Would you be angry?

[pwward]

After my Deore LX crank is knackered on a plane journey I ask a local bikeshop to put a new one on of similar quality.  I tell them put a new bottom bracket in if there is any doubt that it is damaged.  They don't put a new bracket in and replace the chainset with a Shimano FC M440.  After 6 weeks it starts to loosen so I go back.  They put in a new bottom bracket but reckon its unlikely the new crank is damaged.  After 30 mins riding I start to feel it loosen.  They have taken a total of £76 off me and I still don't have a crank that will stay on.  What would you do?[!]

[LowFlyingHawk]

I think it is a question of do-it-yourself or keep taking it to a bike shop.  I prefer to fix things myself (bike, car, computer etc) where I can, so I try to learn early what I need to do and what tools I need to do the job myself.  

In answer to the topic question, I would be recognisably peeved if I took a bike to the shop twice and it still was not fixed.  It would also harden my resolve to do-it-myself.

[Pedaldog]

I have to admit that I'd be a knockin' hard upon their door with a big stick and TELLING, not asking, them to sort it out and do it right!

[luceberg]

Can you see exactly where the movement is coming from?
It can be between crank and bottom bracket, bottom bracket and frame or bottom bracket bearings.
If it's between bottom bracket and crank, then have you tried tightening the crank bolts? If the tapered faces of the bottom bracket were greased (which they should be in my opinion, but only very slightly), then the cranks will loosen slightly and you need to keep tightening them, not to mounting torque pressure, perhaps half that. Eventually you wont need to tighten any more, as all the grease will have been forced out.

[johny c]

Maybe the crank has been pulled far enough onto the axle for the bolt face to touch the end of the axle. I fixed an old 110bcd LX crank with this disease by placing little strips of feeler guage between the taper faces of the axle and the crank, this took up the extra clearance ok. A bodge by any other name but it worked.