Fitting a Gates Belt drive.

[beatlejuice]

I own a Decathlon Network 700. It has an 8 speed Shimano Alfine hub. They are quite distinct because of there unusual back end! The drive side chain stay joins the frame above the bottom bracket. I thought surely this was designed to take a belt. So throwing caution and about £150 to the wind I brought the required Gates bits.
Getting the correct alignment for the belt was a not easy. There is very little clearance for the rear sprocket. It is v close the hub. I had to put the front sprocket on the wrong way round! Comments and suggestions are welcome.

 

[Cycleops]

Interesting. How do you judge the tension? I’ve read they don’t like to be too tight.

I’ve just sussed, this is a conversion, I though at first it was a replacement.

 

[I like Skol]

Interesting. The alignment looks near perfect, I assume the crank has the correct alignment tabs to secure the 'chainring' in that orientation?

Also a little surprised because the disc brake rotor appears to be a 6 bolt mount when I would have expected Shimano to have gone with the centrelock system on their own hubs?

 

[Pale Rider]

Good job - assuming it works reliably.

I can't see a problem with reversing the front ring, although it will increase the chance of a flapping trouser leg catching in the belt.

Gates recommend a fairly high tension, although user experience has found the belt works well enough at lower tension.

No bad thing on a conversion, because the rear triangle on a factory Gates bike needs to be stronger to take the extra tension.

Roll off can be a problem, although the latest Centretrak belts are meant to make that less likely.

 

[FrankCrank]

I own a Decathlon Network 700. It has an 8 speed Shimano Alfine hub. They are quite distinct because of there unusual back end! The drive side chain stay joins the frame above the bottom bracket. I thought surely this was designed to take a belt. So throwing caution and about £150 to the wind I brought the required Gates bits.
Getting the correct alignment for the belt was a not easy. There is very little clearance for the rear sprocket. It is v close the hub. I had to put the front sprocket on the wrong way round! Comments and suggestions are welcome.

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Had noticed those bikes some time back. They have what is called a 'raised chain stay'. To me it seemed a good idea, but they pulled the plug on them a couple of years back for some reason. Their 20" folding bikes of a few years back also had this feature, but have reverted back to the common triangle configuration. Anyways, nice conversion

 

[Nibor]

Interesting. The alignment looks near perfect, I assume the crank has the correct alignment tabs to secure the 'chainring' in that orientation?

Also a little surprised because the disc brake rotor appears to be a 6 bolt mount when I would have expected Shimano to have gone with the centrelock system on their own hubs?

My Alfine 8 hub has a 6 bolt rotor.

 

[fossyant]

Looks like a good 'belt' line there. No issues with the ring being on the inside of the crank arms.

 

[Pale Rider]

No issues with the ring being on the inside of the crank arms.

It always is.

It's the little belt guard that would normally face outwards.

 

[rogerzilla]

I've always thought an old 90s elevated-chainstay MTB would be ripe for conversion. Alpinestars Al-Mega?

 

[keithmac]

As said only issue is getting trouser leg in front sprocket!.

The centre cut in the belt is designed to retain the belt, in 5 years 8,000 ish miles I've never had any issues at all with mine.

I run mine at 60hz on the Gates App, never needs adjusting though!.

Fancy converting my Nuvinci hubbed ebike to Gates but frame isn't correct for that.

 

[beatlejuice]

I took for a test ride last night, ie when down the pub! Unfortunately the people who first inhabited this fair city choose it because it had hills around it. That meant I climbed some 200ft and descended 100ft. Enough to check I had got the gearing right. I kept first gear to less than 30 gear inches which for this old git just about low enough. There was no sign of the belt trying to slide off or jump. I had taken the opportunity to upgrade the brakes from Teckro cable to Shimano hydraulic. This has turned out to be money well spent. The improvement is very noticeable.
If I remove the bit pointed at in the photo there would be some more clearance between the hub and the sprocket. That would mean remove it the sprocket which would be a challenge! Is the bit I am point at do anything vital?

 

[Pale Rider]

Is the bit I am point at do anything vital?

I knew this when I had a chain driven Alfine 11 - it might be an oil control ring, or a cover to save grit getting into the hub.

While it may not be 'vital', I would be very disinclined to remove it because Shimano will have put it there for a reason other than to baffle people on a cycling forum.

You have managed to pull off what could have been a very tricky conversion.

I suggest you quit fettling while you are ahead.

 

[I like Skol]

Looks like a square taper BB? Is it an option to fit a much shorter BB axle (crank clearance permitting) to allow the 'chainring' to move to the outside position on the crank? I guess the BB housing is eccentric to allow chain/belt tensioning?

 

[beatlejuice]

Looks like a square taper BB? Is it an option to fit a much shorter BB axle (crank clearance permitting) to allow the 'chainring' to move to the outside position on the crank? I guess the BB housing is eccentric to allow chain/belt tensioning?

Yes it is fitted with an eccentric BB. I need to find a tool that fits into the two holes that are used to rotate it. My current method is to push a cross head screwdriver into one and rotate the crank. Not ideal!

 

[keithmac]

Just had a look at my CDX front pulley and it doesn't have a belt guard at all, never been an issue.