Phase one was to find the pedal speed that gave Dave the best efficiency so he would optimize his power.
Phase two is to find the longest crank length that allows him to get into a very aero position without losing much power from his upright, most powerful position.
Phase three would then be to calculate the cadence necessary to ride at his optimum pedal speed at the crank length that works best for him (and to retest to confirm we got it right). In addition, we are trying to take into account his historical issue with back and knee pain especially in the aero position.
So after another poor bike season, being hit by Frank Day again, being off season, looking for a new bike, looking at bike fit, etc. I have started, again, to try and gather real data as to what crank length is best for me, a very tall person at 6'5. Everyone has their opinions, but as an engineer, I want numbers, and so far have not been able to find anyone who, IMO, has done some real testing.
Frank has always told me I all the test equipment needed with my Velotrons, adjustable cranks, etc.
So, you have seen my one post working on bike fit and have gotten some great inputs. But none of them talk about bike cranks since basically no one spends the time, or money, to do real testing!
So working with Frank, I have started to do some testing riding at 200 watts, changing RPM's from 110, 95, 80 and 65 after 10 minute blocks and recording HR to gather some data.
I have been riding basically the same 2 routines, one is a 120 watt spin 90 minute session, the other is an interval setup where I warm up with a step 160 to 300 watt, 1 minute steps, then a 150 watt 5 minute, 190 watt 5 minute, and then 4 230 watt, 10 minute with a 150 5 minute spin in between. I spin a 50/16 gear for 84 gear inches.
I have years of data on these ride on how far I have gone.
So last night I changed my powercranks, which are adjustable from 140 to 220mm, from my normal 200mm cranks to 175mm. Raised the seat 25mm and moved a tad forward, and rode my interval test. I usually ride around 20 miles in 90 minutes. (I rode like 27 twice which I made a mistake and changed the gear to 50/18).
So I get on to ride this morning, and after a few seconds I say time to stop, this feels weird. But, I mentally said got to do some testing. As I was riding, it started to feel a little better. What was weird is with 200's, my rpm would be around 80. But with the 175, I was doing close to 100. My speed with the 200's was around 20 mph. With the 175, it was like 23 or so. At the end I was pretty shocked to see the results. 26.85 miles. Only one data point, but in the 50/16 gear, I have never been able to spin that fast and hold it, had such a high MPH, or ridden that far.
So, now I am asking, were these results correct? If so, .....
So, will continue to post more test results as I get them. I will probably do 2 day cycles. Will do the interval work that I did today. Then tomorrow, I will ride the same setup and do Franks HR test.
Then I will shorten another 5mm, raise seat 5mm, stay at a 50/16 gear, and test again.
Seems at some point the cranks will get too short such that I would be spinning way too high of an RPM to hold. But, shall be interesting to test and see at what point I get there.
So going to put on my 175 cranks on my race bike, do a refit, and post the video on the other thread. I will then race 2 races in October with them that I have done before, and doing with some friends. So I can compare time to past, and time to my friends.
So, do these test seem fair? Has anyone else done test like these and have test results?
Dave Campbell | Facebook | @DaveECampbell | email@example.com
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