The Unicyclopedia/Hardware

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The Unicyclopedia
Unicycling Activities
Rolling trials
Big wheels
Ultimate wheel
BC wheel
Double wheeler
Armour and clothing
Buying a Unicycle

Square tapered hubs

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These are known as cotterless hubs outside the US. The square tapered hub is the basic hub that is found on cheaper unicycles and most bikes. The ends of the spindle are the square tapers. The cranks have square holes and are fastened onto the spindle with a bolt or a nut.

The advantage of this hub is mainly that it is cheap. The disadvantages are that the axle may snap or bend more easily than the axle on a splined hub and that the square tapers may become rounded if ridden with a loose crank.

Splined hubs

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The splined hubs are found on high-end trials and mountain unicycles. These hubs are more expensive, but they are also a lot more durable. The splines (small ridges almost like teeth) on the end of the axle fit into an appropriately shaped hole in the crank. This provides more points of contact between the crank and the axle, and the force can be distributed over a greater area. On a square tapered hub there are only four points of contact. A splined hub usually also comes with an axle of greater diameter.

If you intend to do trials and muni, having a splined hub is good, since these riding styles typically produce a lot of stress on the axle.

Common brands of splined hubs are Kris Holm, Qu-Ax, Onza, Profile, Koxx, Torker, KH/Onza, Nimbus ISIS and the new KH Moment.

Loose crank arms

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Loose crank arms is one of the most common problems but fortunately this is usually easy to resolve. For splined hubs, you will need anti-seize and the appropriate allen keys, usually an 8mm and a 6mm. Remove the crank arm by loosening up and removed the retaining bolt and pinch bolt (if your hub has one). Put some anti-seize on the threads of these bolts. Then remove the crank itself and cover the axle and splines with anti-seize. Do not use too much or you'll make a mess. When you put the cranks on, first tighten the retaining bolt (the big bolt) on both sides, but not super tight. Then tighten both retaining bolts. Finally, tighten the pinch bolts. It is important that both the retaining bolts and the pinch bolts are very tight.

It is a good habit to check the bolts regularly. If the unicycle is new it make require that you tighten it a few times before it settles.

Keyway slop

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If you notice that both cranks slip at the same time when you ride or idle, it is likely that your hub has some keyway slop. A minor keyway slop feels like a tiny clicking sensation in both cranks, while a major slop may very well render the unicycle unridable.

The problem is that when the axle is made of steel and the hub is made of aluminum, the different metals cannot be welded. The axle is pressed into a machined keyway in the hub. The manufacturing tolerances for this process are very close. If tolerances are off by just a few thousandths of a centimeter, the hole for the keyways may become just a little too big, and the hub may develop a slop.

It is possible to repair this, at least temporarily, by pressing the axle partly out of the hub and applying Loctite. If your unicycle is new, your best bet is to contact your dealer. Make sure that they have a replacement ready for you before you send back your hub.

Kris Holm has reported that the KH/Onza hub does not suffer from these problems.

Splined Cranks

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Unfortunately every brand has its own standard, though progress is being made to move towards the ISIS standard, as Kris Holm, Onza, Nimbus, Qu-ax and Koxx have adopted this industry-wide standard, though there are some incompatibility issues with the Koxx Hubs not fitting any other ISIS cranks.

Currently we have

Kris Holm (8-spline)

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These cranks come in

  • 140 mm
  • 170 mm

There are also 127 mm replacements manufactured by Qu-AX.

Onza and KH/Onza (36-spline)

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The Onza and the new KH/Onza use the same cranks.

  • 127 mm
  • 140 mm
  • 150 mm
  • 165 mm

KH Moment (ISIS)

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  • 125 mm
  • 137 mm
  • 150 mm
  • 165 mm

Onza Tensile (ISIS)

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  • 140 mm

Profile (48-spline)

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  • 145 mm
  • 160 mm
  • 165 mm
  • 170 mm
  • 175 mm
  • 177 mm
  • 180 mm
  • 182 mm
  • 185 mm
  • 190 mm

Qu-AX (10-spline)

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  • 127 mm
  • 145 mm
  • 170 mm

Qu-Ax (ISIS)

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  • 100 mm
  • 114 mm
  • 125 mm
  • 145 mm
  • 170 mm

Torker (10-spline)

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  • 127 mm
  • 150 mm

Koxx (ISIS spline)

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  • 80 mm (light)
  • 110 mm
  • 125 mm
  • 135 mm (street)
  • 140 mm (reinforced and light)
  • 160 mm

Wheel sizes

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Freestyle is generally done on a 20" wheel, because it gives more fine control than any other wheel size. Almost all serious performances are done with this wheel size. Most skills can be done on a 24" wheel however, and freestyle on a Coker or a very small wheel can be an interesting challenge.


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The trials wheel are usually 19", but it is also possible to do trials on a 24" muni. If you need to ride any distance a 24" may be a good alternative.

Notice that for a standard '20"' trials unicycle with a 2.5" tire, the rim is 19" and this means that you cannot fit a regular 20" tire onto a trials rim, nor a trials tire onto a regular 20" rim.

A muni is usually 24" or 26", except for 20" trials unicycles that may be used as munis by children. Ascents and descents may be somewhat easier on a 24" muni than on a 26" muni. Expect a 24" muni to be somewhat easier to manoeuvre but slightly slower than a 26". 29" Munis are becoming popular too. If cross country riding and climbing is your thing, 29" is the way to go.

If your riding is technical then a 24" muni is probably a better choice. 26ers are generally for trails with not so many technical sections, and 29ers should only be used for fast, smoother XC trails.

28" and 29" (700c)

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These use the same rim, the difference is that the 29" unicycle has a thicker tire, such as a Schwalbe Big Apple (28x2.35) or a WTB Motoraptor or Nanoraptor (both 28x2.1). On a 29" you will feel the ground less - in a good way. Both are good for commuting.

36" (Coker)

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36" wheel unicycles are commonly referred to as Cokers, named after the tire manufacturer that sold the first 36" unicycles. Riding is substantially different to riding a smaller wheel because once you get such a big heavy wheel spinning nicely, it's got lots of momentum. While 36" are most commonly used for distance riding, there have been recent experiments with more aggressive, almost bmx-style, riding. These experiments have led to the proposal of a variant of trials, called rolling trials, where the basic idea of getting over a set of obstacles is taken from trials and applied to a unicycle that can't jump well but can roll over almost anything.

A new 36 inch unicycle that is somewhat cheaper than the Coker, has recently been introduced by Qu-Ax.

There is now another 36" wheel unicycle, the Radial 360 36-inch Unicycle which has noticeably better components than the basic Coker and a slick road tyre.

One of the biggest recent improvements in 36" unicycles is the Nimbus 36" with its twin forked chromoly frame to give rigidity and machined bearing cups and T7 handle.


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Aluminium vs. Steel and Titanium

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Aluminium is weaker than steel, and significantly more brittle. To prevent cracking, aluminum frames must be made much stiffer than steel frames. Still, aluminum has only 1/3 the density of steel, allowing stiff frames made of "oversized" aluminum tubing to weigh less than steel frames. Since the walls are so thin they are however easy to dent, and dents may introduce a local weakness, making it prone to break there. Titanium is a new rising material, which combines mostly the qualities of steel and aluminium. It has no corrosion, high stability and light wheight. Depending to the alloy it is possible to build very stiff and light frames or more elastic frames. Because of the complex fabrication it is, at the moment, about ten times as expensive as steel.

Painting your frame

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The longest lasting and most professional way to go is powder coating. This method is done by a powdercoating shop and is very durable and good looking. Powder coating can cost anywhere from $50 to $100 for a frame. Look in the yellow pages for powdercoating shops.

If your mind is more focused on budget, spraypainting is your best option. Use high quality paint, and put as many coats as you can (recommended 3–8). Also keep in mind that if you have a chrome frame, you should sandpaper it until you get a "brushed metal" look before painting. ALWAYS use PLENTY of clear coat. Again, use as much as possible, because this will keep your paint from being scratched.

Bearing sizes

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All bearings are 10mm(?) wide.

  • 22 mm ID 42 mm OD

These are used on the 2007 Onza ISIS, Nimbus ISIS and KH Moment ISIS hubs.

  • 19 mm ID 40 mm OD (6203-12-2rs)

These bearings fit a Profile hub together with for example a Yuni or a KH Pro frame. It is possible to use a frame designed for 42 mm OD bearings with shims, shims are available from

  • 20 mm ID 42 mm OD (6004-2rs)

This is used on trials and off-road unicycles such as Kris Holm, Onza, and Qu-ax.

  • 17 mm ID 40 mm OD (6203-2rs)

This is the standard on most unicycles, with a few exceptions.

  • 17 mm ID 35 mm OD (6003-2rs)

This is the size used for Miyata, Sem and Pashley unicycles.

  • 20 mm ID 40 mm OD

These bearings are used on the Torker DX, but are hard to come by separately.

It is possible to determine the size of a bearing by looking at the numbers.

The first digit is the type code
6 = "single row deep groove ball bearing"

The second digit is the series number
2 = "light" (as opposed to extra light, medium, heavy etc.)

The third and fourth digit are the bore size code
Some common ones are:

  • 00 = 10mm
  • 01 = 12mm
  • 02 = 15mm
  • 03 = 17mm
  • 04 = 20mm

The 2rs suffix indicates it is a double sealed bearing.

The outside diameter (OD) of a bearing depends on both the bore size (inside diameter) AND the series. A more robust bearing has a larger OD.


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Pedals can be broken into two categories, metal and plastic. Because metal pedals can easily damage delicate surfaces, plastic pedals are a must for indoor riding on gym floors. Special freestyle pedals are rubber coated and have no exposed metal parts for this purpose. Most freestyle and commuter unicycles come with plastic pedals. Extra caution must be taken when riding with wet shoes on plastic pedals, for shoes have a tendency to slip off. For muni and trials riding, metal pedals help prevent the rider's feet from slipping, but these pedals can do serious damage to your shins. It is always a good idea to wear shin guards when riding with metal pedals.

Good pedals for trials or muni are BMX platform style pedals of steel or aluminum, or, less commonly, magnesium. It is important to have a big platform. If you want to do pedal grabs it is also important to have replaceable pins. While too long pins tend to make the pedal stick to surfaces, too short pins do not provide enough grip. Something in between is the best.

While sealed bearing pedals have good protection against water and mud, an unsealed pedal holds up better for pedal grabs.

Good pedals are made by OJC, Snafu, Primo, Wellgo, etc.

It is not a good idea to use clipless pedals on your unicycle, even though they may weigh less. If you lose balance with regular pedals, you can almost always place your feet on the ground, and you'll be fine. But if your feet are clipped in, it's quite a high fall to land on your hands. The wrists are easy to break, and if you land on your head, that's far worse.


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Since you hopefully will spend a lot of time in your saddle, having a comfortable saddle is nice! If you plan to spend more than a half hour at a time sitting on the saddle, a seat with more padding than is found on a basic unicycle seat is recommended. Some prefer airseat conversions, others enjoy maintenance free seats containing various degrees of foam or gel inserts. Saddle comfort varies widely with rider, and what is comfortable for one rider may not be for another.

Saddle Brands

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  • Kris Holm - A large soft seat with lift handle on the front. Comes in various colors. Options include a removable cover or an air saddle. Pretty much the standard seat for medium to upper-grade unicycles. A lot of people would recommend the Kris Holm saddle for distance riding and muni. The Kris Holm saddle is also good for trials although some prefer a Miyata saddle. This seat's design is very similar to the Torker DX and Velo seat.
  • Nimbus - Nimbus makes a low-profile seat with gel inserts that many prefer for trials. Similar to the gel seat.
  • Miyata (Torker LX) - Less bulky than the Kris Holm saddle so preferred by some trials and freestyle riders, but not very strong. Easily converted into an air saddle. Non-standard seat posts are required for this seat.
  • Viscount - Popular entry level seat that comes in multiple colors. Lightly padded but preferred by some because of its thin profile. Screws on front bumper guard rub against fingers when jumping. This seat has a steel base, as opposed to the plastic bases on many other seats, so there is less seat flex.
  • Classic - Similar to the Viscount with metal base but with more robust bumpers.
  • Semcycle - Schwinn style seat which comes in multiple colors. Comfortable and is easily converted into an air seat for extra comfort.
  • Torker CX - Standard on the Torker CX unicycles. Small and very sturdy. Best suited for smaller riders, as larger riders generally find it uncomfortable.
  • United - A solid inexpensive beginner seat.
  • Savage - Inexpensive seat that is easily ridden in both directions. Contains metal bumpers, use with extreme caution.

Other seats such as the United and the Koxx are both suitable for trials.

Air seats

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It's possible to convert your seat to an air seat. The exact procedure depends on the model of seat being operated on, but in general the process goes something like this:

  1. Acquire a small tube - one to fit a 12" wheel is generally suitable
  2. Remove seat bumpers and/or handle (this usually means undoing some screws or nuts)
  3. Remove cover (this often means removing staples). At this point you have a naked seat.
  4. Remove the foam or other padding from the seat.
  5. Drill a hole (min 8.5mm) in the seat base for the tube's valve to stick out.
  6. Arrange the tube; either tape it into a suitable shape or put it in an airseat tube bag.
  7. Place the tube on the seat, where the foam used to be.
  8. Cut the bottom off the foam, so you have a thin piece of foam that will ensure the seat has an appropriate shape
  9. Place the foam on top of the tube.
  10. Reattach the seat cover, and any bumpers and handles
  11. Inflate the tube to the desired pressure, being careful not to overinflate it and damage the seat cover.

Crank length

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Within reasonable limits shorter cranks mean more speed while longer cranks ease climbing and provide more braking power and better general maneuverability.

Crank lengths are very much a personal thing. The right crank length for you will depend not only on what kind of riding you do, but also on your strength and confidence. You should experiment to find out what works for you.


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The common crank lengths for trials are

  • 127 mm
  • 137 mm
  • 140 mm
  • 145 mm

In general precision increases with the crank length. 127 mm cranks may increase hopping height for rolling hops since you can gain more speed. 140 mm or 145 mm may be a good choice for regular trials, but they are rather slow. Also the pedal hitting the ground in leaning turns may become a problem with 140 mm, and even more so with 145 mm.

As for different types of trials, Short cranks are recommended for street/urban trials, medium lengths for all-around, and longer lengths for pure/natural trials.

The common crank lengths for muni are between 150 mm and 170 mm. Longer cranks may be harder on the knees.


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For 20" freestyle riding, cranks range from 89mm to 127mm. The larger the cranks, the more your legs move and cause your ride to oscillate side to side. Smaller cranks have less torque but allow the rider to travel faster and ride with their seat higher. For the beginner, 127mm cranks are standard. most freestylers ride 114mm cranks


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Generally, shorter cranks will give the rider more speed, but less control. Since short cranks provide less torque, though, many of these cycles include brakes for gradual-slowing down or descending.


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This section answers questions about tires for different types of riding, such as:

  • What tire width is appropriate?
  • What thread count is good?
  • How do you make snow chains?

Trials tires

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The most popular trials tires are the Monty, Luna, Maxxis Creepy-Crawler, and Try-all. Most trials tires are around 2.5" wide, and have a square block pattern tread (except for the Try-all, which has a tread designed for natural trials). The things to look for in a trials tire are low weight, low duro rubber, thick sidewalls, and tall sidewalls. The Official 19" Trials Tyre Thread at is a great help when looking for advice on choosing trials tires.

Muni tires

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Tires for Muni are generally very high-volume, low pressure, to provide the most cushioning and bounce. Typical tires for muni are 3" wide and include the Duro Wildlife and Nokkian Gazzaloddi, as well as Surly 4" Endomorph and Larry.

28" and 29" tires

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The size of these tire sometimes confuses people as they are both 700c tires and will fit on the same rim. A 28" tire is a 700x40c. A 29" tire is anything bigger up to 700x60c. The Schwalbe Big Apple 29x2.35" is probably the most popular tire for unicycling on the road. Off-road there are several tires available; Kenda Klaw XT, IRC Notos XC, IRC Mythos XC.

36" Tires

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There are four styles of tire currently available for 36" wheeled unicycles; the original Coker "button tread" hybrid tire,the Qu-ax 36" road tire (also known as Wheel TA 36-inch Street Tire, same as the new Coker XLR road tire), the new lightweight Nimbus Nightrider 36" road and trails tire and the Coker Off-Road tire with block tread in the shape of the "coker" lettering. These tires are nearly identical except for the tread pattern except for the Nightrider which has 2-ply construction rather than 4-ply to save weight and is rated up to 65 PSI rather than 32 PSI.

What else

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How to make your own studded tire

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Affordable studded tires in some sizes are very hard to find. The best I have found are a few pretty cheap (350SEK/€40/$55+shipping) 20" studded tires from a BMX dealer, manufactured by Innova.

So why not make one for yourself? The only costs are a tire, some studs and some work.

This is how I made my studded tire, not necessarily the best way to make it.

You need:

1 tire that fits your rim - it must have a fairly deep tread to make sure the screws have something to grip. (i used a Nokian X-trak)

2.5mm drill

Half-inch self drilling screws for wood


An old tube, or a few meters of duct tape (or both).

A screwdriver

Something to cut the screws with!


1. Take a good look at the pattern on the tire and decide where the studs should be for best performance? Keep in mind that if they are in the middle, you'll have great grip in acceleration and braking, whilst if they are on the sides, they'll grip when your off balance and therefore have more need for that grip.

Considering this, I placed 2 parallel lines of studs. The lines were 1.5 cm apart, and within each line the studs are separated by about 3 cm. That required 92 studs for a 20" tire; if I made one today I might have put more studs in, but it works well as it is.

2. Now you have to drill all the holes. Drill 2.5 mm holes where you want the studs, drilling into the outside of the tire.

3. Start with pressing a few screws in place from inside the tire, using a thimble if required

4. Screw those screws in place

5. Repeat step 3 and 4 until all holes are used.

6. Since the heads of the screws will tear on the tube, you have to do something about it.

Either: Cut an old tube to create a strip of rubber that reaches all the way around the tyre. Make it wide enough that there is at least 1 cm between the edge of the strip and a stud, and glue it in place.

Or: 3 layers of duct tape will suffice. I used: Both, use only the tube for 2 weeks, then i had my first pinch flat, now i have both.

7. Place the tire on the wheel, inflate to high pressure, wait for the glue to set.

8. Cut all the studs to a few millimeters of length using your weapon of choice, being careful not to harm the tire.

This took me about 4 hours of a rather inefficient work, would be able to do it in under 1 hour.

Don't use your new tire indoor, and use high pressure (at least 3 BAR or 45 PSI) to make sure the studs don't pop into the tire. You're all set!

Choosing a rim involves tradeoffs. If you do high drops, you may want a tough downhill rim. But sturdy rims are also heavy, and therefore not so good for hopping.

The most common rim for MUni is the Alex DX32 rim which is 35.1 mm wide.

Qu-Ax uses a DB-45 rim which is 45 mm wide.

Kris Holm designed and sells multiple types of rims. Two rims are 24 inch with 36 holes, one is a 42.2mm wide rim for better grip, and the other is a lighter 38mm rim for distance riding. Another rim is a 700c rim with eyelets. On the new 2007 KH unicycles, the rims are 45 mm wide but with holes drilled intermittently to reduce weight. In this way, the advantages of both types of rims are combined

For 28" and 29" unicycles, a standard 700c rim is used.

On a coker, there are three rims available. The Coker company makes a steel rim, which is serviceable but is known to bend after some abuse. The traditional choice for a stronger rim is the Airfoil rim sold by Darren Bedford has recently started selling a coker with an aluminum rim, but these turned out to be brushed steel as used on the Qu-ax 36" unicycle

If you like extreme MUni, Surly Bikes makes the Large Marge 65mm wide rim in both 26 and 24 inch sizes. This rim claims to be good for riding on sand, snow, mud, or other terrain where you need more grip than usual.

Tire pressure

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Tire pressure is a huge topic among unicyclists.

In short, low pressure offers better grip, while high pressure is better for heavy landings or pre-hops with a lot of force. In detail, high pressure on the other hand lowers rolling resistance and eases turning.

Low pressure may provide a better grip and allow you to roll over small obstacles rather than bounce off them.

Your tire pressure is considered too low if your rim's sidewalls hit the ground when you land a drop. Rim sidewalls pressing the tire on the ground may cause pinch flats.

For freestyle it may be of advantage to use a high pressures, up to 85 psi has been spotted on the forums, (though I don't know the standard, someone with a trials or freestyle uni please add info here). Certain bmx freestyle tires can now be put up to 120psi and one even has Kevlar beading.

Trials and mountain unicycling uses rather low pressure, as low as 18 psi has been spotted on the forums, though psi in mid twenties seems to be more common. A rule of thumb to start with is to use 1PSI for every 10 lbs of rider. A rider who weighs 180 lbs would thus use 18PSI, a rider of 200 lbs would use 20PSI. This is a good starting point, and can then be adjusted to fit the rider's skill and/or terrain.


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Most unicycles do not use brakes, simply because the use of direct drive. (Because the pedals are directly attached to the wheel, if you stop pedaling you will stop moving.) However, there are those who are developing unicycle brakes. The only unicycles that do use brakes commonly are MUnis and some commuter unis.


  • Make it possible to do steeper hills in control.
  • May provide more traction on loose downhill ground, where backwards torque would cause slippage.
  • Give the knees/legs an easier job on long descents.

The most common brake used is the Magura HS-33, a hydraulic rim brake used commonly on trials bicycles. Commuter unis commonly use V-Brakes, but most MUnis must use hydraulic brakes because V-Brakes don't provide enough clearance for a 3" tire.

Geared Unicycles

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The first practical geared unicycles were designed and developed by Greg Harper and Frank Bonsch. The Schlumpf geared unicycle is now in production and available for sale. There is also the new Kris Holm/Schlumpf geared hub with a reinforced ISIS axle and without the torque lever, released in January 2008.

While the previous methods of gearing involved a shifting mechanism inside the hub, some have experimented with using gears outside the hub, usually with a "jackshaft" dual sprocket, and this was developed for the larger-wheeled road unicycle by Pete Perron of Seattle. The jackshaft concept for cycling was originated by Ernesto Colnago of Italy, in a one-off bicycle prototype.