700C on a C&V?
 

An acquaintance and one-time race cyclist has a few 700C wheels leftover from his cycling days (I just missed out on a cache of Campy parts he gave away). I saw them the other day and thought I'd have no use for them, but Could they work on my Dawes? I'm running the original 27x1" rims with freewheel rear now. What would be the advantage? The rims themselves look fairly narrow to my nooby eyes, maybe 3/4"? One rear has a single cog on a cassette, the other has what looks like a fairly close-range cassette. If they would work I suppose the cassette would open up some possibilities for gearing changes. But what about tyres?

Three issues affect the usability of these wheels; #1), the over locknut width of the wheel and your Dawes’ rear drop out spacing. Depending on the year of manufacture, the Dawes may have to have its drop out width adjusted to accept the usually wider freehubs. If you can’t measure the hub width, specs are usually available on line.
#2), the brakes on the bike need to have at least 4mm of extra area to lower the brake pads to. Lower, in this case, “lower” means closer towards the wheel’s axle.
The most common Dawes model that I have seen in the US is the Galaxy model of theSeventies, comparable to a Raleigh Super Course. These were, IIRC, supplied with Weinmann Vanquer Centerpull brakes. I would bet money that they have the necessary extra 4 mm needed to accommodate the 700C wheels.
#3), the Dawes’ derailleur must have adequate speed capacity to work with the freehub’s increased number of cogs. The derailleur could be changed to one that has adequate capacity for this wheel. A derailleur change usually calls for a new cable inner, at the least.

The advantages for changing the wheels is really for #1) a broader variety of tire options. There are fewer models available for 27” wheels, but there are some pretty good options available from Schwalbe and Panaracer in 27”.
#2) The offerings for freewheel combinations are also dwindling, these days. If t you needed to replace the freewheel on the 27” wheel, you might not find a suitable replacement that would align with your needs. Freehubs are prevalent now, so there are more options commercially. There are people like Pastor Bob who might have more guidance on available options for freewheels.

Hopefully, this gives you enough iformation as to whether this swapping of wheels is worth your effort and time.

Other added benefits a lot of times. You can stuff some really wide, cushy tires on there. I just did this with an '85 Raleigh and 700 x 38 clear with plenty of room. Here again though brake caliper can restrict what you can do. Also, if you are friction shifting then you can use a wheel with a freehub and cassette option a lot of times. If the RD doesn't cover the full range then just use the limit screws to lock out a cog or two. This frees up a lot of options for you though and a lot of times a modern cassette will just shift better than an old, non-stepped freewheel.

Yes I do, but I tend to stay away from conversions on bikes that use the 750 reach rear center pull brakes, or bikes that require brake swaps for longer calipers. I tend to advoid converting bikes with a claw derailleurs.

The bikes I like to convert are the bikes with brakes that can reach. It does not work smoothly every time.

I have a Sekai 2700 that does not play well with change. The front caliper needed minor modification to the pads for reach accommodation, the rear was fine.
https://cimg0.ibsrv.net/gimg/bikefor...c877c072ae.jpg

Some bikes, like this Trek, it's as simple as a wheel swap with the only adjustment being a drop of the brake pads to level.
https://cimg7.ibsrv.net/gimg/bikefor...59d1077e75.jpg
In my opinion the light touring mid to upper level bikes of the later mid 70's to mid 80's with caliper brakes work best.

By and large, this is a fairly easy peasy modification.

This question gets asked from time to time. Your reply is comprehensive and spot on, I'm bookmarking it.

Also one thing to check since these are ex racing wheels is to make sure they are hooked clincher rims that will accept most modern tires in wider widths and not tubular rims which will pretty much only except 23/25mm tubular glue on tires

Further to what [MENTION=203117]jamesdak[/MENTION] said.

If you have an extra large cog that the current Rd can't reach, that cog will act as a "dork disk" and prevent one day shifting into the spokes. This provides the benefits of a disk without having the faded plastic or flimsy aluminum stamped disk that some folks find unsightly.