Yes I still have MTB syndrome, I’m unicycling only for 2 years now. MTB very rarely now. Should have started unicycling way earlier, so much more fun.
So Ben, don’t you like to Guni? Can you tell me why, I highly appreciate your opinion. Last week I have read the entire Schlumpf general discussion thread, because the idea of a Guni looks very good to me. a few things are holding me back.
price, € 1200, hub only. I would need a wheel, a KH frame and seatpost.
Reliability, should be better at the moment. I will wait how long Terry’s hub will last.
Slop, is it annoying? I used to do miles long wheelies on my fixed gear MTB, but I hating the slop in the chain.
The Hub puts a torque on the frame in high gear, on the bearing holder. Do you feel that while riding?
I want to be a better unicyclist before I reward myself with a Schlumph hub.
Now I have two speeds, to bad they are divided over two unicycles. A 24x3.0 and a 29x2.4. Now have to decide before my ride: do I want to go technical and slow, or do or want to go faster on easier terrain.
It would be so nice to combine two speeds in one unicycle.
Or I could ride one uni, and strap the other one on my back;)
And back to topic: If shorter cranks don’t give me much more speed, a Schlumph hub will. (If I don’t get scared over 20 km/h)
Or maybe a 36er would be a nice challenge for offroad rides.
Like ben said: If your RPM does not get higher, then the wheelsize must be bigger.
Okay, so if you have read all the guni posts, you probably know that I’m not a huge guni fan. Granted, it is an amazing piece of engineering and it is the only way to gear up a uni, BUT it has a singular downfall:
The 50% step is too tall.
I find that riding a guni off road is a bear in high gear. I don’t know about a 24 or 29, but on my 26guni the high gear is really only usable for smooth terrain and even then it is hard to ride. Know this: Riding a geared up guni is much, much harder than riding an equivallent big wheel.
Is it a reward? Hmmm, hard to say, I guess if you have the cash and already own a range of unis, including a 36er, then sure it’s part of a complete uni quiver, but for me it is the least ridden uni I own.
I think the benefit of a guni is very terrain specific, so where I live (Appalachia) the terrain is very up and down, rarely level, and very rooty and rocky, so I have very little “space” for high gear use. In contrast, Napalm lives where it is very level and relatively smooth (Australia), so he gets a lot of high gear use.
If you like to ride trails on a 36er and wish it were more agile, then a 26 guni would probably work well for you. If you can’t ride a 36er on the trails you enjoy, then you probably won’t get much use from a guni.
Try riding the 29er more with short cranks and work up your spin rate, maybe add a handle and try a different tire. I find that I can go plenty fast on my 29er unless it’s on a road in which case it is slow like a unicycle
It’s hard to judge Guni riding based on opinion. I am like Ben and am not comfortable in high gear off road. I like the Guni on the road. I can climb steep hills in low gears and descend/cruise around in high gear. BUT, there are plenty of people who like bombing down some trail in high gear . It depends on the type of rider you are.
Yup, it really is something you should try before you buy, but then again some folks who bought one and didn’t take to it initially, have come to like their guni over time.
I do like mine at times, but it’s frustrating to me that it doesn’t have more utility for my needs. It cost so much and gets ridden so little, seems wasteful.
If it doesn’t sell, I’ll hold onto it and plan to use it in the summers when I ride out West and for when we move West in 2014
I think that riding fast on short cranks can probably benefit from learning to coast–if you’re into that kind of thing. If you can coast then you probably won’t have much trouble with the lessened torque available for quick corrections.
I’ve never had trouble with short cranks. First time I tried short cranks(on a mid-size wheel), all I could think about was how awesome it felt to be able to sustain such high speeds. I already had a solid base in freestyle by that time, however.
Old but very interesting thread. When I try to pedal very fast on my 20er with 127mm cranks, even though theoretically the maximum cadence is the same for a given travelling speed, in practice there are other factors at play:
When pedalling, our quadriceps do most of the work by pushing down on the pedals. Due to the nature of physics, a near fully extended leg can push much harder than one that’s bent at the knee at, say 90°, that’s why we adjust our saddles so that the leg is almost fully stretched on the down stroke. Shorter cranks reduce the overall up-down range of motion of our legs which means our legs can remain closer to the near fully extended position throughout the entire crank turn. This translates to more efficiency.
If our legs were mass-less then crank length would be less of an issue. Unfortunately legs have quite a lot of mass and pedalling means the mass must move up and down. If one joule is the amount of energy expended when a force of one newton causes a displacement of one metre, a two metre displacement would require twice the energy. Longer cranks = longer greater displacement. Not only that, for a given cadence the legs will need to accelerate and decelerate more rapidly because they must swipe through the same angle in the same amount of time, which involves greater forces, again increasing the energy expenditure.
That’s what I can remember from high school physics anyway.
I recently changed to 140mm cranks and always rode 150mm. I dont yet know about speed but on my 32" it feels more stable. The wheel doesnt sway so much. Mostle have to get used to mounting. Otherwise i should be able to go a little faster. Will try it this weekend
It’s not the “maximum cadence” for a travelling speed, it’s the “cadence” that is the same, unless you are riding a freewheel. The “maximum cadence” which determines your maximum speed is determined by crank size.
While it is true that we can exert the most amount of force with our legs close to extended (160ish°), staying close to that range doesn’t automatically lead to more efficiency. Muscle efficiency depends largely on relative load (how much of the maximum force you are capable of exerting are you exerting), and the velocity it’s shortening at, as far as I can tell. This may or may not lead to shorter cranks being more efficient in many cases, but I know way to little about our biomechanics to tell.
I grayed out the not so great part of your statement… To accelerate a unicycle (or maintain a certain speed) we need a certain amount of energy, no matter which crank size. The shorter path and the extra force needed at the pedal with shorter cranks cancel each other out. The acceleration part is probably mostly accurate though, except your typo, and skipping a few steps of explanation.
Our max speed on a certain unicycle is limited by the speed a muscle can contract. Shorter cranks = more speed capability, with a downside of less control. It’s that simple. The lack of gearing makes it impossible for us to really think about efficiency.
The mass of the leg above the knee also moves through a smaller distance when the leg is closer to straight. But there is a down side of shorter cranks that less of the range of useful muscle movement can be applied.
Efficient transfer of energy in a mechanical system is mostly about impedance matching. Ideally the impedance of the load needs to match the impedance of the drive. Most of the time a unicycle has far too little impedance with a lot of the energy going into moving the leg rather than the uni.
The moving leg mass can be reduced by getting some of the motion from ankle. Less force can be applied by the calf muscle but the force isn’t the limiting factor at high cadence.
At normal cadence I mostly use ankle movement like a suspension as a rapid adjustment to keep in contact with the pedal by extending the ankle as the wheel drops into a depression. A good example of this is when crossing a kerb ramp between the footpath (sidewalk) and the road. If you hit the bottom of your stroke at the bottom of the dip you need to quickly find some extra leg length.
You don’t want the mass of your body taking the whole excursion through the dip and takes too long for your whole leg to speed up. The goal is to more or less make your body go straight across, coming off the saddle while dropping the uni down the dip.
Similarly the shock of a small bump can be absorbed by bending the ankle while the power continues to be steadily applied by the quads. The energy being provided by the quads can be elastically stored in the Achilles tendon and recovered as you come off the bump. Be conscious of keeping the ankle somewhere in the mid range of its movement until it becomes automatic.
Try to think of the uni movement as quite independent of the rider. The massive rider should move smoothly while the uni does the excursions, just like a suspended wheel on a car. Push yourself upwards before hitting a dip to compensate for the subsequent loss of support as you let the uni drop into it and come back out.
Ankle movement can also be used to significantly extend the pedalling arc which is vital on hill climbing. Bending the ankle allows the rider to apply forward force to the pedal earlier near the top of the stroke and similarly, backward force at the bottom by extending the ankle. It becomes less of a series of short sharp shoves to a more continuous rotation.
Scoox, are you thinking about switching to shorter cranks? A couple more experienced riders mentioned they moved to shorter cranks. But that was over an extended period of time. 127/20 seems like a good combination for learning basic skills.
Regarding efficiency: I pulled out my G20 (you read that right) last night and practiced shifting and riding around the neighborhood in high gear. For the most part, riding in high gear felt more efficient, because I was covering a greater distance for every pedal stroke. But, sometimes I started getting out too far in front of the guni, and I would have to suddenly exert myself to make a correction. I transitioned from using slow twitch (low load, repetitive) muscles to fast twitch (heavy load, sudden) muscles. Making too many sudden, big corrections in high gear wears me out. I think the same applies to shorter cranks. They have the potential of being more efficient than long cranks, so long as we’re not playing tug-of-war with them.
The OP mentioned that he wasn’t going much faster on shorter cranks. While it’s easier to spin fast on shorter cranks, it’s more of a challenge to maintain a steady cadence. I noticed that yesterday on my G20 in high gear. I was more likely to lose momentum from corrections.
Yeah, it’s the best one I have yet seen on this perpetual topic, though it is mostly focused on efficiency for reaching and maintaining the highest possible speeds. There are a lot of other things people do on unicycles.
True, but when pedaling a unicycle, there are a lot of other leg muscles that get used besides the quadriceps, sometimes in opposition to them. Pedaling a unicycle on level ground is often described as spinning the pedals, rather than pushing them, and when riding over uneven surfaces, your biceps femoris sometimes has to work pretty hard to keep you balanced.
The flight of stairs I mentioned previously on a different thread consists of steps that are about 1.5 meters long, so they are not exactly steps. They are each about 20 cm high, and not fully horizontal. It is more like a series of downhill ramps than a stairway. When I ride off the end of each one, I have to accelerate upon landing to absorb the impact, then decelerate to stay in control and get on top of the wheel for the next drop. I have to pull backward so hard on the top pedal, especially on my 29, that I am always scared it will shoot out from under my foot, but so far my pedal pins have never failed me. My enjoyment of this activity is part of why I switched back to 125mm cranks on my 29 from 110s, however.
But with shorter cranks do you keep your feet still? I noticed when making speed, I “pump” with my feet to make the rotation, mostly for a short sprint. But at that case I try to keep my legs still - of course they go up and down a little bit since my feet aren’t hobbit feet
Yeah, my calves seem to do more of the pedaling work when I use shorter cranks. Short cranks also put a bit more stress on the backs of my knees, I think, although the real reason that became a problem when it did may have been too much wheel walking and/or returning to the pedals, - I have never been 100% sure- but in any case the problem went away.
