x11 for 40k why not use compact cranks? I am already used to the feel of them and they would help me to spin faster. I know it does not look pro but I am only interested in going faster. If I do go with compact should I ride 172.5 or standard 170mm? I have read an article by Dave Empfield and he advocates riding shorter cranks, due to hip angle and the forward position. I generally avg about 92 rpm @ 25 mph during the races. Obviously not a pro but I always like to learn and get better. Your ideas would be welcomed.

 

[davidg]

Personally, I wouldn't get hung up on the fact that they are compact cranks. All this means is that you can use a smaller inner ring. It has nothing to do with crank length.

If you don't need 53x11 (ie you never TT down a steep hill), then 50x11 might be fine. I have certainly ridden courses where I have spun out on 53x11 (80km/hr does that)

Likewise, if 170 cranks work better for you then use these.

Unless you need the 36, which would be a pretty tough TT course if you did, then I would choose the 53 since you are more likely to use it, even though it sounds like you generally are in the 15 or so judging by your cadence.

The best thing you can do, is to dig out a cadence calculator and look at the figures based upon typical cadence and speeds.

 

[the big ring]

I rode compact cranks on the roadie when I got back on the bike post-injury and found it great.

I find with TT even more than RR, having a close ratio cluster much better, as I find I am more sensitive to cadence changes than in a RR where the effort tends to be varied rather than sustained.

50x36 11-21 would be a great, close-ratio gear combination for almost every TT course.

And to be honest, compact cranks are not that obvious to most people - noone's really going to know you're not on "pro" cranks unless they look really closely.

 

[Extremelee]

Thanks Guys. The TT's I do are flat to some slightly rolling terrain. I can turn the 172's but I just feel smoother on the 170's. I wanted to run 170's on my TT bike but the guys at the shop told me to go one size up from my road cranks, so I did. They were totally against compacts. I will never be using the 36 in a race anyway just the 50. I can't put my finger on it, but in the real world testing I can turn 170 cranks better. My current setup is 50x36 with 11-21. I will check out some gear charts.

 

[David Suro]

92 r.p.m. is a pretty quick cadence. Usually riders who favor spinning a quick cadence over mashing a large gear are more comfortable on shorter cranks.

Experimentation with equipment is a fun part of the sport. You will need to have your fit on the bike evaluated if you switch to longer cranks. Longer cranks generally require the saddle to be lowered and placed forward a bit. Since the cranks would be 2.5 mm longer, the saddle would be dropped 2.5 mm and moved forward 2.5 mm to account for the larger circles you feet will be turning.

It is always best to experiment with gear during training. The first ride on new equipment should always be short and easy to allow you body some time to adapt to the new position and forces.

 

[Bustedknuckle]

Okay guys I am new to the site so go easy on me. I am a 52 year old male and ride about 200 miles per week. I have short legs (30" inseam and long torso). I currently ride compact cranks on my road bike (50x36, 11-23), 170mm. For some reason I feel like I can "turn" the cranks" more consistently on my road bike. When I am on my TT bike with standard 53x39, 11-23, 172.5 mm cranks, I always feel like I struggle to get on top of the gear. I have been given advice that the longer cranks give me leverage but if I cannot turn a 53x11 for 40k why not use compact cranks? I am already used to the feel of them and they would help me to spin faster. I know it does not look pro but I am only interested in going faster. If I do go with compact should I ride 172.5 or standard 170mm? I have read an article by Dave Empfield and he advocates riding shorter cranks, due to hip angle and the forward position. I generally avg about 92 rpm @ 25 mph during the races. Obviously not a pro but I always like to learn and get better. Your ideas would be welcomed.

Get 170mm compact and bob's yer uncle. a 50x11 is still a VERY tall gear.

 

[Milessio]

Don't just copy everybody else - only your results count!

Remember bike shops are only there to sell you gear. They don't have any special information that you don't have access to, so if it feels right for you, that's most important. I cannot honestly say I notice the difference between 170mm cranks & 172.5mm ones, but that's me.

If you don't need the 36 ring, take it off, and the gear lever and cables too. You'll look more 'pro' than everybody else & save weight + improve aerodynamics slightly. You might need to keep the front mech on if the roads are not too good, to keep the chain from bouncing off.

 

[runninboy]

Okay guys I am new to the site so go easy on me. I am a 52 year old male and ride about 200 miles per week. I have short legs (30" inseam and long torso). I currently ride compact cranks on my road bike (50x36, 11-23), 170mm. For some reason I feel like I can "turn" the cranks" more consistently on my road bike. When I am on my TT bike with standard 53x39, 11-23, 172.5 mm cranks, I always feel like I struggle to get on top of the gear. I have been given advice that the longer cranks give me leverage but if I cannot turn a 53x11 for 40k why not use compact cranks? I am already used to the feel of them and they would help me to spin faster. I know it does not look pro but I am only interested in going faster. If I do go with compact should I ride 172.5 or standard 170mm? I have read an article by Dave Empfield and he advocates riding shorter cranks, due to hip angle and the forward position. I generally avg about 92 rpm @ 25 mph during the races. Obviously not a pro but I always like to learn and get better. Your ideas would be welcomed.

Shops are great for basic set up, but then eventually you will find little personal preferences such as crank length, that might be unique to you.
I feel far better on 170's i am taller than you with 4 more inches of inseam.
I was originally set up on a fit kit w 177.5
However my riding style evetually led me to 170's which is what is going on with you. Now when you change your cranks you probably will have to adjust your saddle accordingly. the 50x11 is going to be fine as well.
good luck