As long as you've got a modest 3.6+mm between the outer face of the small cog and the inside of the dropout, the 7-speed freewheel should be fine if you use any modern 8-speed compatible narrow chain. A few frames will challenge these clearance limits with an inward-protruding seatstay atop the dropout, but most are adequately clearanced.
For a quick check, I usually just lay a 4mm allen key against the small cog and observe the distance to the outer face of the drive-side locknut.
Many bikes from the 5-speed era left huge clearances outboard of the small cog, big enough in some cases to allow the chain to fall to the axle. What were they thinking?
David Snyder
Auburn, CA
> I'm looking for drop bars, aluminum, 26.0 clamp
> diameter, without clamp knurling, or with knurling no
> greater than 32 mm in width. I've got a Cinelli 64-40
> that I can get in the stem, but I've got a fair amount
> of knurling exposed on either side, and I'd prefer
> something rather cleaner in appearance. The eBay fare
> (the Ambrosio Champion bars for example) have a
> knurling 40 mm wide (I asked one seller). Does anyone
> have something in their inventory that they would
> consider selling that would be appropriate for a bike
> built in the late '50s to early '60s? I'll use the
> Cinelli if I have to and wait for something better to
> come around, but I'd like to get this polished off if
> I could. The bar is the nly thing left to do on the
> bike.
>
> On another note, One of my frames has a rear spacing
> that's 120 mm, but I was able to get a seven speed
> freewheel to fit in the frame. From what I've read
> this should not be feasible. The back end hasn't been
> 'adjusted' in any way and reads 120 mm quite
> accurately. What bad thing could happen with this
> apparent mismatch? I'm asking because I have a five
> speed freewheel in hand and am contemplating replacing
> the seven speed freewheel with it. I'd expect to have
> to have the rear wheel re-dished, as when I had the
> wheelset built for the Frejus the builder specifically
> asked what speed freewheel I was going to use in order
> to dish the wheel properly.
>
> Scott Baxter