Crankset for Rohloff/Gates?

[jaybeeboston]

I'm finishing a nice light touring & travel bike -- 650 B, S & S couplers, Rohloff Speedhub -- that will be belt-driven, and I'm perplexed about the best crank solution. Rohloff's chain line is wide -- 54.7. Gates makes an Alfine-specific crank set (S-300, I put one on another belt drive recently), but I think the Alfine chain line is only 46 or 47 (depending on where you find the docs). I could turn some spacers on the lathe and set the cog off a bit, but 8mm is a lot for that. Use the outer mount on a square taper triple? Has to be 104 four arm or 130 five arm BCD. I could make up the dif with a wider spindle? MTB cranks?

Any help gratefully received.

[Blacklabbikes]

middleburn with their rohloff spider.

[hmbatrail]

Gates makes the 510 crank specifically for Rohloff.

[shand]

MTB Boost chainline will get you to ~52mm. Note that Gates front and rear pulleys are asymmetric so you have a bit of adjustment of chainline by flipping them. Also, the newer splined lockring hub has a (belt) chainline of 53mm.

[jaybeeboston]

Thanks all. Tim, I can't find any reference to a Gates 510 crankset on their website or via google search. I've been emailing Gates produce support, but they won't answer emails. I'll look into the Middleburn and an MTB Boost. Appreciate the pointers.

[shand]

The Gates S550 crank is a hollow axle style 24mm (splined) spindle crank and is available in a Rohloff chainline but may be OEM only. Not sure. This takes the one piece direct mount rings. If you want to go for a square tapered bottom bracket and standard BCD rings then the S100 and S150 work with Rohloff chainline using the appropriate length BB. I suspect the reference to a 510 crank was a typo.

The Middleburn crank is very nice but very expensive. We used hundreds of these before they went out of business (the name was bought and relaunched a couple of years ago). What I will say about this was that the tolerances around how much the crank was pressed onto the spindle was very poor. This meant too much dicking around with spacers to get a consistent (from crank to crank) chainline.

[jaybeeboston]

Thanks, Steven. I think it probably is an OEM -- last time around I was trying to get a different crank from them and that one was OEM only. I'll either do the S100/150 or get an MTB Boost crank and twiddle it. It's going to be a nice bike -- first one I've built for myself and not a client in a few years. Going to take it to LA in May to visit my daughter, do some riding up in the hills above Santa Monica.

[false_aesthetic]

Re: Visiting LA.

If you're not familiar with the area LMK. I can point you in the right direction (happy to do a weekend ride too).

[jaybeeboston]

Thanks! I'll definitely be in touch.

[jaybeeboston]

Update:

Thanks, Steven, he MTB Boost was the ticket. SRAM GX with the Gates chainring gave me 54.7 spot on. I had to machine off a small (~1mm) bit of the Gates spider arm ends to fit the depressions on the crank spider, but no big deal. If I have a next time I'll machine the depressions longer on the crank arm instead, but it would have taken more time to set that up on the rotary table.

Tom, unfortunately the bike will not be coming with me on this trip. I ended up with the wrong Rohloff axle plate, and it will take a week or more to get the right one shipped from Deutschland. There will be plenty of next times, though, as I have a daughter in Santa Monica, so i hope I can take a rain check on that ride together.

[shand]

I had to machine off a small (~1mm) bit of the Gates spider arm ends to fit the depressions on the crank spider, but no big deal.

Yep. Little known fact. The standard dimension for that part is different depending on if the ring is sitting on the inside or the outside of the crank. I've never trimmed the chainrings down but I've turned lots of crank spiders down on the lathe.

Glad you got it sorted.

Steven

[Gattonero]

middleburn with their rohloff spider.

If you want trouble, yes.

[speedbiker]

MTB Boost chainline will get you to ~52mm. Note that Gates front and rear pulleys are asymmetric so you have a bit of adjustment of chainline by flipping them. Also, the newer splined lockring hub has a (belt) chainline of 53mm.

I'am riding a FSA Gossamer BB386 road crankset, which has 43.5mm chainline. With 3mm spacers between Gates front sprocket and crankarm spider my chainline increase to 52.5mm. On the Rohloff hub I've mounted this Gates-compatible cog with 53mm chainline. So there is only 0.5mm offset left.
This setup works fine on my roadbike.