Wheel Size Difference...
 

What is the size difference between a 27" and a 700c wheel? I've been working up a classic (probably... 1976 or so) Nishiki International to replace my too-small-for-me Bianchi frame on my fixed-gear bike, but I think the Nishiki was designed for 27" wheels and my fixed-gear wheels are 700c. Are there problems running 700c wheels on a frame designed for 27" wheels? Or are they sized closely enough to be problem-free?

Thanks!

You just need a long reach front brake if you run one...700's are a touch smaller...

That's the gist I'm getting. Off the top of your head, do you know how much smaller? One inch? More? Less? I'm starting to wonder if I'm going to need to look at shorter cranks, too; if the 700c's are smaller, the bottom bracket will be closer to the ground, and running fixed I need to worry about clearance for cornering. The frame is a 60 or 61 and I already run 170s.

Thanks again.

8mm diameter (622 for the 700c vs 630 for the 27"), so definitely no problem with the frame. Some brakes can't quite make the extra reach, but most can. If your pads have 4mm to move down from where they are, you're good to go.

The only big issue is the bottom bracket/crank clearance. You're dropping it more than 4mm since 27x1 1/4" tires are bigger than 700cx23 or 25 or whatever. Usually it's no problem, but if your cranks are longer than 170 or you have wide pedals, it's worth getting a good idea of how far you can lean over the bike before you go ripping through any tight corners at 20mph

edit: sounds like you're aware of all that.

Excellent! Thanks for the responses; once again, BikeForums.net to the rescue! :D

You can extend the slot on the brake arm with a small round file till it is paper thin at the end, because the arm below the pad bears no stress.

I just had my (1980?) Nishiki Olympic converted from 27" wheels (6 speed) to 700c wheels (with 8 speed). The bike shop had to file out the brake arms to move the brake pads down a bit, ground out the dropouts a bit to accomodate the new rear wheel, and I think they had to grind out the front forks a smidgeon too. I think the rear dropout grinding may not be necessary for you if you're going fixed gear as it was mostly to accomodate the wider spacing from the extra gears. I guess i you have a wider hub you might need more work - I have no idea what the width of the original 27" hubs were...

The new wheels work very well - or at least, they were till I got hit by a car a couple of days ago :(

You can cicumvent the BB height being lowered 4 mm somewhat by getting shorter cranks. 165 or 160mm should be good to go. Since you're going fixed gear and only need a front break, grab a tektro dual pivot in long reach. They're not expensive at all.

I'm still a little iffy on this filing the brake arm thing. <- Unprovable opinion

You can file a couple of mm, but you have to leave some, or else I'd think that unless you have military-grade washers on your pads the arms would eventually splay out from the pressure.

Try running fatter tires - usually a fatter tire is also taller. This will help keep the bottom bracket from getting too low and it also makes for a cushier ride. I recommend the Panaracer T-serv in a 700x32.