3 ms·
Building a more efficient bike [video]
- grogenaut 3y agoI forget my mech-e skills but those large oscillating masses (the up down linear motion) would seem to be hinderance to efficiency. In a bike almost everything is moving in a circle on a bearing, it's the legs that are inefficient. Another thing is he's not really accounting for lifting the pedals like you do with clip-ins nor back forth motion you do when you get better at biking. I wonder what the torque curve of a trained biker looks like. I'm assuming a bunch of folks here have that in their training data set. I'm just here reading HN in the shade outside relaxing after walking the course yesterday. :)
- Someone 3y agoI doubt this will be a gain, too, but those masses are large in this crude prototype, but not necessarily in the final product.
- thesz 3y agoWith clipless pedals [1] it is possible to produce torque through the cycle. [1] https://en.wikipedia.org/wiki/Bicycle_pedal#Clipless_pedals https://en.wikipedia.org/wiki/Bicycle_pedal#Clipless_pedals Torque is never zero with these pedals. A more efficient bike is already there. Just use right gear.
- jeffbee 3y agoAlso if you just wanted to broaden the time graph of when torque is applied around the crank circle, they already make oval chainrings for that. Although many people say there is no objective advantage.
- waingake 3y agoSurprisingly that article suggests otherwise > Despite wide usage, there is no proven advantage of clipless pedals over flat pedals in pedaling effectiveness, net mechanical efficiency, and muscular activity for both non-cyclists and elite cyclists. [1] https://en.wikipedia.org/wiki/Bicycle_pedal#cite_note-Mornieux2008-8 https://en.wikipedia.org/wiki/Bicycle_pedal#cite_note-Mornie...
- LargoLasskhyfv 3y agoQuill I prefer still. Because once I did jump high. Over the top, of the car from a cop. Blocking my way. Kicking the traffic wand out of the policemans hand, waving STOP in red over his head. Hard, From ABOVE! It shattered. Not that it mattered. Smooth landing, while standing upright, at about 80 kph, yeehaaaaw! Racing away uncaught, who would have thought? They need no special shoes either, fitting into everyday life, why the strife with something that does neither?
- Someone 3y agoAt 30 seconds in, shouldn’t we reach 1/√2 or about 70% of the torque at 45°? Also, the gain for such a new system will depend on how good are cyclists at applying force mostly at the points where torque is maximal. I wouldn’t know, but would think the net gain is smaller than what a model of “cyclists applies the same force all the time” predicts. I also wonder about friction losses in this setup. Ignoring the additional chain (it can be engineered away in the final product), I would think those perpendicular gears and the rollers on the track will add significant losses.
- eimrine 3y agoCan anything be more efficient than a recumbent with an oval?
- xcxcx 3y agoA faired recumbent with an oval and a regen direct drive motor as torque assist
- grogenaut 3y agoHard thing with bikes is they're so light, that regen and battery system will add significant weight and rolling resistance to the bike. It's a saturday so I'm not doing the math to see what the function for tradeoff is :)
- xcxcx 3y agoWell the main problem with recumbents are hills due to higher weight and reduced aero advantage. The motor allows you to trade some rolling resistance for torque assistance
- scott_w 3y agoRolling resistance is a function of tyre and road surface, not weight. On a flat course, weight only affects acceleration (which the motor helps with). Once you’re at a constant speed, weight is a non factor and it’s all wind resistance.
- grogenaut 3y agoI'm an ideal system yes. But I'm fat so if I don't have my tires well or over inflated they're almost flat at most speeds on a road bike where you might be just on the ideal edge. So rolling resistance will be worse for me than I due to energy lost folding and unfolding the tire
- scott_w 3y ago