Cassette spacer - advice sought

[G3CWI]

I would suggest you measure your chainline

I will do this when I get home. Thanks for your interest.

 

[G3CWI]

which says



I would suggest you measure your chainline. If it is a double it is the distance between the centre of the frame and the middle of the two chainrings. If it is a triple to the middle ring is good enough. Then come back with the measurement. It should not be far from 45mm given it is a road bike. Also please provide the make and model code of the front mech (if it is a Shimano the code is something like FDxxxx)

41mm. There is no part no. on the front mech that I can see. It is labelled Sora Triple.

Also, although I cant photograph it, there is a dent in the frame where the mech hits it. I think this was done as an after-thought by the manufacturer when they realised there was a geometry problem?

 

[User16625]

The solution that you think is the solution to the problem is not the solution.

Never mind that, hes happy enough.

 

[mickle]

Yeahbut. He's wrong.

 

[TheDoctor]

That^^
The solution to a dodgy front chainset / mech setup is not to take the cassette to bits.
You're just masking the problem. Not solving it.

 

[RecordAceFromNew]

41mm. There is no part no. on the front mech that I can see. It is labelled Sora Triple.

Also, although I cant photograph it, there is a dent in the frame where the mech hits it. I think this was done as an after-thought by the manufacturer when they realised there was a geometry problem?

There lies the problem. No road triple should have a chainline that is 41mm. It should be 45mm for a sora triple.

Can you provide the make and model number of the chainset?

 

[G3CWI]

Ounce Pro-wheel 50/39/30.

 

[RecordAceFromNew]

Ounce Pro-wheel 50/39/30.

Unfortunately it is a minor make, the website seems half dead at the moment (or perhaps it is always like this), so am having little luck getting some indication re specification.

If you have a Sora front mech it will definitely have a model number, it is small and probably pressed on the frame side of the inner cage, you might need a torch and good eyes to see it. It is probably something like FD-3403, if so this is the spec, and as can be expected says 45mm chainline re design parameter. I am willing to bet money that you will not find a current Sora triple front mech that says anything less than 45mm chainline...

Did you buy the bike new from Decathlon, or secondhand? If secondhand chance is someone replaced the bottom bracket and replaced it with one that is too short. If new when and did it always have the same problem?

 

[mickle]

He's bloody good mind. ^

 

[G3CWI]

Hi. It was new. I will grovel about and look for the part number. Cheers.

 

[RecordAceFromNew]

He's bloody good mind. ^

No better than you mate.

 

[G3CWI]

No sign of a number. It's reasonably clean and I have looked at all the visible parts. However if you are certain that it should be 45mm, how would I fix it?

 

[RecordAceFromNew]

Hi. It was new. I will grovel about and look for the part number. Cheers.

Good. Once you have the model code we will be able to get proof in black and white that Decathlon has supplied you with incompatible (and contrary to industry standards) parts on your bike, which clearly is causing your chain rubbing problem.

If the damage to the frame is minor and superficial then all that is needed is for them (unless you insist on diy) to identify the existing bottom bracket dimension and replace it with one that is long enough on the drive side to deliver a 45mm chainline while not overly screwing up q factor symmetry (i.e. so that pedals are approximately equal distance from the centre of the frame). If the damage to the frame is not minor/superficial, and as you mentioned above done as an afterthought intentionally as a kludge (and a failed kludge), then it begs the question whether it was done with management authority, whether it was done en-masse, and whether it compromises the integrity of the frame.

 

[RecordAceFromNew]

No sign of a number. It's reasonably clean and I have looked at all the visible parts.

This might give you a clue as to where to look.

 

[G3CWI]

it begs the question whether it was done with management authority, whether it was done en-masse, and whether it compromises the integrity of the frame.

This was how these bikes were made. I think that later ones had a different frame. The "dent" has been stamped in as part of the frame manufacture process before painting. The bike is over a year old and has lots of non-original features now so I will not be taking it back. I am more interested in ways in which I can alleviate the problem. Clearly my cassette "spacer" has not gone down well in some quarters (albeit that was a suggestion from here!). It does seem to have provided a fix of sorts albeit at the loss of one set of gear ratios but I am open to other solutions.