Shaft drive bikes were not uncommon in the early 20th century before being eclipsed by lighter, cheaper, more efficient and versatile chain drives. Belt drives make little or no sense I can discern either. Wide and mechanically inefficient compared to chain and less amenable to simple variable gearing. Roller chains are at the top of any drive efficiency ratings. To the best of my knowledge there is no potential existing technology superior to the humble mechanical roller chain for a bicycling drive. It's pretty much all been tried before and found wanting.
Kurt Sperry Bellingham WA USA
On 10/30/07, bruce thomson <masi3v4me@yahoo.com> wrote:
>
> Nick: Has anyone tried the shaft-drive yet? You know like on the BMW
> motorcycle? Internal transmission with electric finger switches, just
> wondering. Now where did I put the phone number of my patent attorney? BT
>
> nick Bordo <nicbordeaux@yahoo.fr> wrote: At the risk of exceeding my 3 per
> day limit and not being vintage: can anyone tell me, preferably onlist, what
> attempts were made in the past at belt drive on bicycles. More importantly,
> how would the best of today's toothbelt drives match a chain drive energy
> loss wise. Because the ideal chainline is a straight one (anyone to
> contradict me on this one ?) , and were a energy-efficient beldrive to be
> feasible, any manually commanded expanding rear wheel pulley wheel (see
> mobylette automatic transmissions for the general idea) would give the ideal
> drive system. An expansion factor of 2.2 on the back pulley mech would
> give a more than large enough ratio choice.
>
> If a belt drive is not a possibility, why has nobody attempted a straight
> chainline variable ratio drive with a different type of chain then the
> standard bicycle chain (the possibilities for expanding a back "cog" are
> innumerable). Or have they. They probably have, the amount of left by the
> wayside innovation in early cycles is probably greater than in any other
> field of transportation. To clarify this, I have yet to see an "innovation"
> in modern cycling that was not tested or produced at one point or another in
> cycling history, then dropped for reasons of cost or else.
>
> Nick March, Mont de Marsan, Landes, France
>
>
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