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Tretta AWD Bicycles put that lazy front wheel to work

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November 27, 2012

Tretta's AWD mountain bike

Tretta's AWD mountain bike

Image Gallery (5 images)

Although they’re very seldom seen, 2-wheel drive bicycles have existed in one form or another almost as long as their traditional rear-wheel-drive counterparts. While most of them have been one-off experiments or short-run production models, Japanese bicycle manufacturer Arte Co Ltd has decided to give the 2WD thing a shot nonetheless, with its Tretta AWD Bicycle line-up.

Tretta AWD bikes have been available in Japan since the beginning of the year, but just made their U.S. debut this September at the Interbike trade show in Las Vegas. While there are no immediate plans for North American availability, the Interbike appearance was aimed at gauging stateside receptivity to the rather unusual bicycles.

Pedaling power is delivered to the rear wheel using the usual right-hand-side crankset/chain/cassette arrangement. On the non-drive side of the rear hub, however, is a cog that drives quite a long chain. That chain stretches from the rear hub up to a set of small cogs located near the top of the down tube.

A much shorter chain goes from those cogs to yet another cog, mounted on an arm that extends from the head tube. A flexible universal joint connects that cog to another one, that is mounted on an arm that is attached to (and that turns with) the front fork. Finally, a third chain extends from the cogs/universal joint down to a drive cog on the front wheel hub.

It’s a set-up that’s difficult to describe, and that Arte unfortunately hasn’t provided any close-ups of, but it’s what allows the system to work even when the front wheel is turned to one side.

Tretta's AWD beach cruiser bike

Tretta's AWD beach cruiser bike

The Tretta bikes were initially designed to provide Japanese commuters with increased traction in adverse weather such as snow and rain, although the applications for mountain biking are pretty obvious, too. Unfortunately, all those extra chains and cogs add to the bike’s weight and will require more maintenance, plus they can’t be used with a suspension fork.

It also looks like that one long chain could rub against the inside of the rider’s leg – that problem and other limitations may be addressed in future versions of the bikes, according to a representative from the company.

Tretta buyers in Japan can currently choose between mountain, cyclocross, beach and city models. They range in price from ¥33,000 to ¥75,000 (about US$402 to $912).

Source: Tretta (Google translated from Japanese)

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
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26 Comments

You don't get something for nothing. That front wheel will cost you energy. And have you ever peddled up a mourtain trail. It's already hard and your front wheel is bouncing around anyway with most the weight on your back wheel.

Maybe it's better -- maybe not....

DemonDuck
27th November, 2012 @ 02:25 pm PST

I see many problems with this design. ... And I am a bike mechanic. No thanks.

Jeffrey Weckman
27th November, 2012 @ 02:39 pm PST

I like the simplicity of the design, Too bad it does not allow for any suspension, even still I feel like it could easily be implemented on those large-wheel (Surly?) bikes.

As for the second drive-chain rubbing on the riders leg, I wonder why they didn't run all of them from the crank instead of from the rear cog (like they seem to have done with the "city bike".

I wish there were more photos (or info) on how the bicycle turns. I imagine this design doesn't allow for very much handle-bar movement.

Milton
27th November, 2012 @ 02:47 pm PST

The only traction you need in rain is for braking.

This is no mountain bike, you can barely turn it, and they run great without 2 wheel drive anyway. on a steep hill front wheel drive will not help.

Snow and soft sand... maybe, but it needs a huge chain guard.

The Hoff
27th November, 2012 @ 05:04 pm PST

Just replace the chains with 1/4" shafts, use larger, but a telescopic shaft for the front forks and you can have All Wheel Drive {AWD} with suspension, done well, less weight {Carbon Fiber} !!!

There are heaps of helical gears that would do the transfer, already on the market.

Mike MacDonald
27th November, 2012 @ 05:33 pm PST

I think drive-by-wire would be a good idea as opposed to a mechanical system like that which is being used for this design, obviously the drive-by-wire system has to be married into the pedal, cog and chain configuration.... that's my thought though, if it can be done it will cancel out the need for all those extra chains and such, which honestly are unsightly and not really revolutionary!

EvanJD
27th November, 2012 @ 06:15 pm PST

AWD bikes are already available through companies such as Christini (www.christini.com). While the bike described here is cheaper than a Christini, that AWD system looks very cumbersome and possibly dangerous. Are they going to shroud all of those chains so there is no chance of clothing or body parts getting caught?

Not only that, but no suspension?

I applaud the designers for their attempt, but this is not a bike I would ever buy. If I was that desperate for an AWD bike I'd pay the extra and get something like a Christini.

Steve Pearson
27th November, 2012 @ 06:15 pm PST

This is a joke right? I mean I have seen a lot of front wheel drive systems and this HAS to be a joke. No one in their right mind would take this serious.

Michael Mantion
27th November, 2012 @ 06:36 pm PST

When you go around curves your tires take different paths and that means that they travail different distances so tying them together will eat a lot of energy and greatly increase tire wear. There is a good reason that 2 wheel drive bike are rare they are a bad idea.

Pikeman
27th November, 2012 @ 08:26 pm PST

Not very useful if you know how to ride. And it would't work on mountain bikes due to the suspension movement, which would require too many pulleys and be too cumbersome.

Aaron Lieberman
27th November, 2012 @ 10:47 pm PST

On my SANDMAN fat bike on 3.8" tires, I already have all the traction I need (even on soft sand, glaciers, volcanic ash...)

The only reason I can imagine for needing this would be for backing up a steep hill, on a single speed with fixed crank...

Of course, I do that every day ;-)

Bart Viaene
28th November, 2012 @ 01:54 am PST

Milton's suggestion about running the chain from the crank doesn't take into account that the gears are on the rear wheel. 2 wheel drive with different gearing to front and rear - now that would be novel!

For pedal driven 2WD I think the best answer would be the gear pack at the pedals with shaft drive forward and rear but isn't this a bit of a (over complex) solution looking for a problem?

Tankman
28th November, 2012 @ 02:19 am PST

"It also looks like that one long chain could rub against the inside of the rider’s leg – that problem and other limitations may be addressed in future versions of the bikes, according to a representative from the company."

Leaving aside the main issue of the weight and efficiency of the design, why not use a belt driver + internal gear-hub?

http://en.wikipedia.org/wiki/Belt-driven_bicycle

Freyr Gunnar
28th November, 2012 @ 04:23 am PST

Face it, the only real point of having a 2WD bike is for cases where you have more power than traction which is almost never the case with a bicycle. The rest of the time where you aren't in 8" of peanut butter consistency mud you have an efficiency loss over a standard 1WD system.

I would also like to see a closer photo of the fork mounted gear. It looks like the front wheel would still have a limited range of motion that would prevent it slow speed turns that require a greater turn of the wheel.

Diachi
28th November, 2012 @ 07:15 am PST

I am surprised no one has mentioned this yet...as a guy this does not look safe in a respect to my junk.

Beisswenger Design
28th November, 2012 @ 08:10 am PST

This is a solution in search of a problem.

pmodiano
28th November, 2012 @ 08:13 am PST

''solution'' looking for a problem

no thanks

wle

wle
28th November, 2012 @ 08:59 am PST

This looks interesting enough to make me want to try one... and then probably give it back and keep my trusty RWD bike.

My main concern with this design is that with that loooong chain slapping about between your legs (can anybody say: chain tension?) is going to get really annoying, clothing will get caught in it and so forth.

A better approach might have been use of a composite shaft drive to the front wheel, with articulated sliding joints allowing the final drive shaft to move with the steering, and potentially absorb vertical movement from a front shock absorber.

Ok I think I've talked myself out of wanting to try riding one...

PeetEngineer
28th November, 2012 @ 10:13 am PST

Two wheel drive makes perfect sense when the front wheel is driven by an electric motor, as on my fold-up Wisper pedelec, but I'm very far from being convinced that it's worth all the weight and complication on a pushbike.

FWIW I was one of the handful of journalists who had the pleasure of riding Yamaha's 2WD WR450 at its launch in Morocco in 2003 and I was won over by its capabilities in soft sand, but it's noticeable that Yamaha has not pursued the idea since, on either tarmac or dirt.

PNB in London, UK

paulblez
28th November, 2012 @ 10:38 am PST

So bike has the usual chain guard, but none for the chain RIGHT NEXT TO YOUR LEG? Another AWD bike that's currently produced:

http://www.christinibicycles.com/ but, as I recall quite a bit more than double the price. Both make me like my unicycle more, cheap and AWD without any chain or shaft drives.

Dave B13
28th November, 2012 @ 11:03 am PST

much simpler to install an electric motor on the front wheel, then u have power to both wheels, and the throttle control the amount of power u wanna on front wheel.

infact a few E-bikes already doing this.

Jimbo Jim
29th November, 2012 @ 12:19 am PST

Not what I'd ever ride - I like recumbents. However, one possible solution to the long chain issue is a floating tube covering the chain(s). Should be simple enough to do and protect adequately w/o addinga lot of weight.

KMH
29th November, 2012 @ 07:02 am PST

...as an avid biker, this looks scary. Greasy chains moving right next to my thigh and groin? I'm scared enough to get my pant legs dirty from my chains on my ordinary bike.

And from physics 101, this should be harder to pedal. In a car for instance, if your engine in your 4x4 is a 200hp engine, the 200hp is split between the 4 wheels (i.e. - 50hp at the wheels). But it's not 50hp because of ineffeciency as some energy is always lost between the engine and the wheels. In an ordinary bike, some of your pedaling power is lost between your crank and rear wheels. In this case, your pedaling power is also lost from the 2 additional sets of chain that drives the front wheel. This 2-wheel drive bike is lose-lose.

Sambath Pech
29th November, 2012 @ 06:13 pm PST

To quote Arte Johnson on Laugh-In, "Verrrry Eenteresting............but Stupid!"

For all the reasons outlined above.

William R. Mosby
29th November, 2012 @ 10:55 pm PST

It looks like many of the commentators have never ridden a bike to work in snow or on ice. I mean everyday riding, not cross country/mountain extravaganza. Neither have they watched videos on the Tretta's site which are informative enough. I don't think Tretta claims its designs are perfect or should be paid thousands USD for. They are just for imperfect riding by imperfect people who want to get a taste of something new. Finally, contrast the price tag to any bike niche products (bents, cargobikes, handcycles ...). Is anyone trying to rob you?

Good job Tretta!

PS: Christini? This article is about bicycles, not motorbikes if you spot a difference!

YuraG
1st December, 2012 @ 05:12 am PST

AWD bicycles are an interesting concept....why would you need AWD in a street bicycle? Novelty? I can see an electric AWD bicycle for greater stability and two light hub motors rather than one heavy hub motor or chain drive. (the heavy battery can be carried in a modified frame shape central position for optimum balance. The only good application for AWD in a bicycle would be a fully suspended Mountain bike. But even the use of composite telescoping drive shafts and gears would add considerable weight to a human powered bicycle. Torque being transmitted through a telescoping shaft would add resistance to the sliding components during suspension travel. That resistance would likely be felt as pulsing in the pedals as well. Seems like an interesting idea, but fraught with challenges. Rear suspensions on bicycles are seen in numerous configurations to try to overcome pedal induced movement and/or suspension movement induced pedal resistance variations already....AWD would add more issues to the soup That said I like the idea! I looked at Christie, those are AWD gas motorcycles; boo hiss. My future intent is to eliminate man made fuels from my life and household completely. Solar house and all electric vehicle fleet is a far better solution. Unless you don't car about loosing most of Florida, some of NY & LA and you like grey air. Oil & ICE's need to be left on the ash heap of history, like the steam engine, except for collectors & nostalgia.

Donald Eyermann
11th December, 2012 @ 08:48 am PST
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