Transmission noise and cassette fit advice please

[oldgreyandslow]

I've had a few issues with my 105 equipped Boardman and the transmission seems quite noisy - rumbling a bit in the big chain ring from the rear I think. I realise that description isn't helpful so I'll run through the history of the bike and hope someone can suggest a few things to check.
Initially after a few months there was some creaking from the bottom bracket – Halfords changed the BB30 bearings under warranty.
I changed the rear cassette from a 12-25 to 12-27, the cassette was a CS5700 105 unit, however the one I removed had no spacer behind it and the Mavic Aksium instruction book that came with the bike seems to show it needs one (see attachment) is this correct? Is this correct, I didn’t fit a spacer but I think I still have it somewhere.
The gears still seemed to be running fine at this point though.
I flipped the stem to try to get a more comfortable position, which seemed to upset the front mech, I tried sorting that, the action was also very stiff and the lever broke. Thankfully Halfords fixed that and I thought all was well. But after a while shifting became noisy, I assume d it was set up.
I decided to revert to the original position with the bars and flipped the stem back and attempted to set the front and rear mech’s up. I have to say though that having had campag for all my previous bikes I found the shimano set up instructions and procedure a right pain in the rear, so much so that I resorted to the LBS (shame on me!).
I put the bike on the stand and it seems to run through the gears OK, no rubbing on the front mech plates and it shifts OK at the rear but it seems to have developed this rumble when on the large ring.
In addition a couple of the rear blades spokes have twisted, I have reset them but wonder if I should get the wheel trued? I have the rear from my Campag bike, although unfortunately the bike itself is irreparable as a result of last year’s RTC, I was thinking of changing the freehub from this bike onto that wheel to see if it makes any difference, good idea or not?
Apologies for the long winded post, any advice or suggestions most welcome.

Thanks

 

[fossyant]

If you can tighten the lock ring on the cassette without the cassette being loose, then you should be OK. Mavic freehubs are slightly wider than Shimano (Mavic wheels will take 11 speed cassettes). If the cassette can be wobbled, then there could be your cause.

Check top jockey is dead in-line with the sprockets - look at bike from low down and behind. Also check the jockey isn't fowling the cassette teeth - you need to adjust the 'B' screw - it's a small secrew that sits at the back of the rear mech near where it's bolted to the frame. Tightening this will push the mech away from the cassette. Your chain may be slightly too short for the bigger cassette !

PS now't wrong with shimano stuff - all mechs work the same.

 

[oldgreyandslow]

If you can tighten the lock ring on the cassette without the cassette being loose, then you should be OK. Mavic freehubs are slightly wider than Shimano (Mavic wheels will take 11 speed cassettes). If the cassette can be wobbled, then there could be your cause.

Check top jockey is dead in-line with the sprockets - look at bike from low down and behind. Also check the jockey isn't fowling the cassette teeth - you need to adjust the 'B' screw - it's a small secrew that sits at the back of the rear mech near where it's bolted to the frame. Tightening this will push the mech away from the cassette. Your chain may be slightly too short for the bigger cassette !

PS now't wrong with shimano stuff - all mechs work the same.

Thanls for the tips. I did torque the lock ring down to the specified torque setting and didn't notice the cassette being loose but I'll double check that.

The shimano rear mech instructions seems to indicate the same chain length is OK for up to 27 teeth I would need more links if I went up to 28. I'll check it isn't fouling and isn't too tight, I'd expect that to be an issue when on the large chainring and smallest cassette cog though and tbh I rarely use that combo

Cheers

 

[ayceejay]

I have just been through this saga myself so I feel your pain. It seems likely that the problem is related to cable stretch that removes the tension that should be there, this is adjusted with the toggles either behind the rear mech or on the down tube. I have Sram on one bike and Shimano on another: the Sram is easy to adjust and runs quietly, the Shimano = not so much. If this doesn't solve your problem you may have to use an Ultegra cassette and a KMC chain.

 

[RecordAceFromNew]

The shimano rear mech instructions seems to indicate the same chain length is OK for up to 27 teeth I would need more links if I went up to 28. I'll check it isn't fouling and isn't too tight, I'd expect that to be an issue when on the large chainring and smallest cassette cog though and tbh I rarely use that combo

There is no way for Shimano to tell you your chain length is ok without knowing exactly what the length of your chainstay is, what the instruction says is your rear mech is ok for 27T sprocket. Increasing the size of the large rear and/or front ring invariably runs the risk of inadequate chain length (which can have very dire consequences). But since you have already done it you can try shifting to large front and large back gently to see if the chain still has a S curve at the rear mech, if not you need a longer chain.

Fossyant's suggestion of looking from behind at whether the top jockey wheel and sprockets do line up vertically perfectly is a good one.

 

[oldgreyandslow]

There is no way for Shimano to tell you your chain length is ok without knowing exactly what the length of your chainstay is, what the instruction says is your rear mech is ok for 27T sprocket. Increasing the size of the large rear and/or front ring invariably runs the risk of inadequate chain length (which can have very dire consequences). But since you have already done it you can try shifting to large front and large back gently to see if the chain still has a S curve at the rear mech, if not you need a longer chain.

Fossyant's suggestion of looking from behind at whether the top jockey wheel and sprockets do line up vertically perfectly is a good one.

Ok fair enough. if the only change is an extra 2 teeth on the largest rear sprocket and all the rest remain the same should it be a problem?
Incidentally I got the 2 links extra info from the Shimano instructions attached, see note about 2 extra links for a 11-28 sprocket

 

[RecordAceFromNew]

Ok fair enough. if the only change is an extra 2 teeth on the largest rear sprocket and all the rest remain the same should it be a problem?
Incidentally I got the 2 links extra info from the Shimano instructions attached, see note about 2 extra links for a 11-28 sprocket

It is impossible to tell, because the generally accepted rule* is that for every 4 extra teeth the chain needs to be increased in length by two (a pair of) links**. That is not to say a longer chain is definitely unnecessary for increases under 4T, because it depends on how close the original chain, while ok, is to the limit.

* for the avoidance of doubt while this rule is good enough for practical purpose, it is not accurate to N significant figures
** only if the original chain was new - if the original chain that presumably works ok was old (i.e. stretched) when installed then all bets are off as far as the rule is concerned

 

[oldgreyandslow]

It is impossible to tell, because the generally accepted rule* is that for every 4 extra teeth the chain needs to be increased in length by two (a pair of) links**. That is not to say a longer chain is definitely unnecessary for increases under 4T, because it depends on how close the original chain, while ok, is to the limit.

* for the avoidance of doubt while this rule is good enough for practical purpose, it is not accurate to N significant figures
** only if the original chain was new - if the original chain that presumably works ok was old (i.e. stretched) when installed then all bets are off as far as the rule is concerned

Seems to be OK, there's a degree of slack in the chain when at either extreme, however I shall probably check the chain length just to be sure. Does a shimano 105 chain have a reusable link like a KMC one or if split is it unusable?

 

[RecordAceFromNew]

Does a shimano 105 chain have a reusable link like a KMC one or if split is it unusable?

Commiserations... I feel your pain.

 

[oldgreyandslow]

Commiserations... I feel your pain.

KMC it is then. Cheers