RE: Theory and practice…
> When I realised I had just struggled up a hill which would have been
> achievable on the Coker (with a leverage ratio much worse) I decided
> that the smoothness of medium/short cranks is more important than the
> maximum torque available from long cranks, except in the
> special case of extreme descents.
Or ascents.
> So, the experience is that, never mind the mathematics, a crank length
> that allows a smooth pedaling action is more important. And if I find
> myself needing the leverage, I’ll achieve it by getting a decent off
> road 24.
I certainly never mind the mathematics. They only tell part of the story.
Mathematical calculations don’t remind you that you’re used to one
combination of wheel and crank size, and you’re just trying the new one for
your first time. You’re not being fair to yourself if you don’t give it
several rides to see if you get used to it.
Until recently, I’ve been using 150mm cranks on my 26" MUnis. They were fine
for me, except in technical or steep terrain, though I had “grown up” with
125mm cranks and only felt fluid and fast on them. But most of my MUni
friends would rib me about my short cranks.
Then Steve Howard sent me his aluminum prototype (the one that’s going to be
auctioned at UNICON), with a 24" x 3" Gazzaloddi tire (nominally 26"
diameter) and 170mm cranks. On my first ride with the cycle, I got lost in a
local park and ended up riding a bunch of pavement and smooth dirt to get
home on time. I really didn’t like the cranks. I couldn’t pedal fast without
bouncing up and down!
But I can now. Plus I knew it was possible anyway. I remember sprinting with
George Peck once, him on 175s and me on 150s. I assumed I could easily beat
him. I couldn’t. Over the short haul, I was not able to go any faster than
him. And, in national MUni races in 1999 and 2001, I watched Kris Holm pull
away from me and recede into the distance; him on 170 or 175s, and me on 140
(1999) and 150mm (2001) cranks.
This past Sunday, I rode the Downieville Downhill. We rode about 18 miles,
climbing 720’ and descending about 4900’. Ouch. It’s Thursday now, and I
only just have full use of my legs back. I put 150s on the Steve Howard
cycle, because I had remembered the trail as being mostly easy and
non-technical. I remembered wrong. Most of the first six miles of the ride
had lots of steep rock fields and other plenty-technical parts. Those 150mm
cranks were inadequate. My thoughts after that ride: 150 is too short for a
3" Gazz tire. Between the weight of the wheel and the type of terrain it
belongs on, you need more leverage.
So – here are the non-mathematical factors involved in all this (I might be
forgetting some):
- What you’re used to
- Rider height/leg length
- Steepness of terrain
- Difficulty of terrain
- Personal preference
Traditionally, I am used to 125mm cranks, as they were both on my racing and
freestyle cycles. It took me a long time to get comfortable with 150s on the
trail. Same thing when I went to 170s. I’m 6’ tall, so 170 is a bit less of
a stretch for me. You might also try an in-between size, like 160. Your
local terrain has a lot to do with it. The Sacramento area trails are
not-so-technical, though they have technical spots. But Santa Cruz and the
Sierra trails have a higher percentage of technical areas per ride. I have
to choose a compromise, or have the wrong sort of cycle for part of each
ride. I’m going more toward the technical, because it’s still a challenge
whereas the easy trails are not.
Lastly, personal preference. For this, you have to give yourself a chance
and see if your body adjusts to the new sizes. One ride is not enough to
tell. I would have thought the same thing when I first rode on those 170s.
But I realized it was not a typical ride (trying to hurry back on pavement),
and I had the experience of watching the MUni masters on their long cranks.
My own new MUni, a Wilder, which I had ordered before Steve Howard offered
me his, will come with either 160 or 165mm cranks (I forget). I’ll see how
those work out…
Stay on top,
John Foss, the Uni-Cyclone
jfoss@unicycling.com
www.unicycling.com <http://www.unicycling.com>
“This unicycle is made all from lightweight materials. But it uses a lot of
them.” – Cliff Cordy, describing the very heavy new prototype unicycle he
brought on the Downieville Downhill