7 speed to 8 speed can it be done?

[legrandefromage]

Fit the 8sp, pop it along to your LBS... Bob’s your mothers brother

they'll just laugh at the funny old wheel

 

[Sir Neil d'Menture]

Re:

I'd thought of that. But I'm still not sure if an 8 speed will fit.

 

[Sir Neil d'Menture]

Re:

It isn't crucial. More of a vanity project. Bike has down tube shifters, but I have some 8 speed Brifters. I thought of putting those on, but don't want buy a new wheel if an 8 speed block won't fit on my existing wheel.

 

[half cog]

Re:

I have a couple of bikes running 8 speed screw on freewheels on hubs that were designed for 7 speed. You can avoid re dishing the wheel by packing out both sides of the hub to the same amount. That will keep the wheel central.You may have to buy a slightly longer axle though. As long as you have some axle in the dropouts and a stout qr you should not have any problems.Sheldon Brown did some trials using a fixed wheel hub with no axle in the dropouts at all. The idea was to try and get some chain ajustment in a frame with vertical dropouts. says it worked well as long as you use an old fashioned strong qr although its one I have not tried.The main thing is the final oln of the hub versus the rear frame spacing. It can and does work though you may have to play about a bit to get it right

 

[Sir Neil d'Menture]

Re:

Thank you. The guy who runs LBS says he has an old 8 speed block in his box of obsolete bits. Gratis, or at least a cappuccino, so I'll pick that up and have a play.

 

[half cog]

Block thickness can be critical when you are doing this so be aware that some freewheels have thick locking rings that can cause problems.Really is just a case of trial and error but as said it can be done

 

[Sir Neil d'Menture]

Re:

Yes indeed. I thought it might be a suck it and see type operation.
I suspect a bit of head scratching awaits.