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2006-11-06 16:26:41.566965+00 by petronius 16 comments

I haven't been on a bike in years, unlike others here, but even I like this sharp design for a folding bike. Unfortunately, I suspect a lot of these "concepts" never make it to the dealer's floor. PS, what's the advantage of a hydraulic drive?

[ related topics: Graphic Design Bicycling ]

comments in ascending chronological order (reverse):

#Comment Re: made: 2006-11-06 17:47:00.660686+00 by: meuon

Hydraulic drive, in theory, is nearly as efficient as chain drive, and has no exposed chain. I think it's a styling benefit, hids the chain. No experience as how it would work in the real world.

and then there is RevoPower.. power that bike with a slick looking wheel with an motor in it.

#Comment Re: made: 2006-11-06 19:48:52.014595+00 by: Dan Lyke

I don't know how practical the hydraulic drive really is, but in theory it could be entirely sealed (no more greasy chain sucking your paints into the chainring) and shifting could be glitch free (possibly even continuously variable, the valve could choose a ratio between two gearings).

But whenever I see something that doesn't actually have a working prototype, I get extremely skeptical.

#Comment Re: made: 2006-11-06 21:33:39.824049+00 by: meuon

Suposedly working drive: http://www.powerengine.com/aitx001hydbiksum.htm and a few more: Chainless Challenge and More and even more pics:Here

#Comment Re: made: 2006-11-06 22:11:09.743333+00 by: petronius

Back in college in the 70s, I knew somebody who had a bizarre french motorbike. The engine was mounted on the handlebars, on a sort of hinged basket. You pedaled to run the generator and start the tiny motor, which terminated in a hard rubber wheel about the size of hockey puck. When the motor got going you threw a lever which tilted the basket down and brought the wheel into contact with the front bike tire, thne you were pulled along at a breathtaking 3 miles per hour. If you applied the coaster brakes the wheel just spun. My friend took it to the local police to ask about a license, but they said the motor was so tiny it was beneath all the registration regs. It was more of a sewing machine than a transport. Never heard of another like it.

#Comment Re: made: 2006-11-06 22:46:46.368916+00 by: Dan Lyke

petronius: One of the electric manufacturers had a similar thing a few years ago. In fact, a quick poke around ZAP! makes it look like they had one, but are just selling the replacement parts now.

Meuon: Cool! In that "wait, you want to use my body power to pressurize a system that's located between my legs to to a hundred and seventy atmospheres? And you think this is a good idea?" sort of way...

#Comment Re: made: 2006-11-07 05:32:06.973745+00 by: ebradway

There are several companies touting chainless shaft-drive bikes, like this one from Dynamic bikes:

Benefits are no oily mess, no dangerous exposed chainrings, simpler gearing (including shifting without pedaling). I wonder if anyone has adapted this to a recumbent? It's an obvious application as the chains tend to be much, much longer!

And Schwinn has a new line of electric-assist bikes coming out:

#Comment Re: made: 2006-11-07 05:37:56.721314+00 by: ebradway

Hmm... I just found this:

But the link from this page on Sussex bikes site doesn't actually refer to a recumbent!

#Comment Re: made: 2006-11-07 13:15:58.990869+00 by: meuon

A lot of bike makers make a batch... and can't sell them, so they stop.

#Comment Re: made: 2006-11-07 14:17:13.629214+00 by: Dan Lyke

I've thought about driveshafts, but can't imagine that in the weights you'd want to use on a bike you could keep flex from absorbing a heck of a lot of power. Interesting that people have tried it!

#Comment Re: made: 2006-11-07 20:46:02.153225+00 by: ebradway

According to this FAQ on Dynamic's site, the shaft drive is made of aluminum alloys and they claim 94% efficiency vs. 75%-97% for chain drive. They also claim that their 7-speed hub has the equivalent gearing of a 21-speed deraileur.

Given that the chain and deraileur is a headache, probably the greatest headache is the tires. Does anyone have experience with non-pneumatic tires?

#Comment Re: made: 2006-11-08 12:50:34.745676+00 by: DaveP

I've spoken with Hugh, the guy who does Air Free Tires.

They don't make ones that'll work for me, since I want high inflation pressures (since I'm a heavy guy, and want low rolling resistance, which means 80+ psi in the tires - they can't do the equivalent).

For people who aren't way the heck out on the end of the bell-curve, they have an interesting product. If you're an infrequent rider (such that you end up having to put air in the tires every time you get on the bike), they'll probably work for you and make you happy. If you ride every day, I'm not so sure. But heck, shoot Hugh an email or give him a call. He'll be happy to talk through your requirements and tell you whether he can sell you tires or not.

To be clear, no experience with the actual tires (Hugh said he couldn't make 'em - call back in a couple years), but I had a very enlightening talk with Hugh, and the customer service rocked.

#Comment Re: made: 2006-11-08 14:58:12.905477+00 by: Dan Lyke

Over on the Tandem@Hobbes list there's currently a thread about the NuVinci continunously variable transmission for bicycles, and the gist there is the same as Dave's: A lot of these technologies are great for cruiser and city bicycles, not so great for the bicycle enthusiast.

The trade-off with tires is weight versus durability. You can put on a set of Conti Gatorskins (or some even heavier and allegedly more durable tires) with some self-sealing tubes and in the unlikely event that you get something in your tire you'll have tens of miles before you actually have to do anything about it, but you'll feel the difference. The tandem folks use 'em because the weight means a little less there and a blowout could be worse, but it's a simple weight/performance trade-off.

The 7 speed rear hub is only the equivalent of a 21 speed derailleur if you've got a 3 speed front end on the bike. You may have the same overall range, but there are people who ride with a rear cluster that changes by one tooth all the way across; less overall range, more ability to stay in your cadence sweet spot.

On the other hand, 94% efficiency ain't too bad, and plenty of people swear by the Rohloff Speedhub despite a little extra weight and limited gearing (largely because there's overlap between the gear ratios on a traditional derailleur and the hub makes what would otherwise be the shift between the front chainrings less dramatic), so something like that with a driveshaft may make it into the high end yet.

#Comment Re: made: 2006-11-09 01:11:13.442021+00 by: DaveP

Warning about the Rohloff Speedhub, now that you mention it...

They're nice hubs, but note that if you try to use one on a tandem, you'll probably tear it up. They can't handle as much torque as traditional gears and chains.

I emailed with a Rohloff rep as well when I was looking at trike-mods. They flat out told me that if I put one on my trike with the gearing I was looking at, I'd turn the inside of it to junk in no time, and they wouldn't warrant such an application.

Just a warning in case you're thinking of putting a chainring that would give you dramatic gear ratios together with a Rohloff Speedhub.

#Comment Re: made: 2006-11-09 01:20:13.769303+00 by: Dan Lyke

While there were a few reports of issues with a Rohloff and fully loaded touring (30 lb bike + 300+ lbs of riders + 100 lbs of gear), the reports on the tandem list were largely positive. Even the people who'd had one break were still recommending them for tandem use, and sometime in the past few years I saw web page of a tandem mountain biking team doing some absolutely insane stuff on a Rohloff hub.

So it's good that they're being conservative in their recommendations (and given the way they apparently stand behind their product, they have to be, 'cause I've read only good about that), but people are successfully pushing them pretty hard.

#Comment Re: made: 2006-11-09 11:49:44.853323+00 by: DaveP

Huh. That's good news. I wonder if they've redesigned or something.

#Comment Re: made: 2006-11-12 01:14:08.665511+00 by: Dan Lyke

Diamondback is apparently coming out with a mountain bike that uses a gear box rather than a derailleur, and <a href="