4 ms·
What are the efficiency numbers when using normal, grease and shield laden bearings? This might have a place in cycle sprints or other short distance discipline
by asteli 7y ago
What are the efficiency numbers when using normal, grease and shield laden bearings? This might have a place in cycle sprints or other short distance disciplines where you have a lot of time for prep, but the benefits are quite moot if you have to swap or service bearings every hundred km.
- avip 7y ago92-96%
- logicallee 7y agoare those actual numbers or are you just showing it is high? I'd have guessed it's more like 99%. isn't anything that isn't heat or noise = perfect efficiency? a normal bike chain doesn't get hot or make much noise at all, does it? seems to me just about 100% efficient. maybe transfers a bit of vibration to the rest of the frame? but not 8%-4% of its transferred force....
- steve19 7y agoI think the GP is right, I did a quick Google and found sites saying 93-97.5% and it depends on power output. I would expect a dirty chain to be worse.
- logicallee 7y agothanks, that is certainly interesting.
- VBprogrammer 7y agoAn athlete will only generate ~200w which isn't a lot for a fairly large metal part with plenty of air cooling. Even if it was only 50% efficient you might struggle to notice an appreciable change in temperature. Motorcycles can have 150hp engines (~100kw) and even then the chain doesn't get particularly hot.
- maaaats 7y agoI might be a bike fanatic, but I'm no professional athlete and I can sustain more than 200W for hours, so my guess is the pro's are quite a bit higher again. (Your point still stands, though)
- VBprogrammer 7y agoYou are right, serves me right for going by memory. 200w is closer to an average cyclist, a pro is closer to 500w. Still, the orders of magnitude don't change.
- braythwayt 7y agoDuring a sprint in 2018, Andre Greipel averaged 1,600W, and hit 1,900W peak. Those are the kind of numbers engineers have to take into consideration when designing for maximum torque, although obviously they are not sustained for hours.
- perl4ever 7y agoWait, you're saying 1 human = 2.5 horses?
- VBprogrammer 7y agoFun fact. Peak horse power for a horse is 14.9hp :)
- jdietrich 7y agoThis paper gives a very detailed analysis of chain drive efficiency: http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf http://www.ihpva.org/HParchive/PDF/hp50-2000.pdf
- logicallee 7y agoWow, thanks. I only had a quick look but Figure 2 seems to show 91.5%-95% efficiency depending on configuration. Very detailed study and it sounds like it would answer all my questions if I spent an hour reading it.