Bent frame?

[fastpedaller]

Alu frames can be cold set to a certain degree, I guess it's because they are alu alloy not 100% alu, but it will weaken them somewhat and is a risk.

- Also bike shops regularly bend alu derailleur hangers back into line. It's going to be weaker but it may be possible.

I (almost) destroyed the dropout on an aluminium mountain bike 4 years ago - In smallest ring, going over rough ground rear mech wrapped itself and tore out of hanger, also bending it. I annealed it and gently bent it back straight. The hole for the mech was oval and had a destroyed thread - This I fixed by using some lumiweld rod, again heated with a blowlamp (and dripped a bit on my knee as well OUCH!)
I then drilled and tapped the hanger, and the dropout/hanger gave good service for 4 years, and I gave the frame away recently, so it may continue for more years.
Annealing aluminium alloy....... a trick I remembered from my school days: Rub a bar of soap on the aluminium, heat aluminium with blowlamp until the soap goes black, and allow the aluminium to cool (ie don't quench it). Bend to shape gently. If, during the process the alloy seems reluctant to bend this MAY mean it will be close to fracture, so repeat the process. It certainly worked for this job.
You'll need to find out if the frame's bent (hopefully it's just a wheel dish problem). If the frame is bent it may be worth annealing before attempting to bend.

[graymee]

Now I've got an internet connection again I can report that Valbrona was spot on when he suggested the wheel dishing was the problem. I might try making myself a wheel dishing tool whilst I'm off for Christmas then re dish the wheel when I head back to the west Midlands for work in the New Year.

[fastpedaller]

Now I've got an internet connection again I can report that Valbrona was spot on when he suggested the wheel dishing was the problem. I might try making myself a wheel dishing tool whilst I'm off for Christmas then re dish the wheel when I head back to the west Midlands for work in the New Year.

That's good to hear. A 'dishing stick' can be made with a few strips of steel riveted together, or if you have more equipment available a "deluxe" version with welding

[531colin]

My favourite DIY dishing stick is a bit of stick with 3 woodscrews.
The middle screw head goes on the hub locknut, the 2 outer ones on the rim.
Just wish I had thought of it!...

[fastpedaller]

My favourite DIY dishing stick is a bit of stick with 3 woodscrews.
The middle screw head goes on the hub locknut, the 2 outer ones on the rim.
Just wish I had thought of it!...

And other variations on the theme

[gregoryoftours]

My favourite DIY dishing stick is a bit of stick with 3 woodscrews.
The middle screw head goes on the hub locknut, the 2 outer ones on the rim.
Just wish I had thought of it!...

Oh ar, that sounds really simple and obvious, and accurate! I think I'll make one, maybe use a bit of aluminium section and threaded rods though. Thanks for this idea!

[cycleruk]

Dishing - put the wheel in the frame and measure one side between rim and chainstay.
Pull wheel out, turn it round and put back in frame. Remeasure rim to chainstay again and that should be the same. Adjust to suit.

[Tigerbiten]

Dishing - put the wheel in the frame and measure one side between rim and chainstay.
Pull wheel out, turn it round and put back in frame. Remeasure rim to chainstay again and that should be the same. Adjust to suit.

That only works if your frame is symmetrical.
The rear triangle on my frame is such that a wheel built with a 9 speed hub has no dish.

[Brucey]

I think that we have potential for semantic (or actual) confusion here;

Tigerbiten's rear wheel has no dish wrt to the flanges, but to some folk would appear dished if measured with a dishing tool. Cycleruk's scheme measures the dish the same way as a dishing tool.

Given a choice I'd sooner think of a new word for the dish that is measured by the dishing tool if we are to avoid confusion. Truly such tools are normally used to check for any offset.

I would be happy to describe Tigerbiten's wheel as 'dishless and offset' BTW.

cheers

[Tigerbiten]

I would be happy to describe Tigerbiten's wheel as 'dishless and offset' BTW.

To make it even more fun .....
My wheel is dished because I use a Rohloff hub.
The way it's built is the short spokes are on the non-sprocket side.

[Brucey]

in which case your actual wheel is perhaps most accurately described as 'reverse-dished and offset' even if the intended wheel is meant to be 'dishless and offset'.

cheers