Bicycle Mechanics - Interchangeability of 700c & 27" wheels/tires

I have seen some people swapping these wheels. Can someone give me a brief rundown of just how interchangeable these are. Can I put a 27" wheel on a 700c bike?

Can I do the converse if the tires fit in the frame?

27" tires/rims do not interchange with 700c tires/rims.
I have heard that you can get away with interchanging the tubes.

If you have short-reach caliper-brakes, they may not be able to engage the braking-surface on the rims of 700C wheels. So check this to make sure. Or you might need to get brakes wih longer reach.

A 27" rim is four mm taller from the axle to the rim than a 700c. Your brake pads may or may not have enough adjustment to work well. A 700c road frame designed for skinny tires may not clear the 27" rims or tires (the rims are usually an inch wide or so). You can get a 27X1" tire which is only 25mm taller than the rim and pretty skinny.

There is absolutely no interchanging of tires. You have to get a 27" tire for a 27" rim and a 700 tire for a 700 rim. Tubes are OK but you have to pay attention to the width too because it can be impossible to stuff, say, a 27X1-1/4" tube into a 700X23 tire.

The hubs of 27" and 700c wheels can come in several different widths.

If I'm correct, I believe you are trying to convert from a 27" wheel to a 700C wheel. Going to a 27" from a 700C wouldn't make much sense, and probably wouldn't have the clearance in the frame.

I did it on my bike, and it was pretty easy, but there a few things to take into account:

1) 700C wheels are a bit smaller in diameter (by 8mm, or 4mm on radius wise) therefore you will need brakes that can reach an additional 4mm down and still contact the rim correctly. You can get Tektro long reach brakes or your brakes may already have the clearance. I had old school dia compe cantilevers and they reached fine with minimal adjustment.

2) Most newer wheels will have 130mm rear spacing, if you have an older frame that isn't steel, and the dropout isn't spaced at 130mm, you will have to find a rear-wheel with the proper spacing. My frame is steel and was spaced at 122mm. Because it is steel it easily bends out a bit for the 130mm rear spacing of my new wheelset.

Other than that, I purchased a cheap front wheel of CL, to experiment with my brake reach.

http://gallery.a-symmetric.com/main.php?g2_view=core.DownloadItem&g2_itemId=233&g2_serialNumber=2

After I saw the reach was fine, and I wouldn't have to purchase new brakes, I purchased the full 700C wheelset, and adjusted the brakes correctly with toe-in, etc.

http://gallery.a-symmetric.com/main.php?g2_view=core.DownloadItem&g2_itemId=574&g2_serialNumber=2

As far as tires, no 700C and 27" aren't interchangeable, however the tubes are.

Tire selection, and drivetrain components (I went from freewheel on my 27"'s to cassette on my 700C) was well worth the upgrade.

Tubes, which stretch a bit are the same for 700c and 27-inch. You just have to make sure you have the right tire width and valve type. Most 27 inch are going to be 1-inch wide (~25mm) or greater and will have schraeder valves. The tires do not interchange.

If you want to convert an old 10-speed to have newer 700c wheels -- and it is a good choice because the tire selection is greater -- you need to check out a couple of things. First and foremost, the braking surface of the 700c rim is 4mm lower than that of the 27-inch rim. This means you need to adjust your brake pads down 4mm. If you can't do that then you need to find new brakes -- which can actually be pretty cheap if you have the standard Dia Compe side-pulls.

Going from 700c to 27-inch is probably not the best idea. You might not be able to get the tires underneath the brakes.

If you do go from 27 to 700, and I have done this on several bikes, you can buy complete wheels that are ready to go (and darned affordable if you ask me) from several online vendors. Just search the forums or ask someone in the Classic & Vintage section. Depending on what the distance between the dropouts is (usually 126mm on a bike-boom 10 or 12 speed) you might need to cold-set (spread) the frame to 130 mm for a modern wheel that isn't designed as a replacement for an old 27. I've done both and it's not rocket science. Again, search the C&V forum because a lot of guys have done it.

Tubes are OK but you have to pay attention to the width too because it can be impossible to stuff, say, a 27X1-1/4" tube into a 700X23 tire.

Difficult, perhaps, but not impossible. :innocent:

Interesting. This kinda opens a few avenues for messing around in the basement. THANKS!

Interesting. This kinda opens a few avenues for messing around in the basement. THANKS!
From your OP, it reall sounds like you want to put 27" wheels on a 700c bike. If that's correct, I believe it's a mistake as 700c rims, tires and bikes made to take them are far more common than 27" these days.

If you already have a 27" bike and want to switch to 700c, which is far more reasonable, see if you can borrow a 700c wheel/tire combination from someone and give it a trial fitting in your frame to see if the brakes adjust enough to align properly. Also, it will tell you how difficult a current hub will be to fit in your rear dropouts.

I am accumulating 27" wheels and recently discovered how annoying it is to find replacement rear aero wheels. Oh, I can find them but the price and rules for new wheels are just getting me p-o'd. I miss my 700c bike and don't want to save it just for the nice surface of the MUP. Long story - just got curious after reading something in another thread. I do prefer my 700c tires, there is no question. But I have some strong wheels - good for commuting and I just mounted some expensive Armadillos on them. Maybe if those wheels will fit I'll commute on that 700c bike again ...

Or maybe I'll just bite the bullet and get a new rear wheel ... GRR

You're not going to put the wheels from the Varsity on your modern bike, are you?

Hey, I was just wondering what if ... :-)

Anyway, you can often interchange wheels of the different sizes, as others have said. I moved from 27" to 700c on one bike, many years ago.

Note that steel rims provide poor braking in wet weather. Not that you mentioned steel, but the rims on a Varsity are steel.

re: "steel rims provide poor braking in wet weather"

Duly noted.

Actually the Varsity now has wheels from a "Continental" I picked up for the wheels alone. They are steel too.

I also picked up a minty black World Sport (women's) from around 1986 and those wheels look like they might not be steel. Not sure though, they are still on that bike. They might go on my Blue LeTour, my main commuter right now.

Yes, the black bike's rims look like aluminum. Just use a magnet as a test. Both of those Schwinns are kinda nice! I think you'll enjoy the rack on the black bike if you move it to the blue bike.

Magnet! Of course ...

Yeah that rack on my blue bike was a shame. I was excited to get a seatpost style but the darn thing swayed left and right when loaded so I had to cut drill and install those thin steel uprights. It's not pretty but it's on there pretty good for now ...

Thanks for the cross post comments and suggestions!

Most 700c tubes are stamped 27" and vice versa.