Trying some shorter cranks - First impressions

Unicycles and Equipment
1

With all the crank length discussions revived again recently, I decided to try some shorter ones for myself and see how I get on. I’ve had my Nimbus 2 26x3 for about a year now, and have always used the 165mm cranks that came with it. I think they suit me quite well, but now I’ve put some 152s on it to see for myself what all the hype is about :wink:

I put the new cranks on yesterday (and raised the saddle a bit) and went out for a test ride on some easy forest tracks to see how they feel. I have just done a few more miles of riding today, so in total I’ve probably done about 30 miles on them, not enough to prove anything but enough to get a first impression.

So, what I think so far:

General feel, mounting etc - exactly the same as the 165s. I honestly can’t feel any difference in mounting or “smoothness”.

Top speed - I tried a couple of sprints today on a smooth track and couldn’t go as fast as I could with the 165s (about 2mph slower). Probably not a fair test until I’ve had a bit more time to get used to the new cranks, but the wheel seems to wobble a lot more than it used to at high speed… the new cranks have a bit more Q than the old ones, so perhaps that is a factor.

Foot position - As I said, a bit more Q, so no problems with heel strikes, especially when feet get bounced about on bumpy descents. I like that, but is the extra Q affecting the high-speed stability?

Lack of torque - This is far more noticeable than I expected with such a small change in crank length. It seems more tiring to ride on rough surfaces or up hills, with far more chance of stalling unless speed is kept up.

Ground clearance - A useful extra half inch leeway in single-track and swerving round rocky bits.

Overall, it feels similar to forcing myself to ride a bike in a higher gear than normal - good for developing muscle strength but not very efficient.

Don’t get the wrong idea - I’m not giving up yet! It’s just that the negative aspects of the shorter cranks (mainly the surprising drop in torque) seem much more noticable than the positive ones (no heel strikes with my big boots, less likely to smack a pedal on a rock, oh and they look nice!) at this early stage. I’ll see how it goes after a few more weeks - will I be a convert or will I go back to the 165s?

Rob

2

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.

3

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

4

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.

5

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

6

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, I’ll stick with shorter cranks.

7

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…

8

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.

9

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 :slight_smile:

10

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 :smiley:

11

You just finished justifying the expense!

12

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.

13

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 :frowning:
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

14

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

15

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…

16

I was thinking something along those lines last night - no wonder you were shagged!
I might get used to how they feel, but at the moment I think the 165s may be better suited to my riding style and routes. I don’t actively seek out steep hills, but living on top of a hill does mean I inevitably have to ride up them! And being so used to bikes with 170s (and favouring a highish cadence) means I don’t feel uncomfortable spinning 165s at a fair speed.

Rob

17

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

18

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

19

Ran into this thread whilst researching my own impending swap to shorter cranks and wondered if there was an even more recent update…perhaps even shorter cranks…maybe an explanation of what “Q” is…and “tractoring”…

Thanks for the help. From the thread I started on the topic, I’m thinking I’ll likely try a whole new wheelset (probably the Sun 28") on my Nimbus 26" muni, and swap out with some pretty short cranks (down near 100 mm, methinks). It’s pretty flat here in KS…one big hill between me an campus, but so far I have yet to try to ride to campus anyway.

20

Q or q factor is how far away your pedal is from the wheel. compared perpindicular to the wheel.
tractoring is slowly going up a hill.