I've got an old Miyata 215 touring bike I want to use as a gravel bike. It has canti brakes and 27" wheels. Can it be converted to 700c wheels without much effort? There's a much greater tire selection with 700c. Thanks,Bill

The brake pads need to move (on paper) 4mm closer to the axle.
Due to rim contour etc., you might have to squeeze it a bit more????

On one bike I had, I could do it on the rear, but not the front, without modification, so ymmv.

This ends up being more difficult than you might imagine. The switch from 27 inch to 700c is pretty easy with calipers but you may not be able to move the brake pads 4 mm with a lot of cantilevers. An additional problem is that the brake pads on a vintage bike tend to be closer together than on a modern bike which means that some modern cantilevers won't work right on the bike.

That said, this is doable but you may have to try different cantilevers before you find one that works. I did this once on a 1983 Trek 720 which was designed around 27 inch wheels. I ended up using modolo cantilevers which worked with 700c wheels. Those are tough to find. I've read that others have had good luck making this conversion with the Deore cantilevers.

Here is a useful thread on the topic,

canti brakes for 27" to 700c conversion?

That will work if the wallet can stand the pain.Might mean having to swap levers as well.

You get what you pay for. It is not an asian part. It has the correct brake pads on it from the start. There is very little or no play in it. They are easy to adjust. I transferred a 15 year old set of them to my sons new touring bicycle. The older models did not have the cable adjuster on the noodle so i ordered the newer noodles and yes they were also
expensive.

yea, But It is adjustable downward [ NB: 622 D is 311r 630 D is 315 r] so difference 4mm (as r=1/2D..)

if you can move the pads down 4~5mm you can use a cheaper brake ...

Having just done this, it is more difficult than you might expect as bikemig raised some great points that I personally had to deal with.

This was on another Japanese touring bike, a 27" Shogun 1500. No modern canti or v brake I tried would work. The pads would sit way too high, and the width of the posts were far too narrow, especially for a modern rim at a modest 17-18mm inner width. I imagine the Paul's suggested might work as they have a good amount of vertical adjustment, but the pads will probably still be spaced too much inward.

I ended up going with 80's era Dia Compe 987's that I found on ebay. There are quite a few other models of similar design that offer an added amount of vertical adjustment.

With new pads and compressionless housing stopping power is very good.

Since 27s were only offered in a narrow range of sizes, bike frames designed in the 27 era often only have clearance for those tires.

Just my opinion: If the old bike doesn't have clearance for tires wider than ~1 3/8, stick with 27s. They're still commonly available, including some high-quality offerings out of Japan and Germany.

I have 700c on my Centurion ProTour15 and using the original cantis (well the ones that came when I bought it).
Works great.

Hmmm... I would call that borderline. As the brake pads wear, they might develop a ridge at the top of the rim unless you're very careful with brake pad adjustment. As the pad wears it will dig into the tire, eventually causing a blowout.
(I had that happen once simply due to poor brake pad adjustment. Annoying.)

I used to see it often with U brakes on under the BB chainstay locations.. just unchecked, for too long..

Pad wear , un adjusted for , has the friction patch usually moving towards the pivot axis ..

pivot above, it wears into the tire..

I don't have a definitive answer just a similar problem.

The brakes on my 1988 Schwinn Voyageur don't work as well as I would hope after I changed the wheel size down to 700c. I believe these brakes to be the original brakes. They were on the bike when I got it. It was in really bad shape and reusing the 27" wheels were not an option. The main issue I have is with the front wheel. The brake pads are at the wrong angle. I've thought about grinding them down at the correct angle to let more of the pad engage the braking surface. Obviously this will GREATLY reduce the life of the pad. I haven't done it yet since I have a build in mind and I'm a few steps away from completing that build. Also the way the brakes are set up currently they work well enough to stop under regular riding circumstances. But braking while fully loaded with panniers and/or in the wet, probably not so much. The rear brake pads are aligned correctly but I can't get an inflated tire between the pads without really helping it in there. The profile of the current canti brakes on both front and rear are very outboard with doesn't allow me to use the current racks and panniers I have. A thinner profile, which the above picture shows, would hopefully allow me to not have to buy another set of racks.

I've read that v-brakes will quickly solve the spacing issue. The problem I have, is v-brakes are ugly. Appearances are important to me.

On a different thread dealing with the same conversion compatibility issues, I also read a new product could work because of its design. They're the Shimano BR-CX50 canti brakes. Not too expensive if they do solve the conversion issue. I plan to buy some of these at least for fork. If I do it before you I'll post results.

It seems as if there could be a little adaptability if need be. I've seen some concave and convex washers that happen to be different widths. I would imagine fiddling around with different widths could result in different pad placement. It also looks like the 'washer/round spacer' between the pad and the rest of the brake could be filed down to a thinner width. I would try it. I've taken some liberties with some of my bikes to end up with a desired result that I wouldn't recommend to others.

I have thought about lacing some wheels together with 27" rims. That would solve all my issues. As I said earlier the original wheelset was trash when I got it. I would have been seriously polishing a turd had I spent any time to repair. The main issue I have with this solution is tire options. There aren't as many tires for a 27" wheel. Plus I would have to lace them together which is not something I'm too familiar with. I know the gist of how to do it but applying the knowledge is something different. So then that gets into paying a good amount of money to lace together a wheel set.

I've also thought about having the canti posts moved/replaced by a frame builder. This could be a good solution to a frame like mine, since the paint is not in good shape. Which could lead into getting it painted or powder coated in a color I like more. But a frame that is pristine, or where no replacement decals are available, possibly not.

I know a professional bike mechanic who has a late '80s Trek 520 with cantis who's tried many different options to set up with 700c wheels and failed at all of them. I don't believe he has tried the Shimano brakes I posted a pic of. He got defeated and put the 27" wheels back on. If I remember correctly, he's just going to lace together a new wheelset sometime in the future.

Hope some of that helps

V-brakes require a different amount of cable pull than cantilevers.

This is a can of worms, you really don't want to open. I've got an early 80's Univega Gran Tourismo. It came with 27" wheels and DiaCompe canti's. It crossed the US E-W fully loaded, successfully and without incident. Couple of years later, I bought a 'racing' bike and it was relegated to the ceiling of the workshop. Years passed and I needed a commuter, so down it came. The 27" wheels were long gone, so I 'upgraded' to a set of 700c's. From then on I fought continually with the canti's. City bus noisy, poor performance. I tried a new set of canti's and they were even worse. Put the original DiaCompe's back on and they sort of worked. Toed to the extreme, they were at least quiet but they were not very confidence inspiring when it came to stopping. After a long correspondence with Paul of Paul's Components, we both came to the conclusion that with the particular frame geometry anything 'modern' was not going to work. Sadly back to the ceiling it went. I then retired and spent more time in the workshop, it cried on me daily. Finally I decided to restore it. Powder coated the frame, polished all the clamp on bits and bobs and built a set of 27" wheels. I had a set of Shimano 200GS (BR-M201) canti's in the take off box. (The Dia Compe's looked like sh*t.) On they went. Result was braking Nirvana. Quiet and responsive. I can even lock the wheels! My old buddy's back on the road and working and looking better than it has for a long long time.

Moral of this story. There are cases where you really can't teach an old dog new tricks. 27" wheels are 'not cool' and tire selection is severely limited but sometimes they are the best product for the job.

Borrow a pair of 700c wheels and see if the pads can be adjusted. Maybe you'll get lucky.
Doesn't cost anything to stick in a wheel and have a look.

If none of the above works (I think an excellent chance some of above could work) take frame to a frame builder and move the mounts down. Not that big a job. Touchup paint will be much smaller than you think.

It's not just "down". Cantilever posts on older touring bikes were also closer together laterally. This leads to compatibility issues with newer cantilever and V-brakes because the brake pads are moving in a different arc than older brakes. This can be worked around by a knowledgeable mechanic but can be very frustrating for those who assume that the switch is straightforward.

That would only be more reason to have a framebuilder - or a good mechanic with a torch - move the posts.

Mount spacing has never been ironclad and there has always been a range that works for any particular brake. No one is going to light torch without a clear idea where they are headed.

Thanks for heads up. I do regularly check the position of the pads when I do lube the chains and adjust if necessary.
The last thing I want is to have them eating to the tires. It is my current commuter and is around 1k miles on it so far.

Appreciate all the responses. In the end I just went with new 27" Continental tires that are more suited for gravel riding. I didn't want all the headaches that might pop up as mentioned in the responses.

Good choice.

If I were you I would keep at least one spare tire on hand.
Other manufacturers who still make decent 27" tires are Panaracer (my all time favourite tire, the Pasela, is available in 27") and Kenda (cheaper but still fine). There are others but these are the ones I know of.

If you smash a rim or otherwise need to replace wheels in the future then you could consider switching to 700c, but there is no need to replace a serviceable set of wheels just for 'newness'.

I too had this same problem on my 1984 Trek 720. The canti posts had a spacing of around 60mm making it impossible to use 700c wheels with the stock brakes. I ended up getting the Shimano CX-50 catntis mentioned above, ditching the stock pads and spacers and replacing with normal road pads with the wheel centering tabs ground off. Works a treat. The rear was simpler because of the wider canti spacing, just used the stock pads and the thinnest spacers provided with the brakes. Works with both 27' and 700c no problems.

...in addition to Continental (the OP acquired a pair), which still offers handmade-in-Germany models...

Schwalbe offers quite a range, including the top-tier Marathon Greenguard.

https://www.bicyclerollingresistance.com/tour-reviews

Hope I'm not violating any zombie thread rules here but just incase someone was curious about a specific model. I recently converted my 1983 Trek 720 to 700c rims from the 27" with the original DiaCompe GC 960 brakes that came with the bike. It didn't work with the crummy narrow road rims that I had originally slated for the job (19.6mm outer width) but a pair of H-Plus Son TB-14's (outer width of 23mm) made all the difference. I regrettably cycled through lots of new cheap canti brakes before going back to the original ones so hopefully I can save someone from that same fate if they're trying to convert an older 720 and have them just reach for some wider rims!

Re: the original post, works great as a Gravel bike! Not the quickest of bikes off the line but dang is it smooth and unloaded it will feed back every extra watt you put into it!