[Part 2] Rohloff splined sprockets (and Chainglider fitment)

[Andre Jute]

Thanks, Pete.

[geocycle]

I've also future proofed by ordering a 17T threaded sprocket.  Should keep my RST frame serviceable for another 10k miles or more.

[Dave Whittle Thorn Workshop]

Machining IS an option, but not something as convoluted as machining the splines. Going by the described design, you should simply need to machine off 4mm (3mm - this chain-line difference is still not clear??) off the inner face of the sprocket carrier. This will place the whole carrier 4mm to the left to re-instate the chain as per the current sprocket design.

I've got one on my desk, sadly its a pre-production one and I'm not allowed to photo it until launch date, you can't do this as there is a tubular section the same diameter and length as the back of a standard Rohloff sprocket, it then rises sharply at an angle to form the bed-stop for the sprocket, if you removed material it would crush the bearing when tightened on this part is stainless, the inner part is pressed inside, this appears to be case hardened and carries the sprocket and cir-clip.

I hope when the splined ones come out that we will be able to put a sprocket on there that has the same spline pattern as something else, perhaps a sprocket from a cassette for a 8 or 9 speed Shimano freehub.  Or maybe an old Suntour five or six speed freewheel.  Or a Sturmey Archer.

The splines are unique in pattern and diameter to Rohloff.

[il padrone]

The splines are unique in pattern and diameter to Rohloff.

Why am I not surprised 

How incredibly useless, selfish, and damaging to the industry. We certainly already have fairly standard splined sprockets that are used for Sturmey Archer. Why not use this? Grrrr.....

[il padrone]

I've also future proofed by ordering a 17T threaded sprocket.  Should keep my RST frame serviceable for another 10k miles or more.

Rotating three chains on the drivetrain, I got 25,000kms out of one 17t sprocket, so you'll do better than that. With the Chainglider I'd expect this may double.

[julk]

I think Helen Lloyd of ‘Take on Africa’ got the most wear out of a sprocket.
And she did not even reverse it!
Julian.

[geocycle]

I've also future proofed by ordering a 17T threaded sprocket.  Should keep my RST frame serviceable for another 10k miles or more.

Rotating three chains on the drivetrain, I got 25,000kms out of one 17t sprocket, so you'll do better than that. With the Chainglider I'd expect this may double.

Yes you are right if you get the chain changes and reversing at the optimum time.  I'm currently on my third sprocket as I've never quite got this spot on. The previous two wore to fish hooks and the chain didn't sit well on them after reversing!

[John Saxby]

That'll hook 'em, for sure, Pete :-)

[macspud]

the solution I would like to see is a redesigned carrier to allow fitting the new splined sprockets in either the current 54 mm chainline position or the new 57 (or 58) mm chainline position.

I think this could be achieved fairly simply (in manufacture, less easy if trying to adapt the standard part by DIY) by machining the carrier splines to an extra 3 or 4 mm depth, then adding two thin spacers (1.5 or 2 mm each). Unless there is a good engineering reason not to do this.

I like your splined spacer idea. It would only need one 3-4mm spacer, I think? though as you say two may be quite useful for giving more chainline options.
It could be made so the current Rohloff specific Chainglider could ride on the spacer, the same way that it rides on the outer seal lip of the threaded sprocket.

In addition to enabling those of us that have the old sprockets to continue using the same bottom bracket width (and perhaps Chainglider), a sprocket carrier redesigned  as above would have the advantage of allowing small chainline adjustments at the hub for 16T and bigger, while maintaining the use of one design of carrier for all sprocket sizes (spacers must be inboard for the small 13, 14 and 15T sprockets, choice of both inboard, both outboard or 1 inboard and 1 outboard for larger sprockets).

The spacer would only need to be inboard for the 13 & 14 tooth sprockets.

It would seem to solve all the problems. Both chainlines using just one splined carrier unit, a bearing surface for the Chainglider, larger range of sprockets, ease of sprocket change/turn, very little if any extra weight.

Yup, A redesigned (by Rohloff in manufacture) splined carrier with splined spacer/spacers. That gets my vote. 

Well done, il padrone   

[mickeg]

...
The splines are unique in pattern and diameter to Rohloff.

I expected that, I was just hoping otherwise.  If General Motors could make you buy air for your car tires from them, they would.

Since I am not running a chain glider, I am not too concerned.  Later if I see some sale price 16t threaded sprockets, I might get one or two.  If not, then I will just get the splined system and probably will get a longer bottom bracket at that time too.

[Danneaux]

I may be coming down on the wrong side of things, but I plan to keep my threaded sprocket until it is dead, then switch to the new system. My reasoning is, everyone will soon be in the same boat, and there is now a considerable installed base of Rohloff users. Everyone buying in the future will have to deal with these issues. Hopefully, if the design is refined further, it will be before I make my purchase.

I do love my bash guard, but moving my chainring from the middle slot to the outer on my crankarm spider and mounting the bash guard to the outside should leave me where I am without increasing my Q-factor. My gearing won't accommodate a Chainglider now, so I'll be no worse off.

My 2012 Nomad Mk2 is my newest bike. All the others are much older and with a couple excceptions, have freewheel-based derailleur drivetrains. I long ago laid in a stock of freewheels and most-used cogs, but at some point those will run out and changes must be made to tap into a reasonable supply of replacement parts. I have already spread the dropouts on the bike I inherited from my father, and this has opened up a world of current gearing options.

I really think things will shake out a bit in time. If Rohloff doesn't make the ideal carrier, I think there's a good chance a firm like TrickStuff might. I feel sure an aftermarket firm with CNC equipment will make a carrier before long to address the offset issue.

Best,

Dan.

[macspud]

I do love my bash guard, but moving my chainring from the middle slot to the outer on my crankarm spider and mounting the bash guard to the outside should leave me where I am without increasing my Q-factor. My gearing won't accommodate a Chainglider now, so I'll be no worse off.

I really think things will shake out a bit in time. If Rohloff doesn't make the ideal carrier, I think there's a good chance a firm like TrickStuff might. I feel sure an aftermarket firm with CNC equipment will make a carrier before long to address the offset issue.

Ah, but Dan, if we could persuade Rohloff, sooner rather than later, to redesign the splined carrier to include a workable chainline and Chainglider bearing surface, maybe we/they could persuade Hebie to redirect the money they would have spent redesigning the Rohloff specific rear end towards a smaller Chainglider front end option, in line with Rohloff's new lower allowable chainring/sprocket ratio.

[Danneaux]

I like your thinking! There! In solidarity, I will sharpen my persuasive skills. 

All the best,

Dan.

[mickeg]

Julk, I am amazed that you could get a sprocket that worn.  I would never have thought that a chain could still work on a sprocket if it was even half as worn out as that.

http://thorncyclesforum.co.uk/index.php?action=dlattach;topic=11609.0;attach=11946;image

[martinf]

How incredibly useless, selfish, and damaging to the industry. We certainly already have fairly standard splined sprockets that are used for Sturmey Archer. Why not use this? Grrrr.....

I can see two good reasons not to use the Sturmey three-peg system on the Rohloff -

- from experience, when I was younger, stronger and living somewhere much hillier than now, in long-mileage, high torque use, the Sturmey style sprockets can wear at the limited contact points (they only have three - the Rohloff and Shimano splined systems have many more contact points). Once worn, Sturmey style sprockets can then move a bit on the Sturmey driver. Perhaps for the same reason of limited contact points causing stress, the smallest Sturmey style 13T sprockets are prone to splitting (with strong cyclists on Moultons and Bromptons). I suspect that low gear on a Rohloff can apply much more torque than any Sturmey-compatible gear hub, so can understand Rohloff choosing a multi-spline system.

- I haven't had time to measure, but I don't think it would be possible to design an adapter that would be compatible with the thread on the Rohloff hub and the Sturmey three-peg system, which requires three fairly deep grooves on the driver (= carrier). I think that may be the reason Rohloff went for their unusual raised spline design on the carrier instead of adopting the more usual grooves like Shimano and Campagnolo.