HPVs

[MTJLT]

Why isn't anyone using linear-stroke propulsion in their HPVs, rather than sticking with conventional cranks? Wouldn't be hard to fabricate a design with push-pull action that would allow variable stroke for different size riders. Thing is, cranks have that nearly dead spot at TDC and BDC. Why not use linear-stroke and have effective thrust throughout the stroke?

And another whacked-out idea: Leading-arm front suspension. With proper tuning it should counteract the front-end braking dive in high compliance suspensions.

 

[Doc Sprocket]

Got an example or two to throw at us? Does linear stroke not ultimately have to be converted to a rotational force?

Cost factors? Availability?

With regards to leading arm frontends- I've never been a big fan. Okay- maybe you can eliminate or fight brake-dive. But there is also the tendency for a leading arm to oppose (instead of comply with) an obstacle met with forward momentum.

 

[newrider3]

Why isn't anyone using linear-stroke propulsion in their HPVs, rather than sticking with conventional cranks? Wouldn't be hard to fabricate a design with push-pull action that would allow variable stroke for different size riders. Thing is, cranks have that nearly dead spot at TDC and BDC. Why not use linear-stroke and have effective thrust throughout the stroke?

Linear stroke as in a rowing machine type thing?
Sounds like it would just be more tiring than standard pedaling.

Dead spots can be eliminated by using clipless pedals and cycling shoes, road and BMX racers use these to allow you to pull as well as push the pedals.

 

[MTJLT]

Re: toystory_4wd

Example ... truth is, I've never seen what I'm talking about ... maybe for good reason. Weight would be the greatest drawback, as it would use two courses of drive-chain, plus a number of freewheel sprockets and the framework to contain them.

See what you mean about the leading arm transmitting shock to the frame. Oh well.