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Upon replacing my rear brake pads, I noticed that my rear wheel is not properly centered. The consequence is that the wheel is pressed against one of the brake pads, as can be seen in the pictures below. I have a Rohloff hub where I can pull the dropout+wheel back in order to tighten the chain, but I don't know how to center the wheel horizontally. In the final photograph (number 4) I have marked with A and B the dropout. Normally, I put in the wheel by turning the bicycle upside down and then let the wheel into the dropout, going "all the way". But If i do so, it results in the rim being pushed against the brake asymetrically. If I slightly raise at A and then close the quick release lever, the wheel is free from the brake, but it is not very stable, I think it's not the normal situation.

The wheel appears centered if I test the distance to the axle when putting it on the floor:

wheel aligned wheel aligned

Dropout looks like this:

dropout

My question: how do I keep the rear wheel centred in the axle and straight for my bicycle (Rohloff hub with longitudinally movable dropout, Magura HS33 rim brakes)?

brakes not aligned

brakes not aligned

wheel not centered

mechanism

Edit:

It appears the wheel is straight, but it was not centered. I have those pads on both sides, and one side was pulled back much more than the other. I determine this based on the length of the visible part of the thread. I fixed it now, but I think the reason it keeps going bad regularly is because one of the screws is missing:

pads-1 pads-2

See the void in the second picture...

I remember that I unsuccessfully hunted for such a screw, but then concluded that it's not essential and continued cycling. But I can't anywhere in this area find a screw with an inbus-head and the right diameter. I used a screw with another head, but couldn't tighter it very well and — as I found out now — it fell out again...

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2 Answers 2

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I have a Rohloff hub with rim brakes (HS33, for the sake), with vertical dropouts, but I also have a singlespeed bike with horizontal dropouts.

I would suggest a procedure much like Daniel Hicks suggested, but in a different order, as to assure everything is fine. So, you should follow these steps:

  • Make sure the wheel is true AND symmetric. You can do it by finding out a bike with vertical dropouts, removing the tire from the wheel, and fitting the wheel with this second bike upside down. Measure the distance from rim wall to one of the sides of the frame. Then, you mount it in reverse (with sprocket pointing to the wrong side) to make sure that distance is the same. If not, the wheel is dished (should never happen with Rohloff), and you should use a spokes wrench to bring the rim to "center". Most probably, a bike shop is the recommended way to do it, but only if you think your bikeshop's mechanic knows better than you (sometimes, they do not).
  • Assuming the weel is symmetric, you should mount it in the frame WITH BRAKES REMOVED, in order to make the weel centered relative to the frame. Since your dropouts are Rohloff OEM, you should: 1) Replace your missing bolt in the first place (always use a washer!!); 2) Loosen these bolts so that the dropouts slide freely; 3) Tighten the wheel's quick release while the axle is fully inserted into the dropouts ON BOTH SIDES; 4) With the chain engaged around the sprocket, slide the chain-side dropout fully backwards so the chain is properly tensioned, and tighten the two dropout bolts; 5) Move the rim sideways, near the brake posts, so that there is the same distance between rim wall and frame tubes on both sides; 6) Tighten the remaining two dropout bolts, on the other side;
  • Only then, install the brakes so that there is the same distance (the manual recommend 2mm) between brake pad and rim. Maguras are a bit tricky to adjust, so again, if you're in doubt, ask a mechanic, but remember that some mechanics (depending on the place you live) don't "capture" the subtle essence of correct setup of Maguras.

The steps described seem complicated, but they are necessary to guarantee, in this order, that your wheel is true, centered on the frame, the chain "tension" is correct, and the brakes are setup properly.

Your bike setup is fairly complicated because of Rohloff OEM dropouts, but mostly, I think, because you use rim brakes with moving dropouts. It means that, for every chain's lifetime, each time you have to compensate for chainslack, you have to mess with four small-sized allen bolts, AND hydraulic rim brake setup. The brake has to be adjusted in this case because, if the dropouts move back, the rim moves back and the previous brake setup is not valid anymore.

Hope all this helps, and good luck! And PLEASE, replace that missing bolt!!!

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Amazingly detailed answer, good work. It sounds like setting up this bike is not straightforward, especially when needing to adjust for chain stretch. –  Mac Nov 26 '11 at 21:12
    
@Mac : that is the main reason the Surly Troll had not become my dream-bike... Nowadays I think Rohloff needs a rigid (unsprung) chain tensioner screwed to the derailer hanger, OEM2 or speedbone-type torque plate, and vertical dropouts, never-to-touch-the-brake-setup-again. –  heltonbiker Nov 26 '11 at 21:31
    
Thanks a lot. I should find this bolt. I searched for it in my town but didn't find any, and one bolt is not easy to find online... I'll let you know how it goes. –  gerrit Nov 27 '11 at 20:40
    
@gerrit most probably this bolt has some standard thread pitch (most probably M5, which means 5mm outer thread diameter). If a bottlecage bolt fits, it is M5. Then you could buy any M5 bolt with correct length on a hardware store, and use it with one or two washers. The bolts don't need to look the same, they just need to work the same. –  heltonbiker Nov 28 '11 at 12:28
    
Also, you could mark my answer as accepted if you want :o) Just check the little green "V". –  heltonbiker Nov 28 '11 at 12:29

On a non-derailleur bike with nuts on the rear axle, and horizontal dropouts, the way to adjust the wheel angle is to pull the chain-side axle all the way back against the chain, tighten the nut just on that side, then slide the other end of the axle forward and backwards until the space between the tire and the chain stays is equal on both sides. Then tighten the second nut.

Your bike appears to have a quick release and vertical dropouts. I can't tell from the photo, but it appears that there may be some sort of a "chain tug" on the chain side. A bit more complicated, and hard to "grok" with the relatively poor quality photos.

But the basic idea is that you need to move one axle end forwards/backwards relative to the other until the spaces on either side of the tire are equal.

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I will clarify my question a bit and add some more or better pics. It's difficult to add good pictures in the poor light conditions. –  gerrit Nov 26 '11 at 14:55

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