I picked up a Trek 614 with 27" tires, replaced them with 1-1/4 Panaracers, all of a sudden my cahoonies were way too close to the top tube when I stopped! HAD to switch!

I don't believe that you can feel the difference that 4 spokes makes, internet tough guy.

don't believe it then, troll.

I have found the "ignore" function to be quite useful. I don't like getting into flame wars, and I'm not disciplined enough myself most of the time to hold back from a reply.

Why did you bury your other bike in the concrete?

Pedal strike? To put this into context, 4mm is between 1/8 and 3/16".

So, the moral of the story is check both height and width prior to converting!

Before doing a 650b conversion, I would highly recommend that you try putting on some wheels with your intended tire first to see what issues you may come up with. 27" to 700c is a smaller jump, but the recommendation would be the same.

That's what I meant to say was that a Schrader tube in a 700/27 size is hard to find a high quality one, you can find cheap poor quality heavy ones at Walmart but not the better quality constructed and lighter weight ones. Thanks for catching that.

We ran out of rebar and the cement truck guy had to get to his next delivery.

For the same spec tire & rim, the physical difference will be about 1.3%.

Well, I can usually tell the difference between a 36 spoke wheel and a 35 spoke wheel, and the difference between a 36 spoke wheel and a 34 spoke wheel is unmistakable. Therefore a 32 spoke wheel... ugh! I get seasick just thinking about it.

I can understand that.

Can you really feel the difference? I have had race wheels with just about every possible configuration over the years, from Shamals to regular 36h rims, and I can't tell a thing. Tires, for sure, but spokes not. Wasn't Sheldon just saying that because there's more weight and torque applied to the rear wheel, its better to have more spokes?

Back to the point, I have converted a couple of 27" bikes to 700c and if you use slightly bigger tires there's really no perceptible difference at all, except for a slightly more plush ride. One of my very favorite bikes is an old gaspipe Fuji 12-speed. Heavy, but immaculate build quality and a very handsome frame (horiz. TT, properly curved fork blades, etc.). Converted to 700c, found it had room for fenders, had some fender bosses brazed in, and it's just great. I think it has the 33.3333 Rivendell tires on it, which are good.

I read thru this whole thread. So I must reply.

I like 27" wheels. It's what I have mostly had, and it's what comes on the vintage 70's bikes I buy.

With that, I was surprised by a set of wheels that came on a Raleigh Grand Prix that I picked up a couple years ago. They were steel rimmed wheels with Schwinn Puff 27 x 1 1/4 tires. Old and starting to crack I thought I would just pull them off and put on new tires. But first a test ride. Wow, I really liked the Puff tires. They rolled well and absorbed road shock. I rode that bike quite a bit. Loved those tires. Wish I could find a pair for my Raleigh Comp.

I've ridden on Puff tires since waaaay back when. Good quality, but not anything special for a 27" tire.
If you like the Puff tires at the pressure you are using, just measure their width and try to find a 27" tire that will inflate to about the same size. I'm guessing those inflate to about 30mm width on a touring rim.

I think that 27" wheels are less likely to be stolen. It's very difficult to sell them.
Thieves know that.

The Sun CR-18 27" rims are excellent, inexpensive and shiny.

This is the best advice in this thread. I did this and found the brake shoes almost made it. Grinding, filing, sanding the brake caliper arms enough to drop the shoes that last 0.25mm was a lot of work.


Check BOTH wheels. The dropout to brake bridge/fork crown distance can very widely. Some 1970's bikes used completely different size Weinmanns on the front and back. It's not uncommon to find the pads in different locations in the caliper slots between front and back.

+1

The 1974 Schwinn Paramount that was in the shop recently (from RiddleofSteel) had a brake bridge that was significantly further away from the dropout than the front fork dropout to fork crown hole. Since I was already doing work to replace the fork steerer, I cut out the old bridge and put a new one in to match the fork distance. This allowed the customer to use the same brake front and rear rather than some mismatched set. Finding a set of brakes with different reaches front and rear is like buying shoes for different size left and right. It's possible, but potentially expensive.

FWIW there are lots of mismatched front and rear Weinmann brakesets on ebay, mostly pulled from old Schwinns I suppose. As long as you like Weinmann center pulls you're golden... I never quite got the logic of the long reach brake in back either. It must have made sense in the 70s. A lot of other bikes besides Schwinn did it too.

Back OT - many bikes from the transitional period of 27"-->700c could accommodate either size. It's only 4mm different after all. I went back and forth several times when I had an '83 UV Specialissima. It took nothing more than a 5 minute brake pad adjustment.

Yep, same situation here. I recently acquired a '85 Bridgestone 500 came with 27' wheels. The 600 model came with 700C wheels. I had a spare set of wheels lying around, tried them , adjusted brakes, they fit. Now I can run 700C, my tubulars, clinchers , options are endless. If I'm in the vintage mode, I put the 27" back on. KB

One reason to go longer reach in back is it makes the rear brake less effective and therefor lass likely to lock the rear wheel in a hard stop. (Campagnolo got the same effect in their early dual pivot brake sets, using an older sidepull design in back to reduce power. I don't like going to more "sponge" iin back. In my winter/rain/city bikes I run the powerful but mushy Mafac Racer in front and much stiffer but less powerful Weimann in back.)

My Peter Mooney was built with the canti bosses located 1/2 way between 27" and 700c. I have only ised 700c on the bike because when it was delivered I was iving on the west coast and 700c was easy to get. (When I ordered the frame, I was looking at perhaps living and working in back county Maine, 1979. I was thinking 27" might be the only choice.)

Ben

I swapped out 27" wheels for 700c wheels recently on an early '80s Raleigh Grand Prix. My son has been riding the bike for the last couple years. The original wheelset (27") was stolen so I replaced them with a nice set of 27" Shimano 600 wheels I got for cheap. I am going to sell the bike soon and I wanted to keep the Shimano 600 wheelset for a future build to match a 600 groupset that I have from that era. I got rid of some 700c wheels so I could keep some 27" wheels. All I had to do was a little brake pad adjustment.

It was standard on lots of old Raleighs, particularly the SuperCourse, to have a Weinmann 610 front and a Weinmann 750 rear (or vice versa). So not a mismatch per se, but just wacky design.

I think we can safely assume you know exactly what you mean, but um well, this could be misinterpreted by someone who doesn't.

It really depends on what you (the generic you) mean by longer reach. The operative measurement is the distance from the caliper arm pivots to where the pad hits the rim. If you keep the same wheel and replace the brakes with a "long reach" version that has the same yoke so that the pivots are in the same place, then you get a longer arm that can hold the pad lower but the actual position of the pads must still be the same as before in order to hit the rim properly. All you get is a centimeter of unused arm hanging below the pad.

In order to lengthen the distance from pivots to rim you must either switch to a smaller diameter rim (27" to 700c) with longer reach brakes if necessary, or switch to a caliper with different geometry.

Of course all this may be obvious so just forget I mentioned it.

Personally, I'd rather have more braking power instead of less, even for the rear wheel. But that's just me.

Be aware that if you're cycling in mainland Europe and need to replace a 27" tire you'll be stuck where you are until the postman arrives as 27" tires are not stock items. Carrying a spare tire just in case is a pain & the time you choose not to do so is when you'll lunch your tire & wish you'd brought it.