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?
Replacing a 700C x 1.25
slothead
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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:
![Image]()
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.
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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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).
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).
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
Thanks again guys
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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.
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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Not at all sure what you mean by this. Are you really riding sewup tires on this bike?
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love it!
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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