Gonzo Bob

Some tires age well and some don't. I've had tires that I've had to toss out after only 5 years, not because the rubber was worn down, but because the sidewall casing had dried out and was cracking and falling apart, probably from UV exposure (Panaracer road clinchers, but I don't remember the model). On the other hand, I have a pair of MTB tires that I think I put on my mountain bike in 1992 that are still going strong. The rubber is slowly wearing down, but the casing and bead are still in great shape (Ritchey Megabyte Z-max).


Back to your original question about a 27"-to-700C conversion. The most important criteria is getting something compatible with your shifters. 27" wheels imply friction shifting but you don't say whether you've converted to indexed shifting or not. If you haven't, ignore this part. If you have, you'll need a wheelset that supports the speeds and spacing of your shifters. I've been out of cycling for a while (but just getting back into it) but I think most road wheels are 130mm rear dropout spacing and support 8- to 11-speed cassettes. If you're running 6-speed indexed shifting, new wheels probably won't work. If you're running 7-speed indexed shifting, you may be able to get an 8-speed cassette tor work but (same cog spacing) you might not be able to use all cogs. Above 7-speed, you should be fine.


My 27" conversion was not so much a conversion, as it was building up a frrame/fork designed for 27" wheels with components from a 700C-wheeled bike that had been through multiple crashes and an encounter with a car (I was the rider for all of those incidents). That build worked fine and I still use those wheels in that bike for daily use. But in 2009, I realized those wheels would not cut it for a loaded tour from Munich to Barcelona that I had planned. So I spent time looking for wheels to buy, but ended up building my own. I found some Shimano 105-SC 7-speed HyperGlide cassette hubs on eBay, got some new WTB 29er rims (DX23 I think) and built my own pair of sturdy touring wheels.

viperocco

The likely recipient, Miyata 215ST, has the early Shimano SIS where you can switch between friction and index shifting. Going to take some measurements today and possibly grab my father in-law's Giant hybrid, not sure how many speeds, and do some test fittings. Thanks

viperocco

Picked this up for 30 bucks. Needed a brake bolt tapped to be rideable.



Index shifting works through all the gears.

Havent come across these brakes before so if anyone knows anything about them...

Gonzo Bob

Early Shimano SIS would be 6-speed. If your 6-speed freewheel or cassette is in good shape, my recommendation is to rebuild your wheels using your existing hubs.

viperocco

So I decided to go with building a single speed/fixed flip flop wheel. I went with a Formula track hub from Ebay, Sun Rims CR18, Sapim spoke and nipples. I really enjoyed the experience building the wheel. The hardest part was deciding what components to purchase; I did the hub first, rim then spokes.
While Sheldon Brown's instructions are very thorough I like to see what is going as well. Here is the link to the video I used.
Other thing to note is there is no dish on a single speed which made it a good first time wheel build. Riding a fixed gear is strange... And now for the pics...

ofajen

Yeah, on my Schwinn Sprint I had to extend the bottom of the slots on the rear brake arms of my Superbe brakes and it’s still barely enough to clear the tire with 40/16 SS. If I went with a RD and positioned the rear axle properly, it would probably require a different rear brake like Tektro 559.

Otti

Road Fan

And if you don't want to deal with replacing brake calipers (a possibility but not a given), there are some aluminum rims still made, such as the Velocity Dyad and possibly the Sun CR18. I have not seen new Araya or Ukai rims for a while, but they are still on the used market. This gets you 27" wheels, good 27" tires, your same old hubs and possibly spokes, and no major reconfiguration to your brake calipers. But usually new rims are a good opportunity to also replace brake shoes/pads, and in the process resetting positions and toe-in.

Road Fan

Whether you have to go that far or farther is bike by bike. Sometimes the brakes have enough slot depth. I've had three vintage treks and wrenched on a few more owned by a bud, and at least for the steel 1980s with caliper brakes, the brake calipers max out at the point where the shoes need to be for 630 wheels, so at least that series of frames was engineered to work for 630 wheels, 622 wheels, and tubular wheels. You won't ALWAYS need to replace with long reach brakes.

Converting to 650b or smaller (584 mm or 559 mm) is another story entirely, as is the situation with fork raking to decrease trail. Those can result in needing new brakes, possibly even requiring brazing on canti posts.

Measure your frame carefully with the calipers you have, to make sure what will fit and what will not.

Vintage Schwinn

Here is a very decent 32mm wide 27 inch (630mm) tire that is not too expensive:
https://www.swifttire.com/product/sa...8-folding-tan/

Here are some folks' long term user reviews on those particular 27 (630mm) tires and some accurate realistic tread widths of several of today's most popular 27 (630mm) choices:
https://www.bicycles.net.au/forums/v...p?f=23&t=97809




https://www.bicycles.net.au/forums/v...?f=23&t=103632