So, it's probably a dumb question...but would 700 wheels fit on a frame made for 27" wheels?

Thanks!

*crawls back to Foo and commuting*

Since 700c wheels are a little smaller the only thing that's a potential problem is your brakes. If you can move the pads down about 4mm you should be fine.

Thanks!

You may need to get new brakes with a longer reach.

You'll prolly find that your brake pads just hit your tyres by a couple of mm even when they're moved all the way down... in order to avoid fitting longer brakes, you can just grind/file a chamfer along the top of your pads. Concrete or asphalt is usually pretty good for this.

You may find your front brake takes more of a squeeze than you'd like, thanks to the reduced leverage... you'll have to fit a bigger brake (not just with longer pad mounts) or a 700C fork to fix this.

A post like this needs the WCTDAS sign!

(well covered topic, do a search)

The wheels will fit but the brake pads may or may not adjust down the needed 4 mm to align with the slightly smaller rims. I've done this conversion successfully on two bikes so it can work.

Borrow a set of 700c wheels and try them on your bike before buying anything.

They always do. They were designed when people trained on clinchers and raced on tubulars and a 27" tubular is the same as a 700 tubular.

My Trek had 27's originally and was able to go to a 700 with nothing more then moving the brake pads.

I should add that there's one other caveat. Sorry if this is obvious. It isn't really a problem with 700c wheels per se, the issue is with rear triangle spacing, - the space between the dropouts in the rear.

As more gears have been added in the back, the spacing has gotten wider to accommodate them. Today 130mm is common for road bikes. Back in the 80's it was 126 and before that it was 120. If I'm wrong about the particulars I'm sure someone will correct me.

Anyway when replacing the 27" rear wheel, it's very likely that a brand new 700c rear wheel won't fit between the dropouts. Steel bikes can be "cold set" to allow the wider wheels to fit. Sometimes you can just jamb them in there but it makes fixing flats an extra pain. Modern wheels use cassettes too and 27" wheels typically used freewheels.

Getting an older set of 700c wheels, which is maybe what you were intending, may allow you to get around this problem as long as they were designed for the same number of gears as your current wheels.

They don't always fit. I've seen cases where the brake pads wouldn't lower enough to align properly so it's not a universal conclusion. Sometimes filing the adjusting slots a bit longer worked and sometimes it wasn't enough either.

Cheaper old bikes with 27" wheels weren't expected to use both size wheels and the brake mounting holes weren't positioned with 700c rims in mind.

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.

+1

put 700/8 spd wheels on my 76 le tour, reset spacing, and had to put on
longer reach brakes, if you buy brakes, you'll probably need the nutted
version.

Just drill out the back of the forks and brake bridge to take the allen head fitting.

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.

+2. Anyone who says otherwise simply hasn't done enough of these conversions to know any better.