radshark

I think this is a picture of the Paragon drops in use:

mconlonx

If you simply must build a belt drive, do yourself a favor and use vertical dropouts with either an EBB or sliding dropout system. Messing around with belt tension and alignment would be a side of the road nightmare; vertical d/o's make wheel replacement real easy.

chainstrainer

Does anyone yet sell the new Gates Carbon Drive CDX-CT? This new belt and pulley system seems to be a marked improvement over the current offerings. Just wondering what thoughts there were here.

JonnyHK 

Not so hard.

Sit on ground with one foot on each crank, hold wheel with one hand and push the legs to tension. Use free hand to tighten up axle nut on one side, swap hands, check wheel is straight, tighten other nut. Spin wheel to check. Ride on.

Took me about 5 mins. I'd need to do at least that much messing about with sliding dropouts.

Thulsadoom

Boom.

I was imagining that a belt drive system on a low speed vehicle like a bicycle could probably be adjusted better by the human eye and hand (feet?) than any tool.

wphamilton

Why notched belts on bicycles? I know it may be a dumb question with a simple answer but ... I understand that those belts are optimal on motorcycles with high torque requirements, but are low hp V belts ever used on bicycles? It seems like alignment, tensioning and slippage would no longer be issues, and bicycles are fractional HP.

unterhausen

I don't think a v belt would work well in a bicycle application. There is no room for error or you end up on your face. In fact, it's really hard to beat a chain and if it weren't for Gates wanting to sell into a new market, the timing belts wouldn't be available for bikes either.

wphamilton

If you don't mind elaborating, why is a V belt more likely to have a catastrophic malfunction? I thought that was one of the strong points, and was thinking more about lower efficiency possibly. If it's not too off topic I'd appreciate your thoughts.

unterhausen

a v belt slips when it's loose. They also slip when they aren't loose. Not exactly the kind of thing that I would feel comfortable trusting my teeth to. I will admit to being a bit of a luddite when it comes to bicycle tech. As a class, belts are less efficient than chains in applications like the bicycle.

Flying Merkel

Bicycles have huge torque spikes to deal with. Picture a 200 lb man standing on the pedals mashing up a hill, or a conditioned racer accelerating. The peak torque could surpass a smaller motorcycle engine.

I like the belt concept. Not sold on the practicality. I've broken chains on a ride & fixed them in less than 10 minutes. Break a belt, walk home.

wphamilton

Hi torque=slip=lower efficiency, pretty much as I suspected. Thanks.

Sorry to derail the thread ... carry on please

fietsbob

Re the hub, I've been using mine on my commuter year round for 5 + years..
just got a second bike with one, a Bike Friday..
no belt drive as the frame folds behind the BB for 20" wheels.
It has a spring tensioner .

It is an option on their 349 wheel bikes as rear section is a unit,
fold is including the BB, hinge ahead of the BB.
IGH dropout swings rearward to tension drive, chain or belt.

Rohloff has drawings to manufacture sliding dropouts ,
their sliding track spec was angled at 20 degrees.
I see that as moving in a direction to not move the brake shoes away from the rim

and the weight of the bike, when one has loosened the bolts,
tensions the drive chain, because the slide has slope,
so perhaps also valid for the belt scheme.

Thulsadoom

Seems like the biggest challenge with belt drive is the continuous belt, and having to split the frame to replace it.

Why not: design a frame with rear stays just wide enough for the internally geared hub; good, strong axle with extension on right side; and belt pulley on the outside of the frame? Slot the dropouts for adjustment? Belt replacement would take seconds...

mconlonx

Because: I can't think of a single IGH hub where it wouldn't be much, much easier to just have a split in one of the stays somewhere. Or an elevated chainstay.

Six jours

I've seen a few frames over the years that are set up like that, although all of them were chain drive. It's an attractive concept, but has obviously never caught on. Probably just the fact that it requires a complete redesign of the entire rear end, which will then be incompatible with pretty much anything else ever made...

vautrain

That's too bad about your District Carbon. I have had nothing but good luck with my District grey/orange, and so I bought a District Carbon to upgrade. It hasn't been on the road yet (I'm upgrading some bits) but I hope I'll have the same experience that I've had thus far, which has been nothing but easy and reliable.

ka.i

That's too bad, but it sound like the bike is not setup right....

I've got 2 bikes with belt setups and there are 2 key things that must be tuned correctly:

- The belt line must be absolutely straight. Gates Belts only allows +/- 1mm of variance in alignment between the front and rear sprocket. If the belt line is off, the result is noise. The Center Track is especially sensitive to alignment due to the center spline on the belt.
- Proper tension must be set. The frame must have a way to apply belt tension. You cannot pull it with your hand. You simply cannot create enough tension if there's not a belt tensioner used. Use an instrument to measure the tension.
If the belt is loose, the result is the belt skipping tooth.

fietsbob

The Tout Terrain design seems good , right dropout is 2 pieces
sandwiched together
1 attached to seat stay, other to chainstay ,

so IGH axle holds them together when ready to go.

BB is Front of a Tandem Eccentric. to snug up chain or belt.

unterhausen

this is a really old thread, I'm closing it before things go sour and people start arguing with someone that's no longer around.