Kommisar89

Outstanding. Not sure that I'll be getting around to that anytime soon but it's good to know it will work. Based on your information and the fit of the various wheel/tire combos I tried today (next post) I suspect the frame is designed to fit both 700C and 650B and also handles 27" just fine.

Kommisar89

Here you can see the fit with 27 x 1 1/4, 27 x 1 3/8, & 700 x 32c. The 700 x 32c seems like a perfect fit. As jj1091 points out, the rear triangle of the French 650b bikes are exactly the same so we have to conclude that the frame is designed to fit 650b & 700c and works just fine with 27 x 1 1/4" as well. The 27 x 1 3/8 works but the clearances are a bit tight. If you broke a spoke you might end up with the tire rubbing the chainstay. Interestingly, while you can see that the 27 x 1 1/4 is a bit closer to the bridge than the 700 x 32c as you would expect, the wide points of the tires seem to fall in about the same position. Probably just the difference in the tire shapes.

noglider 

I have size 11 feet, and my socks fit me, so that means the socks were designed for size 11 feet, right? Wrong. They fit many size feet.

The UO-8 frame, i.e. the frame of many models, happened to fit many size wheels.

RobNew

The Peugeot UO8 (and the AE8 - of which I have one from new) were designed for 27x1¼ tyres. At the time - mid-70s bike tyres were pretty much 27x1¼ or 26x1½ on Adult bikes.
I'm not sure when metric tyres came in for bikes, as I hadn't used mine for a while but I fot a surprise when I had difficulty finding them on the rack!
In Europe we still use imperial sizes for car tyres, typically 15" to 17" and up. To muddy waters a bit the 185 you see after the rim size is the section width in millimmetres!
Michelin tried a move to metric car rims in the 80s (the TRX ) but they never really caught on

noglider 

@RobNew, welcome to bikeforums. The Peugeot bikes of that era were designed to export to many markets as well as to be used domestically. I don't think 27" wheels were ever popular on the European continent, and I'm pretty sure UO8s and AE8s and the like used 700c wheels in those markets. See my post above yours.

gesta

I have 2x ph45m mixtes, px50L, pvn10 and ph8m from mid 70s to early 80s, all euro-spec. Even if they have different chainstay lengths, all have dimples placed in such a way that the widest part of 650b x 38 tire is at the center of the dimple. From the factory, these bikes were equipped with 27”, 700c and 650b tires.

From these bikes, my Px50L was originally a 650b touring frame and as previous comment mentioned, front fork is quite wide - 650b x 52mm (2.1”) tires are the widest usable size I’ve ran without fenders. With some extra crimping, same size fits to rear even better.


Px50L monstercross

RobNew

noglider Hi Tom,
Certainly in my part of Europe back then no-one had even heard of metric tyres!
There were a variety of Continental European bikes available and none of them had metric tyres, I'd be very surprised if the French, Italians and Austrians put Imperial tyres on just for us, much as they don't like us now, they didn't like us then either!
I had enough trouble trying to find the right sized cotter pins for it then, and let's not mention trying to get a cotterless chainset!

gesta

My experience is limited to Finland, but 27” (or 635mm) rims are quite ubiquitous for bike boom era bikes, all price ranges.

noglider 

What part of Europe are you in? I know 27" was common in the British Isles. I can assure you that European makers did put English-size wheels on bikes for the US, UK, and Canadian markets. I think it was in the mid 1980s when we switched to 700c. It wasn't because of nationalistic concerns. It was because tubular tires were (and are) made in only 700c size, and some of us liked to swap wheels. That made more sense with 700c wheels, so the bike industry realized it was better to make bikes with 700c wheels than with 27". There was no great metricization of bikes, and in fact, the French bike industry gave up metric sizes and threads in favor of English sizes and threads. The switch from 27" to 700c wheels was the only move among many possible moves.

dddd

Seems like the crimps should accomodate the fender at the widest point(?).

Switching to 650b rims means increasing the brake reach a full 19mm from 700c rims and 23mm(!) from 27-inch rims.

RobNew

Well I haven't been idle in the past 24 hrs, chaps.
I have somewhere a 1990 ETRTO manual, which I a) used professionaly back then and b) can't find now. So that's no help.
I chatted to a friend who unlike me did not have a cycling hiatus over the past 40 something years. He tod me I had always assumed that measuring the tyres on a bike was the same as a car, that the 27 (say) referred to the bead diameter, so armed with a tape, I set off and measured, as best I could, the 27" (or actually because I was measuting a radius 13½") was approx half-way up the sidewall. So that was that debunked. After all these years I had never measured the bead diameter, being told they were 27" tyres, I assumed that's what it was!
Now, turning to my discussion with noglider I managed, through the wonders of t'interweb to find some period catalogues for Peugeot bikes. This is the UK version, exactly similar to mine on 27" hp tyres
(except I can't post pictures yet....
But the french version of the same bike, is, as noglider says on 700C rims (I have no idea what that actually means) I did have a link to the french catalogue for the AE8, but I can't find it now, sorry.
So, apologies to noglider but it would appear that tyres were market specific as he suggests. I bought my bike in the mid-late 70s so that would tally and by the 80s I had a driving licence so never used the bike that much afterwards.
You chaps have probably seen this web site before, bikeboompeugeot.com/index.html but it looks like a great resource. The OP could probably trawl it with little bother and get the answer to his question.
My chum also thinks I may have difficulty buying 27x1¼ tyres now.

noglider 

@RobNew, here is an article that will both inform and confuse you further.

RobNew

I bought my wife a Peugeot Mixte, it was in lovely condition when I bought it, but stood neglected for a few years. Anyway....

The current (crusty) tyres on it are 28 * 1 5/8 * 1 1/16, or 25-622 or (I think) 700x25 and they look stupid narrow, more like tubs than tyres. This is what put her off it. It needs bigger tyres (and I think it should have them, possibly a PO changed them at some point)

The wheels, as far as I can determine through the rust, are 28 x 1 5/8 x 1 1/8
?

According to my ETRTO manual (1990 - sorry) I should be able to fit 28-622, 32-622 or 35-622 tyres (if they will go between the forks) Does this sound about right

polymorphself 

The U018 mixte I built for a friend got 700x32mm tires with fenders with room to spare. She could easily go 35 and maybe even 38 with fenders. Without them she definitely could. Ignore the rear fender line it’s since been fixed and now sits higher.

noglider 

@RobNew, yes, that's correct!