Rohloff questions

[Brucey]

the six small bolts that secure the reaction arm pass through the remote shifter bracket too, so it all turns together; effectively you have a 'handle' to steer the tab into the dropout when refitting the wheel.



FWIW my gut feel is that the dropout would work OK in terms of raw strength but might be vulnerable to fatigue in the long run unless stiffened somehow. In my workshop it would get a (thinner) infill plate added in the bottom cutout, and maybe some more material added to increase the depth of the dropout section slightly forwards of that. I'd also carefully examine the finish on the cut edges of the dropouts, eg. the inside of the cutouts , and consider improving it eg by grinding off cutting dross and other surface surface imperfections.

cheers

[531colin]

……... In my workshop it would get a (thinner) infill plate added in the bottom cutout, and maybe some more material added to increase the depth of the dropout section slightly forwards of that. ….

Or even a simple plate performing both functions added to the (out) side of the dropout?
Nice photo showing that the axle plate and gearchange furniture are "captive" !
The alloy Rohloff dropout you showed originally is impressively deep in the counter-revolutionary direction!

[Brucey]

more than one way of skinning a cat and all that. Simple is always good! One of the appeals of bonding aluminium plates into the dropout is that it isn't very invasive, so could be done after the bike is built if necessary. Another is that if the stresses are high enough, you would most likely see the bonded joints crack up and then be sure that something is needed.

FWIW the torque loads obviously vary with the gearing, gradient etc but if you are running fat tyres on a 622 rim you are looking at reaction torques into the dropout at least double those seen in a small-wheeler. Thus it may be very interesting to see how folk have modified Bromptons etc to allow fitment of a Rohloff, but it might well not be terribly relevant.

cheers

[slowster]

my original idea was to use the OEM1 axle plate that Brucey shows in the dropout wheel slot. (In preference to the OEM2 with a half-round cutout which engages with something on a modified disc brake adapter ISO/post mount.)

Note that the OEM2 Axle Plate is not just for use with the Speedbone or Monkeybone adapters. As the photograph from SJS's website below shows, it is supplied with a nut and bolt, and the notch/cut out can be held in place by the head of the bolt. Not only do Surly's Troll and Ogre have drop outs with a dedicated slot for that bolt, Shand's Rohloff frames also have drop outs which accept a bolt. I think that the simple round bolt head eliminates the problem mentioned by Ben Cooper of the Monkeybone and OEM2 potentially not being suitable for a rear opening horizontal drop out because of the shallow angle of engagement of the notch in the OEM2 Axle Plate with the corresponding machined cut out on the Monkeybone (see bottom photograph).

With regard to the risk of the reaction forces from the hub bending or damaging the drop out, the distance from the hub axle to the OEM2 Axle Plate notch is a bit longer than the distance from the hub axle to the stub/tab on the OEM1 Axle Plate, which should mean less force transmitted with the OEM2 (compare the photographs below).

One possibility that occurs to me, is that if you are using a chain tensioner and the disc brake calipers will remain fixed, i.e. no need to slide the adapter forwards and backwards in the slot, then it might be possible to use the spare space in the disc brake slot for the OEM2 bolt. I would expect that part of the drop out to be strong enough to cope with the torque reaction forces, especially if the bolt is positioned at the very rear of the slot. The only problem I can foresee would be that there might not be enough space in the slot if a 160mm disc is used and the adapter has to be pushed to the back of the slot (if so, the solution would presumably be a 180mm disc).

If you buy a Rohloff with an OEM2 Axle Plate, and find that you cannot get a satisfactory anchorage for the bolt on the drop out, it would cost £23 or so to buy an OEM1 Axle Plate and fit that instead to use in the drop out.

OEM2


OEM1


Monkeybone Adapter for 160mm disc. You can imagine how the acute angled edge of the cut out below '160' will impede the notch of the OEM2 from properly engaging if the Axle Plate has to be offered up at a very shallow angle. That issue will simply not apply if the notch only needs to engage with a plain round bolt head.

[531colin]

Thanks Slowster. …..I think its 3 options, isn't it?
1. The official (no bodging) option is the monkey bone OEM2 route. (Which puts the "docking" of the OEM2/monkey bone in a situation that's fairly hard to see, eg after mending a flat?)
2. OEM2 docking onto a carefully-contrived bolt head in the dropout...might get away with using one end of a disc brake slot, might have to contrive something. So minimal to slight bodging, and possibly easier to see what you are doing replacing the wheel?
3. OEM arm in the wheel slot in the dropout. Definitely the easiest to see when replacing the wheel, but the most extensive bodging, unless I decide to simply use the dropout "as is" rather than beef it up.

[Brucey]

I'd favour 3) and get the faff over and done with early on, rather than put up with the repeat faff inherent to the other two setups.

I note that you can at least trial the 3) setup without modifying the frame; that can be done later. I'd also expect there to be a fair chance of -once the wheel is in- identifying a better solution than any of the three anyway.

In the latter category might be the idea of bolting a plate to the side of the dropout, which includes a slot (eg vertical, below axle height) which receives the reaction arm fitting early on as the wheel is refitted. The reaction arm/remote bracket would have to swing through an angle as the wheel is refitted, but I don't see that as being an unbearable faff; (much easier than getting the axle in the dropout first and then engaging the reaction arm tab someplace where you can't even see it clearly, I would have said).

cheers

[PH]

I see no advantage to using the OM2 plate and screw unless you have a slot to put it in and only then if you use that to do away with the tensioner.
Having used both, I find the OM1 plate is easier to locate in the dropout.
If it's any help - the Thorn dropout is 6mm inc paint at the beefed up edge and they use an axle plate that fills it, I think it's the tandem version.
Dropout by Paul, on Flickr

[slowster]

I think the key point is that whatever option you initially choose, if you decide you would prefer to try one of the others, it's not hugely expensive or troublesome to buy and fit a different axle plate or even to buy a Monkeybone as well. I don't think any of the options are bodges - they are simply variations designed to accommodate different frame designs. Shand even chose to use the OEM2 and bolt option, despite being a custom frame manufacturer which could presumably easily get Rohloff OEM1 compatible long slot drop outs if they preferred that option.

(To my mind, it's the internal gear box Rohloff with a long torque reaction arm, external 'bare' cables and all the gubbins that goes with it that is a bodge.)

Personally I would not be too bothered about how easy it is to see the various parts when installing the wheel - I'm not sure it's any worse than not being able to clearly see the gaps between disc bake pads when trying to line the disc up to refit a wheel. If punctures were a lot more frequent, I might feel differently, but I could live with any of the different set ups. You might even find that with a bit of practice correctly aligning an OEM2 Axle Plate with a hidden bolt or the Monkeybone becomes instinctive (I think you would be able to use the external gear box as a 'handle' to align and rotate the Axle Plate to the correct angle to slot onto the bolt or the Monkeybone).

I am far less experienced and qualified to judge the suitability of the Longitude drop out with the OEM1 Axle Plate than Brucey, you, PH or Ben Cooper of Kinetics, but it does not look as substantial or strong as the Thorn drop out in PH's post, and I would probably prefer the OEM2. I think what I would do is first see if there was a suitable convenient point for the bolt and nut. If there wasn't and/or the disc caliper adapter did not leave enough space in the slot for a bolt, then in your shoes I would probably buy a Monkeybone and be prepared if necessary to file away enough of it to allow the OEM2 Axle Plate to engage properly.

[Brucey]

FWIW I think the maximum faff is when you have to do 'everything at once', e.g. feed the reaction arm in its slot, feed the axle into the dropout, and feed the disc into the caliper, all starting at the same time. IMHO it is much, much easier if these things are done separately, in sequence; some setups will favour this, others won't.

FWIW I don't think the Thorn dropout is a terribly well thought-out design; they have put a cutout into the dropout right where the reaction load is highest of all, and for what...? must be all of 10g weight saving...?.

cheers

[PH]

Personally I would not be too bothered about how easy it is to see the various parts when installing the wheel - I'm not sure it's any worse than not being able to clearly see the gaps between disc bake pads when trying to line the disc up to refit a wheel.

The difference is not what's in sight, but as Brucey says the order you're doing it and to what extent it's all at once.
I only know my bikes, I think I know them well, but am hesitant to say that experience would transfer to another. With the Airnimal and an OM2 plate, I have to line it up while I'm holding the wheel. With the Thorn, the axle is already on the dropout before I have to adjust the lug on the plate to fit.

If punctures were a lot more frequent, I might feel differently,

Not that I'd wish it, but the opposite might also be true. I think I've only had the rear wheel out of the Airnimal four times in two years, two of those were to transport it and only one was at the side of the road. If I was doing it twice a week, it might have got better at it. I don't want to overstate it, there's a bit of extra faff, it's not enough to describe it as a problem.

[PH]

FWIW I don't think the Thorn dropout is a terribly well thought-out design; they have put a cutout into the dropout right where the reaction load is highest of all, and for what...? must be all of 10g weight saving...?.

cheers

I've thought the same, OTOH the frames have a lifetime warranty.
Rather oddly, it's only a cutout on some models and not when they sell the same dropout separately.
https://www.sjscycles.co.uk/frames/thor ... -per-pair/

[rualexander]

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

[Brucey]

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

[531colin]

Its a bit of mixed messaging, isn't it?
You need this massive dropout to withstand the torque of the reaction arm...
...on the other hand, you can use an M5 mudguard bolt, as long as you use a nut with a collar the right diameter.
The collar looks about half inch to me, I think I'd use a bigger bolt!

[Brucey]

I thought that too. I think that an M5 bolt is only going to work if it is kept fully tightened; friction at the interface ought to spare the bolt all the shear loadings. However if the bolt isn't kept fully tight I think it would pretty soon fatigue if low gears are used much.

I guess there is a bit of risk vs consequence going on here; if an M5 bolt fails in the field, it is an easy fix. However if a dropout cracks, not so much.

cheers