Since I’m too cheap to pay for someone to put me in the best position for optimal power output, my goal for this winter is to figure it out for myself. This most recent race I was my most aerodynamic but my power felt like it sucked. My tools are a set of rollers and a mag trainer. Does anybody have any ideas for the most scientific way of doing this? I have a science background so I’ll be controlling as many variables as possible. Here are some of my ideas:
Ride several 10 mile simulated time trials in various positions, stick with the position that gives me the lowest repeatable time.
See which position allows me to do an all-out effort up to the highest speed.
I’m thinking that test #1 would be most applicable to a triathlon, but test #2 would be interesting to see if I get the same result for both tests. I also think that the test would be most accurate on rollers because the resistance might change slightly from test to test on the trainer. As long as I keep tire pressure constant, the rollers should be the same from test to test because there is no resistance. Also, I have my cyclocomputer hooked up to the front wheel and it would be a pain to somehow rig it up to the rear wheel for the trainer.
Does anybody have any thoughts? Should I try to involve heart rate? I don;t really want to because it seems like it would be too hard to control HR. I currently ride at about 79 degrees, but would like to see if I notice a big change at steeper or less steep positions. I also want to see if lengthening my cockpit would change anything, as well as lowering/raising my armrests.
I often think about this as well. Weather a more aero position, while more aero, may be less powerful.
I think the only really accurate way would be with a power meter. however, how would you know how much wind resistance you gain or lose and weather they are more or less than the power gained—or lost
It’s a good quest, but hard to do without a powermeter. Your power can change +/- 10-20 watts using PE as a guide, and that is enough to cloud any conclusions. Still, you gotta use what you have at hand.
Test #2 is pointless since max power is a sprint thing, and is not applicable to your sport.
Test #1 is tough to replicate. Motivation from test to test is a serious barrier to success. Rolling resistance on the mag trainer will vary every time you mount up. This test will also not account for the aerodynamics of a position and won’t tell you if its faster. Going lower doesn’t necessarily mean you’re more aerodynamic. You should also consider that a new bike position can require that you ride in the position for a few weeks before you are adapted enough to it to have a reliable test. Those intervening weeks are enough for your fitness to change, which invalidates the test. This is why bike fits done on a Computrainer (which seems all the rage) are pointless.
The final issue is that triathlon bike rides are not max-effort rides. We ride at a percentage of our potential, by choice. Therefore, a bike position that limits power at threshold or MAP does not necessarily limit our ability to ride the bike leg of a triathlon at a chosen fixed power output.
Yes, I realize this, and unfortunately no matter how “scientific” I make this process, there will always be variables that could skew the results. I’m thinking that I could at least choose 2 positions that I am comforable in, and do 5 time trials in each position. This should dilute out the perceived effort problem. If there is no clear winning position, then I just wasted some time but at least I still got 10 good workouts. Who knows, one position my be clearly more powerful then the other.
Another thing you pointed out which definately complicated things is the fact that in a new position your body needs a couple weeks or more to adapt to it. Whether this is enough to invalidate a computrainer session is anybody’s guess though…
You should also consider that it takes a while to adapt to a new position.
I recommend finding the most comfortable, aero dynamic position possible and just train all winter in that position.
You could also find someone local that will let you try out a compu trainer. While not supper accurate its well within a ballpark for getting an idea of what wattage you put out in different positions.
Agree with Ash - the issue is adaptability and development, which are dynamic. Basically the approach would be to assume narrower (arm rests) and lower stem height and maybe helmet/head position are the things you can control for aerodynamics, so you just keep squeezing and lowering to find where your times are going back up…BUT you’d have to ride each position for a while to accomodate adaption and to get the feel of what a good day for you is to offset the normal ups and downs of you life/fitness. (this is my same beef with a power meter - it will show lower readings when you are having an “off” day, not just because the set-up is wrong)
So the easy answer is that there is no easy answer. Even if you had an expensive wind tunnel and a pm analysis, you could only use that as a reference for going forward since you will change (fitness and flexiblity) as you progress.
…then I just wasted some time but at least I still got 10 good workouts. .
It’s never wasted time, as you say. It’s still a good exercise. You might learn something about how you like to ride your bike. Higher, lower, forward, back, …?. If you have a keen sense of observation (and you say that you do), then it’s all good.