Rim Sizes?

It has been brought to my attention that a 28" and a 29" unicycle actually have the same exact rim size… only the tire size is different. I have also heard that the same thing holds true for 24"/26" size unicycles. Can some knowledgable members of the forum either confirm or deny this allegation? Thanks…
Andrew (HCR)

Andrew, I believe you might be mistaken, Unicycle.com sells both 24" and 26" rims, they alos sell 29" rims. Other places sell 28" rims.

You might have been a bit confused when someone said something like:
A 24" uni’s wheelsize ins’t really 24"
more like 26" or something. The rim itself is the wheelsize, not the size after measuring.

I hope this answered your question.

Re: Rim Sizes?

Don’t know that I’d call myself a knowledgeable member, but it’s late so I won’t let that stop me. Can’t speak for the 28/29 question, but 24 and 26 inch tires don’t use the same rim. If that was the case, the 26 x 3 Gazz would need to be two inches thicker (from rim to tread) than the 24 x 3 Gazz, and it isn’t.

Now let me take a stab at it.

24 and 26 use different sized rims (I should know, I have one of each)

27, 28, and 29 all use the same size rim, the 700c. The difference is the size of the tire on the rim.

Hope I’m right, and hope that helps.
Daniel

i’m pretty sure daino is right, though i’ve never heard of a 27 inch rim and most the people who use 28 to refer to that size seem to european. I always though on road bikes its a 700C and on mtn bikes its a 29. maybe that’s a slight tire distinction. i dunno. but a 24 inch rim that has a big tire on it probably has an outside diameter close to 26 inches, but it is not a 26 inch uni. we size things by the rim not rim + tire.

Thanks for clearing that up, guys! I can ride the Coker ok, but I’m not very knowledgable about the equipment. I rely on all you technical geniuses to keep me informed :D!

Here’s Sheldon Brown’s page on tire sizing.

There are 27 inch rims. They’re usually found on older road bikes and touring bikes. Road bikes have standardized on the 700c size now.

There is a 28 inch wheel size. And there are some unicycles made with that wheel size. But it is rare and it is more difficult to find a replacement tire for it. 700c is a much more standard and common size. If you’re going to get a 28" uni, make sure it uses a 700c rim and a fat tire. It will be much easier to get replacement tires for a 700c than a true 28".

The 29er is a marketing size. It’s a fat tire on a 700c rim. The fat tire gives it a rolling diameter close to 29 inches. The 29er wheel size got popularized starting in 2002 when Gary Fisher introduced some mountain bikes with that wheel size. The 29er is an odd-ball because its size is based on the fatness of the tire rather than the size of the rim. Most other tire sizes are based on the size of the rim no matter how fat the tire is.

A 24x3 wheel, like the Gazz, has a rolling diameter a bit less than a standard 26" MTB wheel. But it’s still called a 24" wheel.

A 26x3 wheel, like the fat Gazz, has a rolling diameter a bit less than a 28" wheel. But it’s still called a 26" wheel.

Wow! Thanks a lot, John!

this topic is like learning the english language, im glad i was born into it.

JC’s is the most accurate description of the whole tire/rim size thing I’ve heard in a short space. The above statement is technically true, but there is a lot of confusion where people mix up the rim size vs. tire size.

First of all, for Andy, with Cokers it’s real simple. The ‘Coker’ part is the tire. There’s only one tire that size, and at the moment, only two rims to fit it. I’m sure you’re aware of the nicer one, and hopefully saving up for one. Until you upgrade, you’re continuing to push the limits of what a standard Coker wheel can handle.

Beyond that, it’s important to know the rim size being discussed if you need to get parts. When people talk about 24" MUnis, for instance, they often mean 24x3 wheels, which are actually closer to 26" tires. But the size is accurate to the rim. However, some of us ride “regular” 24" wheels on trails as well. So make sure you know what people are talking about. I like to tell people the nominal size for MUni is 26", but that includes some real fat tires on 24" rims.

28"/29"/700c is more confusing, because of the rare existance of 27" and 28" rims out there. I prefer using the term 700c, but most people still don’t know what that means.

For people new to this: the “c” in 700c does not stand for centimeters or any other measurement. To make a long story short it’s like a, b, c, and I don’t know if the 700 relates to a size. It’s just the most common rim size in the world currently. I am hoping most unicycles for cruising will move to this size in the next few years.

yep, its just a denotation in the French wheel sizing system.

sould we get into 650c?

Really? I thought that 28" rims were exactly equivalent to 700C. At least they seem to be in the unicycle world. If this weren’t the case how would it be possible to retrofit a 29" tyre on a standard 28" unicycle rim?

JC - can you cite an example of a commercially available 28" unicycle which is a non-700C, true 28" ?

Maybe this is to do with nomenclature - if you ask a bicyclist what a 28" rim is they’ll look at you funny and not know what you’re talking about. To bicyclists 28" rims are indeed a rare and odd size. Tell 'em 700C and they’ll know exactly what you mean. This makes the info on Sheldon Brown’s site somewhat less relevant to unicycles.

To confuse things more I did once have an old unicycle with a 28" rim which was indeed an odd, non-standard size. The tyre on it said 28 x 1 1/2 and it wouldn’t fit 700C tyres. I haven’t ever seen another tyre or unicycle like this one. This unicycle was made out of old parts lying around in a bike shop.

+()||>-

all the answers are already within the posts already posted.

No they’re not! If you can show me a photo of a commercially available 28" unicycle with a non-700C rim , then we’ll have all the answers.

like John C said

commercialy available? no…why? it an old an abandoned wheel size.

Indeed like John C said

This implies that there are currently unicycles being made with 28" non-700C wheels. Plus the fact that he goes on to say that if you buy a 28" unicycle you should make sure that you get a 700C one rather than a non-700C, reinforces the implication that both types are available. Perhaps that’s not what John meant.

DM used to make a 28", and I’m pretty sure it was a full-on 28" rim and tire. This was in the mid-80s or earlier. Those unicycles are still made, even if they’re not being made anymore. They did not get unmade :slight_smile:

JC, do you know of any more current 28" unicycles? (probably not)

I don’t know of any current 28" (28 x 1-1/2) unicycles that are available in the US. If there are any still being made it would be in Europe (maybe in the Netherlands) or Asia.

It’s just something to be aware of if you try to buy a used 28" unicycle. Make sure that it’s not the odd-ball 28 x 1-1/2 size. Probably more of an issue for people in Europe since that size of wheel was more of a European thing.

That 28 x 1-1/2 size probably has a slighly larger rolling diameter than the modern 28" which has a fat tire on a 700c rim.

I forgot about the 20 x 2.5 trials tire size. That tire size is also based on the fatness of the tire rather than the size of the rim. Another odd-ball. The 20 x 2.5 trials tire size fits on a 19 inch trials rim. It will not fit on a 20" rim as used on BMX bikes and 20" freestyle unicycles.

Re: Rim Sizes?

On Thu, 20 Jan 2005 16:38:00 -0600, “jagur” wrote:

>all the answers are already within the posts already posted.

Wow, you sum that up quite nicely. :slight_smile:

Klaas Bil - Newsgroup Addict

It’s impossible to get old when you ride a unicycle - John (what’s in a name) Childs