Help needed!

[ewos]

OK so I have spent weeks and weeks stripping/rebuilding my Bomber and we are only 1 day away from the maiden voyage but I seem to have a problem with the chain. Rotating the crank backwards, when at the 12 o'clock position the chain is (in my opinion) at the right tension. At the 3 o'clock position it's too slack, 6 o'clock fine and at 9 o'clock too tight.

I assumed that the bottom bracket axle was bent but I have checked it the best I can without removing it from the bike for runout and it seems to be OK. I have checked the wheel alignment, the rear hub (which is missing one cone locknut but I have dismissed this as being the problem) and it has a brand new chain with all the links moving freely.

It's starting to drive me nuts so I approach the forum, cap in hand and ask for your help . . . . cheer's, Matt.

[admin]

in my experience its either the crank or the bb axle, cant be anythimg else.. The only way to be certain is to strip it down and check
Roll the bb axle along something flat and look for any exess movement.
Same goes for the crank lay it on a flat surface and make sure its level.

[77grifter]

I thought at first check the teeth on the chainwheel for uneven wear, then remembered I had a problem with an old raleigh superb with movement in each crank turn, i blamed the pedal first, then a worn arm, then a lack of bearings, then bent BB, turned out it was a duff cotterpin bizarre

[admin]

good point, if the pin dont hold the crank square, it will cause an uneven rotation

[ewos]

OK, I have removed the BB axle and it is bent, through a 180 degree rotation the difference is 0.87mm and rolling it across the glass top on the halogen hob (don't tell the missus!) reveals the bend quite clearly.

So, Bomberman, pretty please with a cherry on top, have you got a spare one that isn't bent?

[admin]

yeah mate, I'll pack it up on sunday for ya and post it monday
PM me your addy