[csh8428]

I couldn't really find anything like this in the forums.
What are some "general rules of thumb" for fitting on the bike?
I used to be a spinning instructor, so I know those, but are they difference for cycling.

I'm also a speedskating coach, so I'm pretty familiar with biomechanics.
I'm getting more advanced in cycling and it seems like the way they set me up in the store isn't aggressive enough. I feel like my hips should be higher, knees farther forward, and upper body lower. (basically more aero and more power).

What I'm looking for is what adjustment should be made and what effects they have?
also: how far over your foot should your knee be when legs are parallel to each to each other?
What angle should my knee be bent at, minimum, not exceed and the bottom of the pedal stroke?
Should I take a spacer out of my headset?
Should I get a longer stem?(I'm pretty short, 5'5" and riding a SM Specialized Tarmac comp)

I can pretty much figure it out if I get an answer to "Doing X to this part of the bike will do Z"

Thanks,

Craig

 

[MB1]

Rule #1 At all times keep the seat higher than the pedals.

 

[Creakyknees]

That's a big ol can of worms you just opened. IMO the real best answer is "carefully experiment, read a lot of opinions, and figure it out yourself"

All the rules of thumb are starting points. And the in-store fitting is usuall sub-optimal if not downright wrong.

Also keep in mind your most powerful position will not be your most comfortable position; you get to choose the compromise.

IMO the critical pieces for power are seat height, and seat fore-aft relation to pedal, and foot placement on pedal.

Handlebar reach/height is primarily a comfort vs style / aero decision, although it can affect handling and power production as well.

Seat height: lots of rules of thumb but the one people forget is you generally want to get the saddle just high enough that your hips don't rock side to side (you don't want to be "reaching" for the pedals). Yes you can go higher and you may generate more power that way, at the cost of potential back strain.

Seat fore-aft: conventional wisdom is KOPS - front of kneecap directly vertical over pedal spindle (axle) when the crankarms are horizontal. This is not such a bad place to start, but it's also not the absolute final word. Experiment, see what you like best. Keep in mind that seat fore-aft and height are related; if you adjust one you're affecting the other.

Foot on pedal - fore-aft is the biggie, rule of thumb is ball of foot over spindle. Experiment with moving the toes forward to see how you like it. Some evidence suggests mid-foot is more efficient but it's new enough that not many have tried it.

Bars reach/height - fashion, looking "pro" generally rules here. IMO, breathing is more important than looking cool so I make sure I can get full lung expansion when in the drops. There is no advantage to a too-long reach, and the disadvantage of a too-short reach are minor as long as it's not extreme.

 

[C-40]

rough guidelines...

I really disagree with that ancient idea of raising your saddle until your hips rock, then lower it a bit. That can lead to a ridiculously high saddle and an extreme heels-up foot position at the bottom of the stroke. A better rough guideline is to position the foot horizontal, with your leg locked out at the bottom of the stroke. Then a 2-3cm rise of the heel will produce the desired 130 degree angle between the upper and lower leg at the bottom of the stroke.

The good old knee over pedal is a good enough place to start with your sadle fore/aft position. Andy Pruitt starts by placing the front of the knee vertically aligned with the front of the crankarm, with the crankarm at 3 O'clock.

As for handelbar drop, I've never used less than 8cm and usually have something in the 9-10cm range. If I get the bars too low, I get neck discomfort on long mountain desecents.

As for stem length, I want enough length so that my knees and arms don't touch when I'm riding with my upper back nearly horizontal and my hands are in the hooks, with my fingers in reach of the brake levers. Any longer stem really serves no purpose. If you want to get lower, increase the drop, not the reach.

 

[csh8428]

Thankx... yall.
Both those posts were exactly what I was looking for.

Just to note I tend to take to the more aero/power positions more than most other people due to speedskating. I'm used to being in a very aero/hunched over position for extended periods of time.


Craig