After having built a few bikes recently that had 27 inch wheels originally with both 27's and 700c's. I have come to the thinking that on a lot of C&V bikes just ride better with the original correct size wheels and tires exspecially if you can keep close to the original gearing. Fooling around with different setups I have ridden both of my current C&V bikes a 620 Jeunet and 64 Gitane with both nicer 27 inch alloys and correct size 1 1/4 tires and nicer 700c with good modern 25 tires. Both bikes ride significantly better with the correct size 27s. Neither does a good job of tracking riding no hands with 700's yet both track good to great with the correct 27's. I wanted to find out if people here agree or disagree with this?

I tend to agree. My experience (only) is that bikes designed for 27's work best with 27's.
I was fully prepared, recently, to relace some OEM 27" rims to modern hubs for a build.
As it was, the bike is OEM 700c, but it would not have bothered me in the least to stay 27"

I've only had 3 27" bikes, but all of them seemed very smooth.
Miyata TwoTen with Weinmann concaves.
Lemans RS with Suzue/Araya.
Soma Competition with Weinmann concaves.
...the jury is still out on the mixte....

I know, I know, geometry, tires, spokes, rims, the age of the volcano, all of these have to do with ride.
But that's what I think, and if it works, I don't generally fix it. Besides, 27" Gatorskins are way cool.

27x 1 1/4 tires equate to about a 32mm tire IIRC. Wider tires are your answer. Get some 32mm 700c tires and give those a shot.

I would, but none of my current bikes will fit them.
Perhaps my tourer will accommodate some 32's.
I can't believe I said "my tourer."
I see Gatorskins in my future.

Hi zukahn1 !

If you are comparing 27x1-1/4 tires to 700x25, then you don't really have an apples-to-apples comparison.
The skinnier tires will roll easier but feel much harsher.

That being said, I prefer 27" wheels over 700 simply because it's easier to find quality rims for less money. Insofar as tires are concerned, I prefer Paselas over any other tire costing much much more, so the wider 700c clincher tire selection is not a factor for me personally.

For the same reasons, I would never even consider a conversion from 27 to 700 with all the concomitant issues. YMMV.

Thanks for the tip I will keep that in mind when it comes time to buy some new tires. I have a closet full of common size 700s mostly 25s and several sets of 27's right now so I'm not really in the market for new tires.

I was going to suggest that the wheel size should not have that much difference, but, as suggested above, comparing a 700 X 25c to a 27 X 1-1/4 is not a good comparison... If the tires on both wheels had similar casing profile then the difference in wheel radius, which will affect the trail and therefore the stability, would be approximately 4mm. 25mm tires might be another 7mm shorter than 1-1/4 tires, so the radius could be up to 11 mm less than with a 27X1-1/4... that is a bigger difference ad more likely to be noticed while riding..

FWIW, I always though the two biggest advantages of switching from 27" to 700c were the availability of different tires, and the ability ot fit wider tires into the same space.


My current main ride is a 27 -> 700C conversion and I am using 700 X 35c tires and it rides and tracks like a champ.

However, the previous bike restoration (more like a revitalization as I am not trying to necessarily trying to return the bikes to any condition other than 'ridable') I left the 27" tires on for quite a while and I loved the way it rode. I was amazed at how fast I could cruise down the highway in a big gear even with el-cheapo $9 tires fromt he hardware store on steel rims. THere is certainly no disadvantage to staying with 27" if you can find decent tires that suit the riding you want to do.

I have compared the same bike fitted with both 27" and 700c wheels on more than one occasion. The 27 inchers offer a slower but softer ride, while the 700c wheels are definitely harsher but faster, in my opinion.

Not sure what tracking with no hands has to do with the tires or wheels, though. Perhaps someone more enlightened could enlighten me.

My Super Course has 25s (27 x 1 tires). It has a bit of a harsh ride. My commuter with 700 x 35s is nice and smooth. fender1 is correct.

I sense much truth in this, I have a 72 LeMans that rode fairly nice with it's stock 27x 1 1/4 but currently I have a 700c wheelset on there, with 38's and it rides heavenly.. to me anyways. I typically prefer narrower tires, but that has nothing to do with ride comfort/oneness with the bike.

i have two frames originally designed for 630mm rims. one has original 630mm araya 20a rims and gripfast 7/8 in. (about 20mm wide) tt tires. the other has 622mm kinlin rims with vitoria diamante 20mm tires. i can and have swapped them around and, handsfree ridingwise, one frame is stable and the other is not.

here they are: top is 79 trek 710 with the 622mm rims and below it is the 86 trek 310 elance with the 630's.





if forget to mention, the 710 is the unstable one. i blame it on the steep headtube angle. the 310 elance is very stable and my favorite ride.

Is yours the 1979/1980 Super Course with the racy geometry? It came in red or gold. Yes, that's a harsh-riding bike, as I remember.

++1! I agree with this, in spades! I run 27's on my touring bike and love the way they ride.

Wider tires offer a larger contact patch w/ the road surface. It can often feel that the bike tracks better though turns etc. because of it. It would also explain the better "no hands". Also a lot of 27" rims are non-hooked beads so they can't be inflated past 80-85psi which results in a cushier feel.

Yeah, I tend to stick to 27s when the bike comes with 'em.

Lots of good reasons for keeping 27" rims on bikes that came with them, but I'm skeptical that anyone can subjectively differentiate between otherwise equal wheels that differ only in diameter by 8mm out of 730mm (about 1%). To be convinced, I would need to see data showing the riders' ability to identify a 1% change in diameter as an isolated independent variable, in a statistically significant, blind experiment. I might even insist that moment of inertia be held constant, and would likewise concede that total bicycle mass be held constant also, with appropriate ballasting as needed to normalize these parameters.

I don't blame anyone for feeling that way. In the case of the bikes I have compared, my 1975 CCM Tour du Canada, a Legnano Gran Premio and a Sekine SHC270, the difference was noticeable to me. And I am not much of a rider.

It is not just the diameter that impacts ride quality. Tire size, pressures, wheel weights all contribute to a difference in feel, as nearly as I can tell.

Good luck with that. Let us know when you finish.

Nah, the Raleigh USA from '83.

There's also a frame geometry issue, though maybe it's negligible. The contact patch on the27 will be a little further aft of the steering pivot axis than the 700.

I think the difference can be more more pronounced on different bikes. I can notice it on the older French and British bike I have built up. While on the early 80's Nishiki I have can't really feel much difference.

are 1 1/4 tyres really standard for the 27"

i always had the feeling that the 1 1/8 was the standard

How those it feel to ride on 27 x 1 1/8 i was thinking of getting a set soon and want to know how much better they right, i belive they have 86 tpi and can inflate to 102(Continental Ultrasport)?

27X 1 1/4" was pretty much standard on most bike boom era offerings. It's a touring tire size. As you went upscale performance wise, 1 1/8 and 1" skinwalls were offered.

I personally didn't notice a difference between the sizes, with both wheelsets built for performance. The 27" were Campy Record hubs, DT spokes, Ambrosio Elite Durex with Specialized Ultralights and Turbo /S. 700C also Record hubbed, DT spoked, Campy Omega Strada clinchers, and Panaracer wire bead Technovas. 27x1" vs. 700Cx25mm.

Ride characteristics very similar regards to acceleration, harshness over bumpy surfaces, cornering, braking. One didn't roll any worse or better.

[QUOTE=zukahn1;13680666]After having built a few bikes recently that had 27 inch wheels originally with both 27's and 700c's. I have come to the thinking that on a lot of C&V bikes just ride better with the original correct size wheels and tires exspecially if you can keep close to the original gearing. Fooling around with different setups I have ridden both of my current C&V bikes a 620 Jeunet and 64 Gitane with both nicer 27 inch alloys and correct size 1 1/4 tires and nicer 700c with good modern 25 tires. Both bikes ride significantly better with the correct size 27s. Neither does a good job of tracking riding no hands with 700's yet both track good to great with the correct 27's. I wanted to find out if people here agree or disagree with this?[/QUOTE

The slight difference in the diameter between a 27" and 700c is not going to make a difference in ride quality. The quality of the rim and hub could be a factor, but the biggest factor is going to be the width and compound of the tire.