• Hey guys - I didn't know where to post this, but I assumed that this would probably be the best place.

    Does anyone think it would be possible to build a hydraulic drive bike with two wheel drive? I was think that hydraulic drive probably has a ton of benefits - can rout the cables anywhere (opening up a load of chassis design steps), you could put hydraulic brakes into the drive, and I imagine it'd be really quiet.

    Thing is, I assume it'd be heavier and less efficient, and when it fails, it'd make a huge mess. But are the negatives really that bad?

    I also imagine a two wheel drive bike would come in useful for things like trial biking and singletrack.

    Thoughts from any engineers?

  • Typical motor and pump efficiencies are around 85% each, making the pump-motor combination somewhere around 72%, and small bore pipe loss would drive this lower still. M.I.T. suggest a measured efficiency as low as 60% (http://dspace.mit.edu/bitstream/handle/1721.1/36699/77549265.pdf?sequence=1)

    Compare this with a chain and derailleur efficiency of 93 - 98%. Even if your design had a similar overall weight, you (the rider) would need to provide around 30% more power to achieve a similar performance.

    It's the sort of thing you might do to prove it can be done, or if styling takes priority over engineering...

  • (opening up a load of chassis design steps)

    As it turns out, chassis design doesn't need opening up. The basic 11-tube frame and fork is really hard to beat on all sorts of measures.

    I imagine it'd be really quiet

    A properly set up roller chain is already quieter than the tyre noise :-)

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