Belt-Drive Full sus update

thepodge – Member
looks industrial but good. I want one for my trance but they (belt drives) don’t take well to tensioners

My understanding is that there is not a lot of chain “growth” on the Trance or Anthem, so it would be interesting if someone measured that, because it may be possible to belt drive one if it is just a few mm.

Has anyone tried putting a tensioner on a belt drive?

I realise a singlespeed-style tensioner at the rear won’t work but what about a tensioner at the crank end or halfway along the suspension arm? Surely you’d be able to get enough length change? (This is total armchair engineering, I don’t even know how much chain stretch is require for a short travel full susser!)

I’ve always quite fancied trying a belt drive on my bike. I haven’t been able to find out where to get Rohloff suitable parts though; not that I’ve been trying particularly hard…

V8 – tensioners won’t work as the belt can’t be bent backwards.
I guess you could use a reverse sprung one though, as long as you still get adequate belt-wrap on the sprocket.

timangus, fitting the belt to a Rohly is a bit of a faff. Rohloff wil only change the fitting kit themselves (its not just a case of whipping the cog off), and only if you’re putting it onto a certified frame design. They claim its to do with frmae stiffness, which I believe to be as much an issue with a singlespeed as a Rohly. I suspect its more the Rohloff can’t handle the potential torque “bursts” caused by the belt ratcheting, which is why you have to fit a snubber. Also the Rohly can’t handle the recomended tension, hence having to run it slacker which increases the chances of ratcheting. Vicious circle! Especially since the Gates snubber design is pants and can’t handle the stresses caused by the belt climbing off the teeth as I’ve demonstrated. However, I have seen it done:

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Dropout Right[/url] by trafficbikes[/url], on Flickr

I was thinking something mounted to the chainstay similar to the old DCD but sprung. might work for four bar systems but in the trance the chain goes through the frame and there are no joints / splits / pivots to thread the belt through

Heh, probably not worth the effort for now then.

out of interest, when using belt drive, why don’t the valleys between the teeth on the chainring\sprocket just fill up with mud? Are they hollow underneath or sommit?

5lab – yeah, they have holes in. Only ridden in mud once (before I bent my previous snubber) and it seemed fine. Time will tell.

timabgus – yeah it is. I’ve thought about doing it to my Rohloff, but figured its easier not to. So this is being built singlespeed, and I intend to put a belt on an ALfine-11 in the future.

V8 – tensioners won’t work as the belt can’t be bent backwards.

I figured they would be similar to car cam belts? no problem bending them.

It says here:
caution must be used before and during installation to avoid damaging the carbon tensile cords that make up the backbone of the belt’s strength. Excessive bending and twisting creates crimps which can lead to belt breakage under high load.

hmmm, i see what you mean, they make it sound as if it is particularly fragile!

Not to worry, it would be a while till I could afford an Alfine 11 for my superlight anyway, i’m just geeking 🙂

geek out, I say!
Its not that fragile, just doesn’t like being bent backwards.

Watch this space for info on my A…

A tensioner could be rigged up below the front sprocket and push down. It would have to be for a setup with very little chain/belt growth though.

None of my conversions use no more tension than I would use with a chain.

I don’t see any point in having the lighter belt drive if I have to have heavier duty components elsewhere.

Fundamental to getting off with low tension are no lateral flex/movement and precise chainline.

I’m more interested in the lack of maintenance than the weight. so I’d be happy if it weighed a bit more.

ir_bandito – where did you get the Gates parts from?

Bought them direct from Gates Europe. Mrs Nicolai in fact 🙂

email sales@carbondrive.net

delivery from Germany is shocking as they use UPS (£30!). Worth getting together as much of a bulk order as you can to justify it.

I did find a shop in the States selling it the other day
http://www.rememberdelaware.com/m-1097-gates-carbon-drive.aspx
Don’t know how exchange rate and delivery compares cost wise.

UPDATE:

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DSC_0407[/url] by ir_bandito[/url], on Flickr

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DSC_0406[/url] by ir_bandito[/url], on Flickr

Assembled last night. To be tested tonight, once the front brake is bled.

IT WORKS!!!!! IT ****’ WORKS!!!!!!

Happy me.
🙂

🙂

Nice one! Been following this thread for a while now.

Is that dropout handmade/custom?

Well done. That’s a good snubber you have there, should be bulletproof 🙂

what is the A like to ride? do you have to be super smooth? the only people who seem to make bb pivot frames these days are free ride / dirt jump companies.

Chef – yes, I made it with a milling machine and profiled it with a hacksaw.
There was a hint of belt-slipping on a very rough climb last night, which I’m sure still down to frame flex through the pivots. So the next plan is to get another pair of dropouts made to convert thePro2 to bolt thru which shiould stiffen it up a lot more. And while I’m at it, I’ll add tensioning bolts, and move the mounting bolt holes so I can get a smidge more tension in the belt.

podge, I’m sure the RP3 shock and SPV forks help with the boingyness. It is a lovely bike. Climbs well and descents are great fun so far.
I would quite like to do a conversion to a Cowan DS, or one of the new Commencals with the concentric pivot…

Albeing well, I’ll be riding it at Dyfi.

I think I might just have to find my self a frame. there is a brand new off the shelf Taiwanese one that looks ideal except it has standard vertical dropouts.

ir_bandito most drop outs take 10mm as standard you could upgrade to 10mm bolt up or 10mm through bolt with a DT Swiss QR if you are feeling flush or a superstar one for cheep. There is alot of stories about the 12mm Maxle light breaking and the 12mm hope centre tube failing under load.

I’ve picked up a 12×135 conversion kit for cheap of the classifieds here, and plan on using the superstar bolt-thru (or original Maxle – not Lite, if I can find one). Syntace would be nice though.

Long term plan is to get some belt-capable frames designed and manufactured, using knowledge gained which I wouldn’t have had a clue about otherwise.

After the bolt-thru on the A, I’m going to get an old steel frame and change the dropouts for something a little special that I’ve come up with 😉

thepodge – Member
I think I might just have to find my self a frame. there is a brand new off the shelf Taiwanese one that looks ideal except it has standard vertical dropouts.

Just use a eccentric external BB, eg the Forward Cycle one.

Where are the frames?

so, one of these:

and convert the hub to 10mm, using normal dropouts.
Hmm… its an idea…

would the ebb take the high loading of a belt drive? I can’t see why not but then I’ve never messed with an ebb.

can’t remember the name of the frame manufacturer but I have it linked at home, I’ll mail you and ir_bandito when I’m back as I might be able to help.

I have my doubts about EBBs and belts, having had a couple of EBBS in the past.
That said, a few manufacturs do them.

Yup one of them there superstar jobbers and one of these

http://www.chainreactioncycles.com/Models.aspx?ModelID=18761

similar to 12mm, still QR = winner. Tis what i have planned for my Iron Horse Mk iii

http://www.tankcycle.com.tw/product.asp?gpid=3&Fkindno=F000002

I’ve seen a few people with prototypes that look exactly the same as this just with different stickers. Spot had one with belt drive at last years expo.

not keen on the wheels but that looks nice.

Is there any reason you have not used that little roller/tensioner at the front of the drop-out to actually tension the belt same way as they do on cars?
I believe that some of the belt development takes place in the factory along the road from me.

its not a tensioner, its a snubber. i can’t remember what its there for

The snubber is there to stop the belt riding up on top of the pulley. It doesn’t touch the belt in normal conditions so there is no added friction.

The belt will ride up if the rear cog goes out of alignment with the front, eg during chainstay lateral flex. By having the snubber at the 7 o’clock position it is possible to remove the rear wheel in a vertical dropout with minimal interference from the snubber (the snubber would have to be removed otherwise).

To get a mental picture of what is going on, think of a set of parallel lines arriving to mesh with another set of parallel lines. It only takes a little angular displacement to put that out of sync.

I’ve actually replaced the roller (standard Gates issue) as it was sticking on the pin (my fault as a tolerance issue) and wearing flat from the belt, rather than turning. Fitted a 2RS bearing which works much better. Now only getting problems with the belt slipping off the side of the pulley occasionally. After having a good look and a ride on the Orange Strange proto, its got two flanges on the pulley, so I might bodge an outer one on…

In the words of Mr Tong “We Continue!”

The roller worked a treat to prevent ratcheting, but the frame flex meant the belt was still slipping off the side under power. Hopefully converting the Pro2 to bolt thru will reduce that, but in the meantime, I’ve just made an external flange for the sprocket, from an old cassette.

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DSC_0468[/url] by ir_bandito[/url], on Flickr

Update as soon as I get a chance to ride it…

On the subject of flanges, despite Gates insisting they’re not needed, I’ve found some Spot branded ones in an online shop, and even in the Gates Carbon Drive parts list, but no mention of them in the instructions…

Centre-Track appeals.

I love this thread – keep up the good work.