Rear Cassettes

[Bristolian]

I have a basic, wheel-on, turbo trainer that is starting to get some use. To save wrecking my rear road tyre I purchased a used rear wheel which came with a turbo tyre and a 9-speed cassette already fitted that has the same gears as my road wheel. So far so good 👍

When I got the wheel, I checked that the low limit, high limit and indexing settings of the rear derailleur were good. This check was done with the bike in the maintenance stand, so without any load on the drive chain. However, I find that when I put the bike on the trainer the rear derailleur is noisy in the lower gears (bigger cogs) and when in the higher gears (smaller cogs) it has a habit of changing to the next smaller cog of its own accord.

I can prevent this from happening and quieten the larger cogs by increasing the cable tension by winding the barrel adjuster up by 3-4mm but should this be necessary if the gearing is the same as the road wheel? I've yet to put a calliper on the cassettes to see if there are actually any differences but to the naked eye they are the same.

I would appreciate your thoughts and suggestions

 

[I like Skol]

It might just be the case that your drivetrain, or the cassette on the 'new' turbo wheel, are worn and simply not meshing very well?

 

[Bristolian]

It might just be the case that your drivetrain, or the cassette on the 'new' turbo wheel, are worn and simply not meshing very well?

Many thanks for the response. Guess its time to take a closer look at the wear on the cassettes.

 

[Alex321]

It is also possible that the bearings are a little worn on the hub, which could cause the wheel to twist very slightly when under load, but not when running free.

 

[Bristolian]

It is also possible that the bearings are a little worn on the hub, which could cause the wheel to twist very slightly when under load, but not when running free.

That's an interesting thought. Looks like I'm going to be busy this weekend

 

[fossyant]

I'll add that cassettes aren't always in the same position in relation to the frame on different manufacturer's hubs. They can be a fraction of a mm different, needing a slight adjustment on the indexing. I've got round this by buying a set of spacers of varying widths, so can fine tune the fit between wheelsets - I've three bikes that I swap wheels, all have different hubs.

 

[Bristolian]

I'm planning to strip the cassettes down at the weekend and mic up the spacers to see if there's any difference.

Could I also get this problem if one (or more) of the cogs has been put on the wrong way round (i.e. with the markings facing the wheel)?

 

[Ian H]

Hs anyone found the thread on front cassettes?

 

[I like Skol]

Can't put the cogs on wrong way round, they are keyed one way. Try it.

 

[Bristolian]

Can't put the cogs on wrong way round, they are keyed one way. Try it.

D'oh! Good point. Didn't think that through before I asked the question

 

[fossyant]

HG, yes, but older IG cassettes you could reverse the sprocket to get longer life. My best bike runs IG - Dura Ace, so I have got the dremmel out to reduce the width of the HG wide tooth to get a 26 sprocket in there - IG didn't come in such a huge sprocket !