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Different cranks on a 24in uni

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  • Mikefule
    replied
    Originally posted by nickgauntlett View Post
    Hi All,
    I think the topic on how different crank lengths effect Speed has been worked to death. However my question is very slightly different.
    What I was hoping to find out how many more mph can get from switching from a 150mm to a 100 or 125 on my 24in muni.
    The hope being is my current financially strapped time I can use my 24inch for 5-10miles rides and make this possible by swapping back and forth from the normal 150 to a smaller size depending on whether I’m riding for distance or my usual woodland/hill rides
    This is the original question.

    There is a reason why there is a minimum crank length in 24" unicycle racing. Riding flat out, shorter cranks are faster. However, in mixed riding, it is less simple.

    A true 24" diameter wheel has a circumference of just over 75".

    A brisk cadence of 100 rpm would give you a speed of about 8.4 mph.

    A change that gives you a 10% improvement would add 0.84 mph to your speed.

    My point here is that you can optimise crank length for your desired riding style, but a small percentage of a small figure is a small amount.

    If you want to go faster, you can do this with equipment (shorter cranks) which will entail a compromise elsewhere (slower acceleration, less control) or wit technique (learning to spin faster).

    Truth is, you can only find your own personal best compromise by experience.

    Somewhere around 110mm to 125mm gives you a fairly fast "gear" on a 24, without too much loss of versatility.

    Leave a comment:


  • saskatchewanian
    replied
    Originally posted by finnspin View Post
    I don't know any quick release seat clamp that is worth it....
    The Salsa Flip-Lock is a good one. I have them on almost all my unicycles.

    Leave a comment:


  • finnspin
    replied
    I don't know any quick release seat clamp that is worth it. I have the Nimbus one on my Muni, and if you want it nice and tight, it's usually more annoying to use the "levers" and easier to just use it with an Allen key.

    Most people don't change the pedals to a different hole mid ride, so I think just a regular seat clamp is fine. You are already getting the tools out of your backpack to change the pedals over, may as well use them to adjust the seat height too.

    Leave a comment:


  • nickgauntlett
    replied
    Thanks guys, great advice, I do have a quick release however I think it maybe the wrong size (slightly too small) it’s a old KH are all KH quick release the same size ?

    Leave a comment:


  • ruari
    replied
    I have the VCX+ three holed cranks on my 26" (one size up) and I really love them. I must admit I spent the vast majority of my time at the 100mm setting but it is nice to have the others as I sometimes (not this year) have to deal with snow and changing the position improves traction and control, at the expense of speed.

    Originally posted by Nasher View Post
    Speaking as a 65 year old pensioner, who regularly rides 10 miles on a 26" muni with 165 cranks and has recently managed 10 miles on a 20" giraffe, may I suggest that, as you are on a budget, rather than spend your money on different cranks, you use whatever equipment you have and work on improving your fitness, technique and stamina

    Wouldn't cost anything but your time
    165mm, Jeez... I don't know if I would ever get to the speeds I can comfortably manage with 100mm if I had to use 165mm. My 26" also came with 165mm cranks originally but if I had kept them and tried to get up to my current speeds, I suspect I would still be working on it (years later). I think it took me less than a week to start to feel very comfortable on shorter cranks however, and I got a good speed boost almost instantly. Keep in mind that speed increase was clearly nickgauntlett's goal, given he asked how much faster shorter cranks would allow him to go.

    Of course, using smaller cranks doesn't change the number of revolutions you have to do but it does make it easier to do those revolutions. You also can't keep cutting crank length and gaining more speed. I tried 89mm as well but anything gained on speed on the flat was lost on hills and less control meant a UPD was more likely.

    In my mind, a nice set of triple holed ISIS cranks are a good investment as well because they are cheaper than 3 sets of cranks, you can adjust length easily and being ISIS you can transfer them to another unicycle in the future.

    I also want to second saskatchewanian's suggestion of a good quick release seatpost. I would also suggest you mark the seatpost with your 3 positions (or use a seatpost with measurements down the back) so that you can make those adjustments even more easily and quickly.
    Last edited by ruari; 2020-02-12, 11:47 AM.

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  • saskatchewanian
    replied
    I will also agree that 100/125/150 should be a very good choice for trying out different sizes and drastically change the nature of your unicycle between settings.

    I highly suggest getting a good quality quick release seatpost clamp to go along with it as you will want to adjust your seat every time you change petal positions.

    Don't take that chart too seriously. The numbers are math based and show the effective gear ratio between the radius of the tire vs the radius of the cranks. The categories on the other hand are subjective based completely on my experience at the time that I made the chart.

    Leave a comment:


  • finnspin
    replied
    100-125-150 sounds pretty good to me. I don't expect you to use the 150 hole much, but 125mm and 100mm both sound about right for what you want, and gives you some choice.

    If you do eventually upgrade to the 29" in the future, it's also a good size for that, and you could potentially swap them over to that uni at that point.

    Leave a comment:


  • johnfoss
    replied
    Actually those 100-125-150 cranks should be pretty cool. Ride the 125s for a while, but then give the 100 holes a chance. With a smooth tire, at least, you will really enjoy them on the road, once you get used to them. 125 is the size used for Track racing, and good for a wide variety of riding. Also can be fun for fast Muni if the trail isn't too technical. Enjoy!

    Leave a comment:


  • nickgauntlett
    replied
    Thanks John for your view.
    In regards to your question, I have maybe the very original KH 24 frame that kris made, it has one of those KH fusion thick seats. It did have the original 8splined hubs/cranks but have replaced it with a nimbus isis hub. As of yesterday I decided to get nimbus vcx cranks 100-125-150, which since reading the recent posts sounds like they maybe the wrong size to what others recommend. Was originally going to put that money to a new 29er but savings were going forward 2 steps back 1 so decided to upgrade the current uni instead

    Leave a comment:


  • johnfoss
    replied
    Originally posted by slamdance View Post
    Guess what, the longer cranks with more mass going up/down helps to stabilize you.
    That's an interesting point of view. With the legs doing a larger range of motion, it should be more of a destabilizing thing. But if your topic is Muni, there may be something to that, as having a "wider stance" on the pedals not only helps with leverage, but also gives you a larger "step". Your feet can be farther apart, which can help with stability/control on the chunky stuff.
    Originally posted by slamdance
    If you are already experienced with different unicycle wheel sizes and cranks it's no big deal, but the first time you do this it is a big deal. Like most of use we "forget" that learning experience. Good luck.
    Yup, so true. My "size flexibility" is not what it once was, when I was always jumping from one uni to another. Currently 90+ percent of all my riding is done with 150 cranks, on 26" and 36" wheels. I jumped onto a 20" with 89mm cranks the other day, to be in a picture with the two girls that ride them in the Cirque du Soleil Amaluna show (the Sakaino sisters from Japan; excellent show!). I hadn't thought about the cranks, just that the seat was going to be really low. The short cranks made me look/feel like a beginner rider for a moment, even with them holding me up (on their unis). One of these days I've got to try those out on my Freestyle uni -- which I hardly ever ride...
    Originally posted by Setonix View Post
    Thought it could be cool to see how much side-wind I could take before falling off.
    Sounds like you want to try the "bitch-slap" test. It can be surprising with sudden gusts!
    Originally posted by Quax1974 View Post
    IMHO the distance you’re looking after is totally doable without changing to shorter cranks.
    But shorter cranks will make you faster.
    This is true. But riding a 24" with 150mm cranks on anything smooth is basically a waste of energy. That's just too long, even for light Muni.

    Nick, what I didn't read in your posts was whether or not you have an ISIS crankset. If it's a Nimbus, you probably do. That means the cranks are going to be more pricey than square taper, a factor to consider. If you do buy some cranks, I would recommend the KH 117/137s. You get a decently short size for the road, and a fast size for all but the most challenging of trails. I used to use 145s on my 24" Muni, which had a Profile hub (and no brakes). That size was a great compromise between speed and leverage, for me.

    But those cranks are $120 US (and out of stock), so your other option is to buy a less-expensive 24" uni to ride with the wife & kids, and set it up for comfortable Road riding. Maybe start with a bigger wheel also, like 26 as a compromise. Then try 102mm cranks, unless your area is hilly. They're not too short. I once raced a marathon (mostly flat) on a 36" with 102s.

    Your cheapest solution is to buy another tire, but like you said, changing the tire is a pain if you want to do it frequently. So if you don't have square taper cranks on your current uni, I'd just save up for a road machine, and be extra happy being able to ride them both without needing tools.
    Last edited by johnfoss; 2020-02-10, 08:46 PM.

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  • nickgauntlett
    replied
    Awesome advice on high plus highly encouraging, not too fussed about getting high speed just quick enough to keep up with my 9yr old on a bike with minimum exhaustion
    Summary is by the sound of things is, anything is possible with enough training

    Leave a comment:


  • Quax1974
    replied
    With my 24” Muni with stock 145 mm cranks I made hilly road rides up to 13 miles at a speed around 6 mph with a a heavy Duro Wildlife Leopard 3.0 Muni tire.
    This is without spinning “fast”.
    Only on my first outing with a group of really experienced riders I have seen what fast spinning is.

    I tried 125 mm two times and first couple of minutes it felt quite weird but quickly it became clear that I could ride at higher cadence.
    Since both rides were part of group training with frequent stops I did not get a higher average speed.
    I switched back to 145mm because I was preparing for a hill climbing event and wanted to train in the correct set up.
    Since the event I’ve been riding the 27.5 Muni but I did replace the stock 145 mm cranks for 136 mm.

    IMHO the distance you’re looking after is totally doable without changing to shorter cranks.
    But shorter cranks will make you faster.
    And eventually you’ll be able to climb at 24.125 mm as well

    Contrary to what I often read on this forum I found the shorter cranks easier to mount.
    Perhaps because I have a lousy free mounting technique with too much weight on the back pedal.
    In my case that means that the lower leverage of the shorter crank is a plus.

    My local climb that I started uphill practice on:
    Distance: 0.9 km
    Avg Grade: 5.6 %

    Initially at 24-145 I could not make it to the top due to my legs burning up.
    After some training I could make it several times in a row
    And eventually I could easily ride it several times in a row at 27.5-136

    Some math, from the crank ration tables (My own version of the table includes also 27.5” wheel size)
    24-145 has a gain ratio of 2.10
    24-125 has a gain ratio of 2.44
    27.5-136 has a gain ration of 2.57
    The table suggests you can go up to 3.6 for hilly road riding.

    Leave a comment:


  • Setonix
    replied
    Originally posted by Nasher View Post
    But I must thank you, as you have just given me an idea for my next ride - 10 miles on my 20" uni - just need storm Ciara to die down & it'll be my next ride - can't wait!
    I was a pity I got home after dark last night with the family and then we had to eat and all, but I seriously thought of riding around with the storm picking up. Thought it could be cool to see how much side-wind I could take before falling off.

    Leave a comment:


  • BruceC
    replied
    Originally posted by Pinoclean View Post
    Experience definitely makes a difference. The better you are at riding the more you adjust easily to the change.

    .
    I've always been really bad at swapping between unicycle sizes and even cranks on the same uni. 29 to 36, 36 to 29, 36/150 to 36/127, 29 to 24...., 36 to 19 ahhhhh !! Couldn't ride properly for the first 20 minutes, and then took a week to get accustomed again.

    Mounting of course suffers, but so does turning, especially tight turns, rough ground and a combination of all. Steep hills require different techniques and feel for different wheels/cranks.

    The only solution is practice and attention to your weak points.

    So now I make an effort to swap unicycles and cranks often, try to remember the bits I have trouble with and concentrate on those. One day I'll just jump from one to other without a care, but I suspect by that time I'll be too old to ride.

    Leave a comment:


  • Pinoclean
    replied
    Originally posted by slamdance View Post
    If you are already experienced with different unicycle wheel sizes and cranks it's no big deal, but the first time you do this it is a big deal. Like most of use we "forget" that learning experience. Good luck.
    Experience definitely makes a difference. The better you are at riding the more you adjust easily to the change.

    I ride two different length cranks between left and right and the only thing I noticed when I made the change was that my seat height felt different. Apart from that didn't feel any different to ride.

    Leave a comment:

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