Originally Posted by
cia dog
We don't know what year the bicycle is nor did the OP mentioned he was switching to cassette, but switching from 27 to 700 and remaining with a freewheel WILL NOT cause a problem with the rear triangle, or spacing. The only time you will run into a small issue is if the OP will go from a 5 speed cluster to a 7 then all he will have to do is to redish the wheel, cold setting the dropouts usually was never required...note I said usually. My 84 Trek had 5 speed 27 inch wheels originally and I went to 700 7 speed with nothing more then readjusting the brake pads and redishing the wheel. The only time that cold setting would be required is if, as you stated, the bike is a pre 80's and has 120mm spacing or if the OP wants to go to cassette. Some of the low end bikes of the early 80's had 120mm spacing yet, simply because they were using new old stock tubing and lugs to save cost.
The OP is going to have to have a custom wheel built instead of a pre made factory unit. If he's needing a new hub Phil Wood is another good source but expensive thus I would go onto E-Bay and look for some lightly used hub or NOS like Ofmega which is Campy knockoff but a darn good one, or even a used Phil Wood that you can always send to Wood to have it rebuilt
Even if the OP has an earlier bike he can still go with a 700 but would be limited to a 5 speed maybe a 6 speed cluster and would probably have to redish the wheel. They still make new 120mm hubs, IRO makes a 120mm hub for freewheel and Formula has a hub that can be either fixed or freewheel and I'm sure there are others if you did a web search. Thus with the right hub the OP wouldn't have to do anything major...not that cold setting is major. I had a friend who had a late 60's Paramount and he wanted to save the original 27 wheels but wanted a 700 so he could get better tires, and made the switch with no problems, though he wanted to remain with a 5 speed cluster and 120mm.
Also, you can buy most 126mm spaced freewheel hubs and remove a drive side spacer (the thick ones are 5mm), and redish for 120mm. If you did that it would give you more options in finding a hub.
I ended up cold setting a 70's Peugeot just going from a wheel 5 speed freewheel to a wheel with a 6 speed freewheel. Was it absolutely necessary? No, but like I said in my post, while sometimes you can wedge the wheel in there, it make changing tires a pain and you're better off cold-setting.
Mostly I just wanted to clue the OP in (and he may have well known already) that he needs to be concerned with the hub width as well as the size of the rim. If he was expecting just to drop a new 700c wheel in there, he may have issues besides just the brake pads.