Changing the rear wheel question?

[junkie_ball]

Ok so this may seem like a simple and stupid question but i'm gonna ask it anyway. I have a spare rear wheel i use for my turbo trainer. The wheel is the size and i have the same rear cassette mounted to this wheel as i do on my road wheel. Although when i change the wheels out i seem to have to re-index the rear wheels. Just wondering if this is normal? My logic tells me I'm using all the same equipment and gear ratios so i shouldn't have to do this.

 

[PaulSecteur]

I have found that if I change like for like wheel, mavic to another mavic, or shimano to another shimano then all is ok.

However, If changing from mavic to shimano or vice versa then some tweeks will be needed.

Though I would have thought that all manufactures would be working to the same dimensions for hub and axle diameters so interchanging would not need a re-index.

 

[Smurfy]

Modern cassettes have the sprockets very close together, so it doesn't take much to upset indexing. Although the width of the hub may be exactly the same, if the cassette is a slightly different distance from the dropout, you may get a little chain noise and need to adjust.

 

[Ajax Bay]

Is one wheel (either wheel) one with cones and bearings, and the other press-in bearings? The distance from the locknut (outside surface, which abuts the drop-out) to the centre line of the smallest sprocket must be the same for both wheels, otherwise you will experience minor problems (as @Smurfy has suggested). Any difference in this distance should be small enough to compensate for by rotating the outer casing adjustment barrel (where the cable enters the RD). You may need to adjust one or both of the limit screws (or stay off the large and small sprockets on the turbo).

 

[junkie_ball]

Not sure what bearings are in each wheel as managed to buy the spare wheel with the correct setup and correct cassette. Like people have said using the barrel adjustment on the RD does the trick about 3 quarters of a turn but was wondering if this was normal sounds like it is though.

 

[Tojo]

I have Campag, Vision and Shimano wheels running 6800 ultegra cassettes and swap them over without having indexing problems, are you sure you have the right spacers fitted on the free-hub behind the cassette...... what cassette size are you running 9, 10.....?

 

[junkie_ball]

I'm running a 9 speed shimano cassette which is the same ratio as the one my road tyre. Thinking about it more i think it maybe a spacer issue as my road tyre has a disc brake where as the wheel i use for the turbo doesn't as I'm not worried about having a rear brake indoors. Just never thought about it before, I've just upgraded to a smart trainer from a mag, when i used the mag trainer never noticed this issue (although that trainer was very noisy) i did change out the skewer but can't believe that made much difference.

 

[Ajax Bay]

The distance that must be the same is the distance from the inside of the drop out to the plane of the smallest sprocket. If that's the same the indexing should work. Skewer doesn't matter. Ratios shouldn't matter either: I have a much closer block on the wheel I use in my (retro) bike on the turbo - not having to climb Devon 1 in 5s. Cassette must be same speed (which you've said it is).

 

[Karlt]

On my wet weather commuter I have a 126mm rear sprung to 130mm to take 8sp (must cold set it some day) and with the cheap wheels from Decathlon the chain fouls the dropout on the smallest cog unless I put a 1mm washer on the drive side between locknut and dropout; with Shimano wheel no such subterfuge is required, so yes, the exact position of the sprockets can vary by a bit. In this case the first wheelnis true 8sp and the Shimano is 9/10/11 with a spacer

 

[cyberknight]

I have changed wheelsets from shimano to some superstar wheels with no issues yet on the commuter i changed to a new pair of the same wheels , r501s and had to re index .
Go figure

 

[Ajax Bay]

i changed to a new pair of the same wheels , r501s

I figure you 'changed to a new pair of the same model of wheel'. Go measure.

 

[cyberknight]

I figure you 'changed to a new pair of the same model of wheel'. Go measure.

yup r 501 for r 501

 

[junkie_ball]

Well i measured the distance from my drop out to the smallest gear on both road wheel and trainer, they are within half a mm or so. So i guess some indexing would be needed as not quite the same. I can't seem to index the trainer wheel properly though. I have to adjust the barrel about 3 quarters of a turn to make the gears move up and down properly but then it seems to be indexed to far as starts clicking (when riding no when just turning pedals by hand) like its trying the change up but if i adjust any less than three quarters of a turn the gears won't change up and down possibly. Anyone think the half or so mm could make that much different that the limit screws would need changing (can't believe they would as i understand they are for only stopping the derailer moving too far in or out and that adjustment seems fine)? Something i want to avoid as its only a training wheel and can't be dealing with having to reset the limits screw every time i change it.