rsleiken13

I have a 1978 Raleigh Super Grand Prix that was given to me recently. I've been refurbishing it for use as my beater bike, and I need some help.

I believe the frame was designed for the 700c wheels that I got it with. I've switched to a 27-inch wheelset (the old wheels were shot), and and they seem to fit alright. Even the brakes work fine after a slight pad adjustment. The thing is, I hate the brakes and want new ones.

What can I replace them with? The bike currently has Weinmann center-pulls, but I would prefer calipers. How do I make sure to get brakes for a 700c frame with 27-inch wheels? Or is that not something I need to be concerned about?

Also, my newsed (new to me, but used) rear wheel came with a five-speed freewheel. I swapped it for the six-speed one that came on the wheels I got with the bike. I've had to do a lot of derailleur adjusting to get the chain to work right. Is there anything else I need to do adjust to make the chain run smooth other than maybe add spacers to the hub/axle?

FBinNY 

Brakes don't care about the bike or the wheels. They only care about one thing: the reach, or the vertical distance from the mounting bolt to the rim.

Actually using 27" wheels is probably working for you a bit by shortening the reach by 4mm. This helps bring it closer to current norms and should widen the available options for you.

BTW- you'll run into another issue. Most brakes sold today have short center bolts which won't reach through your fork. It's easily surmounted by drilling the back side of the fork out to accept the allen key nuts in use today. Then only a matter of buying the right length nut.

FastJake

As FB pointed out, the only important thing is reach. Measuring reach: https://www.sheldonbrown.com/calipers.html#reach

But the more important question is: why don't you like your brakes? If it's an aesthetic issue or you just don't like the setup process for centerpulls (it can be a pain sometimes) I understand the want to get something new. But if they aren't providing adequate braking, they can probably be adjusted to do so. IMO, centerpulls are better than some of the old flimsy sidepulls that are out there, and can provide more robust braking.

Swapping out a 6s freewheel in place of a 5s is usually no big deal. As long as it's working for you, no need to adjust anything but the derailer. As far as spacing is concerned: my theory is that the outermost sprocket should be as close as possible to the right dropout without having any chain/sprocket rubbing issues on the frame. Following this method will reduce dish in your rear wheel, making it stronger.

JohnDThompson 

If possible, buy two front calipers. Drill out the back of the fork as FBinNY suggests, and use the other on the rear with a standard nut instead of the allen head -- no drilling needed!

FBinNY 

This is good advice because drilling out the rear is next to impossible. Using the front brake as the rear solves the problem nicely for the cost of a regular 6,, nut and washer.

If you have to pay much more for 2 fronts vs. a normal pair, you can usually get by with a pair, and use the rear up front. The bolt will be just long enough to clear one wall of classic steel forks, (measure the crown wall thickness from the bottom and confirm that the rear bolt is at least 6mm longer than that). You'll need a longer nut to reach, and the length will be so critical that you'll probably need to buy an overly long one and saw or file it to a custom length.