Cassette rumble

[johnnyh]

Hi all,
I bought an 11-28 SRAM PG 850 cassette for the lads bike, a cassette I use on one of mine, with the intention of giving him a bail out gear for hills.
It arrived and I fitted it with no bother.
The indexing was fine and the derailleur had clearance without need for adjustment on the 28, and all seemed good....

However, when shifting to use the 11 or 12 cogs there was a bad rumble and vibration.

I tried 3 different chains, SRAM 8 speed, SRAM 9 speed and the original Kmc, but nothing helped. I took the casette off and re- installed it but no change.
I switched back to the stock sunrace and all was good whichever chain I used.

I am suspecting a duff cassette, but does anyone have any other thoughts before I send it back?

Cheers

Johnny

 

[I like Skol]

What is the smallest cog size on the sunrace cassette?

 

[johnnyh]

The sun race has a 12 and 13 as its smallest, the SRAM starts at an 11.

 

[the_mikey]

I don't know what this rumbling is, but I too use SRAM 11-28 9 speed cassettes. Try to identify where the rumbling is coming from. Also if you were previously using 12-25 or 12-26 then the new chain may need to be longer that the old one (although this shouldn't affect the top gear).

I've just tested my gears, the top (smallest sprocket) gear does make slightly more noise than the next gear (just general noise, not the clattering of mis-indexed gears) , but not so much that it's unusually loud, and it's only really noticeable in the garage where it's very quiet.

 

[johnnyh]

This one really rumbles and vibrates through the bike, not good

 

[I like Skol]

Are you sure the indexing and stop screws are set correctly? A different cassette may not be aligned exactly the way the old one was, particularly as it is a different brand. Also check the derailleur jockey wheel isn't contacting the cassette for any reason. I don't think it should on the smaller sprockets but it might and could need the B-tension screw adjusting?

 

[Globalti]

It's rumbling because the chain has worn to the old cassette and you've made the mistake of fitting a new component in a worn drivetrain. If that's not the case, it's rumbling because it needs oiling.

B tension adjustment would only matter on the biggest cogs.

Your son won't hear the rumbling noise when cycling at speed on the smallest cogs.

 

[Andrew_P]

Have you tried wiggling the cassette, I had a rumble and the cassette felt loose. My freehub was breaking away, but could yours be not tightened up enough or needed a spacer?

 

[ushills]

Is the chain rubbing on the stays due to the small size of the smallest sproket.

 

[Jenkins]

If this is only in the 11 & 12 tooth cogs I would check that you have fully tightened the lockring. These two cogs are separate from the main block and, if the lockring has not been correctly tightened, will have a small amount of play creating the noise.

I've just cured a similar problem on one of my bikes where gears 8, 9 & 10 (the loose cogs) had a minute amount of play of less than 1mm creating a rattling sound when used. Tightening the lockring a few clicks has silenced the driveline.

 

[Milzy]

I have just done the same mod & no rumble. Maybe it is duff?