Shaft driven bike

[mickle]

But the original assertion was that one shaft is the same as another and that nothing significant had happened in 100 years. As you say, there are differences between different applications (carbon tubes, for instance) and changing the shape of the bevel gear's teeth has reduced the losses at either end of the shaft.

A clean, new chain on fresh teeth might be 98% efficient but I doubt that anyone who uses their bike for cycling through the muck and grime will be seeing that level for much beyond the first few hundred yards.

Shafts were also less popular because of the gear options, not just because of the efficiency differences. It was easier to get a wide spread of gears with cogs on both axles. Shaft drive were limited to 3-speed hub gears one just the wheel axle.

I think (I read the article a few days ago so could be wrong) that there's a simple release system so pulling the wheel out should be straight forward.

And I stand by that assersion. No great technological leap has occured in the area of shaft drive bevelled gears for 100 years. The condition of an old worn out bicycle chain has to get very very bad indeed before it matches the inefficiency of a brand new top o' the range shaft drive. That's the beauty of chains and sprockets, provided they aren't actually rusted solid they are remarkably efficient right up to the moment they fall to bits.

The benefits of shaft drive are clear, cleanliness and low maintenance among them, but you can't argue that shaft drives achieve anything like the efficiency of chains.

 

[benb]

The benefits of shaft drive are clear, cleanliness and low maintenance among them, but you can't argue that shaft drives achieve anything like the efficiency of chains.

These people argue exactly that, but I take their calculations with a huge pinch of salt. I do think that chain and sprocket are perhaps not as efficient as some people think.

We need an unbiased comparison of efficiency of the systems.

 

[GrumpyGregry]

If those people are convinced of the superior performance of shaft drive why do they sell chain driven hub-geared bikes too?

 

[mickle]

Wiki entry is good reading on the subject.

 

[mickle]

And Shmeldon says:

An alternative drive system, replacing the chain and sprockets with right-angle bevel gears and a shaft running inside the right hand "chainstay."
Shaft drive was briefly popular around 1900, and occasional attempts are made to revive the design. Unfortunately, shaft drive turns out to have more problems than advantages.
A shaft drive requires heavier frame construction around the bevel gears to maintain their precise alignment under load. The drive system is heavier and less efficient than a good chain drive.
For reasons of clearance, the bevel gears of a shaft drive bicycle must be considerably smaller than the typical sprockets used with a chain drive. The smaller size of the gears causes an increase in the stresses on the whole support system for the shaft. This problem is exacerbated because the stresses from the shaft drive are not perpendicular the triangulated structure of a bicycle frame, and so are not well-resisted. .
Most of the advantages touted by proponents of shaft drive are only advantages compared with open-chain, derailer gear systems. Many proponents of shaft drive use specious (if not dishonest) arguments "comparing" shaft drive systems with derailer gear systems. Any such comparisons are meaningless, it's like comparing apples and locomotives.
A valid comparison of shaft vs. chain drives can only be made if both bikes use the same type of gearing, whether single-speed or with an internal gear system.
These same advantages can be obtained with chain drive using a fully-enclosing chain case, as with old English roadsters and many current Dutch bikes.
Shaft drive proponents also often compare sealed, enclosed shaft drive systems with open, exposed chain drive systems. This is also a misleading comparison. All of the advantages claimed for shaft drive can be realized by the use of a chain case.

 

[benb]

Thanks for that.
I do like the clean lines, but looks like very much a niche market.

Belt drive + hub gears = all the advantages.

 

[GrumpyGregry]

Thanks for that.
I do like the clean lines, but looks like very much a niche market.

Belt drive + hub gears = all the advantages.

chain drive + hub gears + hebie chain glider = none of the claimed disadvantages of a belt drive with proven technology.

 

[byegad]

And I stand by that assersion. No great technological leap has occured in the area of shaft drive bevelled gears for 100 years. The condition of an old worn out bicycle chain has to get very very bad indeed before it matches the inefficiency of a brand new top o' the range shaft drive. That's the beauty of chains and sprockets, provided they aren't actually rusted solid they are remarkably efficient right up to the moment they fall to bits.

The benefits of shaft drive are clear, cleanliness and low maintenance among them, but you can't argue that shaft drives achieve anything like the efficiency of chains.

I have to say that Mickle is right on this one Ian. You can stiffen the shaft so it doesn't wind up but turning the rotation through 90 degrees twice costs and that can't be worked around.

 

[byegad]

Weight is obviously an issue, but I can't see how a shaft loses more energy than a chain. Please explain your thinking.

Sheldon says it better than me.

But ask yourself this. If it was possible to get the claimed efficiency and weights were the same the tolerances need to be much, much closer to get the bevel gearing to work, so the frame has to be stiffer and that would add weight. As is, after all the reinventions, and the last one was less than 10 years ago, this has never caught on. I'd suggest if you could match the tolerance and stiffness requirements AND stay within acceptable weight limits then the cost is going to kill the idea anyway.
Like so many other 'brilliant inventions this one has more age than first apparent and like the four limb powered bike, which keeps coming back, because it looks like such a good idea until you try to do it, it will turn up on a regular basis and be rejected for the same old reasons.

 

[Riding in Circles]

I have never claimed that shaft drives are anything like as efficient as chains, as per usual the self declared cognoscenti are finding something to argue about where there is no argument, I stand by the fact that there have been significant improvements in shaft drive technology in the last 30 years, I am as usual at a loss to see where I made any other claims.

 

[Riding in Circles]

chain drive + hub gears + hebie chain glider = none of the claimed disadvantages of a belt drive with proven technology.

The new belt drives are as efficient as chains but you cannot use them on a derailleur system so you invariable suffer losses in the gear system, but a like for like hub gear with a carbon/kevlar belt will produce the same efficiency as a chain.

 

[tyred]

Mine and made in 1951:


Rudge by braveheart1979, on Flickr

Fully enclosed chain to keep the chain clean and rust free and keep your jeans oil free, fully enclosed gear system, built in lighting system powered from dynamo within the Sturmey hub, all still working fine after 60 odd years. Maintenance involves a few drips of oil into the various oil ports and on the brake pivots every now and again. I don't see what advantages a shaft drive offers over this design.

 

[benb]

Mine and made in 1951:


Rudge by braveheart1979, on Flickr

Fully enclosed chain to keep the chain clean and rust free and keep your jeans oil free, fully enclosed gear system, built in lighting system powered from dynamo within the Sturmey hub, all still working fine after 60 odd years. Maintenance involves a few drips of oil into the various oil ports and on the brake pivots every now and again. I don't see what advantages a shaft drive offers over this design.

That is gorgeous. Let me know if you want to sell it!

 

[tyred]

Not for sale!

 

[GrumpyGregry]

The new belt drives are as efficient as chains but you cannot use them on a derailleur system so you invariable suffer losses in the gear system, but a like for like hub gear with a carbon/kevlar belt will produce the same efficiency as a chain.

I agree. But, as a result of owing one belt drive bike and having had a long term loan of another, I remain deeply sceptical about the claimed longevity of contemporary belt drive components and changing them is expensive and nowhere near as easy as swapping a chain you bought in your LBS.