| ??? 03/12/12 06:57 Read: times |
#186591 - More time than money if access to machinery Responding to: ???'s previous message |
Kai Klaas said:
Joseph said:
Would it really be that expensive to accomplish? I think, yes. You must have a very robust construction which must be able to withstand heavy kicks. Also certain crahses must be taken by the contruction when the pedal "touches" the asphalt in curves or during harsh handling. So you need a frictionless guide for the pedal movement which is free of play and can accept shear forces. On the other hand you need an elastic holding fixture for the strain gauge which can pick up the pedal forces and transform it into stretch. The elasticity must be very high even linear up to the highest forces without any fatigue for months or even years. At the same time the rider must not feel this elasticity but the kick must be hard and direct. I think to find a satisfying solution will be a hard and long way. This must be a very accurate construction and the used materials must be high-quality as well. Yes, I think this will become very expensive. Kai Klaas You can find lots of references exactly how existing systems works. One variant used is that the axis the pedal is mounted on have part of it cut open, creating a shear box. So the basic pedal is not really different - just the inner axis. Another much used variant is instead to have the sensors on the spokes that holds the chain rings. By the way - you don't need a linear solution. You can correct in software as long as you don't run out of resolution. And torque is very easy to calibrate. In the end, I don't really think we are talking about any big money, if someone just have a bit of time, and access to a CNC machine. There are quite a number of one-man garage companies that develop and sell most of the bolt-on bike items including hubs, pedals, crank assemblies, ... Their main resource is mechanical skill - not money. It would probably even be possible to get in contact with such a company to get them to make a modification on one of their parts. |
