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Trying to convert 27" to 700C w/ Cantilever brakes...

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Trying to convert 27" to 700C w/ Cantilever brakes...

Old 06-27-09, 10:18 PM
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bigwoo
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Trying to convert 27" to 700C w/ Cantilever brakes...

I'm trying to convert my '83 Schwinn Voyageur SP w/ 27" wheels to 700C.

I could have sworn that we had several threads w/ advice on how to do this when the frame has Cantilever brakes, but nothing is showing up in the search function...

Can anyone help me?
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Old 06-27-09, 10:53 PM
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I did this on an old Peugeot I picked up. I had the 700 wheelset, and the bike needed wheels. So I made it work. Getting the brake pads to interface properly is usually a problem.

If you stay thinner than 700cx32, you should be able to fit to a frame originally designed for 27x 1 1/4. But it depends - changing wheelset size is always a trial and error thing. You have frame clearance issues, the aforementioned brake pads hitting the rim (and not the tire sidewall), and the slightly higher center of gravity (by switching to 700c) might alter the way the bike rides and corners.
Plus you are usually faced with hub spacing not being the same. 27" are usually the older (narrower) spacing than the newer 700c. So, it's a pain in the booty. Easier to stay with the wheels the bike was made for.
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Old 06-27-09, 11:13 PM
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Wouldn't going from 27" to 700c put the center of gravity lower?
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Old 06-27-09, 11:16 PM
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Originally Posted by robatsu View Post
Wouldn't going from 27" to 700c put the center of gravity lower?
I always thought 700c was bigger. At least the wheels I put on that Peugeot BARELY cleared the fork bridge. I figured that's why the tubes were labeled for "28 inch" tires. Thought it was strange, but maybe I'm screwed up. Guess I better jump over to Sheldons site and get straight!

Last edited by bikemeister; 06-27-09 at 11:23 PM. Reason: new material
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Old 06-27-09, 11:20 PM
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Thanks Bikemeister,
Good insight....The issue for me is getting the Canti brakes to hit the rim perfectly...... The Voyageur SP were/are a fantastic full-blown touring machine so there's no significant issues w/ clearance or handling.....
I'm switching from the (respectable) alloy 5spd freewheel 27's that Schwinn spec'd them with to a very fine set of vintage Mavic Module 3CD touring 700C's w/ a 6 speed so I should be OK there too....

Robatsu is correct: Switching to 700 will lower the BB/center of gravity, which is a good thing Man!

I thought I heard a few members say there was a hardware kit to make the Canti's hit the rim perfectly w/ most types of pads....?
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Old 06-28-09, 12:43 AM
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If you have Dia-Compe 981 cantilevers it is easy.

I have them on my 86 Voyageur. This model (possibly others too) featured a brilliantly conceived hidden adjustment slot for moving the arms up or down a few mm. to make them equally suitable for either size wheel. I think these cantis were available from the early 80s. See the photos here showing details of a disassembled brake to better understand what I mean: https://www.flickr.com/photos/strongl...7606108523956/
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Old 06-28-09, 03:09 AM
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Originally Posted by stronglight View Post
If you have Dia-Compe 981 cantilevers it is easy.

I have them on my 86 Voyageur. This model (possibly others too) featured a brilliantly conceived hidden adjustment slot for moving the arms up or down a few mm. to make them equally suitable for either size wheel. I think these cantis were available from the early 80s. See the photos here showing details of a disassembled brake to better understand what I mean: https://www.flickr.com/photos/strongl...7606108523956/
Nice link, most cantis don't have that much adjustment. It's nice to know there's something else out there.
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Old 06-28-09, 06:11 AM
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I've also done that conversion but had to find cantis that had enough adjustment range (essentially they have a long slot for the brake pad, just as a sidepull with lots of range would). A set of Shimano BR-MC70 cantis worked for me.

Neal
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Old 06-28-09, 03:39 PM
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I thought of a trick for post mounted cantis but HAVE NOT TRIED IT. Just so you know we're talking about an untested scheme.

The strategy is to lower the brake pads by splaying the cantilever arms further apart, which will move the pads outward and downward.

Loosen the brake cable tension, then readjust the pads closer to the rim to take up the slack.
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Old 06-28-09, 06:12 PM
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Then again, you could just go "fixie" and forget about the brakes!
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Old 06-28-09, 06:24 PM
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I agree with the Dia comp suggestion, my single speed had 27" wheels but I used them dia comp and now they fit my 700c wheels nicely
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Old 06-28-09, 08:19 PM
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Thanks for all of the great input you guys...
Great news!!
Whatever model of Dia-Compe Canti's the 1983 Schwinn Voyageur SP was built with, they work perfectly on 700C as well as 27"!! https://www.trfindley.com/flschwinn_1...983Ltwt06.html

I honestly thought that I was going to run into a difficult time, but it took less than 10 minutes to get them adjusted. They have GREAT stopping power on my 700's!!

p.s. to Bikemeister,
I suppose that you are right... If I go fixie my bike will be cooler and faster!

On the off chance that anyone cares, this is my project: https://www.bikeforums.net/showthread...light=voyageur

https://

Last edited by bigwoo; 06-28-09 at 08:34 PM.
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Old 06-28-09, 08:43 PM
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Originally Posted by nlerner View Post
I've also done that conversion but had to find cantis that had enough adjustment range (essentially they have a long slot for the brake pad, just as a sidepull with lots of range would). A set of Shimano BR-MC70 cantis worked for me.

Neal
+1 On the Shimano BR-MC70's! I have converted 2 Schwinn (1985) Passage bikes using the Shimanos. They were easier to set up and had better braking power than the Dia Compe 981's (Sorry Stronglight!). In addition, there is a good chance your Voyageur has only one hole to mount the springs to. I found the Shimanos to be the best brake for this type of conversion.

Plus w/ all of those sweet old mountain bikes you get out your way, you probably already have a set lying around!
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Old 06-29-09, 04:34 AM
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Originally Posted by fender1 View Post
+1 On the Shimano BR-MC70's! I have converted 2 Schwinn (1985) Passage bikes using the Shimanos. They were easier to set up and had better braking power than the Dia Compe 981's (Sorry Stronglight!). In addition, there is a good chance your Voyageur has only one hole to mount the springs to. I found the Shimanos to be the best brake for this type of conversion...
I don't have a set, but I'll definitely keep an eye out for them now! I'd forgotten about those. They were great looking brakes - the MC70s were the Deore XT model of the mid-1980s, if I recall correctly. Glad to hear they work so well!

The later Shimano cantis of the 1990s may have even been more powerful or "practical" than those MC70s... but I never liked the way the "Low Profile" style looked on any bike.
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Old 06-29-09, 06:23 AM
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Originally Posted by bikemeister View Post
Then again, you could just go "fixie" and forget about the brakes!
You can only forget about the rear brake. Only suicide candidates ride with no front brake in the street. Besides, it's also illegal in many countries. Track bikes are to be ridden in velodromes.
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Old 06-29-09, 07:06 AM
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ie center of gravity change: it's only 4mm change of radius from 700C to 27", the slight drop with 700C is a total of 0.6% change in height. Tough to notice.

This is also why most bikes can run both 27" and 700C, 4mm adjustment in the brake shoe height isn't much.
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Old 01-26-21, 11:49 AM
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Originally Posted by stronglight View Post
If you have Dia-Compe 981 cantilevers it is easy.

I have them on my 86 Voyageur. This model (possibly others too) featured a brilliantly conceived hidden adjustment slot for moving the arms up or down a few mm. to make them equally suitable for either size wheel. I think these cantis were available from the early 80s. See the photos here showing details of a disassembled brake to better understand what I mean: https://www.flickr.com/photos/strongl...7606108523956/
I thought I had read every post on every thread I could find on how to get these to work and somehow missed this one till now! OMG you no idea how happy I am right now. All of my 981s were set up with the arms in the top position still, which obviously is less than ideal with 700c wheels. I moved the left rear down just to see what it looks like, and I left the other side as it was. Not an easy pic to take but I think it shows the difference in the arm angle well enough. Thank you so much for your advice and pictures on Flickr!

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Old 01-26-21, 01:36 PM
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The current Dia-Compe 980 cantis look to have a nice long brake shoe slot, and the wide-profile design works well with the typical vintage narrow boss-boss spacing. I might look at those next time I need to do a 27">700c, or 700c>650b canti conversion:
DC980 | DIA-COMPE

I had good luck on this Paramount with Shimano CX70 cantis. They have a decent height adjustment range, and the included spacers help with narrower boss spacing. I don't have a good front view, but in the photo you can see the shoes are at the bottom of the slot. Don't think these are still in production, but should still be out there. Shimano also had a slightly cheaper CX50 canti as well.

I've also used the Deore XT/MC70/M700 cantis on other builds, but they didn't have enough shoe height adjustment for my Paramount conversion. The rim diameter difference may only be 4mm, but actual boss position can vary, and in this case they were too high to allow the MC70 brake shoes to hit the rim squarely/safely.

As for center of gravity issues, I agree that the difference in general should be pretty subtle. What may not be subtle, though, is the increased possibility of cornering pedal strikes, depending on the bb height/drop. Remember that how far lower the bike sits isn't only a function of the rim diameter, but also the tire width/height.

This generally shouldn't be a problem as long as you're not dealing with a 75-80mm bb drop, which would be very unlikely on a vintage touring bike designed for 27" wheels. Or using 23-25mm tires on your touring bike, which is also pretty unlikely.

Just putting this out there 'cause I'm a worry-wort.

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Old 01-26-21, 04:27 PM
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I’m fighting that battle now as well with a Miyata 610 frame. I shopped around a little for the XT MC 70 brakes but hard to find and pricey when found. I just tied with a set of Tektro 710’s (I guess a touring version of the 720) and they didn’t work, so my Heron tourer is getting an upgrade with those. I have set of Dia Compe 988’s on the way, hoping they will work out like the 980’s. I’ll post an update when they’re installed.

By the way, browsing through the Dia Compe website, they have a lot of cool stuff for tricking out a modded C+V bike - fenders, alloy compact cranks, racks, etc.
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Old 01-26-21, 04:42 PM
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About to do the same on my 86 Voyageur this week, seems like I should have an issue.
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Old 01-26-21, 04:53 PM
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Originally Posted by polymorphself View Post
About to do the same on my 86 Voyageur this week, seems like I should have an issue.
Mine's an '86. Do you have the stock Dia Compe 981s?
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Old 01-26-21, 05:01 PM
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Originally Posted by stronglight View Post
If you have Dia-Compe 981 cantilevers it is easy.

I have them on my 86 Voyageur. This model (possibly others too) featured a brilliantly conceived hidden adjustment slot for moving the arms up or down a few mm. to make them equally suitable for either size wheel. I think these cantis were available from the early 80s. See the photos here showing details of a disassembled brake to better understand what I mean: https://www.flickr.com/photos/strongl...7606108523956/
I'll back up Stronglight's suggestion on the Dia compe 981s. But also, most vertically adjustable cantis will be able to adjust to the difference in rim wall height from 27" to 700C, which is just a difference of 4mm (700c rims are 8mm smaller in diameter, so 4mm smaller radius).

I had a 1988 Voyager and I also switched from 27" to 700C. I used Shimano BR-MC70 cantis (1st gen XT) which to the best of my recollection did not have a vertical height adjustment and they still worked great. It depends in each case where the manufacturer placed the canti posts vertically relative to the rim. You'd think this would be a standard height but it varies quite a bit. If they're placed higher than usual and the canti is also at the bottom of its vertical working limit, the transition to 700C wheels may not be possible. If the cantis are lower than usual, then the transition will be easy-peasy. If they're at typical height, most cantis with a vertical adjustment will work.
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Old 01-26-21, 05:07 PM
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Originally Posted by shoota View Post
Mine's an '86. Do you have the stock Dia Compe 981s?
Yep!
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Old 01-26-21, 05:42 PM
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Originally Posted by polymorphself View Post
Yep!
Oh right on (not sure how I missed your profile pic. Maybe you meant you *shouldn't have an issue. Cause I don't think you will. The only other thing I noticed is that the old brake pads were clearly made for the wider brake track of 27" wheels, and they overlap the brake track on my new 700c wheels. No bueno for long term use. I'm about to order some new Kool Stop pads that should fit better.
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Old 01-26-21, 05:44 PM
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Originally Posted by shoota View Post
Oh right on (not sure how I missed your profile pic. Maybe you meant you *shouldn't have an issue. Cause I don't think you will. The only other thing I noticed is that the old brake pads were clearly made for the wider brake track of 27" wheels, and they overlap the barke track on my new 700c wheels. No bueno for long term use. I'm about to order some new Kool Stop pads that should fit better.
Whoops, you're right I meant shouldn't! And good call I'll order some too, which did you go for?
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