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How to convert 27" wheels to 700c?(16 posts)

How to convert 27" wheels to 700c?galeek
May 13, 2002 3:12 PM
I am working on restoring a old road bike and wondering if can I simply replace 27" rims with 700c rims. Can I still use those spokes?
Don't Go There.grzy
May 13, 2002 3:58 PM
On paper: maybe.

In reality: no.

You're opening a huge can of worms. Install 700C rims and now you have issues with brake reach, to say nothing of the small, but noticable influence on overall bike geometry and handling. Even if you aren't worried about this a 27" wheel from an old road bike will most certainly have a bunch of frozen nipples - if not all of them. Then face the reality that the spokes really are too long. If you don't run out of threading the ends will poke through the rim strip and give you the "auto-flat" feature. I could go on and on, but the tried and true advice is to keep old bikes as old bikes. You don't even want to think about the drivetrain issues. The only way things can get MORE fun is if said old bike happens to be French. Then you're in for a real treat - you have to go either high-end or junk for parts. Got 2 old Motobecanes that provide hours and hours of pure titilating frustration. Maybe that's why they don't get ridden. Or it could be that the ti steads are just too nice to ignore. You wanna go out with Cinderella or her sisters?
brake reachSteveO
May 14, 2002 3:14 AM
depends on the rims and brakes. ive replaced 27 with 700 with no brake-reach issues whatsoever.

What drivetrain issues? The drivetrain knows nothing about wheel diameter (unless youre refering to dropout spread; but thats not really a function of wheelsize)

Do agree though, you probably dont wanna go messin with the same spokes.
brake reachgrzy
May 14, 2002 9:17 AM
Well, for every time you've had no problem you can bet others have had a problem. In fact there used to be a special brake bolt for dealing with this. Can you assure him that he will not have any problems what so ever? No. Should he be advised that it can be an issue? Sure.

The drive train thing is more of an expansion. If he realizes that he can get built up 700C wheels for less than he can convert his he's going to run into the hub issue. There are two aspects to the hub issue: one is the obvious width problem and needing to spread the rear dropouts; and the second part is what do you use for a cog set? Suddenly his Mallard (or what ever) 6 speed *freewheel* isn't going to work. Even the 7 speed stuff doesn't work very well. Now he's looking at running an 8 or 9 speed cogset and the skinny chain it requires. Then there is the problem of the skinny chain not shifting well on the old crank with the wide spacing between the chainrings. So now a new crankset looms, but there's the BB to consider. And least we forget, a way to shift the 8 or 9 gears. It goes on.

I guess in the best case scenario he could simply reuse the spokes and nipples and run a 700C rim with absolutely no problems. But expereince has shown that it never works that way. Maybe he's a lucky person? The upgrade thing on an old bike is a modern day Pandora's Box.
brake reachSteveO
May 14, 2002 9:49 AM
"Can you assure him that he will not have any problems what so ever? No. Should he be advised that it can be an issue? Sure."

i completly agree. i thought he should be ADVISED that it could work, not TOLD not to go there.

thats all.
re: How to convert 27" wheels to 700c?Akirasho
May 13, 2002 3:59 PM
... depending on the hub flange... you could rebuild the older hubs on 700C rims but I doubt that the spoke length would be correct.

http://www.sheldonbrown.com/tire_sizing.html
http://www.sheldonbrown.com/home-drop.html

You can use an online spoke calculator to confirm this. You'd probably be best served remaining with 27" unless you're handy... There are still sources for 27" rims (depending on the type you need).

We abide.

Remain In Light.
re: How to convert 27" wheels to 700c?curlybike
May 13, 2002 4:36 PM
What make and model hubs are on the bike? You will have to lower the brake blocks on the arms a full 4-5 MM in order to have the blocks hit a 700c rim. Most old 27" wheels are best trashed and start over. There is no chance of using the spokes for 700c, if you keep the same hubs. They are probably ruined anyway. The cost of the spokes is minor in the big picture.
A few reasons to not try this...Lone Gunman
May 13, 2002 6:38 PM
in addition to what everyone else has already said. Go with 27s if that is what the frame is built for. Otherwise, they look silly and brake reach is a problem. Sun CR18s are a decent rim in a 27" if you can find them through a Sun Dealer. Check the site to find one and call, I was quoted a price of $35 each for 32 hole rims, very rare. If your hubs are 36 hole, you have more options. I ended up buying a set of Wolber rims from Scotland (not here yet).
again...SteveO
May 14, 2002 3:16 AM
brake reach 'could' be a problem.

lots of people have successfully converted by doing nothing more than buying new wheels. Dont know about looking 'silly' though...the ~.6 inch difference is imperceptable to my untrained eye.
Can only speak from my own experience...Lone Gunman
May 14, 2002 4:42 AM
It was very obvious on my '78 frame. You also need to take into account that the tires are larger as well so .6 inch diff in a rim and a tire that is a range of 28 to 35mm size tire, and with the brake blocks extended out to the max....Well you see it and it is obvious they don't belong.
Not again...grzy
May 14, 2002 9:20 AM
Lots more people have had problems doing this than haven't.

Can you assure him that he won't have any problem givne that you know nothing about the brakes or frame that he's using?
Not again...SteveO
May 14, 2002 9:55 AM
"lots more people have had problems doing this than havent"

Is that a quantifiable fact?

"Can you assure him that he won't have any problem givne that you know nothing about the brakes or frame that he's using?"

Im wasnt intending to assure anyone anything, I just like ALL perspectives to be known; not limited perspectives (like the perspective of someone who only tried this with only shortreach brakes).

But as long as your asking, I CAN assure him he wont have problems if he simply pulls out a spanner, ruler and simple math. That solution is a lot more precise than 'DONT GO THERE'
Suregrzy
May 14, 2002 2:16 PM
Never debate a fact and the facts can be determined. Maybe this is what we should've both advised from the beginning.

If you were a betting man which way would you go given an even bet?
What are you trying to accomplish?Spoke Wrench
May 14, 2002 5:07 AM
If you're trying to put together a cheap bike to ride, there are cheaper ways to do it. For less than the cost of laceing up a pair of wheels, you can usually buy a complete, low end, bike shop quality, road bike at a garage sale.

If you just enjoy the challenge of force fitting parts together and making them work, have at it. Even if it doesn't work, you'll at least learn in the process. A year from now, you could be answering other people's questions.
But sometimes they slip right on...retro
May 14, 2002 7:47 AM
All the above is more or less true, I imagine (I don't quite buy the argument that the small change from 27 to 700 will affect the geometry noticeably), but sometimes you can just swap over. When good 27-inch wheels and tires got hard to find, I put 700s on my cantilever-brake Trek with just a brake adjustment.
Same here...timfire
May 14, 2002 1:17 PM
Me and a friend just upgraded his old schwinn. We got a set of 7-speed 700 wheels to replace his 5-speed 27in wheels. We did have to spread the frame (but only slightly- we were able to spead it with our fingers) and we did have to lower the brake pads as far as they would go, but it worked without a problem.

With the 700's it's nice to have more tire options.

My advice is take the bike into a shop where you can have them test-install a set of wheels to see if it will work (That's what me and my friend did).

--Timothy Kleinert