Rohloff questions

[531colin]

IMG_5321 by 531colin, on Flickr

In the end it was ever so easy; a lightly-modified ISO adapter bolted into the unused ends of the slots makes a perfect guide for the reaction arm.

More difficult to see with the thing assembled..

IMG_5310 by 531colin, on Flickr

A bit of white paper behind lets you see the small gap between the reaction arm and its new guide.
The wheel all goes in "one thing at a time".....axle into the slot, then disc between the pads, then reaction arm onto its boss.

[slowster]

Looks good. How far could the axle be moved backwards in the drop out while still maintaining engagement of the bolt in the axle plate? Would it be enough to take up sufficient slack from chain wear that you could dispense with the chain tensioner? (I appreciate that you might well not want to dispense with the chain tensioner, but it would be interesting to know if it was an option.)

[531colin]

The cutout in the torque reaction arm isn't much bigger than the head of the bolt it locates on, so there isn't much scope for pulling the wheel back.
I get the impression that there is a fair amount of torque to be resisted? If you used the longer torque arm and cut a slot in it I don't know if it would withstand the torque? (Brucey commenting on the possibility of the dropout slot opening up with the in-slot reaction arm makes me a bit doubtful!)

[Brucey]

the highest reaction torque will be 'backwards' in bottom gear, and it will scale with the input into the hub. In high gears there is a (smaller) forwards torque to be resisted instead. You can get a good idea of the relative amounts of torque if you look at Rohloff's own dropouts; I estimate they are at least four times stronger in the 'backwards' direction than the forwards direction. There is also some information in the Rohloff manual. Note that the Rohloff designs are meant to be strong enough for tandem use, which may incur average torque values which are almost double that of a solo.

On Colin's frame one way of making the wheel moveable would be to have a captive nut in the reaction arm, and then to bolt into it through the dropout. OK, this is more faff when taking the wheel in and out, but it looks like it will give you about 3/4" wheel movement...?

Just a thought anyway

cheers

[PH]

Came across this page in the Rohloff manual a while ago which I found interesting, there's a table of the torque at the bottom on the page
https://www.rohloff.de/en/service/handb ... -anchoring

That looks a neat solution Colin, nearly finished?
I was tempted by the idea of a guide when it was first mentioned, but in practice haven't found in necessary on the Ogre with horizontal dropouts, though I don't have a chain tensioner to contend with. I was a little apprehensive about the wheel removal/fitting, I needn't have been. Once it's resting in the end of the dropout and using the lower part of the gear mechanism as a handle as Brucey suggests upthread, it all goes together very smoothly, I included a Surly Tugnut from the start, but it'd probably be fine without it, it's a nutted axle. The wheel comes out as easily as hamish suggests, though it needed a little paint removal from new.
While shuffling stuff around between bikes, I also added a Monkey Bone* to the Airnimal. Partly because it had the securing bolt for the OEM2 plate forward of the dropout, which Rohloff say not to do on a vertical one, it's also made slotting it in a lot easier. I reduced the size of the sprocket at the same time (I was swapping chainsets anyway), which gives more room, it's been a big improvement and I can live with the increased wear as it's a bike which will do less miles per wheel removal than the others.

*The Monkey Bone was originally a third party part, from Cycle Monkey in the US, hence the name.

[slowster]

If you used the longer torque arm and cut a slot in it I don't know if it would withstand the torque?

The OEM2 Axle Plate which you have is longer than the Axle Plate supplied for use with a reaction arm bolted to the chainstay (photographs below for comparison). I don't know how much increasing the depth of the slot by filing enough of it (5mm-10mm?) to accommodate chain wear would weaken the Axle Plate, but the existence of the shorter Axle Plate suggests that the OEM2 Axle Plate might itself be strong enough to cope with the greater reaction force when the bolt is at the bottom of a DIY extended slot. I think the questions would then be:

1. Would the modified OEM2 be strong enough with the bolt in what would normally be its standard position?

2. Would the greater reaction force when the bolt is at the bottom of a DIY extended slot force apart the drop out?

With regard to 2, I guess the fact that the short Axle Plate needs such a long reaction arm bolted to the chainstay does not bode well. On the other hand, when the bolt was at the bottom of the extended slot and the force was greatest, the axle would be furthest forward where the drop out is strongest.

To be clear I would not suggest you try this, I just find it an interesting thought experiment.

With regard to tandems, Rohloff supply a beefed up version of the OEM1 Axle Plate which does indicate that if nothing else the torque forces can damage an ordinary OEM1 (again photographs below for comparison).

OEM2 Axle Plate


Axle Plate for use with Reaction Arm


OEM1 Axle Plate


Tandem Axle Plate with longer stub and fewer bolt holes

[531colin]

When I'm out and get a puncture and have to change the tube, I want the wheel to go back with the minimum faff.....like vertical dropouts....fit the wheel, bottom it in the dropout, do up the Q/R. So, something has got to "stop" the wheel. ....as currently set up, thats the reaction arm bottoming on its fixing......and then I know the brake will line up.
For that convenience, I'm happy to have a chain tensioner.

If I wanted to get rid of the chain tensioner, then I would have to put up with moving the wheel to tension the chain, and moving the brake to suit. Fixing a flat at the roadside I would still want something to "stop" the wheel. Adjusting the chain tension could be done at a convenient time and place, as long as there was an adjustable "stop" I could move the wheel to set chain tension, fix my "stop" and move the brake to suit. For me, that would mean doing a bit of brazing on the dropout so the existing reaction arm bolt is working in a slot of the right width, not fixed in the corner of an irregular cutout. (as I think this frame used to be made?)

I don't like the idea of a long slot in the reaction arm, just in case the forces were enough to open the slot when the fixture was at the open end of the slot. Brucey's idea of a nut brazed to the reaction arm works, but then I would be looking for another "stop" which I could adjust to set the wheel position in the dropout.

[Brucey]

for use with no tensioner, a set of chain tugs might work? the RH one would be best taken off the axle/skewer when the wheel is refitted, else the chain might not go over the sprocket nicely.
I think a tensioner might be easier to live with...?

cheers

[slowster]

I fully accept a chain tensioner is most likely the better option with the Longitude. I've not used a chain tensioner myself, so I would be interested to see what 531Colin's assessment is when the bike is in use.

Anyway I'm looking forward to seeing/hearing more of the eventual build and what choices are made.

On that note 531Colin, if you are going to fit mudguards I would recommend reohn2's approach of fitting a rear mudguard on the front. I initially fitted a standard 65mm Bluemels front and found that thanks to wind resistance mud and water sprayed forwards from the top of the tyre often ended up on my lower half or on the front of the forks/head tube, and I realised that the wide MTB tyre and large gap between the mudguard and tyre resulted in a lot more mud and water spray than a narrower tyre and closer gap.

I've now fitted the rear mudguard from a Bluemels 75 U Long set to the front, and it's very good. Not only does it eliminate the spray problem, it's more rigid than the standard 65mm Bluemels and has much more clearance between the stays and the sides of my 2.35" tyres. The downside was the cost, especially if two sets are purchased so as to have a rear mudguard for both the front and rear (although I bought mine more cheaply from a German retailer), and the need to do a bit of very simple tweaking to fit the rear on the front. If you think you might be interested in doing the same, I can provide more details.

[531colin]

No secret that this is my first encounter with Rohloff; so what do experienced users think of this thing?

IMG_5323 by 531colin, on Flickr

(For the uninitiated, its a pulley sort of thing; the 2 cables from the Rohloff shifter need to turn it in different directions. The 2 cables terminate in diametrically opposite holes, and are fixed by M4 grub screws. (the cable fits in a drilling in the pulley, the grub screw goes in a drilling at right angles....kind of hard to put into words?)

IMG_5325 by 531colin, on Flickr

The grub screws are in open-ended holes, so the cable is "clamped" between the end of the grub screw and whatever bit of the hole the cable then contacts. I wasn't impressed by this as a means of securing the cable, so I ground a couple of M4 grub screws to length so they could fit in the "bottom" of the hole and the cable would then be clamped between the 2 screws. I also silver soldered up the end few millimetres of the cut end of the cable, just to keep it tidy.

IMG_5327 by 531colin, on Flickr

I suspect I'm over-reacting, and its perfectly serviceable as Rohloff make it?
Subsidiary question; the nipples on my Rohloff cable are an odd shape, with flats rather than a simple barrel....does the twist shifter require special cables/nipples?

[slowster]

When I got a Rohloff I trawled through various information on the internet to try to improve my understanding of the product, much of which my memory is now pretty hazy about, but I think the cables might be brake cables and I seem to recall reading a comment where someone reckoned that they were made for Rohloff by a manufacturer like Clarks or Fibrax or similar. As you have probably found in your bedtime reading of the Rohloff manual, Rohloff say not to lubricate the cables, but I think plenty of users do and I doubt it matters a great deal.

WRT the transfer box, I didn't come across any significant reports of problems, and it just struck me as a simple reliable bit of kit. In contrast there was a review by someone of the Gebla Rohbox which is designed to replace the Rohloff standard transfer box and thus make the Rohloff compatible with SRAM brifters. He found that the Gebla Rohbox was not as reliable (far more complicated internals and I think he might have been using it in very harsh conditions, e.g. possibly submerging).

The Thorn forum is a good source of information, e.g. these threads:

Lubrication of external transfer box ?

Rohloff Ex-box Maintenance

I found the advice in the manual to adjust the cables to have ~2mm of play does make a difference to ease of shifting (allows the wrist to get a bit of momentum before it meets the resistance of the indexing).

[slowster]

Searching further I found this thread on the Thorn forum, with the following comment by Thorn's workshop manager:

The important thing is the head diameter, only 1.1mm Rohloff, Fibrax and Sram cables have the correct diameter head. 1.2mm cable heads unless filled down tend to damage plastic cable drum in the shifter. Rohloff cables are also ground wire so tend to flow better round the pulley in the shifter and EX Box so do give a smoother shifter feel.

[Billy007]

The Rohloff hub is pretty easy to install providing you have the right bike frame for it. I dunno why you seem to be having such a drama. I followed the Rohloff instructions, they are quite straight forward and intuitive, it doesn't take long at all, but I did lubricate the inner gear cables and it has been fine. The gear change has been easy, slick and precise, a joy. Not once in 5 years have I had a problem with it. I have only had to adjust the barrel adjusters once on the gear transfer box to take up a little slack that had crept in last year. Apart from that and the periodic oil changes it has been fit and forget, well not forget, fit and use more like it. A great piece of kit.

[PH]

I suspect I'm over-reacting, and its perfectly serviceable as Rohloff make it?

I've never considered it might be an issue and it never has been. When I've come to remove them, they're kinked where the grub screws has deformed the cables, I suspect it's this kink that holds it securely, possibly more so than being sandwiched between two flat surfaces. EDIT - It isn't like Rohloff don't understand these things, the connectors for the cables on an internal shifting hub have two grub screws on each part.
I've used Rohloff and SRAM cables, they work fine. Thorn say they use Fibrax cables in all their builds and these are made for them, not sure why they'd do that, I'd have thought that even OEM hubs come complete with cables, but it's there on SJS's website. I probably change mine more often than necessary, I have a workshop roll of brake outer that I'm unlikely to use in my lifetime and always have some spare inners ready. Because it doesn't effect the indexing and the deterioration is gradual, I find it's easy to miss how sticky they've become till I change them.

[531colin]

The Rohloff hub is pretty easy to install providing you have the right bike frame for it. I dunno why you seem to be having such a drama. I followed the Rohloff instructions, they are quite straight forward and intuitive, ........

The Rohloff instructions for lacing up are interesting, but I'm sure I would have remembered if they had said to lace up a disc wheel 1 cross all inbound?
I'm not having a "drama" at all; the weather is cold and wet, I'm having a pleasant time messing about with some bike stuff and also having a nice chat about it with some like-minded people on an internet forum.
Choosing a frame because its designed for a Rohloff is a valid choice, but it isn't my choice. See https://forum.cyclinguk.org/viewtopic.php?f=5&t=142977