I Have been wondering this for days. How much does the ride change between these two sizes? I ask because I am going to build a conversion this summer, and I am wondering why not just put single speed specific 27s on the frame? This is assuming that I would get an older frame like that but those frames seem to dominate craigslist. The only reason I see to get a 700cc wheelset is availability. So, if one wants the wheelset "to match" the frame, are there any other downsides to using 27 inch wheels?

I guess I just don't know why 700cc is the new road/track bike standard.

Thanks

There aren't a lot of wheel and tire choices for 27", and what's out there tends to be heavier and fatter -- not a lot of 27x7/8 tires out there, whereas 700x23 gives you a ton of choices.

yeah I didn't think of tire and tube choices. So really the only reason to keep the wheels 27 would be aesthetic and/or making the bike period correct. The later would be negated by making it fixed anyway, assuming its an old road bike.

Aesthetically, there's very little visual difference between a bike with 27" wheels and the same bike with 700c wheels. On most bikes, anyway.

I think the 27's ride a bit better, as they are slightly larger. I run Conti Gatorskins on my old Fuji S.S. and prefer them to 700's on that bike. Unless you are building a flip flop rear wheel, I'd say save the cash and use the 27's.
I believe 700's became the standard in Europe, then over here. Not sure why the change.....
Cheers

The main problem, other than aesthetics, is that when you go from a fat 27" tire to a skinny 700c tire, you are dropping the BB a lot more than just the 4mm difference in the radius of the rims, because the different tire sizes add to the differece. If you go with 700c rims on a 27" frame, I recommend that you stick with relatively fat tires or you will greatly increase your chances of pedal strike.

In Absentia is correct, depending on the style of the rim, there is very little difference between the rims until you get into deep v's and such. You won't find those in 27" sizes.

And mihlbach is right about pedal strike. Happened to my buddy on his (lower left) a few times.

The main thing is the tire choices available for 700's. Not a whole lot out there for 27". Most people run their 27inchers because its easier to do that rather than getting 700's AND having to buy new brakes to fit the new wheel size. And if you have an older frame (mine is a 1970) then you have to buy brakes with a longer reach.

You can get 27" rims in flip/flop configurations as well:
https://cgi.ebay.com/NEW-27-ROAD-BIKE...QQcmdZViewItem

700's (on left) & 27"

Let me be the first wiseass to say it: it's not 700cc; it's 700C

Otherwise, it would be cubic centimeters, which is something so very very different....

i rode 27" for a few years until about august. 700c definitly gives me a much better experience in every aspect.

No they don't. It's not the form factor difference that you're noticing, it's the quality difference. You probably went from 20 year old crappy wheels to brand new nice wheels, of course that will be better in every respect.

another thing to consider is that a lot of old 27" rims from the bike boom days are steel, not aluminum. Heavy, but more importantly (if you have a front brake and use it) is that steel rims have really bad braking, especially when wet.

Mac

700cc

I had also wondered about the BB clearance, and have been trying to make the same decision. Yeah, it's only a couple mm, but we also change crank length by a couple mm to minimize pedal strike.

I haven't decided yet. One thing buggin me, is that I'll probaby go through tires more often than my roadie.... so 700 would be nice.

you *had to* do it, huh?


By the way, I always wondered how nimble some of those chopper bikes are, when cornering.


By the way and back on topic (sorta): I believe ERTRO 630 (27") wheels should provide a smoother ride than ERTRO 622 (700C), at equal tires + tubes.

I also believe we shold all switch to ERTRO designation, as is the only one that makes some sense.

no real noticeable difference in ride quality between a 27" or 700c wheel. Maybe from the tires.
I ran a 27" rear wheel with a 700c front for awhile, that was very noticeable. 1) the rear 27" was tight on the frame, 2) the handling is amazingly tight.

Well, the difference in diameter (at equal tires + tubes) is a bit more than 0.1% - no wonder it's hard to notice.

More like 1%

oops

Yeah. I screwed up by only an order of magnitude.

and the quality of the build and the components. I was running an old pair of squishy 27" wheels from the 80s on my beater. Then I built a new pair of 27" wheels with Sun riims and it was soo much stiffer and faster. Ride quality has nothing to do with 700c versus 27".

Despite the lack of rim and tire choices, 27" wheels do have positive aspects. For a bombproof beater conversion, the wider rims and somewhat fatter tires available for 27" are a good thing. I'm tall and the bigger wheels make my huge 62cm frame look more normal. Right now I have my 27" wheels crammed into an old Centurion frame that was built for 700c. As a result, the bb is as high as my Bareknuckle, and the clearance is really tight making it look a lot better.

my conversion had 27" tires on it but i switched them to 700c 's because it was just what my bike shop had in stock.

ive noticed no real difference.

How much does it change things if you dont convert the bike? I just want to put new wheels on this old road bike I have

ummm... no.

27ers are to street what 29ers are to the dirt