Mate and I were discussing this at the weekend. We both think that internal gearboxes are ‘the future’ but couldn’t agree on whether a belt drive would be as efficent as a chain?

not in UK slop and grime(tm)

The mainissue with belts is stopping stones getting into them – that wrecks the belts. Used on road motorcycles with big guards to stop the stones. Even BMW won’t use it on offroad motorcycles

other than being clean they have no real advantage over a chain

Ok on a road bike then?

AFAIK belts are more efficient than chains because they don’t wear and stretch the way chains do.

However, hub gears are still less efficient than derailleurs, so the overall change would be a drop in efficiency.

also you need an E-stay bike or a split rear triangle to get the belt in there.

belts are less efficient: a chain properly adjusted is over 98% efficient.
belts last longer is why the motorcycle manufacturers started using them, so theoretically they would be more economical. But they’re such a PITA to fit that they are still a rarity.

Nicolai Argon

Belts aren’t less efficient than chains on motorbikes, they’re almost identical in performance when new but chains lose efficiency over time while belts don’t. Don’t know if that’s a valid comparison for pushbikes of course, the stresses are different. Oh, Buell use belts on their sort-of-off-roader, the Ulysses, and still offer the lifetime warranty.

But for pushbikes, chains are simple, light, and flexible. I can’t see that belts offer any advantage over that.

Also if a belt fails you’re completely screwed whereas a chain you can just take a link out and not use your big cogs. They don’t need lubricating as readily and won’t stretch as quickly though. Also if adopted would have the opportunity to be far less expensive than a chain due to material costs, number of components and assembly complexity.

I would love to see someone “break” a belt on a pushbike….

Everyone knows there’s rabid belt hungry dogs at the side of the trail all over the country just waiting for this to catch on.

This thing about needing a split triangle to fit the belt – would it be possible to have the rear cassette outside of the frame, thus removing the need for a more complex frame design? Just a thought – I am sure some clever soul will be along just below to tell me it will never work…

Did I notice recently that Trek were using then on their bikes ?

My understanding is that for cycle use the belt has to be run at quite a high tension to avoid slipping, this causes increased friction and reduces efficiency.

ji – one day possibly, but there’s too many standards getting in the way first.

Hubs (SS or internally geared) will be designed around chainline inside the rear triangle. If you moved the rear chainline “outside” you would need to move the crank arm out too, increasing Q-factor and potentially bimoechanical problems.

Even if you did move the sprocket outside of the rear triangle, and made the rear triangle narrower using a narrower hub to maintain chainline, you would need to transfer that drive to the tyre (which is on the inside of the triangle), possibly by driving around the axle but through the drop out, inside another sleeve that mounts the hub in the drop out – probably not a great solution. By far and away the tidiest solution is a split rear drop out either welded on as a replacement by a frame builder or a specific build.

Of course, the easiest solution though would be to use an elevated chainstay…but that looks rubbish so would never fly 🙂

Of course, the easiest solution though would be to use an elevated chainstay…but that looks rubbish so would never fly

stick with the “money + buildings” thing stoner 🙂

E-stays are mechanically quite inefficient. Chainstays stop the BB rotating on the downtube and make things nice and stiff without lots of extra metal – though clearly we can “do” e-stays on bikes as most all suspension bikes have them in one way or another – however they have lower torsional peak loading as the suspension takes the sting out of the drive train tension.

Nicest belt drive I’ve seen are the GT cruisers, with dropped chainstays. Look lovely them.

ji – The Windcheetah recumbent bike uses just such a drive arrangement (with a chain) – Single large chainstay, block on one side, wheel on the other. So it could be done – but as a one-off non-standard design these are expensive.

Still no real benefit over a chain inside the rear end as has been used for a good few years now….

I have not actual data to support this, but my feeling is that the Chain will be more efficient.

As for belt drive being “the next big thing“. I would hope not, but then again, we ride in the shadow of an industry which is totally geared up to selling us all, the next big thing.

I have 4 bikes, all chain drive. I’m not replacing them with belt-driven bikes just because some company cracks the perceived technical issues involved.

Anyway, as others have pointed out, I just can’t see a belt taking the abuse a chain will. Perhaps if I rode bone dry, dusty trails all year round, and if I liked hub-gears/gear boxes.

No, its not for me and it wont be my must have feature on a bike.

As for Gear boxes, No thanks to them too. I like being able to service my bike, with a minimum of tools. Not something I’d be able to do with a gear box in my bike.

Solo.

what’s a “dropped chainstay”?

though clearly we can “do” e-stays on bikes as most all suspension bikes have them in one way or another

as I said, it would look rubbish 🙂

what’s a “dropped chainstay”?

It’s elevated downwards 🙂

and that’s supposed to be your preferred, elegant solution is it? 😯

new glasses for richards please!

🙂

oh look. More eye-popping ugliness! 🙂

GTs did look pretty good when i saw them in october. But as far as i’m aware, Hotwheels now have no plans to bring them into UK.

I think they’re a bit like Blu-ray compared to DVD at the moment: some advantages but not, on the whole, a big enough leap forward to overcome the inertia of sticking with a very good, well-established alternative. It doesn’t help the people trying to push them that a lot of people’s first thought is probably of something like a thicker, less stretchy elastic band- I know they’re not, but I don’t have an intuitive idea of how flexible/durable/etc they are, unlike a chain.

http://www.singletrackworld.com/2009/02/reviewed-orange-p7-belt-drive-prototype/

I knew I had seen something on them recently!

Its funny how the Orange prototype always gets a mention but not the Whyte that was doing the rounds quite a bit earlier. 😕

As for Gear boxes, No thanks to them too. I like being able to service my bike

but the whole point of them is that there IS no servicing, beyond an occasional oil change – provided, that is, you keep them well away from water 🙁