Pulley system for belt drive

[circuit]

I am looking in to belt drive systems. Of course I would like it light... Looked in to Gates polychain and centertack systems, but they are quite expensive.
And where does one buy the CenterTrack kit in europe?

Also saw this post somewhere on the forums:

Have you considered getting a hold of a Zero Motorcycles 'replacement' pulley set meant for the XU/DS/S model: 25/28T > 132T 8mm Polychain GT Carbon?

Could not really find this anywhere. Original Zero pulley seems too big.

Any ideas?

 

[LockH]

Oh oh. ES "Search found 2284 matches: +belt +pulley". So. Investigate and report back maybe?

 

[circuit]

Oh oh. ES "Search found 2284 matches: +belt +pulley". So. Investigate and report back maybe?

Been there, done that. Very few mentions of centertrack and almost all build use belt as primary reduction and then chain. Almost no build with direct belt drive.
But thanks for help anyway.
What's next?

 

[LockH]

Giggle search for "washing machine belt pulley" maybe? (Sorry. Google spelt... funny.)

 

[bobc]

circuit - I've used toothed belt on my (human powered) road bike for 5 or 6 years now. On my first bike I bought a gates carbondrive belt but made my own pulleys by stacking laser cut laminations. So on that bike I learned that the carbondrive belts are incredibly expensive (£76 just for the belt), Al belt drive chainrings fatigue and fail at ~3000miles (I have stainless steel at both ends now), DIY laser kit is cheaper than whatever you buy, is the size/ratio you want and the laminated system lets you get the belt line perfect (a must with belts). I've probably done 12kmiles on that transmission now, no sign of wearing out.
To reduce the belt cost I've tried to make a system with an industrial toothed belt (14mm). I tried a fibreglass reinforced belt but that was not strong enough, it really needs the carbon. For a bike transmission you need a ~10mm wide belt. I was able to buy a suitable 20mm wide belt for £26 (ebay) and slit it down the middle to get 2 10mm belts. I am close to getting this bike on the road.
If you're interested and want to see pictures I'll post some on here
I've never used the centretrack gear, the normal (HTD profile) stuff is easier to work with if you're doing DIY
Bob

 

[circuit]

Hi Bob, I saw some pictures of your system - awesome work. I wonder how did you manage to slit the belt in half.
I also found your cad drawings. Too bad Gates does not publish these. But from closeups it is evident that quantities are so small that Gates itself machines the pulleys on CNC centers, which somewhat explains the cost. I have found a kit I need, two pulleys and a belt = 310$. That is not gonna happen....

 

[rs4race]

I am looking in to belt drive systems. Of course I would like it light... Looked in to Gates polychain and centertack systems, but they are quite expensive.
And where does one buy the CenterTrack kit in europe?

Also saw this post somewhere on the forums:

Have you considered getting a hold of a Zero Motorcycles 'replacement' pulley set meant for the XU/DS/S model: 25/28T > 132T 8mm Polychain GT Carbon?

Could not really find this anywhere. Original Zero pulley seems too big.

Any ideas?

Polychain is more for positioning applications. Check the powergrip line. A little looser backlash for power transmission and you can get smaller pitches and widths. look for pulleys labeled gt2 or gt3.

 

[rs4race]

You can also check for HTD style belts. They are the predecessor to the gt series and I believe not under patent anymore so they are widely available and much cheaper.

 

[Miles]

Hi Bob, I saw some pictures of your system - awesome work. I wonder how did you manage to slit the belt in half.

You don't have to do this yourself. Any half decent supplier will slit off whatever width you want.

 

[circuit]

That is good to know, thanks.
However the biggest problem remains with pulleys. I could follow bobc steps and make my own pulleys somehow, but would prefer not to dive in to it, as the project is getting too big already.
For example, which bikes/motorcycles should I look in to to find suitable replacements pulleys? Obviously harley pulleys will be too big and heavy (and expensive?). Zero is too big. What else? Optimally I would want a 3.5:1 ratio.

 

[Miles]

How much torque will you be using? There's the Strida pulley that I used on the Moulton. That's 100t. Recumpence had batches of 80t 8M pulleys made - not sure what the status of those are...

 

[Miles]

http://www.funpartsxpress.com/wp-content/uploads/2014/12/Acc-cat-2014-update1.pdf See page 10

 

[miuan]

Maybe you'll find this shop helpful
http://www.zahnriemen.de/

 

[circuit]

Thanks, that is some interesting info.
However I see that prices, listed on below PDF are not too far from Gates centertrack..

http://www.funpartsxpress.com/wp-content/uploads/2014/12/Acc-cat-2014-update1.pdf See page 10

Torque up to 140 Nm, which is probably very close to human power, perhaps?

 

[bobc]

I'm 115kg. my cranks are 170mm. When I stand on the pedals, that's 191Nm (115 x 9.81 x 0.17)
A less gravitationally challenged (pie repudiator) might well be near 140...

 

[dirkdiggler]

Check http://www.sdp-si.com/
They are cheap and have all kinds of pulleys and belts if you are in the US. They bill the shipping after the fact, which can be eye opening.