Rohloff questions

[rualexander]

Is this an option for the OEM2 axle plate?
https://www.tritoncycles.co.uk/componen ... olt-p19595

is it just the adaptor thing with the M5 thread in it? If so it is a very expensive 'nut'....?

cheers

Yes it's just the 'nut' and it is expensive, but then again it is an official Rohloff part, so not surprising it's pricey.

[slowster]

I am doubtful that the adapter nut, which SJS incidentally sell for less, would be a good solution for the Longitude:

- torque reaction forces in the lowest gears would be pushing the hub axle further forwards in the horizontal drop out*.
- the distance from the mudguard/rack eyelet to a horizonal line drawn through the middle of the drop out would probably have to be within a narrow range, e.g. more than ~40mm and the notch in the OEM2 Axle Plate would not reach or engage (properly) with the nut. If the distance is a lot less than 40mm, then that would limit how far the hub axle could slide forwards and would keep it at the back of the drop out.

I imagine it might be possible to overcome these issues by fitting some form of limit stop, as 531Colin is planning to do anyway, which would stop the hub being pulled forward in the drop out by the torque reaction forces, and if the distance from the drop out to the eyelet is less than 40mm, the depth of the notch could be increased a bit to compensate.

With regard to fitting a limit stop in the LH drop out, Rohloff stipulate that the inside face of the LH drop out must be flat for a 40mm diameter around the hub axle**. So a limit stop that protruded beyond the inside face of the drop out within 20mm of the hub axle would not be suitable (and therefore my previous suggestion of a Surly Monkey Nut Mk2 would not be suitable). That is potentially an advantage of using an OEM2 Axle Plate anchored by either a bolt in the disc brake caliper slot or a Monkeybone: the bolt or Monkeybone would serve the function of a limit stop for the LH side, and a Surly Monkey Nut or similar could be used in the RH drop out.

531Colin, if the frame warranty matters to you, then I think you need to ask Genesis if it is OK to fit a Rohloff, and which Axle Plate and anchoring methods are permitted by them.

* See diagrams and instructions on page 147 of the current Rohloff manual. The diagrams illustrate how the issue applies with a vertical drop out, so it is necessary to mentally make allowance for the different impact if the drop out is horizontal.

** See diagrams and instructions on pages 29 and 30 of the manual

[slowster]

I've been thinking about this some more:

If an OEM1 Axle Plate is used, then the rear hub will have to be pushed to the front of the drop out, because the distance from the mid-point of the axle to the end of the anchoring stub is ~35mm, and once the radius of the axle is added that will take up all the available 40mm length of the drop out.

If the two forward faces of the LH and RH drop outs were not sufficiently square and the wheel were slightly out of alignment as a result, then:

- if the face of the RH drop out were slightly further forward than the LH drop out, a Surly Tuggnut could be used on the RH drop out to correct that and provide fine tuning. (I've just measured the Surly Tuggnut on my fixed gear bike, and it looks like it would just fit, i.e. by my measurement it can accommodate a distance of up to 36mm from the rear faces of the drop out/track end to the centre of the hub axle).

- if the face of the LH drop out were slightly further forward than the RH drop out, then I would try adding some extra layers of paint to correct that. I don't think a tug nut, Surly or otherwise, could be used on the LH drop out because it would foul on the stub of the OEM1 Axle Plate.

It might also be advisable to anticipate what clearance there would be between the chosen tyre and the mudguard behind the seat tube and bottom bracket if the wheel is as far forward as it will go in the drop out. Obviously, this will depend upon choice of tyres, mudguard and even wheel size (the Longitude is designed to be used with both 27.5+ tyres, i.e. 2.8" or wider, as well as 29"). Reohn2 has an older model Longitude, but might still be able to advise on mudguard clearance assuming the chainstay length is the same.

If an OEM2 is used, then again I would probably use a Surly Tuggnut on the RH drop out to fine tune wheel alignment, and also to prevent the wheel being pulled forward in the RH drop out under high torque pedalling in the lowest gears.

My personal preference would be to use a 21 tooth rear sprocket with a 42 tooth Surly stainless chainring (assuming that size would not foul on the chainstay), either the 110mm BCD version on a Spa TD-2 chainset, or the 130mm BCD version on an RD-2 chainset. IME a 122.5mm UN55 bottom bracket combined with the TD-2 or RD-2 should give the required chainline for a Rohloff fitted with the current standard splined sprocket carrier.

[Brucey]

I am pretty sure that Colin, being a practical sort of chap, would, should it occur, 'solve the problem' of the wheel not being perfectly square in the forward part of the dropouts, using a file, in about two minutes.

It is very easy to come up with complicated solutions to such problems.

cheers

[slowster]

I am pretty sure that Colin, being a practical sort of chap, would, should it occur, 'solve the problem' of the wheel not being perfectly square in the forward part of the dropouts, using a file, in about two minutes.

Nevertheless I hope some of the points I've raised will be of some value in planning the build, even if only to be able to confirm either that they will not apply or that there are better or much more obvious solutions than any I might suggest.

[531colin]

This isn't looking too tricky once I've got the parts in my hands....
OEM plate...

OEM2 plate and bolt...

I think I'll be using the OEM2 with the bolt in that handy hole in the dropout. I might cut/grind a bit of ali. just to take up the spare space in the dropout cutout. (nice phrase, that!)
Putting the wheel back in I think the sequence will go...axle in slot...disc between pads...engage reaction arm...do up Q/R...put chain back on

I can't see any point in using OEM plate if it means stiffening up the dropout, I don't think I need to stiffen the dropout with the OEM2?

[reohn2]

OEM2,job done.
TBH I can't see a need for anything other than the bolt.

Personally I wouldn't use a chain tensioner,IMO chaintugs should do a good job of chain adjustment which will only be needed occasionally and brake caliper adjustment should be a corresponding doddle at the same time,meaning less dangley bits to pick up debris
and muck on the chain .

Looking forward to photos of the finished article

[PH]

I think either would work fine, but having seen it in the dropout I think I'd prefer the OEM2 option. Your axle will be in the dropout before you need to line the plate up with the bolt, unlike on my Airnimal where I have to do the two simultaneously which is the only fiddly bit.

[slowster]

I think chaintugs would only work with a solid nutted axle. I guess it comes down to personal preference, i.e. solid axle plus chaintug(s) and no chain tensioner vs. QR plus chain tensioner.

I suspect that if using a QR hub it would be best if the hub were slammed to the front of the drop out and for the faces at the front of the drop out to be square to allow the wheel to go straight in with no need to fiddle around further to get it aligned.

I think an added advantage of using a larger rear sprocket than the standard supplied 16t sprocket, e.g. a 21t, might be that it would give more chain slack once the tensioner is unhooked and the chain lifted off the sprocket, which might make wheel removal a bit easier.

[PH]

I think an added advantage of using a larger rear sprocket than the standard supplied 16t sprocket, e.g. a 21t, might be that it would give more chain slack once the tensioner is unhooked and the chain lifted off the sprocket, which might make wheel removal a bit easier.

I take my chain off the chainring, slack isn't an issue.

[PH]

OEM2,job done.
Personally I wouldn't use a chain tensioner,IMO chaintugs should do a good job of chain adjustment which will only be needed occasionally and brake caliper adjustment should be a corresponding doddle at the same time,meaning less dangley bits to pick up debris

That would also require moving the anchor bolt every time you adjusted the chain, which is why Genesis had a slot there.

[Brucey]

I guess the brake caliper is going to be out of the way of the OEM2 plate? Otherwise that does look fairly straightforward.

cheers

[reohn2]

I think an added advantage of using a larger rear sprocket than the standard supplied 16t sprocket, e.g. a 21t, might be that it would give more chain slack once the tensioner is unhooked and the chain lifted off the sprocket, which might make wheel removal a bit easier.

I take my chain off the chainring, slack isn't an issue.

Correct,I wasn't thinking straight on that one
Looks like a tensioner will be needed after all with the OEM1 or 2

[slowster]

Looks like some of this might not be quite so black and white. There seem to be plenty of photographs of Surly Trolls with a Rohloff for example on the internet which do not have chain tensioners, e.g.

http://www.whileoutriding.com/gear-reviews/bikes/surly-troll-review-a-few-thousand-kilometres-down-the-dirt-road
https://northernwalker.wordpress.com/2013/10/28/behold-the-trollhoff/
http://cyclemonkeylab.blogspot.com/2015/03/review-surly-troll-with-rohloff.html

It's not entirely clear to me how the chain is lifted off the sprocket to allow the wheel to slide back, since I assumed the anchoring of the OEM2 would prevent the axle being slid forward in the drop out to give the necessary chain slack, although in the first link Cass Gilbert (a very experienced Rohloff user) says "the wheel needs to be toggled forward or to the side before you can unhook the chain". The use of Surly Tugnuts seems common, and Cass Gilbert is using one with a QR.

The Longitude does not have the Troll's sliding slot to anchor the bolt for the OEM2, but in any case I would have thought that a Monkeybone would be preferable to the sliding slot, since it serves the dual function of disc brake adapter and OEM2 anchor: moving the disc brake in the slot to compensate for chain wear also moves the anchoring point for the OEM2 the same (requisite) amount.

[hamish]

I have a Troll with the OEM2 plate.

It works well. To get the chain off I just loosen the QR, flop the chain tug off to one side, push the wheel forward a touch and the chain can be derailed from the chainset and set to one side off the sprocket so allowing the wheel to be pulled back.

The OEM bolt only stops the left hand side of the hub moving forward The right side can move plenty to derail the chain.

I think the Surly system is fine. It's a shame that Genesis didn't keep on with the OEM bolt slot.

If I was starting from scratch I'd probably consider using a nutted axle Rohloff... My hub was transplanted from a bike with the OEM 1 system.