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I've got a set of 35mm roady tyres on the tourer that I'm building up from a Moda Inner frame. The clearance at the back is very tight, to the point that I think any flex will have the tyre rubbing the chainstay. On looking at the previous (too small) cx frame that I previously had built up for the same purpose, and with bigger tyres still, I can see that the chainstay are massively crimped to provide buckets of clearance.
So, is this something I could do myself, carefully, just a little bit, with a rag and a big enough set of molegrips? Or will it end badly?
It's usually done before the frame is heat treated.
If you do it without heating the frame it'll crack, if you heat it then the aluminium is likely to be seriously weakened.
I'll have a fiver on it ending badly with a possible hospital stay due to skin abrasion.
I'm not an engineer but I reckon it'll weaken the structural integrity of the chainstay which MIGHT lead to it folding under you. The other frame will have been designed to have that crimp in place and might use thicker-walled tubing to provide strength
Or I might be wrong, give it a go. What's the worst that can happen
Or will it end badly?
It will. Make sure you film yourself riding it so we can all see the result.
What if I glue a spoon to the outside of the stay to add strength? 🙂
The problem is that al-loo-min-um work hardens. Ie if you mechanically deform it, the material gets harder and is much much more likely to then crack. A heat treatment after working is normally used to restore grain order and anneal the material. Now you can do local annealing (using the blow touch and soap method) but i think i'd want to have a trail run on something less critical. if you know the frame material you could get a small sample tube of it to see what happens??
In all cases, actually putting in a "flat" without totally crimping or causing a wall collapse will not be easy, usually, the tubes would be packed with sand or similar to provide internal support to prevent collapse
you could fit a 190mm fat bike hub - spreading the stays would increase tyre clearance.
much less likely to die with slightly narrower tyres
You've kinda got most of the answer but some of it is a little muddled.
Short answer; any modification of a potentially heat treated Aluminium frame will make it more likely to crack - definitive answer is very difficult to give without undertaking long winded CAE analysis.
If you could anneal it then modify it and then re-heat treat you might get away with it - again it depends upon the stresses in the frame and the safety margins included in the original design.
So; it's your frame, your skin and your decision 😆
Good luck 8)
Having looked at it again, I think the wheel is slightly out of dish, as the clearance is alright on one side and really tight on the other. I think a redish of the wheel should bring it back to just about okay on both.
Question is, do I buy a spoke key or take it to the shop...
Why the either/or? Buy a spoke key, have a go, then take it to the shop to get fixed. Win-win 😆Question is, do I buy a spoke key or take it to the shop...
I reckon you'd be potentially wrecking a frame, but you'd probably manage to ride out the failure.
If it were me I'd just buy a smaller tyre if it's still too close once you've re-dished it.