crank comparisons

Unicycles and Equipment
1

Crank comparisons.

The story so far…

After over a year of riding a 24x3" muni with 150mm cranks, mainly for getting around town and mild muni stuff; I fit my little used 28-er with a fat tyre.

The comfort of the new tyre distracts me from the loss of control that comes with 125mm cranks and after a few weeks I find myself quite competent on the 29-er with 125’s.

So much so that I order some 110’s from unicycle.com.

The first ride with these I find myself feeling a little unstable and have difficulties on hills, especially downhills.

Today I went out for the second time and things were a little improved.

However, my impressions are that I’m not percieving any noticable improvement in speed or smoothness and that steepish hills are impossible. I also wonder if any improvement in speed would be offset by the loss on hills and in the extra messing around getting balanced after minor bumps etc.

Since this is only the second ride there’s a good chance that these problems will dissapear with more practice, I’m aware that I felt much the same way going from 150’s to 125’s, but now I can definitly appreciate the good points of 125’s.

I’m in a no lose situation because, as xxxxx pointed out, if I decide to switch back from the 110’s to 125’s, they’re going to feel very controlled.

Having read other posts on the subject I suspect I may well switch back, especially as I live in hilly Sheffield and as I like to go off the roads into a bit of mild muni stuff. However I intend to stick with the 110’s a while so I can form valid conclusions.

Getting back from the ride I decided to take my neglected 24x3 muni out.

The difference in the turning circle of my legs after 125/110’s was vast, I could ride ok but my thighs were really having to shift.

Given the mass of human thighs I now understand why riding a muni involves so much sweat, I reckon as much energy must be used in simply lifting and lowering the knees as goes into forward motion of the uni.

On the good side that should make muni riding good for exercise.

I also noticed that there had been no saddle soreness on the 29-er, but a noticable amount really early on with the muni- not massive but the start of something that would be a factor in an hours time.

It occured to me that the large leg turning circle of the muni may lead to more chaffing than on 28/29-ers with smaller cranks.

Half way through I encountered a tricky bit that would be impossible on the 29 and suddenly remembered what the muni was for!

The rest of the ride involved bouncing over rough stuff and going up and down really steep hills; I arrived home drenched in sweat.

I would like to ask a question of those who’ve ridden both long and short cranks- do you reckon that shorter cranks are better for saddle comfort given that there is less rubbing of the inner thighs on the saddle?

2

Re: crank comparisons

onewheeldave wrote:
> I would like to ask a question of those who’ve ridden both long and
> short cranks- do you reckon that shorter cranks are better for saddle
> comfort given that there is less rubbing of the inner thighs on the
> saddle?

I reckon that shorter cranks are better for saddle comfort because with
a smaller, smoother pedalling circle there’s much less bouncing up and
down in the saddle than with longer cranks. That was my experience
switching from 150’s to 125’s on the Coker (I’m now using 140’s, which
give the best of both worlds).

The inner thigh rubbing idea makes sense (and we all know you can’t go
far wrong with a good bit of inner thigh rubbing), but had never
occurred to me before.

–
Danny Colyer (remove safety to reply) ( http://www.juggler.net/danny )
Recumbent cycle page: http://www.speedy5.freeserve.co.uk/recumbents/
“He who dares not offend cannot be honest.” - Thomas Paine

3

The friction thing has to be lower with short cranks. But other than that, crank length is a relatively minor part of saddle comfort.

Danny sounds like he doesn’t have a good “spin” on his longer cranks, causing him to bounce up and down. This can be hard to damp out with real long cranks at high speeds.

Saddle comfort can be controlled much better with a good pair of shorts, a handle or handlebar, and experimentation to find the type/brand of seat that works best with your own personal… crotch. There is no definitive “most comfortable” seat, because different people like different ones.

4

Tadaaaaaaa! Mikefule takes the bait… :roll_eyes:

125s are 17% shorter than 150s.

110s are 12% shorter than 125s.

Thus the step from 125 to 110 is smaller than the step from 150 to 125, so the change should be easier.

But 110s nare 27% shorter than 150s, so that’s a major difference.

Adjust your seat height carefully. At first sight, 110s are 15 mm shorter than 125s, so it would be tempting to raise your seat by 15mm because the pedal is 15mm higher at the bottom of its travel. However, I find there is a general tendency that as cranks get shorter, the amount of seat adjustment decreases. I can’t say more except to warn: do not assume that the standard ‘leg straight, heel on the pedal at the bottom’ is the perfect seat height.

The advantages of short cranks are two:

When cruising on the flat, you can maintain a higher cadence comfortably.

When really going for it, you can hit a higher maximum cadence.

The disadvantages are

Mounting needs more precision

Idling needs more care

Stopping is trickier

Uphills are harder work

Downhills are dodgier.

Practice will improve all of these things. I have ridden reasonably challenging off road on a 28 with a skinny tyre and 110s, and a 24 with 102s (or even 89s).

But there is no sense in going for the shortest cranks you can manage. You need to get used to the feel of the cranks, and learn to feel ‘at home’ on the uni. You need to learn the little tricks of timing, and when to fight and when to let the uni have its head.

The downhill problem is that the shorter cranks allow the pedals to flick past the point of no return much more easily.

I strongly recommend that you persevere with the 110s. On a 28 or 29, they are a fine size for fast smooth riding. 125s for more challenging stuff, possibly. A good handle is worth 10% or more on the length of your cranks.

As for seat induced discomfort, I find that shorter cranks encourage a faster cadence, and this seems to translate into a slightly more mobile lower anatomy, so generally, I get less pressure pain. Chafing shouldn’t be a problem if you wear the right clothes, and you’re not ashamed to adjust your cargo manually.

5

Re: crank comparisons

On Thu, 28 Aug 2003 15:40:18 -0500, onewheeldave
<onewheeldave.sw2mt@timelimit.unicyclist.com> wrote:

>I would like to ask a question of those who’ve ridden both long and
>short cranks- do you reckon that shorter cranks are better for saddle
>comfort given that there is less rubbing of the inner thighs on the
>saddle?

Thanks for the write-up. I’m onto the same as you.

As for the question above: I used to be a victim of rubbing/chafing
until I switched to wearing cycling shorts exclusively (on the uni,
that is). So now I have no chafing whatsoever, on any crank size.
Klaas Bil - Newsgroup Addict

I go a sort of ok speed on my Coker… - Roger Davies

6

I switched from 150s to 110s a few weeks ago, and after some experimentation I’ve settled on a seat hight which is actually lower than before. Basically I was impatient with the slowness of the 150s, and had the seat unnaturally high to reduce knee/thigh bounce.

In terms of control, for me the key with shorter cranks is patience. With 150+ cranks I can correct most any balance problem in a pedal cycle. With 110s, I sometimes need to solve 70% of the problem in the first cycle and save 30% of it for the next one. The tempation is to take an easy UPD at t=0 rather than risk a harder one at t=2.

7

anybody ever make a saddle shaped like a donut? that sound like it’d be comfortable

8

On what axis?

A huge donut shaped saddle with the axis horizontal and parallel to the wheel axle would be comfy for the rider to sit inside. He or she could lean backwards against the inside curve of the donut to relax on the cruising sections. In the case of a forward UPD, or a falling tree branch, the donut shaped saddle would provide good rider protection. On the other hand, the rider wouldn’t be able to see where he or she was going.

9

on what axis? man, how do you eat your donuts? vertical, like those things you sit on after getting butt surgery. except you sit further back on it than that, since it’s not your bum that goes over the hole

10

Two nations separated by a common language. :0)

Over here, a doughnut can be a ring doughnut (which is what you meant) or a jammy doughnut which is approximately circular in plan, with no hole.

My hilariously witty post assumed a ring doughnut was what you meant.

Then there’s the dieter’s donut which sings, “Donut forsake me oh my darlin’…”

11

Re: crank comparisons

johnfoss <johnfoss.sw4pv@timelimit.unicyclist.com> wrote:

>The friction thing has to be lower with short cranks.

What’s a friction thing? Can you please be more specific?

>But other than that, crank length is a relatively minor part of saddle
>comfort.

Ignoring the “But other than that,” part of this sentence:

“crank length is a relatively minor part of saddle comfort.”

Crank length has nothing to do with saddle comfort, except for two
things:

  1. The upper inner thigh rubs back and front against the seat less with
    a shorter crank (smaller circular movement of the foot) than with a
    longer crank (larger circular movement of the foot).

  2. Greater force must be applied to the pedals when attached to shorter
    cranks versus when attached to longer cranks. This force must be
    subtracted from the rider’s weight (force) to get the net weight
    (force) being applied down on the seat. Seat comfort is related to
    that fraction of the rider’s weight that rests on the seat. The
    cranks can be easily made short enough to reduce that weight to
    zero (the rider must apply his full weight on the pedals to ride).
    Clearly, with very sort cranks, crank length is a major factor
    (almost only factor) in saddle comfort.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

12

The friction thing was indeed the extra thigh rubbing which comes from the extra thigh movement with longer cranks.

My opinion is that it is a factor cos most of my saddle pains have been from chaffing rather than pressure ones (which would be affected by your point no. 2)

no.2 is interesting, I’d never thought of that.

13

Ride no.3

Went well, I exceeded a few of my expectations.

With the 110’s more UPD’s, problem mounts and hill difficulties than with the 125’s, but not massively so; I’m staring to feel more at home on them now.

With mounting I’m reminded of some vid clips of the 'Great Unicycle Ride across Iowa (GURAI), where some of the guys were using Cokers with what looked loke sub 125 mm cranks.

There’s a characteristic hesitation at the top of the mount where a little battle to gain control of the wheels momentun takes over.

The secret to the mount seems to be to use a static mount, to slightly push the wheel forward just prior to jumping, to aim solidly for the pedal and getting your weight over the axis; then get your balance and ride off.

These are all things I’d got solid on the muni and it’s transferred nicely to the 29-er, I’m pretty pleased with my success rate and today managed a couple of uphill mounts that I thought I would have problems with.

There was some frustration with pedestrians on the pavement, with the muni it’s easy to hang behind them then hop onto the road, pass them and go back to the pavement.

With the 29 it’s possible to ride slow enough to stay behind, but it doesn’t feel good.

Also I was very wary of going on the road cos I’m still not used to the cranks, but on the couple of occasions I did venture onto some empty ones it was great to open up the speed.

Overall it was a really good ride, not so much in terms of fun but more about interest; it’s great to get this different perspective of the mounts now everything is slowed ride, also to have to think ahead more cos of the momentum of thing thing.

At one point I also felt a distinct pulse, cos the wheel is so much more stable than the muni there was a definite steady foot stroke thing that, at one point, started to feel a little mystical.

I reckon this would be more apparent on a big open road eating up the miles on a unicycle tour.

I’m definitely going to persist with the 110’s and I can see that, if the improvements continue, I’ll not switch back to 125’s.

I’m going to throw out two questions: -

  1. Most of the time I’m not feeling much speed benefit. I know this is partly cos I’m hesitant to fully go for it due to inexpereience and also being next to the road and relectant to UPD.

However I’m wondering how perception relates to reality where speed is concerned on a uni i.e. sometimes on the muni I’d pedal like mad and feel as though I was going really fast.

Whereas on the 29-er I suppose I’;m going as fast when cruising as full pelt on the muni, but maybe don’t feel it cos my legs aren’t frantically pedaling?

  1. What’s the situation with handles for tourers? I’m a little reluctant to switch the Reeder in cos it’s my muni handle.

I’m aware of the double handled reeder for Cokers, but I’m wondering if there’s a handle which projects further forward?

This is because I don’t like the ‘crotch grabbing look’ of the normal handles, especially the two handed ones; also, wouldn’t a longer handle give even more leverage?

Lastly, anyone successfully done a home made touring handle?

14

Check out the unitours web site (www.unitours.org) to see lots of different touring handlebar setups. Though Paul Wyganowski has made a lot of the handlebars shown, most of them seem to be variations of one kind or another.

I have a set that used to belong to Bronson Silva. I’ve mounted it differently on my uni (very low) for a more aero position. Eventually I’ll take what I’ve learned from that handle and apply it to a new one for someone to build me.

Check out my "Misc. MUni and Commuting, 2003 album here:
http://www.unicycling.com/ofoto/unistuff.htm

15

My take on Question #1 is that as you relax more and more on the 110s, you’ll “go for it” more often and be able to spin faster and faster, until you’ll be able to ride fast enough that you won’t be able to run out of a UPD.

Your legs will be frantically pedalling, and you will be going quite a bit faster than on the off-road because a) the wheel is larger, b) you’ll be on a harder surface than typical off-road, c) your tire is less flexy and has less rolling friction, and d) your throw is shorter.

16

I’m not sure I like the sound of that.

17

quote:

Originally posted by U-Turn
… until you’ll be able to ride fast enough that you won’t be able to run out of a UPD.

Onewheeldave replied: <<I’m not sure I like the sound of that.>>

Simple: take your shirt off and rub your belly with lard. You’ll slide further and slow down more gradually.

It’s best to apply the lard before riding, rather than waiting until the UPD appears inevitable.

18

Re: crank comparisons

On Fri, 29 Aug 2003 13:21:26 -0500, Ken Fuchs <kfuchs@winternet.com>
wrote:

> The
> cranks can be easily made short enough to reduce that weight to
> zero (the rider must apply his full weight on the pedals to ride).
> Clearly, with very sort cranks, crank length is a major factor
> (almost only factor) in saddle comfort.

This sounds somewhat hypothetical to me. How short would a crank have
to be to require the full rider’s weight just to overcome friction and
keep the uni going? I bet that such a short-cranked uni would be very
difficult to control anyway.

Klaas Bil - Newsgroup Addict

I go a sort of ok speed on my Coker… - Roger Davies

19

Re: crank comparisons

On Sat, 30 Aug 2003 05:15:58 -0500, U-Turn
<U-Turn.syz1o@timelimit.unicyclist.com> wrote:

>d) your throw is shorter.
U-Turn (or anyone) can you explain what that means please?

Klaas Bil - Newsgroup Addict

I go a sort of ok speed on my Coker… - Roger Davies

20

Re: crank comparisons

klaasbil_remove_the_spamkiller_@xs4all.nl (Klaas Bil) wrote:
>On Fri, 29 Aug 2003 13:21:26 -0500, Ken Fuchs <kfuchs@winternet.com>
>wrote:

>> The
>> cranks can be easily made short enough to reduce that weight to
>> zero (the rider must apply his full weight on the pedals to ride).
>> Clearly, with very sort cranks, crank length is a major factor
>> (almost only factor) in saddle comfort.

>This sounds somewhat hypothetical to me. How short would a crank have
>to be to require the full rider’s weight just to overcome friction and
>keep the uni going? I bet that such a short-cranked uni would be very
>difficult to control anyway.

Not as short as you may think, especially for 36" and larger big wheels.

Of course, I wouldn’t suggest actually using cranks so short that a
rider’s full weight must be on them to maintain forward progress on
level ground. They should be at least a bit longer to allow for some
slight hill climbing/descending or (de)acceleration without the need to
pull up on the seat or handle. Note that a speed of 20 MPH (32 KPH) or
more may be required to provide enough wind resistance to counter
balance a rider’s full weight on the pedals (perhaps practical on big
wheels only).

However, the argument that crank length is a major factor in seat
comfort (affecting weight on the seat) is still quite valid, unless of
course one chooses to use very long cranks for some (good) reason.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>