in a recent thread you said about crank size:
Do you do “cross country, mixed terrain, and some road work” all on a single unicycle. And if so, could you please describe it?
Elaborate? Hmmmm? Er…
Firstly, my fleet, by wheel size, crank size and tyre:
Coker, 150, standard Coker tyre
28, 110, 700c road -biased tyre
26, 170, 1.95 (a pure MUni)
24, 89, 1.95 (General purpose uni.)
20 (for tricks etc. only) on 110s.
On the present set up, I keep the 26 as a pure MUni, as it is slow, but good at rough stuff. I might occasionally do a short section of tarmac between sections of difficult terrain. I can never make up my mind whether I prefer 150s or 170s on the MUni.
The Coker is mainly used off road on what I would call ‘cross country’. That’s mixed terrain, with some short sections of tarmac, some surfaced tracks, lots of hard mud tracks, and occasional more difficult stuff. I call it ‘cross country’ rather than ‘MUni’ because it’s mostly in the river valley, where the ground might be difficult, but there are few significant hills. I do ride the Coker on roads, but I am careful about when and where as if things go wrong, it can be dangerous. You’re a long way up, and the wheel has a lot of momentum.
The 28 is almost purely used for road and surfaced tracks, mainly because of the narrow tyre. However, it is surprisingly capable ‘cross country’ and even ‘light MUni’ as long as there isn’t too much mud. The skinny tyre has little traction.
The 24 is the one which, I think, prompted your question. I used to have 102mm cranks on it. The 89s on it at the moment are a bit ‘extreme’ and, whilst good fun, are not necessarily practical.
With 102mm cranks, the 24 will do cross country and light (mainly downhill) MUni. Cross country, the trick is to keep it moving, and rush at obstacles. Keep it revving, because there’s very little torque.
On the road (or good surface) it’s good for about 14 - 15 mph top speed, and will average about 7 - 8 mph for sustained distances. The control is good enough for me to be able to idle with confidence, and if I need to dismount for a junction, it is safe and easy, and there is no danger of a humiliating failure to remount.
So I’ll give as an example I ride I did last year on the 24 with 102s. I parked my car and rode the 24/102 about 1 - 1.5 miles by country lane, then about a mile along a tarmac surfaced private road before cutting across packed mud bridle paths to a river bank. I rode a couple of miles along the river bank (rutted footpath and tussocky grass) then a short difficult section of broken ground until I popped out back on the road.
About 1/2 mile of road, then more riverbank for a couple of miles. From there, I took the country lanes back towards the car, covering several miles of public road. The last few miles were bridle paths and then the final 1 - 1.5 miles were road (in the dark, and displaying lights).
Roughly, that was 15 - 20 miles on a 24, including public roads, bridle paths, broken ground, footpaths, but no significant hills. In my book, that makes the 24 with short cranks a good all rounder.
The short cranks give enough control to ride down steep flood banks (levies) and most hils that I find on public roads. I’ve even ridden up some short but bumpy hills on this combination.
With 110s, it would be almost as fast, and would be that bit more competent on the off road sections. I think it was John Foss who wrote that he’d hit 16 or 17 mph in a short burst on a 24 with 125s.
As usual, a thourough answer. Thanks. That was an increadibly long ride for a 24. I’d say at least a 4 Circus commenter.
Being sometimes slow to catch on…It occurs to me that a good way to virtually expand my unicycle arsenal is simply to get a variety of crank sizes.
The poor man’s Unicycle multiplier.
Unfortunately, my 24 is vintage 1972 with cottered cranks, and everything recently is cotterless. So not everything will interchange, but still a good idea.
I started to take my riding seriously about a year ago, as a result of which I have lost approximately 1.5 stone (21 pounds) so…
My unicycle has shrunk my arse ‘n’ all. 
Seriously, at UK prices, cranks are about 7 - 10 Pounds Sterling, which is, I guess, less than 15 US Dollars. So a 24 inch unicycle with a range of cranks will be versatile and reasonably priced.
Changing cranks on a cotterless set up takes less than 5 minutes. It’s even quicker if each set of cranks has its own set of pedals.
Tip: mark the left fork and the left crank with tape as a fail safe to ensure you don’t inadvertently put the cranks on the wrong side. It’s so easy to do if you work with the unicycle upside down. Strange but true. I ruined a crank like that, as the pedal worked looses and stripped the thread.
You can buy cottered cranks separately, but in a limited range of sizes. I know unicycle.uk.com has some in the catalogue. Try also DM Unicycles. I went to an event last year and Dave from DM had some 50 mm (2 inch!) cottered cranks for sale. 
Swapping cottered cranks is a bit of a pain, and, strictly speaking, you should use a new cotter pin each time, but I doubt if anyone does.
If you wanted to consider this route to budget versatile unicycling, I’d suggest a Nimbus II (Yuni II) as a good cheapish frame, with a flat fork crown in case you want to do clever tricks. It has an aluminium alloy wheel, and cotterless cranks. It’ll come as standard with 150mm cranks. This is IMHO the longest practical length for a 24 (with a normal tyre) as anything longer might catch the ground too often.
A set of 125s will give a fair amount of extra speed but with little loss of control. 110s will be even faster, but you will need confidence to idle or ride on rough ground. 102s are manageable.
89s are very ‘black and white’ - you are either in control, or you’re flat on the floor. There are very few grey ‘nearly moments’ with 89s.
Of course, that leaves open the question of tyres. Skinny tyres are faster on tarmac/concrete, but less comfortable. Fat tyres are slower but more comfortable. You don’t kneed knobbles or deap tread patterns UNLESS you are riding on mud. A knobbled tyre will offer LESS grip and LESS control on a hard surface. Changing tyres takes much longer than changing cranks, so it makes sense to go for something fairly ‘general purpose’. When you find out what sort of riding happens most often, then is the time to specialise.
If you wanted only one set up for all round general use, you couldn’t go wrong with 125mm cranks. I don’t know how good or confident you are, but 110s are a reasonable option if MOST of what you ride is fairly horizontal, even if it’s not smooth.
I’ve never ridden on 140s, but they are only about 7% shorter than 150s, so in real terms, it’s a case of personal preference, rather than a major change.
Re: Mikefule, please elaborate
On Mon, 31 Mar 2003 08:34:55 -0600, Mikefule
<Mikefule.l5tpb@timelimit.unicyclist.com> wrote:
>Skinny tyres are
>faster on tarmac/concrete, but less comfortable. Fat tyres are slower
>but more comfortable.
Check the thread “28” recommendation…" of about 1.5 weeks ago. It
was quite convincingly argued that for unicycle use, fat tyres have
LESS rolling resistance while aerodynamic drag is negligible.
To which I can add, in hindsight, that a fatter tyre on the same rim
increases wheel diameter which makes the unicycle an additional bit
faster.
Klaas Bil - Newsgroup Addict
"You can put a chicken to sleep all by yourself, put it on the ground and tuck its head under its wing for a count of about 100. It will snooze for a couple minutes. "
that makes no sense whatsoever. a unicycle will have more rolling resistance for a given tyre pressure than a bike because of the bigger footprint that come with concentrating the mass over one wheel rather than two.
Adding to the normal rolling resistance of tyre deformation there is a resistance due to the fact that even in the skilled rider the tyre is always twisting, thereby deforming the tyre in another axis. You will also shed the wobblefactor due to large tyres loading up in turns.
Thinking this way it’s even more important to reduce the contact area on a unicycle than on a bike if you’re trying to get rolling resistance down.
To be honest though - my uni with the 27inch x 1 racing tyre is not hugely less resistant than my 700c 29er with cyclocross tyre.
The saving in energy through rolling resistance is certainly lost through having to work harder to correct the balance of the skinnier tyre. The 27 is distinctly skittish and skips all over the tarmac when running fast - probably due to having no give in the tyre and being so light.
Research shows that a set of cottered cranks are $10 at Unicycle.com. Another $2 for the pins and I’m flying Ma!
Heck, I’ll get 89ers and one step up too.
Thanks for the germ, 'fule.