24 inch Vs. 26 inch

[The Bruiser]

would a 26er make much of a difference over a 24er for XC?

[U-Turn]

Yes, it would, depending of course on what you are focusing on. There
is a much, much larger selection of tires and tubes for 26"; you will
be somewhat faster; and roll over obstacles a little better.
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[Mikefule]

Plenty of threads on this, I'm sure, if you search.

Keeping it fairly simple: given a similar tyre, the 26 is around 8%
bigger, which means around 8% faster on the flat. Muni speeds around
6-8 mph means an extea mile an hour at most.

However, the bigger wheel is less vulnerable to small irregularities in
the ground, and rolls over things more smoothly. Therefore, average
and "journey" speeds are much higher.

On the other hand, the 24 is lighter, and more manoeuvreable.

The 8% will matter on hills. It's like changing a gear on a bicycle.

Various schools of thought: a 24 for hard hoppy droppy MUni, a 29 for
fast cross country. Where does a 26 fit in? Somewhere between?!
Choice of wheel size is dependent on what is available. Maybe the
ideal size is 25 inches, or 27, but you have to choose between 24, 26
or 29 because those are available. Is 26 the ideal compromise, or is
it neither fish nor fowl?

My MUni is a 26. If I replaced it, it would be with a 24 with a fatter
tyre, I think. The fat tyre makes the effective diameter nearer to 26.
But then a fatter tyre on a 26 would make it a bit nearer to a 28!

More tyre choices available for 26 than the other two sizes.

Buy one of each!:D

[john_childs]

Post by The Bruiser
would a 26er make much of a difference over a 24er for XC?

It really depends on the type of XC you plan to do and the type of
trails you plan to ride. Different areas of the country have different
style of trails and different people have different preferences for how
they ride (aggressive vs. speed). So what's great for me or someone
else may not be what is best for you.

If you like speed, ride buff trails and don't do much hopping to
maneuver on the trail then a 29er would actually be the choice for XC.
If you like more technical riding, rocky or rooty trails, and need to
hop to get over logs then a 24 with a fat tire would be the choice. A
26" XC wheel is kind of the odd size out now. The 24" beats it for
maneuverability and hopability and the 29er beats it for speed. If you
go for a 29er for XC get something with the KH 700c rim. Nothing else
is wide enough to make for a good XC muni wheel.

So it depends on the trails and your riding style. If you do some of
both then get both the 24" with a fat tire and a 29er. Then ride the
one that best fits the ride you want to do that day.
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[Loosemoose]

I have a 26" Muni, which I use exclusively for all my Muni/Offroad
stuff, and it's always seemed to me to be a more capable machine than
the 24" I used for the 2 years previously. Maybe its my high strength,
but I can use my much heavier 26 for all the technical stuff I did on
my 24, and on sketchy stuff (wedges between rocks, dropping onto edges,
riding in channels) it performs much better and is much more
predictable. I've got a LM rim on mine, which increases tyre stability
somewhat over a 'standard' 26.

I'm more than happy with mine, and would have no qualms in recommending
a 26 to anyone who wants to do muni. For someone with a lighter build
(I'm 6ft, 190lbs) it might restrict technical maneuverability, but I
think its something you get used to rather than something that holds
you back.

Loose.
--
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[plumsie]

I have got a 26" muni and think it's great, I find that 24" uni's seem
slow and unstable by comparison.

I definately reccommend 26" as a size for muni, it might be heavier but
it's not an issue unless you are doing insane trials type stuff.

I always wonder why more people don't ride 26's as there is a better
availability of parts and a wider variety of parts. it seems that 24"
became a sort of standard size for uni's at some point in the past so
people are sticking with it for the sake of it.

[Mikefule]

I guess 24 has become a "standard" largely because of Kris Holm's
influence. The KH24 seems to be a benchmark Muni. (I say that based
on what I've read here, not on what I've seen.)

Another problem with 24s: pedal strike. Given similar tyre sections
and cranks, on a 26 a rock needs to be an inch higher before your pedal
hits it.

On the other hand, if you choose cranks according to your leg length
and riding style, then the 24 will be lower geared and it makes a real
difference to control on steep downhills.

[Mikefule]

I do mostly longish fastish cross-country riding...
So I find the 26" to be a good choice for my riding style, but then I'm

Or maybe that 12 that I saw in Nottingham the other day, then I might
keep up with you.:p

[rob.northcott]

I was meaning "ish" in comparison to the likes of Joe Marshall. But
thanks for the ego massage :D

Rob

[phil]

Ooo, this is convenient. I was thinking the same question the other day
on taking the muni out on the Malverns. A lot of tracks up there are
rather narrow with raised shelves of grass either side; excellent pedal
strike territory. These sections generally coincide with bits with a
very large drop off to one side or a hill so steep you would have a
very long walk to get back up to the unicycle, if you still had enough
unbroken bones to do so. Being somewhat unwilling to launch myself off
a cliff I ended up riding very slowly and cautiously, dismounting on
bits that without the drop would be excellent fun.

My muni is a 24" with 165mm cranks; if there was a perfect muni for
avoiding pedal strikes this isn't it. Presumably a 26" would be
better?

Phil

[rob.northcott]

I ride a 26x3" muni (with 152mm cranks) and I'm very happy with it. I
do mostly longish fastish cross-country riding, and I've thought about
a 29er a few times. But there are some very rocky sections on the
routes I commonly ride and I'd be afraid of pranging the rim without
the big 3" tyre, although a 29er tyre would probably be fine in
practice. I haven't ridden a 24" muni much so I can't really give a
direct comparison, but my 26" does seem to pull away from people on 24"
wheels quite significantly on anything but steep or technical climbs -
I suppose it goes an extra six inches for every pedal revolution, so
that's pretty noticeable in absolute terms even though it's less than
10%.

So I find the 26" to be a good choice for my riding style, but then I'm
probably somebody who should be riding a 29 :rolleyes:

Rob

[plumsie]

So I find the 26" to be a good choice for my riding style, but then I'm
Rob

With a 3" tyre on a 26" uni the total diameter is about 28" and so
riding a 29" uni would probably make very little difference to speed.

I compared my 26 with someone's 28 at crawley last year and found that
the total diameter was exactly the same.

Tyre choice makes it as versatile too as I switch between the 26x3"
duro and 140 or 170mm cranks and a 26x2.5 hookworm with 125mm cranks so
it's great for fast trails, muni or commuting.

The 26" is a great all round uni and I would recommend it to anyone.

Pete

[rob.northcott]

Post by plumsie
With a 3" tyre on a 26" uni the total diameter is about 28" and so
riding a 29" uni would probably make very little difference to speed.

Yes, a 26x3 is 28" overall diameter. But the big fat downhill tyre is
much heavier than a 29er. It's probably not much different top-speed
wise, but less weight to lug up the hills, so journey speed should be
higher. That's what makes me think a 29er would be good for my riding
style. But the 26 is a very good all-rounder.

Rob

[johnhimsworth]

I'm always curious about this idea that a 24x3 is the same diameter as a
26, and a 26x3 is the same as a 29. Maybe if the tyres are hugely
different in size, but for something like this they won't be. a skinny
tyre on a 26 might be the same as a 24x3, but that isn't really
relevant - the question here is a big fat 24" tyre or a big fat 26"
tyre. Even where the 26" tyre is smaller, there is a difference. The
24x2.6 wheel on my muni is noticeably smaller than the 26x2.1 wheels on
my bike, so I'm always curious about everyone saying they're the same.

Apart from anything else the air volume is very significant for muni.
If you're talking about riding that can be done on a 29er, then that'll
be faster, but I can think of lots of riding that while the extra bit
of speed is nice, is still very technical and a big tyre is nice to
have. Just because you're rolling not jumping doesn't mean there aren't
any big rocks.

John

[rob.northcott]

Post by johnhimsworth
I'm always curious about this idea that a 24x3 is the same diameter as a
26, and a 26x3 is the same as a 29.

The 24" or 26" for bike wheels is quoted as a nominal outside diameter
for the size of tyre considered "normal" for that rim, rather than the
method used for car tyres where they quote the rim diameter. A
"normal" tyre for a 26" mountain bike wheel is something like 2", so
using a 3" downhill tyre adds two inches to the overall diameter. So a
24" rim with a 3" tyre is actually something like 26" diameter, and a
26" rim becomes about 28" diameter. A "normal" 700c tyre is much
skinnier, ending up at about 28" diameter the same as a 26x3". A 29er
700c tyre is a bit fatter (700c x 2"/50mm?).

But I agree with you that a big voluminous tyre is good for muni even
if not hopping - that's the main reason I've not swapped my 26x3 for a
29er, for fear of pranging the rim on rocks all the time.

Rob

[pdc]

I've got a lightly used 26" Profile Yuni I'm considering selling.

[johnfoss]

Post by johnhimsworth
I'm always curious about this idea that a 24x3 is the same diameter as a
26, and a 26x3 is the same as a 29. Maybe if the tyres are hugely
different in size, but for something like this they won't be.

Maybe, maybe not. The problem here is, people toss around tire sizes as
if they are exact. They're not. My 26" MUni has almost the exact same
tire diameter as my 24" MUni. It very much depends on the tire. So if
one doesn't include the tire width in one's description or question,
it's hard to answer.

All things otherwise being equal? Bigger is faster, but also heavier.
And also a little weaker/prone to tacoing. I like faster, but the rim
on my 29" is a little too skinny for the tires I've been running on it,
so I've run into a couple of very inconvenient tire failures far from
the car. By contrast, my 24" (with 3" Gazz) is nearly indestructable,
and I never have to worry about the same problem. But it's slower.

A 26" Gazz on a strong rim is really heavy, but probably very strong.
Rotational weight is always the least desirable kind, but if speed is
more important, go bigger.
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[rob.northcott]

Post by johnfoss
A 26" Gazz on a strong rim is really heavy, but probably very strong.

People keep coming up with that one. Surely a 26" wheel and tyre is
only 8% heavier than a 24" with the same type of tyre. And that's
ignoring the weight of the hub and cranks, which is constant whatever
size rim you use - which gives an entire 26" wheelset actually a
slightly better weight/speed ratio than a 24" (I know this is
over-simplifying things for real-world performance, but I'm just making
a point).

You can't have it both ways:
"It's only slightly quicker"
but "It's really heavy" :p

Unless the 26x3" downhill tyres are a thicker heavier construction than
the 24" ones - I suppose that could be true.

Rob

[U-Turn]

The 26x2.6 and 24x3 Gazz tires are the same weight (manufacturer's
numbers). Presumably this implies that the tires are also close to the
same volume. I don't have the diameter measurements handy at the
moment.
--
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[Mikefule]

Post by rob.northcott
"It's only slightly quicker"
but "It's really heavy" :p

Various applications of the words "quicker" and "heavier".

Quicker as in higher speed, or quicker as in more responsive -
responding faster to rider input.

Heavier as in more dead weight, or heavier in the sense of more
rotational inertia.

The 26 tyre will be around 8% heavier in dead weight terms (all other
things being equal). The rim will also be about 8% heavier.

But the weight of the tyre is about 8% further from the centre of the
hub. Put crudely, that makes the rotatinal inertia about 1.08 x 1.08 =
1.16 as much which is alomost a sixth as much again.

So the bigger wheel accelerates more sluggishly, and brakes less
eagerly. That's why Cokeurs (and Cokeuses) find that a lighter inner
tube alone is enough to make a significant difference: the weight and
the radius are both factors.

On the flat at constant speed, the effect of the bigger wheel (26
rather than 24) will be to make the speed only 8% higher -at a given
rpm-. On a ride where there is a lot of acceleration and deceleration
(including climbing and descending under control) the effect will be
more noticeable.

[rob.northcott]

That all makes sense Mike. Fair enough. I said I was over-simplifying
things :o

But more rotational inertia should make the ride smoother and therefore
easier to maintain high rpm...

OK, I'll give up now. I like my 26 anyway :D

Rob

[Mikefule]

Post by rob.northcott
But more rotational inertia should make the ride smoother and therefore
easier to maintain high rpm...

That is perfectly true at a steady speed on flat or only slightly
uneven ground. :) That's why the bog standard Coker is so easy to
ride, but the Road Razor requires concentration.:cool:

(Road Razor: the skinny 700c)

[joemarshall]

Post by johnhimsworth
I'm always curious about this idea that a 24x3 is the same diameter as a
26, and a 26x3 is the same as a 29. Maybe if the tyres are hugely
different in size, but for something like this they won't be. a skinny
tyre on a 26 might be the same as a 24x3, but that isn't really
relevant - the question here is a big fat 24" tyre or a big fat 26"
tyre. Even where the 26" tyre is smaller, there is a difference. The
24x2.6 wheel on my muni is noticeably smaller than the 26x2.1 wheels on
my bike, so I'm always curious about everyone saying they're the same.

Like John says, my 26x2.6" is just under 2" wider in diameter than
John's 24"x3". My 29x2.1" is over 2" wider in diameter than the
26x2.6". Even the 26"x3" is nowhere near as large a diameter as the
29er tyres people are running. All this talk of them being the same is
weirdy stuff.

Joe

[U-Turn]

Tire volume and outer diameter are different things. I have to take
some measurements to do the math for the volume of an approximately
torical space for the two setups.
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