Twisted Frame?

[Cee-jay]

My stepson brought his mountain bike around the other day. The rear wheel had lost its nuts and come out of the drop outs and was wedged between the rear forks. I have managed to get the wheel out and spinning it I cannot see that it is twisted at all.

On putting everything baxck together again, I note that the original 145mm rear axle is now too short to fix between the rear forks. Measuring it, It looks like I will need to put on a 170mm axle. Is this safe to do so? Does it mean the frame is twisted? Is there anyway I can straighten it if it is. 30mm difference in size seems like a huge amount to me. If I just put in the new axle would it be safe to ride?

 

[I like Skol]

Sounds like the rear spacing has been forced open when the wheel came out of the drop-outs. Only solution is to reset the spacing by squeezing the rear triangles closed again. You could try doing this by hand but that is risky. Best option is to do it gradually using a long bolt or threaded bar and some washers across the outside of the dropouts and wind it in until the spacing measures 145mm. Once you remove the bolt the spacing is likely to spring out again so measure the new distance and then wind in the bolt in to reduce the distance to less than 145, maybe 135 and then recheck. It might tame a few attempts to get it right, the main thing is not to try and do it in one go and go too far!

Once the spacing is right check the frame for any sign of cracking or damage. Look for paint flaking or creasing near where the rear triangle meets the seat tube top and bottom.

What metal is the frame, steel or aluminium?

 

[I like Skol]

By the way, don't fit a longer axle. Even if you could find one that length it would result in problems with bent axles due to the length, especially if the young lad likes jumping and stuff.

 

[Sharky]

Something is a bit odd. Bit confused by the numbers. The rear spacing could be 135mm, then if you add on 5mm for the thickness of the fork ends, you are already at a length of 145mm, without allowance for the wheel nuts.

Is this the original rear wheel?

 

[I like Skol]

Isn't 145 spacing used for fat/boost bikes?

 

[Cee-jay]

Manythanks to all who replied. GFrame is steel, I have managed to squeeze the forks togethere a bit more aand will continue to try bit by bit. I think eventually it will gradually get back to where it was. I am trying to be careful to avoid cracking forks. Bike was originally built in one of the eastern european blocks so that may explain why the odd size, but in saying that I notice that halfords stock 145mm hollow axles. I have manage to get a solid steel axle at 170mm just in case!, but hopefully willnot need to use it. Thankfully Stepson is now 28 yeas old so has gone beyond the jumping stageand just uses his bike to get to and from work

 

[I like Skol]

145mm axle is standard length for 135mm spacing. 5mm each end sticks out into the dropouts.

 

[Rusty Nails]

Before setting the dropouts back to the correct distance apart it is also worth checking that the rear triangle hasn't been bent sideways in the incident. It only takes a couple of minutes.

 

[Nigelnightmare]

As "I like skol" said The axle length for a 135mm dropout will be 145mm for QR axles.