7 speed chain clearance problem

[jebon]

I'm putting my 92 Kona Explosif up to speed and fitted new 7sp cassette and chain.

However the chain is extremely close and sometimes rubbing against the frame. I had to put a tiny spacer on the backside of the cassette to make it tight. Freehub is the original from the DX hub.

Any suggestions to solve this? I'm thinking either a narrower freehub that fits the cassette better or a 8 or 9 speed chain. Don't know if this will work well.

Smallest cog is 11T.

Thanks, Jess

 

[legrandefromage]

An 8spd chain is the same as a 7spd.

Have you measured the axle of the rear wheel? It could be a 130mm axle designed for a 130mm frame - yours will be 135mm and the 135mm axle is spaced to suit.

Can we have a pictre of the cassette side of the wheel out of the frame?

Somebody may have just spaced the axle wrong too, leaving to much or too little for the frame.

*For the cassette, I am sure that the spacer you use goes between the 6 and 7th cog!

Here is a 7spd HG70 for comparison

And there are only 2 sizes of Shimano freewheel (ignoring 11 and 12spd) and they are 7 and for 8spd width cassettes which go up to 10spd

To fit an 8spd freewheel you'd need to re-space the axle and re-dish the rim to suit otherwise it would be even worse!

 

[jebon]

Yes, the spacer is from another older cassette. This new one doesn't have the spacer.
I will try and measure and also post more images.
I just found it odd that I couldn't tighten the new cassette to not be loose.
Will try and fit the old one again and see if it's the same.
I've read that 8 and 9 speed only differs on the outside. Does that mean I
Can actually fit a 9 speed chain that's narrower on a 7 sp cassette?

 

[legrandefromage]

You can run a 9spd chain with a 7 or 8spd cassette

 

[jebon]

The axle is 135 so I think it's as it should be. One thing that puzzles me is that I have four 7sp freehubs and they are all the same width which makes me think that this new 7 sp cassette is not wide enough for a 7sp freehub.

Anyway, I have now cleaned and fitted the original cassette to see if there are a little K's left in it.
Otherwise I'll maybe try with a few mm of spacers on the axle and/or a 9sp chain

 

[weeman_mtb]

Re:

I might be talking rubbish here but I think that older freehub wasn't meant for an 11 tooth cog, hence you've had to use the spacer to move the cassette over to lock it up. That's why the chain touches the frame in top gear I think.

I believe you'll need a cassette with a 12 tooth small cog and get rid of the spacer.

 

[Woz]

Re: Re:

I might be talking rubbish here but I think that older freehub wasn't meant for an 11 tooth cog, hence you've had to use the spacer to move the cassette over to lock it up. That's why the chain touches the frame in top gear I think.

I believe you'll need a cassette with a 12 tooth small cog and get rid of the spacer.

That hub is for both Uniglide and IG/HG cassettes. Think your statement is true if it was Uniglide with the last
sprocket being the screw on to keep it all together - probably a 12 being the smallest.

I'm looking at a period correct 7 speed 11 - 28 cassette now, made for IG chain with thick sprockets, and
just to muddy the waters even more, the washer goes between 5 and 6 sprocket positions.

Also to note, I've had three 135mm rear spaced frames with 7 speed XT, STX or LX hubs with no issues relating to chain rub. Your hub looks OK to me. I've also put 8 speed cassettes on by just leaving the large sprocket and last spacer off.

My guess is that the newer sprockets are a tad different, is it Shimano or SRAM or Sunrace? I would solve
this without too much messing around and slap a 1mm spacer on each end of the axle.

 

[Woz]

Here's an old trick that may just work - I had a similar fiddle with a XTR hub and a SRAM road cassette for some odd reason.

Remove that 1mm washer between the freehub and cassette, have a good rummage in your parts box for an old 105 / Ultegra cassette lockring that included a thin crush washer. If not, have a go at making your own. See here: https://felixwong.com/2002/09/shimano-c ... -cassette/ You will need to check very carefully where it all bottoms out, but it's worth a try.

 

[hamster]

Re: Re:

I might be talking rubbish here but I think that older freehub wasn't meant for an 11 tooth cog, hence you've had to use the spacer to move the cassette over to lock it up. That's why the chain touches the frame in top gear I think.

I believe you'll need a cassette with a 12 tooth small cog and get rid of the spacer.

Correct. Freehub bodies that take an 11T have a step at the end which the 11T sprocket sits into. It's the same on 8/9/10 hubs too.

 

[weeman_mtb]

Re: Re:

I might be talking rubbish here but I think that older freehub wasn't meant for an 11 tooth cog, hence you've had to use the spacer to move the cassette over to lock it up. That's why the chain touches the frame in top gear I think.

I believe you'll need a cassette with a 12 tooth small cog and get rid of the spacer.

Correct. Freehub bodies that take an 11T have a step at the end which the 11T sprocket sits into. It's the same on 8/9/10 hubs too.

That's exactly the photo I wanted to put up to show my point last night but it was late, I wanted to go to bed!

If you're really careful you could grind the last bit of the splines off your freehub to make it like this.