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Hi,
I was wasting my life looking on ebay when i came across
http://www.ebay.co.uk/itm/Vintage-Walens-Trident-Shaft-Drive-Bicycle-Hybrid-Bike-REDUCED-START-PRICE-/230773108830?pt=UK_Bikes_GL&hash=item35bb26305e
i have never seen such a thing before but there are two such bikes on ebay. Now i'm not the most wise of all people and thought i would ask how did this no catch on? It seems a brill idea! It allows freewheeling so isn't a fixie so to speak and for lack of hassle it seems great. Anyone know more about it? or why its not on more commuter bikes?
I've got a shaft drive project ongoing with these people - http://www.sussex.com.tw/
Dave wants to do a shaft drive fat bike, but I think he's nuts.
But then he gave me a job, so that's no basis for any assessment.
We've got 2 of these at work:
[img] 
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Shaft drive onto Nexus 7-speed. Really horrible to ride, but they're very poorly maintained with loads of play in the cranks and transmission. Heavy too.
I imagine horrible amounts of transmission whip, like an old Landrover Discovery 😉
They used to have them for hire outside reading station.
They had soem jump bikes in MBUK ages ago, the main problem apaprenlty was the shaft can twist quite considerably relative to achainst stretching so the drivetrain feels springy.
you get a lot of transmission loss from shaft drive, purely from mechanical inefficiency compared to a chain/belt drive system
the biggest obstacle will be price i would think, they will be competing against bikes with 1/8" chains which are very cheap and last a long time as well as being very efficient.
just my 2p, i could be wrong.
like you say i suppose chains are so cheap that this doesn't really make sense but i am still impressed! It looks pretty to me! and is nice to see an alternative. just wonder if there would be potential if there were some big players involved - surely there is some room for some carbon there? they use carbon fibre drive-shafts in cars nowdays? i realise the cost would prob render it uneconomical. Just never seen one before:)
I really like these;
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900 euros with a 5 speed hub gear drive;
[url= http://www.hawkclassic.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=46&category_id=6&option=com_virtuemart&Itemid=2&lang=en ]http://www.hawkclassic.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=46&category_id=6&option=com_virtuemart&Itemid=2&lang=en[/url]
they are horrible to ride,
feels like the brakes are constantly on,
so much drag!
hired one in south of france, was nackered after doing only 15 miles. (was 30° + tho)
chains are generally very efficient
Roller chain is something like 96% efficient for a well maintained one (while us humans are about 6% I think). As soon as you use bevel drives to turn the drive direction (two off on a standard safety push bike) you start to incur mechanical losses. Don't have any figures to quote for efficiency though.
BTW - an Ordinary (Penny Farthing) is direct drive. A shaft drive is no more direct than a chain (and you could perhaps argue that as you are having to change the drive rotation twice through the bevels it is actually more remote than a chain where the powered wheel and the drive are operating in the same plane).
As soon as you use bevel drives to turn the drive direction (two off on a standard safety push bike) you start to incur mechanical losses. Don't have any figures to quote for efficiency though.
http://www.roymech.co.uk/Useful_Tables/Drive/Gear_Efficiency.html
A sample of 1, but this suggests otherwise. I'd like to think the bigger losses would be in whatever gearbox is used to give a usable range, not in the bevel gear drive itself (assuming the bearing supports for the shafts are stiff enough so the gears don't skew at the meshing point as the torques will be pretty high of the gear size).
wasnt there a company in the 90s that made one with a flexible shaft which could be used to power the front wheel as well?
that would be an awesome talking point wouldnt it?
cant see any practical application though.
I did some work with Muji (Japanese retailer) a loooong time ago on shaft drives. The system worked ok and satisfied a brief (no chain!). They cost a lot, were noisy and were a pain in the arse to build.
also front triangle on OP's bike looks horribly flexy. yuck.
maybe belt drive is the next big thing?
wasnt there a company in the 90s that made one with a flexible shaft which could be used to power the front wheel as well?
[url= http://christinibicycles.com/bikes.php ]Christini[/url]
Not ridden one, but was suprised at how light it was when I picked one up in a shop once.
Supposed to climb very well due to traction at front wheel, and less likely to lose the front wheel on fast descents