To calculate 4.44 gears revs, you multiply by 1.16.
Actually that's incorrect; with the 4.44 FD, you need to use a multiplier of 1.08(29). The figure of 1.16 you've quoted is needed when making calculations with the 4.77 FD.
excuse my ignorance if im missing something here, but how would wind resistance and friction cause a change in mechanical gearing? roadspeed and engine speed should be directly linked through gear ratios, right? if roadspeed is staying at 100km/h but revs are at 3500rpm instead of 3261rpm, doesn't some part of the driveline have to absorb those extra revs?
That's a good question. Basically, there are effeciency losses throughout the system from things such as slip and friction. To do the calculations, I essentially, multiply RPM by gear ratio by rotations/km based on tyre geometry. Unfortunately, this doesn't account for effeciency losses. These losses are beyond my capability to measure, but I have estimated them based on some testing which have worked out to be fairly accurate with 4.10, 4.56, and 4.57 FD ratios.
Ahh I see. I guess it didn't make sense in my head because I imagined a similar scenario with a bike - ie. if you're riding at a constant speed means your feet are turning the pedals at a certain rpm, but if you're riding into a strong wind at the same speed your feet don't need to turn the pedals faster, just harder. Given that you've done practical testing I guess slip has a something to do with it. Thanks
Originally Posted by zhong
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