NoPhart

I've always been told you can't run a tensioner with a Gates Belt Drive. Well this years Eurobike has just that!



This design was my thought all along, but it has been shot down for years as undoable. What's up with that?

Joe Minton

LOL -- Go look under hood of your car.

Joe ;o)

350htrr

Now, that is great... A double ring is next, right?

fietsbob

Snubbers are used on rear ends too they press right on the belt on the cog.

prathmann

Don't know about your car, but mine doesn't have any suspension components that vary the distance between the crank and cam shafts.

350htrr

It's not suspension on cars it's the belt driven stuff, the AC Water pump, the belt has exactly the same thing on it to keep it tight...

fietsbob

Not your bike ? why worry about it?

You need to know the engineering data as to the belts flexibility larger than a certain radius May be within safe limits..

2old

Three problems with a belt for me: most prominently, if it breaks, you're walking (I've had chains break a couple of times in 30+ years of riding up to 5000 miles off road a year and was able to repair them easily and make it home); also, initial set up can be difficult and you need a frame with some kind of "break point" in order to replace the continuous belt.

JonathanGennick 

Trek runs a tensioner on the back end of their Link 5 commuter bike:

Lync 5 | Trek Bikes

So the idea has been around for a bit.

fietsbob

NB: they use another belt, and cogwheels, not Gates.




...

prathmann

The only cogged belt (ie. where no slippage is permissible) on car engines is a timing belt between the crank and cam shafts which is a fixed distance. The question with suspended bike frames was whether such a cogged belt would work ok in situations where the distance varies. That question was not addressed in car engine applications.

350htrr

You have a point, I was just thinking hard-tail. But it's still the same idea with that pulley, but with some movement allowed by a spring on the pulley to keep tension the same when the distance lengthens or shortens, as I see it....

NoPhart

Not worried about anything (?)...

In the past the only Full Suspension MTB's that would accept Gates Carbon Drive Belts were those like this Lenz Rohloff MTB with swingarm axis the same as the pedals.



I think it is great if this belt guide setup works. I'm in the middle of my first Gates CDX build right now. Hoping the Carbon Drive is all it's said to be.

PatrickGSR94

Timing belts have tensioner pulleys also. Without them it would never be tight enough to not slip/jump teeth, or loose enough to be able to remove/install the belt. Believe me, I've done numerous timing belt changes over the years.

JonathanGennick 

What frame are you building?

fietsbob

Where the rear pivot is is The significant Bit .. I'm more into The Bike Friday Folders, [Rohloff & Chains]

I have a Pocket Llama , they hinge behind the BB, so have a chain tensioner.

their Tikit, a fast fold folding bike , have the BB as part of the rear section , and so all work as a unit,
Belt stays at same tension setting..

they used that design on 2 additional models,, 'Silk' & new NorthWest Tour

Mechanical Logic,
I'm guessing , but the snubber roller by the crank , is big enough to stay within the belt design's flex range,
and compensates for minor axle to BB length changes as the rear end absorbs bumps..

Life span of belt in this design is unknown, perhaps less.. I'd have an extra belt on hand , in your truck at least..





...

NoPhart

Soma B-Side V.2 Belt Drive Bafang BBS02B 750W/48V Hardtail:

https://www.bikeforums.net/electric-b...ion-bluid.html

If the guide setup works well, one might be able to add a Gates Carbon Drive Belt to a Raleigh Misceo iE by adding a frame break. It's a great electric shifting IGH Shimano STePS E-bike.

prathmann

I'm well aware of the tensioner on car timing belts and have also had to change one. That isn't the point. The question regarding feasibility of a cogged belt on FS mountain bikes was whether they would work well in a situation where the distance between the two connected points is changing. This bike seems to answer that question affirmatively while previous car engine designs didn't address it.

PatrickGSR94

Except on certain variable compression ratio concepts/designs.

allan6344

I have a Rohloff with CDX Gates on my Winter (brand) custom road bike commuter. I'm still happy with the choice of a Gates CDX belt over a chain. Eric Estlund the builder, had to get the frame tested to meet the Gates requirements but it didn't seem to be a big deal. I bought extra belts but they are still on the shelf.

RRC22

Those look like really good cog pulleys. I've seen a posting before where the rider smack the front pulley against a curb and broke the composite cog pulley. Not a Gates brand, so no place to buy the replacement except in China. Smack a chain drive and you can smack it again to get home, then get a replacement anywhere.

speedhunter

Chain drives are move convenient for E-bikes as chain is much more efficient than a belt system.













Chain drives are move convenient for E-bikes as chain is much more efficient than a belt system.

allan6344

I would not agree with chains being "much more efficient" at 3 watts for a chain vs 4 watts for a belt in relation to an e-bike discussion. I don't think it would count as a statistically significant difference.

NoPhart

I agree. The long life, lack of maintenance and silence clearly outweigh such a small efficiency difference IMHO. That's why I went with a Gates Carbon Drive on my current hard-tail build. A year or two from now I should have some real world experience with it to report.

BruceMetras

I don't know if I missed your review or not, but have you put any miles on your new bike?