M730 chainset problem

[stew-b]

should there be any shims with the outer chainring bolts? they wont tighten enough to hold the rings properly but are only a fraction from being tight?

 

[stew-b]

anybody? its the only thing keeping my bike off the road now :cry:

 

[Carsten]

anybody? its the only thing keeping my bike off the road now :cry:

they may have had very thin washers to fine tune chain ring distance but those should not have any impact on the chain ring bolts. do you use the stock bolts and rings?

Carsten

 

[stew-b]

they are the stock biopace rings and apear to be stock bolts.when you lock them together with no rings they lock to a point where they butt against each other and cant get any tighter,when you then assemble them on the crank they hit the same point and havent yet nipped the rings up,hence me thinking they need 0.5mm of washer or similar..

 

[Sithlord]

Hi fella,

I know it might sound daft but when you use the allen key to tighten, you do use a chainring tool on the rear to hold the female part whilst tightening with the allen key ?

Si

 

[stew-b]

no,i have requested one in another post but i dont think its going to help as they spin up to this stop point very easily and good circlip pliers are having no effect.i think i might end up grinding a mil off the bolts

 

[Sithlord]

What I would do is .. remove the allen nut and bolts completely from the chainset then dry assemble them on there own, when they are tightened together completely , measure the 'spare ' distance from nut and bolt .. then measure the overall distance , then go back to the chainset with the rings , dry fit into position then measure the width there... then compare the measurements.. then determine wether you need new 'chainring' bolts or cut you existing ones down, also check for any fouling on the tab arms where the chainring bolts pass through for clearance... hope this helps ...

 

[stew-b]

thats what i have done already,the measurements are the same,i suspect this chainset was disasembled before i had it and i wonder if they missed some washers on putting it together,i really need an exploded diagram of the chainset i guess.

 

[Carsten]

according to the exploded view in the shimano dealer hand book there should be NO washers. and that's how all my M730 cranksets are. shimano used very thin washers here and there to fine tune the chain ring distance or to perfectly center them but no thick washers.

i've removed a chain ring bolt from a NOS M730 crankset and if they are tightened together completely the distance between nut and bolt is 6.5mm but the chainrings and spider are thicker than that.

carsten

 

[stew-b]

thanks,thats helpful,this is a nos chainset also.i can measure those dimensions now.