Chainless bike

[Quicken]

Hi,

I just spotted this article on gizmag, about a chainless bike from dynacraft:

gizmag Article: Bicycle design eliminates chain, derailleur and sprocket

More images here:

gizmag Article: Bicycle design eliminates chain, derailleur and sprocket

I've never seen a chainless bike before. Is it unique? The bike is available for what sounds like a very reasonable $300 US dollars, and a description of the features is online here:

https://www.dynacraftstore.com/estore/catalog/product_info.php?cPath=21&products_id=28&osCsid=67bb2886296aa42121c81e5453c024b7

Dekra: Men's

• Lightweight Aluminum frame
• Shock absorbing front forks and seat
• D-drive chainless operating system
• Sophisticated Metallic Sienna body paint
• Handlebars with thickly cushioned hand grips
• 26" x 1.5" alloy rims
• Front and rear alloy brakes
• Shimano Internal 3-speed gear hub derailleur with SL-3S35 shifter
• Plastic platform (9/16") pedals with CPSC reflectors
• MTB type alloy front hubs
• 26" x 1.75" tires and tubes
• Steel kickstand
• Shaft drive type crank and sprocket, alloy crank
• Alloy seat post with quick-release adjustment
• Lifetime warranty on frame, forks and D-drive system
• Two year warranty on all other components

Weight is around 16 Kg. I'm wondering if it would be possible to fit an electric motor to this beastie. What do people think? I'm going to email them to find out how much it would cost me to import one.

Cheers,

Q

 

[flecc]

The Zero bike with shaft drive has been available with shaft drive in this country for some while, and it's coupled with a seven speed Shimano hub so is better. There's been favourable test reports, I'll dig out the details if you wish, but shaft will never be as efficient as chain and sprockets.

Also not quite as clean as you might think. The hub requirements mean that the bevel gears are exposed when the wheel is removed, so the grease can get contaminated with roadside grit etc. Neat and clean looking though.

There's also an American electric coming shortly with shaft drive, the Schwinn which you can see details of in threads here.

You could only fit a front wheel hub motor like the Heinzmann to that bike you've seen, the Currie motor won't fit onto hub gear bikes.

 

[rsscott]

Hi Quicken,

it has already been incorporated into an electric bike :

Schwinn Bikes - Bike Detail

The UK distributor Moore Large can order one in for you.

 

[Miles]

This Taiwanese company has been churning them out for years:
Taiwan Sussex chainless transmission bicycle manufacturer:asia

Miles

 

[Quicken]

Never mind. I just checked and they only ship to US addresses. Curses!

Q

 

[rsscott]

Sorry Quicken, who did you contact ?

 

[rsscott]

This Taiwanese company has been churning them out for years:
Taiwan Sussex chainless transmission bicycle manufacturer:asia

Miles

Following your link, it appears the UK distributor is: zero cycles

 

[Quicken]

Sorry Quicken, who did you contact ?

I was referring to the original bike with that last post. For some reason the thread hadn't updated properly for me, and I couldn't see all the responses I had already received. Thanks everyone btw. Looks like I should have done a little more research before posting. Just thought it looked like a good idea, and it's good to know there are uk and electric versions available.

Cheers,

Q

 

[flecc]

To round this off, there's a full test report on the Zero which can be downloaded from Velovision here as a PDF, 400kb. Scroll down for Issue 10, June 2003.

 

[rsscott]

......but shaft will never be as efficient as chain and sprockets.

From the Zero site they say:

"The performance of the shaft drive system ranges from 90 to 95 % efficiency. In comparison, the efficiency of a good clean chain may be up to 98.5% efficient. Due to exposure to dirt and the elements however, the efficiency of a chain drive will reduce more dramatically over time than the shaft drive system."

After several thousands miles on our electric bikes would a shaft drive be a better choice in the long-term ?

 

[flecc]

Only if the chain was terribly neglected and rusty might this just be possible. If oiled or greased from time to time, even a very dirty chain would be unlikely to ever lose the difference. The efficiency at the top end they are quoting for the shaft drive is unrealistic and is for the drive only excluding the hub gear.

Chain has always been accepted as by far the most efficient drive system, and no drive through bevel gears will ever match it in like for like circumstances. What they say about loss of efficiency is disingenuous in the extreme. Their gear system is exposed to road dirt as well, as I've hinted at in my wheel removal comment above. There's no sealing of the bevel gears at the rear due to the need to remove the back wheel complete with one of the bevel gears on the hub, so both dirt and damp can easily get in.

In another thread reply I commented that it would be better if gears were incorporated into the shaft drive system so that the wheel could be removed as a simple bolt on to the bevel drive face like a BMW motor cycle or similar to car wheel. That would leave the bevel gears properly sealed.

 

[Miles]

In "Bicycling Science" (3rd ed. p.343 table 9.5) there's a table comparing the efficiencies of a shaft-drive+hub gear with clean and rusty chain drives...

There was a vogue for shaft drive bikes in the 1890s.... interesting that there was another one in the 1990s

Miles

 

[flecc]

Yes, strange how these things return at wide intervals Miles

I hadn't bothered to refer to Bicycling Science since I was well aware of the overall situation, but the table you quote shows that even in the very worst possible and unlikely case, the chain still matches the shaft, and is normally very much better, even when dry and rusty.

Additionally, that was for an ideal shaft drive, the unsealed Zero system not being that.

 

[Miles]

The other disadvantage of shaft-drive is, of course:

"A shaft drive bicycle is only 1 kg ( 2.2 lb) heavier than the equivalent bicycle using a chain system." [quoted from Zero Cycles FAQ].

Miles