54 or 57 mm chainline for Rohloff in Gen2 Bosch Tern Vektron

Electrically assisted bikes, trikes, etc. that are legal in the UK
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Lodge
Posts: 142
Joined: 28 Feb 2016, 8:59pm
Location: Staffordshire Moorlands

54 or 57 mm chainline for Rohloff in Gen2 Bosch Tern Vektron

Post by Lodge »

I am in the process of transplanting my old ~46000 km Rohloff to a Tern Vektron to replace an Alfine 11 that's currently in there.

The issue is finding a suitable way to offset the Bosch Generation 2 drive sprocket out to either 54 mm (for a threaded Rohloff sprocket) or 57 mm (splined). The Gen2 Bosch works nicely with the Alfine as it has a narrower chainline very close to the 47.5 mm standard Bosch gearbox sprocket.

Does anyone on the forum happen to know of a suitably offset Bosch-compatible sprocket, preferably with 20 teeth so I can get the desired gear-inch range?

I've managed to get another (transplanted) Rohloff to work nicely in my wife's later model Tern. But that has a later generation Bosch motor with a conventional spider and the 54 mm threaded Rohloff sprocket lined up nicely with the outer chainring position.

And in case anyone is wondering, we like internal gear hubs. Bikes sold on get the derailleur gears from the new bikes and we transplant the IGH. The Alfine is going back on my now rarely used Brompton, from which the black Rohloff came for my wife's Tern (it's very hilly round here, hence the primary machines are now electric). And the 46000 km Rohloff has been in two previous machines...
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