Bicycle Mechanics - noob questions re: rims

I picked up a Gitane Grand Sport De Luxe last week for a SS or fixie conversion. Outside of a slightly bent front rim, the bike is in decent shape considering its older than I am. Problem is, the bike is a size 54, which is juuuust a bit too tall for me in terms of standover height. My brother rides a newer size 56, though, which fits me fine both standing and in the saddle. It's got to be a difference in the rims/tires.
My thinking is I'd be just fine with an inch or so of space to spare. I'd like to try and make this work as best I can, since free of charge is the best deal you can get.

(1.) Can I fit a smaller rim set on this bike, if so, which size should it be, (2.) would it be possible to get a flip flop hub in that size, and (3.) will I be able to adjust the brake(s) accordingly to fit with the new rims?

The rims currently on the bike are 27x1 1/4 rigid A, and the brakes are center pull brakes.

thanks in advance

you can probably go with 700c rims, but might need to get longer reach brakes. The difference in rim diameter is only about 8mm though which equates to only 4mm difference in top tube clearance. It will allow narrower tires, but I doubt if you will get an inch between rim, and tire changes.

You could get 650c (26") wheels and put them on the bike as long as you don't plan on using any brakes. If you want a front brake, you'd probably have to change the front fork and then you'd have a time trial looking type bike. As for getting a flip flop, any hub for 700c wheels can be built into a 650 rim, the important thing is the number of holes, and the spoke length will be different of course.

You need a smaller bike. It shouldn't be too hard to find a similar bike with the correct size frame. Since it is too tall for you it's most likely also too long. Start over, it's not that hard you can do it.

Al

One problem with using a smaller-diameter rim size on a fixie is that, while it will get you more standover clearance by lowering the top tube, it will also put the bottom bracket closer to the ground and you will be more likely to bang pedals on the ground when going through a turn.

One problem with using a smaller-diameter rim size on a fixie is that, while it will get you more standover clearance by lowering the top tube, it will also put the bottom bracket closer to the ground and you will be more likely to bang pedals on the ground when going through a turn.


Even on a freewheel bike that gets to be a problem when you go from 27" to 26" wheels. I've ridden a bike set up that way a few times, and the pedal strike was a problem when pedaling through even moderate turns. Sure freewheelers like to coast through fast steep turns, but who wants to only be able to pedal while going dead straight? I liked that bike with 26" wheels, but the BB was just to low for the setup to be practical. I would never do that to a biker, and I wouldn't recommend it.

I agree that if the bike's too large for you as far as standover height, it may very well be too long in the top tube as well. And Tim makes a good point about bottom bracket height relating to fixed gear bikes. But since you say it may just be a single speed conversion instead of fixed, and since I've seen lots of old road bikes that, as long as you could stand over them without injuring yourself, they fit fine otherwise, I'll chime in on the brakes..........If you go from 27" rims to 700c, you'll need to be able to adjust the brake shoes 4mm lower to reach the rims. You should be able to tell if that's possible by looking at the brakes as they are now with the 27" wheels on the bike. The good news is that old centerpull road brakes are about as good as it gets when it comes to having lots of reach, so you'll more than likely be able to make the switch from 27" to 700c with your current brakes if that's what you decide to do. Keep in mind, though, that the main advantage with this will be wheel and tire selection, as you're only going to lower the frame by 4mm, all other things being equal-

Thanks for the input. I'll likely just find another frame at this point. I thought pedal strikes could be a problem and thought maybe someone more knowledgable would have a solution.

Anybody want an old Gitane?

Thanks for the input. I'll likely just find another frame at this point. I thought pedal strikes could be a problem and thought maybe someone more knowledgable would have a solution.

Anybody want an old Gitane?

Yeah, got pictures? I have fixie spares to trade