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Possibility of [b]maybe[/b] swapping/buying my Pompino for a larger size. Mine has 135mm dropouts.
Any problems with that much spread as I have 2 rear wheels (Flip/flop + Sturmey 3 speed) which I really want to keep but are both 135mm axle. I also have a bit of leeway re chainline, so don't expect any probs there and steel is bendy.....right ?
Advice/opinions please
a good mechanic will "spring" a steel frame for you. Was very common when road bikes went from 126 to 130
leggyblonde - Member
a good mechanic will "spring" a steel frame for you. Was very common when road bikes went from 126 to 130
Big difference in "springing" a frame by 4mm and bending it 15mm to go from 120mm to 135mm. I'd speak to on one before I did that and bear in mind you need to get it right because of chainline, brakes and wheel alignment I'd look at replacing the hub or investigating if you can change the hubs to 120mm spacing
KS - you are right re changing axle/hub but it's extra hassle and expense. I've done it on the Pomp the other way round ie. a 120mm axle into a 135mm frame without a problem. It's only 7.5mm each side so I wouldn't think it will affect wheel alignment at all and brake alignment very little.
I'm more concerned about weakening welds rather than the 4130 but as I'm not an engineer it would be good to have some qualified opinions on tolerances.
Just bend it and straighten the dropouts. That's what a shop/framebuilder would do.
Just bend it and straighten the dropouts
I like that idea - it's not like it's a high tech ultra thin tubing, is it !
I have done this sort of thing many times without a problem. The important thing is to make sure the dropouts are parallel at the end of the job.
I use a car screw jack with a couple of lumps of wood to protect the paint. Do it a little bit at a time.
Good idea. Do you have to take it a few mm wider as presumably there is a 'memory'?
Alternatively, if the drop-outs were spread enough by hand to get the back wheel in, wouldn't the effect be the same over time?
I wouldn't think the bending out would be a problem, but how do you square the dropouts?
Maths was never my strong point but 7.5mm either side can't be more than a few degrees difference (assuming they were spot-on in the first place) and it'll be bolted up anyway.........if they are too far out to bolt up, I have a big hammer 😉
sounds to me like a lot to bend. ewspecially as you have to bend each side twice - once the get the width then back again to get the dropout parallel
I'd ask a frame builder to do it. Heating the frame might be worthwhile
A fram builder such as Argos will cold set the frame and bend the dropouts back parrallel .There is a tool for this to check allignment ,or you could make one yourself
Yhanks for all the replies. There is a framebuilder not too far from me so if necessary I can go there.
I'd reduce the spacing on the non drive side and dish the wheel to compensate. if you can't get 15mm off the non drive, then look at the driveside, but I wouldn't take more than 5mm off that side.
Worth a try before bending the frame.
you don't need to dish the wheel until you know the spacing works and you can put it back easily if it doesn't.
Dunno, It's a long way to go, it's not like just springing a 126 backend out to 130 (which works fine to get a modern hub in an 'older' frame).
It's not so much a tubing / welding integrity issue, although that will come into it, but the chances of doing it without a jig, and keeping things straight / consistently spaced don't appear to be on your side ...
Assuming there is one, any minimal difference in tube length, (down from that on the 135's) should get eaten by the decent length dropouts they have tho'.
Ive done it a few times using sheldon as a guide.
http://www.sheldonbrown.com/frame-spacing.html
BTW I may have a long SA AW3 hub axle in the shed...
The SA axle I have is 135mm but thanks anyway. Sheldon always has the answer, I like his 'plank of wood' tool but I think Epicyclo's car jack method will give more control.