I broke down & got a 20" to see if it would make
learning mounting & hills easier.
So far, it hasn’t made either task easier. The shorter
cranks on the 20" seem to make it just as hard to
get up hills as the longer cranks on the 24". Perhaps
there’s a mechanical advantage issue which is as, or
perhaps more, important than the gearing.
most things depend on what you learned on, however you could try longer cranks for hills.
mounting just takes practice, i personly find it esier on a 20" but i’ve been riding just 20"s for a year now.
I started going up steep hills on a 20" before the 24" muni appeared. If it’s flat I don’t think there’s really much difference; the crank lengths make up for the wheel size difference.
What I did find however is that if it’s bumpy the 24" is a lot easier; the 20" is affected more by rocks and lumps that require constant attention while going upwards, where the 24" was less fickle over what it rolled over.
Phil, just me
I have a 24 inch Chrome Torker, and a 20 Stealth Torker. I learned on a 20 inch, but the moment I tried the 24 I was able to do things on it that I couldn’t do on the 20, ie. ride backward and idle. When I got back on my 20, I was able to ride backward and idle right away.
For hills I prefer the 24 because of the added torque of the longer cranks. I use my 20 for hopping practice and such.
I think It’s more a matter of personal preference then anything else.
Daniel
My 20 had 5 inch cranks when I got it, and my 24 had 6 inch cranks (that’s 125mm and 150mm in new money).
The mechanical advantage is identical. 5 inches = 25% of 20 inches; 6 inches = 25% of 24 inches.
Cranks longer than 150mm are an acquired taste. I find the smoothness of 150s more than compensates for the extra leverage of 170s - at least on UP hills.
The 24 is more stable than the 20 - things happen more predictably on a larger wheel - and it is less likely to ‘trip over’ small obstacles like pebbles and pot holes.
The 24 will therefore go up hills better than the 20.
The 20 will be marginally easier to mount. By the time you start worrying about which is the best for serious hill climbing, I would expect your freemounting to be more or less 100% in normal conditions. Mounting uphill is harder, and it may help to mount facing across the hill then turn to ride up.
Re: hill climbing on 20" vs 24"
On Thu, 2 Jan 2003 16:29:54 -0600, phil
<phil.gnh0z@timelimit.unicyclist.com> wrote:
>If
>it’s flat I don’t think there’s really much difference; the crank
>lengths make up for the wheel size difference.
>
>What I did find however is that if it’s bumpy the 24" is a lot easier;
My experience is like Phil’s: if the crank length to wheel diameter
radius is the same, the hill-climbing ability is roughly the same
provided the trail is smooth. (But Mikefule the crank length expert
does not agree.) If the trail is bumpy, a larger wheel will “see less”
of the smaller bumps. However, in Phil’s case his 24"x3" is sold as a
“large balloon tyre” (quoted from unicycle.uk.com) and his 20" may
have been skinnier. Obviously, a fat tyre helps with bumps as well.
OTOH, a fat tyre generates noticeably more rolling resistance
especially when run at an appropriately low pressure.
hill climbing on 20" vs 24"
I vote that GizmoDuck (a.k.a. Ken Looi) is the authority on climbing paved hills, at least, for his accomplishments on Baldwin Street in New Zealand, the world’s steepest street. I think he used a 20".
Re: hill climbing on 20" vs 24"
Authority huh? Thanks Gluteus!
Most of the roads where I live are about 15-25% grade (a rough guestimate based on the fact that Baldwin St is 38%. The hill I currently train on probably averages 30% and is 3km long. (I grind up there on my 26’ with 170mm cranks.) I haven’t tried this with the 20’ simply because it would take too long to ride up on a 20’. I imagine it would be about the same degree of effort though, provided the crank/wheel ratio was the same, which I don’t think is the case but someone else can do the calculations :o.
But I agree with Mike, you won’t notice much difference until you hit the rough stuff, in which case a bigger tyre and wheel will roll over things easier. However, I prefer to mount straight up the hill with a runup because the extra momentum gets me started. Another thing I find useful is to support all your weight on your arm/handle and to stand up on your pedals like a bicyclist. Alternating between standing vs sitting helps relieve sore muscle groups when climbing.
Keep it turning,
Ken 
p/s
I think Baldwin street could well be ridden on 26’ with 170mm cranks. I was going to try this but my MUni didn’t fit in my suitcase when I went down to Dunedin.
Re: Re: hill climbing on 20" vs 24"
I don’t think I disagree. I don’t think I’m an expert either.:o It’s just that I’ve had lots of fun experimenting with cranks, and the maths is fairly simple.
So, assuming 125mm cranks on a 20, or 150 mm cranks on a 24 and a smooth surface, the hill climbing ability will be similar. Assuming a slightly uneven surface, the 24 will have the advantage. Taller riders will usually get on better with bigger wheels and longer cranks, and the converse presumably applies.
Anyone who doubts that there is more to it than crank ratios needs to consider the thought of hillclimbing on a Coker with 228mm (9 inch) cranks or a 12 incher with 75 mm (3 inch) cranks. Clearly two very different leg movements!