New hub/wheel cassette chainline position

[peter wyeth]

Have just fitted a new a Boost (brand) electric motor hub rear wheel with 7 speed cassette to my partner's '90s Specialized but the position of the cassette put the highest gear too close to the dropouts so the chain would foul against it. Axle widths all seem the same to the old wheel but the outer edge of the hub looks meatier than the original.

I've 'solved' the problem by placing a 1mm-ish washer between the axle and dropout and it's all working fine with only a little derailleur adjustment. Brakes sit fine and needed no adjustment.

My question is, is this OK? Or should I be looking for a different spacer between cassette and hub instead? Will this negatively effect chain line (seems to be running OK)?

Thanks in advance,
Pete

[gregoryoftours]

1mm difference is negligible and is absolutely fine. Putting a spacer between the cassette and hub instead would do nothing for the original problem because it wouldn't change the clearance between the smallest sprocket and the dropout.

[531colin]

Have just fitted a new a Boost (brand) electric motor hub rear wheel with 7 speed cassette to my partner's '90s Specialized but the position of the cassette put the highest gear too close to the dropouts so the chain would foul against it. Axle widths all seem the same to the old wheel but the outer edge of the hub looks meatier than the original.

I've 'solved' the problem by placing a 1mm-ish washer between the axle and dropout and it's all working fine with only a little derailleur adjustment. Brakes sit fine and needed no adjustment.

My question is, is this OK? Or should I be looking for a different spacer between cassette and hub instead? Will this negatively effect chain line (seems to be running OK)?

Thanks in advance,
Pete

Is there a spacer currently behind the cassette?
If there is, it might be worth carefully trying it without the spacer.....the downside is this might move the cassette/chain/R. mech. too close to the spokes....be careful!
Other than that, I think you will be fine with an extra washer on the axle....I don't know if you can put this extra washer under a locknut (for example) on this particular hub just to be tidy.

[peter wyeth]

Thank you!
There is the regular spacer you'd find on a 7 speed. There's enough meat to move it a towards the hub with little risk of spoke contact. Was thinking of using the spacers you get with single speed kits but to be honest, I don't want to go removing the cassette to be fine tuning it.

If the washer trick is fine, I'll stick with that but agree that putting it under a locknut is would be the far tidier option

[Norman H]

Ideally you you should also loose 1mm from the non drive side if that's possible. Adding or subtracting spacers from beneath the locknuts would be best practice.

[531colin]

Is your electric hub designed to take 8,9,10 speed cassettes, with a spacer to fit 7 speed?
i don't think it would need a spacer if designed for 7 speed.

[peter wyeth]

Is your electric hub designed to take 8,9,10 speed cassettes, with a spacer to fit 7 speed?
i don't think it would need a spacer if designed for 7 speed.

It's designed for 7-10 spd, I believe. They do 7 to 11 but I'm guessing a different hub body for the 11spd? There is a visible black spacer on the new wheel of similar size to the one on the wheel it replaced.

[TheBomber]

7 speed cassettes always used to be bolted together- with the bolt heads protruding where your cassette spacer is sat. If yours is bolted together, and the spacer doesn’t have any notches cut in it for the bolt heads, then the spacer will effectively be too thick and cause the problem you describe. If so you could cut/file the notches or remove the cassette bolts as they’re not essential.

[531colin]

That’s a good spot…a spacer to fit 7 speed cassette on an 8,9,10 speed hub needs cutouts to clear cassette bolts.
Is it the case now that 8,9,10 speed hubs are routinely used for 7 speed with a spacer, rather than a bespoke 7 speed hub?