Contents

1. Unicycle Maintenance

2. How To Straighten Your Frame

3. How To Change Your Cranks

   1. Cotterless Cranks
   2. ISIS Cranks
   3. Splinned Cranks
   4. Cotter-Pinned Cranks

4. Tensioning and Truing a Wheel

5. Check Spoke Tension By Ear

Unicycle maintenance

Unicycles are not complicated but they do take a little bit of maintaining. Here are some of the key points: Creaking cranks

Stop riding immediately and tighten! If these are left they will destroy the cranks and hub. The creak comes with downward pressure of the pedal and is often confused with loose spokes. Cotterless cranks, remove the caps from the end of the cranks and tighten with a 14mm socket spanner (or 8mm allen key). Splined Cranks, check these instructions Creaking spokes

After some time spokes stretch and slacken, this is not normally terminal for the wheel but does weaken it. Tightening a wheel is a job that is normally considered to be a job for an expert, but if approached carefully, it is not difficult for the lay-person. If the wheel is just loose, but central, tighten each spoke using a spoke key by a quarter turn, being careful not to miss any, repeat until spokes are tight. Loose pedals

Stop! Check that you have the seat facing forward and you have the right pedal on the right-hand side. If your pedals come loose it is almost certain that you have the right-hand pedal on the left side and vice-versa. If this is left for any length of time then the crank and pedal will be destroyed. Tighten with a 15mm spanner. If you have damaged your pedals and cranks we do sell replacements. To remove the cranks you need to use a crank extractor. Loose seat bolts

When learning, the constant dropping of the unicycle can cause the bolts that hold the seat to its post to come loose. Check and tighten these regularly. Use an 11mm or 10mm socket spanner to tighten. Loose frame bolts (Dodger)

If you feel the frame clicking or moving then stop and check the bolts, if left loose the frame cracks and will be destroyed. Use a 13mm spanner or socket to tighten. Frame bolts (unicycles other than Dodgers)

It not very common to find these bolts coming loose. If they do then they should be tightened immediately. It is considerably more common to find them over-tightened! If the wheel does not rotate freely then the bolts should be slackened by about a quarter or half turn. If the bearings are left over-tightened for too long they will wear and require replacing. Under inflated tyre

It is bad practice to ride a unicycle with a flat or an under-inflated tyre, because all your weight is on a single tyre, so you need to have the pressure higher than you would on a bike. An under-inflated tyre can also cause the wheel to buckle under rapid turning or bouncing. Worn tyres

When a unicycle has been ridden for a bit you will notice that there is one or possibly two areas of the tyre that are getting considerably more wear than any other. This is due to idling and turning. This can be remedied by letting the air out of the tyre and then rotating the tyre through 90 degrees.

How to straighten your frame

Frames can get bent by various means or sometimes they just need fitting to a new hub. Bending of the frame can be done by doing kick-up mounts in the gym or by jumping down loads of stairs and landing badly or on larger frames the forks widen after doing lots of turning and then this pull the bearings off; although sometimes frames are just not straight or are too wide as they come from manufacturer and need tweaking. This is not a hard process but takes a little patience.

It is easy to correct the straightness of most frames, there are some frames you should NOT try straightening… these are carbon fibre or aluminium frames.

• Check if the wheel is bent. Spin the wheel within the frame and if the gap changes then this may be the problem not the frame. You should get the wheel straightened before going any further.
• Check that the wheel is not dished. To do this mark the side of the wheel that is closest to the frame with a marker or tape. Then remove the wheel from the frame and re-insert it the other way around (so the left crank is on the right - remember to put it back afterwards). If your mark is still closest to the frame then the problem is the dishing on the wheel which is out. This should be corrected before going any further.
• Check that the frame has the same length legs. There has been a problem with some frames being manufactured with one leg longer than the other, but this is very very rare but is worth checking. Without the wheel in place measure from the bottom of the seat tube to the edge of the bearing housing. This distance should be identical. If it is not then the correction should be made with a thin metal shim placed above the bearing in the bearing holder, a soft drinks cans can be used but be careful when cutting them.
• If the wheel is consistently closer to one side than the other after you have done three tests above then your frame needs tweaking.
• Place the wheel in the frame and mark the side that is closest to the wheel with a marker or tape.
• Take the wheel out and place the frame on the ground with the marked side to the top. Place your foot on the frame between the crown and the seat and then apply a gentle pressure on the frame pushing it towards the ground.

• Turn the frame over. Place your foot on the frame again and this time pull the leg upwards.

• Place the wheel back in to the frame and check the positioning of the wheel. You will probably need to repeat this process several times until the wheel is central in the frame and the frame slips over the bearings easily. The standard width on bearings varies but is 100mm centre to centre on most Taiwanese bearing and 83mm on Japanese ones, although ideally you should aim to have your frame about 1 or 2mm smaller than you require so that there is a slight inward pressure on the bearings.

How to change your cranks

There are four types of cranks,

• Cotterless
• ISIS
• Splined
• Cotter-pinned.

Cotterless Cranks

This is the standard crank that comes on most modern unicycles. The hub axle has tapered ends with a square cross-section and a bolt or nut to hold the cranks on. The cranks are forced onto the axle to create a friction fit and locked in place with the bolt or nut. You should never ride with loose cotterless cranks as this will round the corners off the axle and distort the square hole in the crank, preventing them from fitting tightly ever again.

To remove cotterless cranks you will need a crank extractor. First remove dustcover (if fitted) then unscrew (anti-clockwise) nut/bolt with 14 socket spanner or 8mm allen key. Retract the central shaft of the crank extractor fully before screwing the outer clockwise into the crank fully. Next turn the shaft to extract crank. Then unscrew the outer threaded section to separate it from the crank.

To fit cotterless cranks; gently seat the crank on the axle stub and affirm its position with a mallet (not metal), then tightly lock in place with the bolt/nut. Make sure the righthand crank is on the righthand side and the lefthand crank is on the lefthand side before riding otherwise you will wreck the cranks.

ISIS Cranks

These are a type of splined crank but have tapered axles so their removal is similar to cotterless cranks BUT you must use a crank extractor with an ISIS head otherwise it will damage the threads in the axle.

Splined Cranks

Splined cranks are stronger than cotterless cranks and therefore are more suitable for muni or trials unicycling, but require slightly more maintenance. There are several different models

• Onza
• Kris Holm
• Profile
• Qu-ax
• Koxx
• Onza/Kris Holm
• Qu-ax ISIS
• Onza ISIS
• Nimbus ISIS and
• Kris Holm ISIS.

With the exception of the Onza with the Kris Holm/Onza cranks and all the ISIS cranks with each other (not Koxx), these cranks are not cross-compatible as they fit different spline formations. The bolts will probably need to be tightened after a week of riding and checked regularly after that. For more information read maintenance of splined cranks. Never ride with the cranks on the wrong side or you will destroy them.

Cotter-pinned Cranks

These do not come on any new unicycles. The crank is held in place by a tapered bolt, called a cotter-pin, which is at right-angles to both the axle and the crank. To remove the cotter-pin; unscrew the nut slightly then carefully hit with a hammer/mallet. Repeat this process until the pin is completely removed. Do not completely remove the nut and hit it with a hammer since this tends to bend the pin, making complete removal a little more difficult. When you change a cotter-pinned crank it is recommended that you also replace the cotter-pin. Before riding, make sure the righthand crank is on the righthand side and the lefthand crank is on the lefthand side before riding otherwise you will ruin the cranks.

Tensioning and Truing a Wheel

If the spokes are still very loose, so that you can wiggle the rim back and forth easily, tighten each spoke one full turn. Start at the valve hole and work your way around until you get back to it, so that you won't lose count. Make sure you are turning the nipples the right way.

When you work with a screwdriver, it is easy to figure out which way tightens them, clockwise. It gets confusing when you start using the spoke wrench, because now you are working from the back side of the clock!

Continue bringing up the tension one full turn at a time until the wheel begins to firm up.

Once there begins to be a little bit of tension on the wheel, you should start bringing it into shape. There are 4 different things that you need to bring under control to complete the job:

• Lateral truing
• Vertical truing
• Dishing
• Tensioning.

As you proceed, keep checking all 4 of these factors, and keep working on whichever is worse at the moment.

Try to make your truing adjustments independent of each other. For lateral truing, spin the wheel in the stand and find the place on the rim that is farthest away from where most of the rim is. If the rim is off to the left, tighten spokes that go to the right flange and loosen those that go to the left flange. If you do the same amount of tightening and loosening, you can move the rim to the side without affecting the roundness of the wheel.

For example, if the rim is off to the left,

• and the center of the bend is between two spokes, tighten the spoke that goes to the right flange 1/4 turn, and loosen the spoke that goes left 1/4 turn.
• If the center of the left bend is next to a spoke that goes to the right flange, tighten that spoke 1/4 turn, and loosen each of the two left spokes next to it 1/8 turn.
• If the center of the left bend is next to a spoke that goes to the left flange, loosen that spoke 1/4 turn, and tighten each of the two right spokes next to it 1/8 turn.

After adjusting the worst bend to the left, find the worst bend to the right, and adjust it. Keep alternating sides. Don't try to make each bent area perfect, just make it better, then go on to the next. The wheel will gradually get truer and truer as you go.

For vertical truing, find the highest high spot on the rim.

• If the center of this high spot is between two spokes, tighten each of them 1/2 turn.
• If the high spot is centered over one spoke, tighten that spoke one full turn, and each of the two spokes next to it that go to the other flange, 1/2 turn.

It takes a larger adjustment to affect the vertical truing than the horizontal truing. Vertical truing should usually be done by tightening spokes, gradually building up the tension in the wheel as you go along.

As soon as the lateral truing gets reasonably good (within a couple of millimeters) start checking the dishing. Put the adjustable feeler of the dish stick over the axle on one side of the wheel and adjust it so that both ends of the dish stick touch the rim while the middle feeler rests against the outer locknut on the axle. Then move the stick to the other side of the wheel without re-adjusting the feeler. If the dish stick rocks back and forth while in contact with the outer locknut, the spokes on that side of the wheel have to be tightened to pull the rim over. If the ends of the dish stick sit on the rim but the feeler won't reach the locknut, the spokes on the other side of the wheel need to be tightened. If the dishing is off by more than 2 or 3 millimeters, you should start at the valve hole and work your way around the rim tightening up all 18 spokes on the appropriate side the same amount, perhaps 1/2 turn.

When the dish is starting to get within 1 or 2 millimeters of being correct, go back to working on the lateral truing, except now you will not be alternating sides. If the rim needs to move to the right to improve the dish, find the worst bend to the left, adjust it, then find the new worst bend to the left, and so on.

All the time you are doing this you need to keep checking the vertical truing, and whenever the vertical error is greater than the lateral error, work on the vertical.

You also need to keep monitoring the tension on the freewheel side spokes. There are three ways to check tension. One is by how hard it is to turn the spoke wrench. If it starts to get hard enough that you have to start worrying about rounding off the nipple with the spoke wrench, you are approaching the maximum. Fifteen years ago, this would be the limiting factor, and you would just try to get the wheel as tight as you could without stripping nipples. Modern, high quality, spokes and nipples have more precisely machined threads, however, and now there is actually a possibility of getting them too tight, causing rim failure.

The second way of judging spoke tension is by plucking the spokes where they cross and judging the musical pitch they make. If your shop doesn't have a piano, and you don't have perfect pitch, you can compare it with a known good wheel that uses the same gauge of spokes. This will get you into the ballpark. Before I started using a spoke tensiometer, I used to keep a cassette in my toolbox on which I had recorded my piano playing an F#, a good average reference tone for stainless spokes of usual length. For more details on this method, see Check Spoke Tension by Ear

The third, and best way is with a spoke tensiometer. Every well equipped shop should have one. Average freewheel-side tension should be up to shop standards for the type of spokes and rim being used. More important is that it be even. Don't worry about the left side tension on rear wheels. If the freewheel side is correctly tensioned, and the wheel is correctly dished, the left side will be quite a bit looser. You should still check the left side for uniformity of tension.

   Thanks go to Sheldon Brown for this tutorial. The entire wheel building tutorial can be found here.

Check Spoke Tension By Ear

Correct spoke tension is essential in order for a wheel to be strong and durable. An instrument for measuring spoke tension, the tensiometer, is available to wheel builders. However, unless you are musically tone-deaf, there is another instrument which does the job faster and easier: a musical pitch pipe - or a piano or church organ, or whatever other well-tuned musical instrument you happen to have in your workshop.

Like the strings of a guitar or harp, bicycle spokes ring when plucked. The resulting musical pitch is higher if a spoke is tighter, and the optimum pitch does not depend on the thickness of the spoke. To know what the musical pitch should be, all you need to know is the approximate spoke length and whether you will be using plain-gauge spokes or butted spokes, which are effectively shorter since their ends are thicker. At the end of this article is a table of optimum musical pitches. You may go there now in case you only need to look up a pitch and spoke length. Please read the rest of the article first if you haven't done that already. You may also read a scientific explanation of how spoke tension relates to musical pitch.

Check spoke tension on a wheel which is reasonably true. On a radially-spoked wheel or one whose spokes are not laced, you can pluck one spoke at a time. If spokes are laced, pluck them where they cross. You will be listening to the sound of two spokes at once.

If the tension of two laced spokes is very different, you will hear a dull thud. Pull the spokes across each other with your fingers to see which one is looser. Lift the looser spoke away to pluck the tighter one alone and check its pitch. Check for rim damage or a crooked rim joint near the unequally-tensioned spokes. Re-bend the rim if necessary so the wheel will true up with the spokes at a more nearly equal tension. If you can't achieve a true wheel with even spoke tension, it's time for a new rim.

If the tension of the two laced spokes is approximately the same, as it should be, you will hear a single, clear musical note. In a typical 700C three-cross wheel, this should be an G with plain-gauge spokes and an A with butted spokes.

This pitch corresponds to approximately 1/3 of the yield strength of good-quality spokes - about as high as you can take the tension and still leave an adequate margin of safety. A common error in wheel building is to leave the spoke tension too low. Low tension makes for a weak wheel, since spokes go slack under smaller loads, and fail to hold the rim steady. When spokes are tight enough, the nipples can be a bit difficult to turn; this makes many wheel builders leave wheels too loose. On the other hand, wheels are sometimes over tensioned, and then spokes are likely to pull up the rim around the spoke holes.

Before assembling a wheel, dip the spoke threads in grease or a commercial spoke thread compound to reduce friction. Also place a dab of grease on the surface where each spoke nipple seats into the rim. A spoke is a good tool to grease the spoke holes. If you do not lubricate the threads and nipples, you may not be able to bring the spokes up to optimum tension.

Check musical pitch all around a wheel. In a new wheel with a good, lightweight rim, it should not vary from the optimum pitch by more than a musical semitone or two (one or two steps of the pitch pipe) up or down. A heavy and/or steel rim is stiffer - as is a deep-section aero rim. If you must compromise spoke tension to true such a rim, use your judgment. No spokes should be so tight as to risk pulling out or so loose as to risk a flabby wheel. Even with a fine rim, do not try to true the wheel by equalizing musical pitch. No spokes are perfectly uniform, and no rim approaches perfect roundness without some coaxing from the spokes, so there will always be some slight variation in pitch between spokes.

If a rim pulls up around the spoke holes when you stress it after raising it to the musical pitch recommended in this article, you must use lighter spokes or a stronger rim. Failure to heed this warning can lead to rapid wheel failure.

Due to the dishing of a rear wheel, the left spokes are under lower tension and have a lower musical pitch, if the same gauge and number of spokes are used on both sides of the wheel. The pitch should be about the same for all left-side spokes.

An elegant trick to build a stronger rear wheel is to use thicker spokes on the right side than on the left side. 14-gauge plain-gauge spokes on the right and 14-16 gauge butted spokes on the left balance nicely; with this combination, spokes on both sides ring at approximately the same pitch, indicating that they are both carrying optimum tension.

You may ask why this approach makes a better wheel than using thicker spokes on both sides. After all, thick left-side spokes would be stronger. They would also be at the same tension as the lighter spokes would, though at a lower musical pitch. But because they elongate less, thick spokes on the left actually go slack and give up control of the rim under a lighter weight load; and even when the load is not so great that they go slack, the rim warps to one side at the bottom of the wheel where it bears weight, due to the unequal lateral component of stiffness of the right-side and left-side spokes. The reason that thinner spokes on the left work better and last longer is that they are stretched by the same amount and have the same stiffness against lateral (side-to-side) motion of the rim as the thicker spokes on the right.

If you need instruction in wheel building, read Sheldon Brown's article, on his Web site, which is as good as anything I've ever read on the subject.

Use the following table in connection with that article. The table shows musical pitches corresponding to optimum spoke tension.

   Thanks go to John Allen for this tutorial. The complete original article can be found here.