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27" to 700C conversion

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Old 10-02-11, 08:05 AM
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27" to 700C conversion

This kid who works for me is keen to but an old Peugeot from a friend of his for $100. I looked at the bike, and it looks pretty nice. The frame is nicely straight and it looks to me like the bike has never been crashed or abused. It is old school however, 1" quill stem, 6 speed freehub, etc. My advise to the kid was to buy a newer bike but he is really into this one, so I'll help him out.

The thing he wants to do is replace the wheels. I haven't looked but 100% chance they are 27". I know that 700C are a bit smaller so the brakes are an issue. The bike has friction shifters so I think we are OK with upgrading to a cassette. What I am concerned about is the hub width, are we likely to encounter weirdness with a new set of 700C wheels fitting either the front or the back of this bike?
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Old 10-02-11, 08:25 AM
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How old is that frame? If it predates the 1990's it may have French threading and that will make working and repairing it a lot more challenging.

If it's new enough, the brake reach will be the big issue if it really has 27" rims but many brakes will adjust the 4 mm downward needed to align the pads over the smaller 700c rims.

Assuming the brake reach isn't a show stopper, the dropout width on his the frame is likely spaced at 126 mm and any hub above 7-speed will be 130 mm so you have three choices;

1. Buy a 126 mm 7-speed rear wheel and it will fit directly
2. Buy an 8/9/10-speed 130 mm rear wheel and force fit it into the 126 mm dropouuts. This is not that difficult.
3. Buy an 8/9/10-speed 130 mm rear wheel and have the frame cold set to 130 mm.
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Old 10-02-11, 08:50 AM
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The Classic & Vintage forum is filled with examples of such conversions.

A quick photo would do wonders for people willing to help. The issue of french threading might be real, but would be only headset and BB. Replacement parts are readily found, but just not as readily as standard (BSC) threads.

Measure the rear dropout width. If the bike is 70's, it may be 120mm (5-6 speed). Later, 126mm. Again, these hubs and freewheels are readily available, and often quite cheap as others discard them.

Front will be 100mm, the width of 98% of bikes. No problem.

Does the lad want to go fixie? Hubs not necessarily so wide, either.

Old steel is currently very hip, so the lad is in with his peers. In addition to the C&V forum, there is also a Single Speed Fixed Gear section. Please tell him NOT to dremel off the derailleur hanger. When he's ready to move on, someone may actually want that frame with the gear hanger intact.

Photos, please!
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Old 10-02-11, 09:00 AM
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Thanks, I was wondering about the front hub width. You guys do bring up a good point though, I don't know what shape the BB is in. It may be that replacing it may be tough if it has French threads. I'll take some pix and take this to the vintage forum.
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Old 10-02-11, 09:10 AM
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Originally Posted by LeicaLad
Measure the rear dropout width. If the bike is 70's, it may be 120mm (5-6 speed)!
If it's 120 mm it was designed strictly as 5-speed. The only 6-speed freewheel that would fit was the unusual Sun Tour Ultra-6 narrow spaced 6-speed. All standard width 6-speed freewheels and early cassettes used 126 mm dropouts.
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Old 10-02-11, 09:26 AM
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Originally Posted by HillRider
If it's 120 mm it was designed strictly as 5-speed. The only 6-speed freewheel that would fit was the unusual Sun Tour Ultra-6 narrow spaced 6-speed. All standard width 6-speed freewheels and early cassettes used 126 mm dropouts.
This is, technically, true. BUT, many of us have run a standard 6-speed freewheel on 120mm hubs/bikes. I did this -- not knowing anything about different axle widths -- on my 1971 Gitane Tour de France that I bought new. When the 6 speed freewheels came available, we were told to add a spacer next to the axle to allow clearance for the chain on the smallest cog. It was a tight fit (yes, it was spreading it, but we/I didn't really know that).

I still have that bike, and it's still running a 6 speed freewheel w/ a spacer. It has never been properly cold set. The hubs are 120mm.

OTOH, my 1963 Hetchins was properly coldset to 126mm, so I'm running Phil 126mm freewheel hubs and a 7-speed freewheel on it.

The Suntour Ultra freewheels are another way, but they required a thinner chain. In theory, that's easy these days, but I'm not sure which specific chain to recommend. I'd skip this option, IMHO.

Photos, when you can.
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Old 10-02-11, 09:36 AM
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...an old Peugeot from a friend of his for $100....
Paying too much .. unless there is a Reynolds 531 badge on the frame tubes.

there will be, French is unique, challenges like fork Uses a 22.0 stem, not 22.2
like the rest of the world, so hard to find any alternatives.

Last edited by fietsbob; 10-02-11 at 09:40 AM.
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Old 10-02-11, 09:49 AM
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So he wants to put some new red deep v 700s on it?

Obviously, you'll have to spread the rear. Thing is, the chain line might be a issue as well, it depends on the crank and spindle length. I suspect the set-up may loose some of the cross-chained gears...but all that may mean is he'll loose access to a few of the new cogs.

If you have other bikes, simply try switching rears and see what works before you start spending money. It's always possible he might end up eBaying a vintage Araya 700c wheelset, they're available.
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Old 10-02-11, 02:57 PM
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Originally Posted by LeicaLad
This is, technically, true. BUT, many of us have run a standard 6-speed freewheel on 120mm hubs/bikes. I did this -- not knowing anything about different axle widths -- on my 1971 Gitane Tour de France that I bought new. When the 6 speed freewheels came available, we were told to add a spacer next to the axle to allow clearance for the chain on the smallest cog. It was a tight fit (yes, it was spreading it, but we/I didn't really know that).
Well, you were doing what later became common when 130 mm hubs replaced 126 and were force fit into 126 mm frames.


Originally Posted by LeicaLad
I still have that bike, and it's still running a 6 speed freewheel w/ a spacer. It has never been properly cold set. The hubs are 120mm.
Are they really still 120 mm or did you add the spacer and recenter the axle making them effectively 126 mm?

Originally Posted by LeicaLad
The Suntour Ultra freewheels are another way, but they required a thinner chain. In theory, that's easy these days, but I'm not sure which specific chain to recommend. I'd skip this option, IMHO.
The Ultra-6 freewheels required a narrower chain that became the standard for 7-speed and later 8-speed so it is now known as 7/8-speed or even 6/7/8-speed chain. Available nearly everywhere these days. I'd skip the Ultra-6 option too but only because those freewheels are now hard to find and shifted poorly when they were current.
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Old 10-02-11, 05:59 PM
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Originally Posted by HillRider
. . .
Are they really still 120 mm or did you add the spacer and recenter the axle making them effectively 126 mm?
Well, the hub is still the early '70's NR high-flange. It has a single 2mm spacer outside the freewheel, so I'd say it's currently about a 122.5m -- 123mm. I did a major overhaul on the bike last month, but didn't think to measure the rear OLD. I did notice that it's still a tight fit putting the rear wheel back in!

My garage queen '71 Super Corsa is still running a 5-speed freewheel on it's original 120mm hub. I keep thinking I'll do the same spread on it, but just haven't gotten around to it.

Originally Posted by HillRider
The Ultra-6 freewheels required a narrower chain that became the standard for 7-speed and later 8-speed so it is now known as 7/8-speed or even 6/7/8-speed chain. Available nearly everywhere these days. I'd skip the Ultra-6 option too but only because those freewheels are now hard to find and shifted poorly when they were current.
Thanks for this observation about the chains. I'm glad to understand that, but also agree that the Ultra-6 didn't shift too hot. Shimano HG teeth were a very nice advance.

Anyway, this is simply chat while we await photos, eh?

Cheers!
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Old 10-02-11, 06:55 PM
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In terms of the BB, you always have the option of tapping the BB to English thread if they don't want to bother with the cost and pain of replacing a french BB.
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Old 10-03-11, 08:07 AM
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Plenty of 25 year old peugeots have parts in line with more modern standards.

What wheels are on the original bike? Alloy rims or steel? If the hubs are in good condition, and If the rims are straight and not steel, then I would consider leaving them on. You don't get as wide a choice of tires with 27" but good ones are still available.

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Old 10-03-11, 09:16 AM
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Originally Posted by catchabadone
In terms of the BB, you always have the option of tapping the BB to English thread if they don't want to bother with the cost and pain of replacing a french BB.
NO NO NO!!! Some shells can be reamed out and tapped italian, an english bb can be forced in to a swiss shell but you can not sucsessfully re-tap a french shell to english, there wouldn't be any metal left on the drive side and the threads on the nds would so weak they wouldn't be useable.
A Phil BB would be cheaper and more reliable than converting to italian, VO BBs are less than a third the cost of a Phil and who knows? the original parts may still be useable.
There is nothing practical about working with old Pugs, aside from the threading issues, the tube diameters are different as well so nothing "standard" works. They are purely a labor of love, I have three mid '70s PX-10s to prove it!
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Old 10-03-11, 09:51 AM
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Running 700c on a 27" frame is a beautiful thing. You'll have room for big touring tires (much more comfortable ride) and even fenders. Long reach brakes should be available. My ancient Peugeot had french threaded BB but I was able to find a Stronglight original. I cold set the frame to 130 rear drops. It was a rescue job from a neighbor's garbage. I now run it as a single speed w/ 700x32 tires and, over the years, it has become my FAVORITE ride (and I have lots of great bikes).

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Old 10-03-11, 11:32 AM
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Originally Posted by dbg
Running 700c on a 27" frame is a beautiful thing. You'll have room for big touring tires (much more comfortable ride) and even fenders.
True. I had an '83 Trek 400 I bought used that came with 27" wheels and the original owner had upgraded the brakes from whatever it came with to long reach 105 dual pivots. Fortunately, the brake shoes would adjust downward the needed 4 mm and I fitted 700c wheels and had plenty of room for fenders and could have gone to at least 700x28 or possibly 32 tires.

You can't do that with modern road frames but most cyclocross and all touring frames have that kind of clearance.
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Old 10-03-11, 12:18 PM
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Originally Posted by HillRider
True. I had an '83 Trek 400 I bought used that came with 27" wheels and the original owner had upgraded the brakes from whatever it came with to long reach 105 dual pivots. Fortunately, the brake shoes would adjust downward the needed 4 mm and I fitted 700c wheels and had plenty of room for fenders and could have gone to at least 700x28 or possibly 32 tires.

You can't do that with modern road frames but most cyclocross and all touring frames have that kind of clearance.
650b wheels came about for roughly the same reason right? Fitting bigger tires/fenders on a tight 700c road frame?
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Old 10-03-11, 12:36 PM
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Originally Posted by himespau
650b wheels came about for roughly the same reason right? Fitting bigger tires/fenders on a tight 700c road frame?
Well, that was the first thought but brake incompatibility pretty much ended that approach. Current 650b frames and forks are purpose built.
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Old 10-03-11, 12:48 PM
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Originally Posted by catchabadone
In terms of the BB, you always have the option of tapping the BB to English thread if they don't want to bother with the cost and pain of replacing a french BB.
Must repeat that you CANNOT re-thread a French bottom bracket to English.

If the bike has cottered cranks and have good cups you can replace the axle with a square tapered spindle, The Phil Wood option is wonderful, and Velo Orange has the most cost effective and simple solution for about $45.00.

Just built up an AO8 (french threading all the way) and just left the old cottered crank and am running it as a single speed with a coaster hub as the crank was in fine shape and besides being heavy, will provide a decent service life. I have spindles to replace the cottered crank if I desire... have been working on French bikes for a long time and do a lot of upgrades.

As for wheels... in most cases the stock brakes will adjust the 4mm to run 700c wheels as export models came fitted with 27's and domestic models were fitted with 700c and most were spec'd with the same brakes.

The rear dropout spacing is usually not a big deal as there is sufficient flex to fit a 126 hub into a 120 spacing and if you want a permanent solution have someone who knows what they are doing cold set the frame to what you need.
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Old 10-04-11, 09:03 AM
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The original MAFAC brakes on an early '70s Peugeot have sufficient reach for 700c wheels.
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Old 10-04-11, 09:10 AM
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Originally Posted by fietsbob
Paying too much .. unless there is a Reynolds 531 badge on the frame tubes.

there will be, French is unique, challenges like fork Uses a 22.0 stem, not 22.2
like the rest of the world, so hard to find any alternatives.
You obviously haven't shopped for low end or high end Peugeots lately. A UO-8 for $100 is not out of line and you don't buy a PX10 (even a bare frame) for $100.

An inexpensive British headset allows one to use a non-French fork. It's not so hard.
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Old 10-05-11, 01:47 PM
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Originally Posted by himespau
650b wheels came about for roughly the same reason right? Fitting bigger tires/fenders on a tight 700c road frame?
650B bicycles and wheels have been around for a long time, mostly for touring, commuting and utility bikes, mostly in France. It almost disappeared, but for the efforts of la Confrerie des 650B, who kept pressure on manufacturers to continue production. There were, and are, also some 650B enthusiasts in Japan. Rivendell reintroduced the size in the US about seven years ago with their Saluki and Bleriot models. After 650B rims and tires became more widely available , a few clever cyclists hit upon the idea of fitting wider 650B wheels into frames originally designed for 27' or 700C wheels. I first read about this in a 2004 Rivendell Reader.

I converted a Univega Nuovo Sport to 650B, and think that 650B x 38mm tires are much more comfortable on our broken up lousy roads around here.
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Old 10-06-11, 06:42 PM
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Originally Posted by ironwood
650B bicycles and wheels have been around for a long time, mostly for touring, commuting and utility bikes, mostly in France. It almost disappeared, but for the efforts of la Confrerie des 650B, who kept pressure on manufacturers to continue production. There were, and are, also some 650B enthusiasts in Japan. Rivendell reintroduced the size in the US about seven years ago with their Saluki and Bleriot models. After 650B rims and tires became more widely available , a few clever cyclists hit upon the idea of fitting wider 650B wheels into frames originally designed for 27' or 700C wheels. I first read about this in a 2004 Rivendell Reader.

I converted a Univega Nuovo Sport to 650B, and think that 650B x 38mm tires are much more comfortable on our broken up lousy roads around here.
I always thought converting large wheels to small wheels with fatter tires was the original intent of the 650B size.
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Old 10-06-11, 09:07 PM
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Originally Posted by ironwood
After 650B rims and tires became more widely available , a few clever cyclists hit upon the idea of fitting wider 650B wheels into frames originally designed for 27' or 700C wheels. I first read about this in a 2004 Rivendell Reader.

I converted a Univega Nuovo Sport to 650B, and think that 650B x 38mm tires are much more comfortable on our broken up lousy roads around here.
Sheldon Brown also championed this idea. BTW, what did you do about brake alignment? The radial difference between 700c and 650b rims is 19 mm and that's way more than any good quality caliper or cantilever brake will adjust. Disc brakes?
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Old 10-07-11, 12:06 PM
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Originally Posted by HillRider
Sheldon Brown also championed this idea. BTW, what did you do about brake alignment? The radial difference between 700c and 650b rims is 19 mm and that's way more than any good quality caliper or cantilever brake will adjust. Disc brakes?
Weinmann or Dia-comp centerpull750s will work on a lot of old frames, but I don't think the long reach Tektros will on this model bike. The dia-comps are still being made.
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Old 10-07-11, 12:09 PM
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I'm surprised this hasn't come up yet but if the bike is a bike that was inported during the boom years of the 70's for Peugeot. Then it likely has simplex derailers which will need to be changed if the kid wants to upgrade to more modern gearing. These derailers couldn't find all five gears on the rear a lot of the time and would likely be hopeless at finding 7 or 8.
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