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Discussion Starter · #1 ·
I have some relatively old wheels which have 700C x 1.25 tires mounted on them. Can I replace those 1.25 tires with 700 x 25C tires? Or are there more specs that I need to consider?
 

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Discussion Starter · #3 ·
Just re-checked and yep, you're right, it does say 27 x 1.25, and thanks for the links. Looks like it's new wheel time.
 

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if making a 700c conversion, make sure your brake pads will reach the smaller wheel diameter or plan on making further changes.

i've made three 700c conversions: on two of my 1970s road bikes and another from 1980. the '70s bikes got new dual pivot calipers. for the 1980 bike, i was able to file the caliper arm down a bit to gain another millimeter of necessary pad reach.

it's not always necessary to make the conversion to gain the tire choice you want. i like 23mm tires which aren't available in the 27" size. but 25mm tires are readily available (called 1"). and the tire model i usually ride is available in 27".

and if "period-correct" components are important to you, long-reach brakes for a 700c conversion are sometimes difficult to find.

certainly do the upfront planning before making the conversion.

here's one of mine, a '76 motobécane grand record with 700c polished sun m13ii rims, sapim race spokes, vintage campy hubs, and panaracer pasela 23mm tires:



the tektro dual pivots look a little out of place, but not too bad. and, with kool-stops, not many vintage calipers can stop as well.
 

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Cranky Old Bastard
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27" tires indicate an old bike.

Upgrading to 700c wheels may be a lot more complicated than you realize. A lot of the oldies out there aren't worth the money spent to change.
You may need long-reach brakes. You can't get 5 or 6-speed cassette to fit a newer wheel.

You're probably better off just to ride it as it is. You can still get tires: Mountain Bike Tires | Road Bike Tires | Bike Nashbar (and they have 27x1 1/8 too).
 

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Discussion Starter · #6 ·
Thanks Randy and Frank, I was not aware of the 1" and 1 1/8" tires. That solves a lot of issues. Unfortunately I converted the old road bike to 700c tubulars and I would like to maintain that option, but that will mean adjusting brake reach whenever switching, so I think I will have to make up my mind and stick with one of the configurations.

Thanks again guys
 

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Upgrading to 700c wheels may be a lot more complicated...
while most prefer 700c to 27", moving from one to the other doesn't necessarily represent an "upgraded" bike. you can still buy new 27" rims and build wheels yourself as i did recently for this 1970 gitane:



i used sun cr18 rims, sapim spokes and the original normandy high-flange hubs.

You can't get 5 or 6-speed cassette to fit a newer wheel.
and on the new rear wheel, i used the original 5-speed freewheel.

you can also buy new 27" wheels with new hubs, but the hubs are usually gross and look out of place on vintage bikes.
 

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Discussion Starter · #8 ·
while most prefer 700c to 27", moving from one to the other doesn't necessarily represent an "upgraded" bike. you can still buy new 27" rims and build wheels yourself as i did recently for this 1970

i used sun cr18 rims, sapim spokes and the original normandy high-flange hubs.


and on the new rear wheel, i used the original 5-speed freewheel.

you can also buy new 27" wheels with new hubs, but the hubs are usually gross and look out of place on vintage bikes.
i've got 3 old sets of hubs that still have the old 5-speed freewheel thread on them. Two sets are high-flange hubs and one is a low-flange set. One of the high-flange sets has the original 27" rims and the others both have 700c tubular rims on them. One of the low-flange sets has Campy (Tipo or Record, I don't remember which) hubs and I recently found some New-old-stock Campy tubular rims to use with the Campy hubs in a new rebuild.

The high-flange clincher wheels will stay the same based on this past discussion and I'll look for them 1 or 1.125 tires to fit the (and also some slightly smaller and lighter tubes for them). If they ride well, I may stick with them somewhat permanently (and keep the Campy wheels as 'museum' pieces :) )

Years ago when I switched to sew-ups, I really enjoyed the simplicity of them (and still do until you have a flat), and added thorn-catchers to make tire repair time minimal. Replacement on the road is also simpler with the sew-ups . The clinchers have the added benefit of a little heavier 'protection' against flats, but not much, especially if these new thinner tires are thinner walled too (which I suspect they are).
 

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I did a conversion to 700c on my Schwinn 11.8, mainly because 700c has a much better choice in high end tires, such as Conti 4000s.
 

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Two sets are high-flange hubs... the low-flange sets has Campy (Tipo or Record, I don't remember which) hubs and I recently found some New-old-stock Campy tubular rims...

The high-flange clincher wheels will stay the same based on this past discussion and I'll look for them 1 or 1.125 tires...
love it!

Years ago when I switched to sew-ups, I really enjoyed the simplicity of them (and still do until you have a flat), and added thorn-catchers to make tire repair time minimal. Replacement on the road is also simpler with the sew-ups.
never ridden them for any length of time. i do like their weight savings.

i'm doing some work for a friend -- major wheel true on three tubular rims and a wheel build on another tub rim. i overshot the spoke length by a couple mm on the build. it's a mavic gp4 rim whose e.r.d. wasn't well documented online. but, being a tubular, i guess i don't have to worry about the protruding spoke puncturing rim tape and a tube like this problem might for a clincher. it was my first build on a tubular.
 
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