Compatability ?

[wss]

Hello, Looking to update a 80's vintage bike for my sister looking to get back into riding. I've did some searching and want to confirm if I have the facts correct.

The bike has down tube shifters presently. If I want to change out the Shimano 7400 series 6 speed freewheel for an 8 speed freewheel will I need a 9 speed STI shifter to make it work?

[ultraman6970]

This is the confusing part....

Cheers :P

[oliver1850]

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[EricEstlund]

There are still 8speed sti levers, as well as 9 speed freewheels. I'm not sure how the bike is equipped- there will likely be respacing/ redishing of the the wheel and possibly other issues. It's often less frustrating to do a larger update all at once then back and forth across compatibility issues if you are trying to piece in a new group.

[oldpotatoe]

Hello, Looking to update a 80's vintage bike for my sister looking to get back into riding. I've did some searching and want to confirm if I have the facts correct.

The bike has down tube shifters presently. If I want to change out the Shimano 7400 series 6 speed freewheel for an 8 speed freewheel will I need a 9 speed STI shifter to make it work?

First make sure you have enough axle end on the rear wheel for a 7s or 8s freewheel(I recommend 7s max, minimize axle overhang), THEN you need 8s shimano STI. 9s STI shifts 9s spacing, which is narrower than 7s OR 8s.

[oldpotatoe]

I believe what you want to do will work. I'm assuming a 7400 rear derailleur is what's on the bike. If you look at a pair of 9 speed Shimano bar cons they say right on them "compatible with RD-7700 (9sp) and RD-7400 (8 sp)". The 9 speed STIs should work the same way. The limit screw on the RD will prevent your shifter from making the last shift.

The 7700 bar cons should work too. Cheaper and probably will outlast the STIs.

I've never tried to do this, but have a pair of the 7700 bar cons. I could set it up and give it a test to make sure it actually works before you go out and buy parts.

You will have to widen the lock nut spacing to 130mm to make the 8 speed freewheel work. It might need a new axle, but you may get by just adding spacers.

And if you get to the point of selling the DT shifters, I'd be interested.


But that's for 7400 DA series 8s rear der, that WILL shift 8s spacing when mated to 9s STI or barcons. The previous DA rear der, 6 and 7s had a different dimension than the 8s. DA 6s and 7s rear der actually had the same dimension as ultegra/shimano 600 of the time.

But he can try it.

[oldpotatoe]

There are still 8speed sti levers, as well as 9 speed freewheels. I'm not sure how the bike is equipped- there will likely be respacing/ redishing of the the wheel and possibly other issues. It's often less frustrating to do a larger update all at once then back and forth across compatibility issues if you are trying to piece in a new group.

No 9s freewheels AFAIK.

[wss]

I've never tried to do this, but have a pair of the 7700 bar cons. I could set it up and give it a test to make sure it actually works before you go out and buy parts.

And if you get to the point of selling the DT shifters, I'd be interested.

Thanks but don't go through the trouble.
I'll keep you in mind.

To all, thanks for the replies.
The rear skewer has over 10mm of extra thread showing past the skewer nut.

[old_fat_and_slow]

Thanks but don't go through the trouble.
I'll keep you in mind.

To all, thanks for the replies.
The rear skewer has over 10mm of extra thread showing past the skewer nut.

@wss

skewer is not the axle. Axle is part of the hub.

http://www.parktool.com/uploads/images/blog/repair_help/hubparts.jpg

Axle protrusion (shown below), is I believe, what oldpotatoe is referring to, and is asking you to double check.





http://www.parktool.com/uploads/images/blog/repair_help/hub101.jpg


http://www.parktool.com/uploads/images/blog/repair_help/hub69.jpg

Also, you may want to go to the Park tool site for more help on this.



.

[EricEstlund]

No 9s freewheels AFAIK.

Sun Race does, though at 32t is most likely won't work with the 7400 rear drl.

My main point is that if one is already replacing shifters and a freewheel, re-spacing a hub and possibly redishing a wheel, and setting a rear triangle and drop outs it may be in that persons best interest to get parts that are all factory designed to play well together. There is quite a bit of work in there to struggle at the end.

I sometimes have folks that want to go from 7sp-9 speed set ups, but want to do it one part at a time. My advice is always to save up enough to buy the whole conversion at once t save on frustration and un-even wear across semi-compatible parts. It just makes the bike more fun.