Bike Fit and Power Output
I have been working with my bike fit recently and was wondering about power output. When and if my bike fit is corrected does this just make me the most comfortable, most aero, best position for power output, or what? We all want to feel comfy on the bike for those long rides so it is the other parameters I am most interested in. I haven't tested my new position yet other so don't know the outcome in regards to power or speed but is it likely to drop or increase? More aero would mean faster unless power drops to much due to position. Speed is the end result we are after so how best to get it. Do I need to test each new position change to find that sweet spot between most aero and highest power output ? I am confused.
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Great questions. I think I can give you some consensus answers, which may not be super-satisfying, unfortunately. You lay out the three parameters, though: comfy, powerful, and aero
"Most comfy" and "most aero" are usually mutually exclusive. But notice that I said "most comfy", not "comfy". Depending on your goals, the trick is to find the most aero position that you feel comfortable tolerating. My n=1 experience is that you can make small adjustments to your aero fit that can make a big difference here. These can include somethign as simple as a small tweak of the angle of the bars or saddle up or down just a little.
"Most aero" and "most powerful" may also be mutually exclusive, but you are right that it's speed that matters. Otherwise, we'd all be riding road bikes, eh? I don't know anyone who has a magic answer here, but you can afford to lose a little power if you don't get slower. After all, if you go just as fast but use less energy...
Depending on what was done for you, "getting low" often means a bit more closure of the hip angle and a small drop in power, just as you imply. Until you can get outside and at least get an idea about speed, you may want to keep a couple of sets of parameters around to mess with. So yes, you may want to go out and do some riding as part of your optimization.
There are people who do a "power fit", i.e., find their most powerful position on a stationary mock up bike, but it's my understanding that this does not usually find the fastest position in the real world of wind resistance.
Your fit is 10% a function of your goals, the trick is figuring out how to the mix of comfort, power, and aero that works for you.
With a power meter and the time to do some detailed CdA testing on the road or in a wind tunnel you could figure out the position that optimizes your power/drag to give you the highest speed. If you want to go to that level of detail start hanging out on the wattage group and you can figure out how to do the testing.
The trick is the comfort part as there are guidlines in the FIST system, but at the end of the day comfort is individual. You have to figure out what position you can hold for 112 miles AND run off of. The other challenge with comfort is riding on a fit bike for 5 minutes at a time is a whole different world then 112 miles. Therefore the perfect fit you get from a fitter might need to be tuned as you go outside and get some long rides down.
For the last few years, I personally thought I could focus only on the aero and power part of the equation. I just assumed that if I could ride in the position for 5 hours that meant I was comfortable enough. The result of this is i've slowly gotten lower and lower on my bike which has earned me some nice bike splits but at the same time my runs off the bike have been getting worse. This year I'm actually looking at slightly raising my position to give me a more open hip angle and see how that works. My thought (ok total guess) is that the few minutes I may loss on the bike will hopefully give me 10 or more back on the run as I have never run within even 20' of my predicted potential off the bike in an IM and my best run off the bike was 2 years ago in a position that had 2cm less drop.
As an alternative to going higher, have you considered moving your stem out a cm or so longer? You're much stronger, much younger, and I assume more flexible than me, but it doesn't have to be a big adjustment to give me a lot more air. This may be more sensitive to me because my back tends to roll up a bit more than flatten out the way it should...but it's an alternative you can check for a very cheap price, i.e., that of a stem. (The only bad thing is if you have to re-cable if you like it...)
One thing to do (again, my total n=1) is compare a photo/video of yourself from the side with the shorter vs. longer stem to make sure it doesn't move your head in some weird place, and to check your back.
Wm
He raisedd my seat about 1.5 inches, moved it forward d/t the fact seems I get more power on the edge of seat, dropped the seat ankle and lowered the aero bars a little more.
During my FTP today it seemed as I needed to be in a higher gear (sweet) to get the power I was getting and up my rpm's. Overall I felt comfortable.
What is the usual drop from the seat and aero bars?
I ride a Cervelo PC3
Thanks
Thanks William, I actually think the issue is my hip angle as it slow creep from about 95 to 92 over the last two years. In my latest adjustments I was able to get to 95 again by moving the saddle a little forward and going with 1 cm less drop from 13.5cm to 12.5cm. So I'm really not much higher up and still pretty low considering I'm 5'8".
I'll definitely keep your suggestion in mind though and I have a complete set of stems from 70 - 110mm so I can try everything out.
Like usual I'm still messing around but this position has felt pretty good and I was able to stay aero for 2 hours on the trainer so I think it's pretty close to locked in. Once I'm happy with it, I'll post some pictures for more feedback or other things I haven't thought of.
@Carl, I don't think there is a single answer to your question as it depends on many varibables... your height, goals, comfort/pain threshold, etc. I would say 5cm to 15cm is probably the range for most folks, but that is just a random guess.
FWIW, I believe I am in a pretty agreesive position and at 5'8" I raced last year at 13.5 cm of drop. I have gone as low as 15 for a 70.3 but I was pretty uncomfortable by about mile 40. As I mentioned above, I'm messing with my position this year (like every other year) and right now I'm at 12.5 cm with my saddle further forward to see if it does anything to help my ability to run better off the bike.
For a more precise answer, here is the FIST answer to your question: http://www.slowtwitch.com/Bike_Fit/...op_25.html
Matt I am headed to the site and going to do some reading and measuring of my bike. I am 5'11" and weigh 156 pounds. Thanks
Great input from everyone, thanks! My notes:
@William, few thoughts on suggestion for Matt. Aerobar pad position fore/aft will clearly affect support of the upper body and ultimately lead to it's effect on the run. Moving pads forward ahead of the optimum, regardless of age, core......means more load on the lower back which leads to discomfort late in the ride and coming off the bike with fatigued lower back.......setting a stage for a slower run. Not sure that it may lead to improvement for Matt. Also aerobar fore/aft position is a clear source of comfort for most sometimes more so than how low are you.
In choppy swims and with a lots of sighting, lower back gets fatigued early on.
Aerobar up/down adjustment correlated with seat fore/aft-rotation around BB, will ultimately affect muscle recruitment for running. Matt is onto something, I suspect. May actually find that a slacker angle will leave his running muscles alone for running.
Very interested in Matts experiment and your further input on this. I seat very steep and low. I am very comfortable in it as I never get up, even on the trainer. I can ride for hours like that, but not sure if it is affecting my ability to run after.
Comfort, power, aero is usual sequence when fitting the long course athlete. The compromise is well explained and understood above, nothing to add there.