Trying some shorter cranks - First impressions

I'm surprised that the difference in torque was noticeable in most
circumstances. It's only about 8%. From my bicycle touring days,
that's about half a gear. On the other hand, you do ride on steep
rocky trails so every little helps. You're a tall bloke, so maybe the
longer cranks suit you. I couldn't possibly ride on 165s - I'd bang my
knees on my chin. I gave away my 170s.

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Mikefule said:

I'm surprised that the difference in torque was noticeable in most
circumstances. It's only about 8%. From my bicycle touring days,
that's about half a gear.

It surprised me as well Mike - I wasn't expecting it to be very
noticeable. In fact, I have even seen posts from people who reckon
they find it -easier- to climb hills on shorter cranks, because of
extra smoothness. I'm suspecting that some of the steeper climbs that
I commonly ride (mostly road, like the one we went up on our ride a few
weeks ago and the very steep bit on my route home from work, about 1:6,
possibly 1:5 for a bit) will cross the line between hard but possible
and walking, which would be a shame.

I do suspect that 165 may just happen to be well suited to my legs and
riding style. But I'm going to keep the 152s on for some time and see
what happens. I'll ride it to work next week and see what happens on
those hills.

Rob

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With shorter cranks, you will "stall" sooner. By stalling, I mean
reaching the point where you simply cannot apply sufficient force to
the pedals to propel the unicycle up the hill. However, on a long hill
that is not steep enough to provoke a stall, the smoothness of the
shorter pedal stroke can help. So, shorter cranks are better up to a
point, then worse after that same point.

This is a wild and woolly generalisation.

I did that ride with you on 150s (or 152s, which is as near as dammit
the same) and you were way faster on the climbs - but I find it
impossible to make progress on longer cranks, so it is clear that skill
and fitness play a massive part. I am disappointingly unfit for a man
who fences two nights a week and dances one night, in addition to
unicycling.

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Well, today was the first real test of the new cranks after a couple of
rides to get used to the feel. I rode to work this morning on my
normal route and... was quicker than I had ever done it before.

My time was just under an hour (can't say exactly because the GPS got
turned off in a UPD near the end 🙁, but something like 58 minutes).
The fastest I had ever managed before was 1 hour 3 minutes, so probably
took five minutes off the time, which is a quite significant 8%.
Average speed was 8.8mph and top speed 13.6 (that was only a very short
burst on a nice safe bit of smooth track, but still faster than I've
managed before).

It wasn't all good though - my legs were suffering coming down the
steep road hill in the middle, and the soft slightly undulating grass
at the end felt like riding through treacle and resulted in two UPDs,
one of which I had to roll out of (so I was doing a fair speed) and
must have been when the GPS got turned off (I haven't fallen off there
for ages, but it has always felt a bit sketchy and on the edge of the
control envelope).

So, not bad so far. I'll see how it goes on the way home, when I've
got to go UP that steep hill. I think that's where things may not be
so good...

Rob

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Thanks gents for the thoughtful discussion. I put 140s on my KH24 a few
weeks ago, reduced from 170s, and I put 125s on my 36", down from 140s.

Just a couple more observations, some of which may be unique to my
riding style. I ride very high in the saddle. Also I was a
competitive long distance runner which means lots of knee lift is
unnatural for me. And I am a bit over 6'1" tall.

Adjusting - The adjustment period is a bit trying. I find that my feet
slip off the pedals periodically on the MUni. It's taking some fiddling
to get the seat at just the right height.

Long climbs - I find that long climbs with shorter cranks don't punish
me in that same gasping, breathless way as I experience with the longer
cranks - esp. the 170s. It seems I'm chunking up bits of lung just get
enough air with longer cranks. I'm smoother with the shorter ones.

Descents - I find descents are a bit easier with the shorter cranks in
two respects. First, it's easier for me to keep up with the spin with
the shorter crank. Second, lighter / less back-pedaling is sufficient
to maintain control. Ergo, I can go faster with the same level of
control. This is especially true on the 36" with the 125s, but also
true for the KH24 with the 140s. (I'm sure there is a point of
diminishing return here, which I certainly found on my 29" with 102s -
speed but no control.)

*Very* steep climbs - Of very course, steep climbs are more difficult
on both, but I can manage them on pavement pretty well with the 36" (so
far); On very steep rough terrain, it's sometimes becomes difficult to
maintain the required piston cadence while maneuvering around ruts,
rocks and roots on very technical climbs with the shorter cranks.
Sometimes the shorter cranks just don't seem to cut it. But I'm giving
them -- and myself -- some more time to adjust.

Uphill mounting - Finally, I find uphill mounting to be much more
challenging with the shorter cranks. On the 24" with 170s, I can
usually get started again. I usually do a partial roll to standing with
the KH on uphills, which almost always works. Sometimes with the
shorter cranks, I have to mount facing down, and turn around. Only
once could I just not get turned around; it was on a very steep, newly
dozed mountain road (soft, loose, rocky) - a logging road of sorts.
Again, perhaps with more time...

All in all, I really like the shorter cranks. I'm going to keep them on
for a while, unless a change my riding style dictates a required change
in the cranks again. I have one more ride to try on the 36" with the
125s- one I did with the 140s. If I can manage 'it again'
(http://tinyurl.com/7tzvp), I'll stick with shorter cranks.

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I finally got around to switching from 165s to 140s on my 24 at the
weekend. It felt like a totally new machine. much nicer to ride. over
the past 9 months it's been the least ridden of my 4 unis, I never felt
comfortable with such an exaggerated pedalling action. (I've a 30"
inside leg). Only spent an hour or so mucking about on the local
common, but rode down & hopped up some steps I've never made before &
found some nice little hidden new trails.

Best ride for ages! (pedants who know me may point out that I've been
for 3 rides in the last 3 months)
The Muni may no longer be the 3rd choice for an off-road ride...

--
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I swap frequently between 140 and 170 on my 24" muni, in town for trials
and street riding the difference is un-noticeable after a while, except
the extra speed. On the local BMX track the 140s just don't cut it, the
hills are steep enough that they need to be worked up, you can't rely
on momentum, and the 140s just can't get the torque, the stall point
falls much earlier and means that despite the extra speed i can't get
over some of the jumps with them. Offroad i prefer the 170s (i also
rode 152s for a fair while, just remembered) but then i do have a habit
of doing shorter rides with very steep hills in them.

--
kington99

Dave

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kington99 said:

I swap frequently between 140 and 170 on my 24" muni

I'm thinking that's what might end up happening. The 152s seem to be
working out quite well for my trip to work (although I'll have to see
how that steep road climb works out later...), but it's all fairly easy
surfaces with nothing very technical - in fact I may even be better off
with a lightweight 29er or something on that route rather than my heavy
26x3. But I do sometimes (try to) ride rougher stuff and then I think
I would really miss the bit of extra torque from the 165s. Swapping
cranks often is not too healthy on a square taper hub though... I'll
stick with the 152s for a bit unless I'm planning on trying some really
steep stuff.

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Yes i was going to say don't do this on a square taper hub, I have old
skool KH and they just slide on and off, dead easy to swap around 😄

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Dave

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rob.northcott said:

I'm thinking that's what might end up happening. The 152s seem to be
working out quite well for my trip to work (although I'll have to see
how that steep road climb works out later...), but it's all fairly easy
surfaces with nothing very technical - in fact I may even be better off
with a lightweight 29er or something on that route rather than my heavy
26x3. But I do sometimes (try to) ride rougher stuff and then I think
I would really miss the bit of extra torque from the 165s. Swapping
cranks often is not too healthy on a square taper hub though... but
I'm more of a cross-country rider than an agressive jumpy-droppy
munier, so I'll stick with the 152s for a bit unless I'm planning on
trying some really steep stuff.

Of course what I -really- need is a 29er for fast cross-country and a
24" muni with longer cranks for rougher stuff, but I can't really
justify the expense at the moment, so the 26 will have to do as an
all-rounder 🙂

You just finished justifying the expense!

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I swap cranks on my unis from time to time, and they all have square
taper hubs. It has never caused a problem. I do the job carefully,
and don't overtighten. I estimate that I have changed cranks:
4 times on the Coker
4 times on the MUni
A dozen times on my 20.
A dozen times on my 28.

That doesn't count times when I have removed them to get at bearings,
or to spread the wear patches on the tyre etc.

In fact, it's a fairly routine job for me.

But then, I'm from the Wheels Are Round For a Reason School of
Unicycling.

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OK, removing and refitting cranks a few times isn't too bad.

My ride home from work today wasn't very enjoyable at all on these
cranks 🙁
I survived the soft humpy grass bit on fresh legs, and made it most of
the way up the steep road hill - in fact I think I could possibly have
made it to the top, but a car came up behind me and forced me to
dismount and let it past (it's a very narrow road). At the top of this
climb is another steep grassy climb that I've never made more than half
of, then a long flatish gravelly path along the old railway line where
I usually ease off a bit to let my legs recover for the next climb.
Today I didn't have that choice - it was sprint or trip on every stone,
felt like really jerky progress. Really draining, physically and
mentally. By the time I got to the top of the last climb (walked, no
energy left) it's usually just an easy cruise home the last mile or so
on the flat, but today I kept UPDing and hardly had the energy to
remount. I arrived home absolutely knackered. The time was actually
quite respectable, even slightly quicker than average, but it was just
not enjoyable.

No points to the 152s tonight then. I'll keep trying though... but at
the moment I suspect I'll be going back to the 165s in the end.

Rob

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But on the plus side, at least I feel better about struggling to keep up
with you on my 152s.:p

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No, but I carry a heavy spanner.
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Mikefule said:

I swap cranks on my unis from time to time, and they all have square
taper hubs. It has never caused a problem. I do the job carefully, and
don't overtighten. I find the more recent bolt-into-the-axle hubs a massive improvement in

this regard; there is loads of thread to engage, enough length to avoid
cross-threading and you can really clamp them down without fear of
damage. Older hubs with little nuts onto about half a centimetre of
thread on the axle were a different matter, though... I stripped
several of these; it was a severe pain in the rear how easily some
tiny, weak and vulnerable little flanges of metal could wreck the hub
and make you have to rebuild the whole wheel.

I now change cranks on the 29er with reckless abandon - occasionally
I'll change the cranks more than I actually ride the blummin' thing,
generally due to preparing for rides I never get round to doing - but
before I avoided crank removal as much as possible.

Phil

edit: spalling misteks...

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rob.northcott said:

The time was actually quite respectable, even slightly quicker than
average, but it was just not enjoyable.

No points to the 152s tonight then. I'll keep trying though... but at
the moment I suspect I'll be going back to the 165s in the end.

I found exactly this the first time I rode my old commute on a coker, I
couldn't get up hills I could easily get up on the 29er. After a couple
of weeks of getting used to the coker on hills again, I was riding them
every time, and faster. Similarly, when I swapped down to 110 cranks on
the coker, I couldn't get up the one really steep hill for a couple of
weeks, but then magically my legs got stronger and it was back. I think
on the coker it took about 300 miles to get the strength up.

Joe

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Just thought I'd dig this old thread up and add an update. The 152s are
still on my muni and now I've got used to them I think I do prefer them
to the old cranks (165). It's definitely a bit more effort climbing
steep hills, and it can be a bit wiggly at top speed on the road or
smooth trails (possibly because of the extra Q on the new cranks) but I
am generally covering ground faster than I was with the 165s (it's
instantly taken a good five minutes off my ride to work) and I've been
glad of the extra half inch of ground clearance a few times. The extra
Q also means that the heel-strike problem is gone.

So overall I think it has been a successful swap for me. One place I
still think longer cranks would be better is for rough uphills, but
I've never been any good at slow tractoring anyway - I tend to use the
brute force and speed approach.

Rob

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