The G Line belt drive kit is pretty simple to fit, with one scary bit – you’re going to have to cut your frame in half. But only a little bit, and it’s hard to mess this up! The fitting is a little different for Alfine or Rohloff, but here’s the basic idea:
Remove the rear wheel and right dropout / tensioner (and the left tensioner if you’re fitting a Rohloff). Now to get the scary bit out of the way – you need to cut a slot through the frame:
I use an angle grinder with a 1mm cutting disc to do this, but a hacksaw will be just as good, or a Dremel with a cutting disc. It’s a good idea to touch up the exposed surfaces with touch-up paint to prevent any corrosion – corrosion would only be cosmetic, but best to avoid anyway.
Now squeeze the belt through the gap, and rejoin it using the new tensioner, joining plate, and longer bolts. These are different for Alfine and Rohloff:
For Alfine, the new tensioner goes on the inside of the frame, and the joining plate goes on the outside – longer bolts hold everything together, and a 5mm bolt joins the joining plate to the rack mount.
For Rohloff, the joining plate goes on the inside, two spacers go on the mounting bolts, and the tensioner goes on the outside.
Again, a 5mm bolt connects the joining plate to the rack mount hole.
Now you can fit the front cog – it just replaces the chainring, but note that the belt cog is not symmetrical, it has an A and a B side, and it should go with the B side out for clearance.
If you are converting an Alfine hub, now you need to fit the belt cog to the hub – rotate the plastic retainer so the two yellow dots line up, lift off the retainer, cable fitting and plastic spacer. Then use a small flat-blade screwdriver to carefully pry off the split ring, and remove the cog.
Fit the belt cog – again it’s not symmetrical, on the G Line it should go in the outwards position similar to the front cog. Use the small screwdriver to pry the three prongs to get it on fully, and then replace the split ring, plastic spacer, cable fitting and retainer.
Now fit the back wheel – as normal for Alfine, for Rohloff see the Rohloff G Line instructions. It’s easiest if you put the belt onto the rear cog before fitting the wheel fully, as it has to go under the snubber roller on the tensioner.
Now you need to adjust the snubber roller – this is the smooth roller that presses the belt firmly onto the drive cog to prevent skipping. It’s in a slotted mounting, so loosen the retaining nut half a turn, enough for it to slide up and down, push the roller down firmly, and tighten the retaining nut again.
Now you can half-fold the rear triangle, hook the belt onto the front cog, and hook the tensioner under the belt. Spin the cranks to make sure it rotates smoothly.
And that’s it! If you need to remove the rear wheel for a puncture, it’s similar to for a chain drive – just half-fold, unhook the tensioner and remove the belt from the front cog, and remove the wheel.