Right, been out all night so sorry not got back to so many of you til now (hopefully you should all have emails by now)… Anyway…
To answer a couple of questions…
80-90rpm is not spinning like mad… That's a slow-normal cadence for me! 100rpm is getting more like it, 120rpm is quick… 175rpm on a fixie is ludicrous, but fair play I bet it gave you a rush! 😉
Anyway, have tested my calculations against the great Mr. Sheldon Brown's on his website… And there's a slight (like 1-1.5%) discrepancy on the speeds being chucked out… But it seems to go both ways depending on wheel and tyre size used, but it's never more than 1.5% different… So… I need to work out exactly how Sheldon Brown has calculated the total circumference of a bike wheel, cos it's obviously different to the way I assumed to (wheel diameter in mm, 559 for 26", 622 for 29er, + tyre height/width x2, all xPI, to give total circumference)… So if anyone can shed any light on this, especially regarding rim diameters (seems it's not so obvious as I first thought), then let me know!
Off to do a bit more research on it now… But it answer to all the worrying about cadence seeming way too high for intended MPH… You're wrong, your cadence is that high… To get within 1-1.5% of the MPH my calculator is chucking out anyway… 😉 My only other thought is that perhaps his site does quite a bit of rounding up/down in a calculation before you get the final answer (which is only to 1 decimal place anyway), whereas mine is going to the Nth decimal place in the calcs, only does it round up/down to 2DP in the answer column… Who knows!
FWIW the rest of the calculations come out spot on with those generated on Sheldon's site…
avdave2 will take a look at that when I get onto my PC (it's a .exe file, I'm on my Mac at the mo) and take a look… If it's any good, I'll probably get in touch with him…
