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Maintenance

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FAQs


Crank Sizes

This is not an easy question, it depends what you want to do with your unicycle. All the unicycles are sold with standard length cranks but you can upgrade your unicycle with different size cranks. As a general rule, the shorter the crank the faster you can ride, the longer the crank the more control and power your can have. Cranks are measured from the centre of the wheel to where the pedals are threaded in.

16" Unicycles
Can only be fitted with 100mm cranks or smaller otherwise the pedals touch the ground when riding.

20" Unicycles
75mm are for advanced freestyle, 89mm are still too short for beginners but are good for advanced skills such as pirouettes. 100mm cranks give a smooth fast ride but make idling harder, 114mm cranks are a good length for freestyle tricks and hockey. 125mm cranks give a lot of torque and are good for learners. 140mm are for Trials, 150 mm are a bit long.

24" unicycles
114 mm cranks are very smooth and should only be considered if you are a speed fiend, 125mm cranks are smooth and still quite fast, although are ok for idling, 140 and 150mm cranks are great for off road and learners. 165mm are sometimes used for very steep Muni but tend to hinder most riding.

26" (& 29") Unicycles
114mm cranks make a great long distance machine on flat surface but very hard to idle, although some riders do go as short as 75mm. 125mm cranks are smooth and make a good street machine. 150mm cranks are great for standard Muni riding and tricks work. 165mm are for heavy mountain climbers, these give you the ability to go up almost anything!

36"Unicycles
89mm cranks, yes; you can put them on a 36" unicycle and they make an incredibly fast unicycle - experts only! Sensibly you should consider 114mm the shortest for general riding and make nice smooth action although 125mm cranks create an extremely fast machine for most use. 150mm cranks are standard for beginning with and should be considered the the starting point for all but experienced riders.

 


Upgrading Parts

Saddles
When you are learning, you can destroy your saddle with the constant dropping. We sell a wide range of saddles from the cheap plastic seats such as Dodger and Qu-ax to Nimbus Gel and Kris Holm. You can also change your saddle to have one with a Handle which is useful to make jumps and to have a more comfortable position to ride. Make sure to take a look at our range of Saddles.

Seatposts
Have you outgrown your existing unicycle? We can sell you an extra long seat posts to revitalise it or a seatpost rail or angle adaptor? Even if your unicycle has a non-standard size we can supply shims to fit most sizes. Older seatposts tend to be 22.0mm newer models tend to be 25.4mm, we stock both. Be sure to take a look at our range of Seatposts.

Seatpost Clamps
It can be very annoying to be constantly straightening your seat so one of the most common upgrade is to fit a double bolt seat clamp. These clamp the frame and the seatpost keeping them in position even under the worst conditions. Learners though are the other way round they need to be able to move their seat position regularly until they find the optimum height for their riding style, for them we sell replacement quick-release clamps.

Frames
If you have a Dodger and you are getting into bouncing then it is worth considering upgrading to a Nimbus frame or if you are looking to do more advanced stand-up tricks then the Nimbus II frame. If you are a good off-road rider and you want a high performance Unicycle, you should buy a KH frame. Frames come with either 40mm or 42mm bearings. If you are wanting to upgrade you frame you need to check it will fit on your bearings.

Brakes
Yes, it is possible! For Muni downhill. Once you are used to them they can give you more control for technical downhill riding, or you can use them as a drag-brake to save your legs on long downhills. You can get a Kris Holm frame with them fitted or you can get a special frame like the Nimbus II with Magura fitting and buy the Magura Brakes set.

Rims
One of the most common upgrades for Muni riders is changing the rim to the almost indestructible Halo Combat rims or the Kris Holm rims but we do stock other strong rims too.

Tyre
One of the biggest, easiest and cheapest upgrades you can do to your unicycle is replace the standard tyre. On a unicycle all your weight is on one tyre unlike a bike so you need a larger volume than standard, high-pressure tyre with strong sidewalls. For Freestyle we sell Primo Wall which is one of the best tyres of its type in the world. For Trials we sell the 19" Creepy Crawler, and for muni the Gazzaloddi and the Halo tyres in 24" and 26", both of which offer massive improvements over standard tyres. For the 29

 


Cranks Types

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.



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. Some extractors have a removable ISIS head so you can use them on cotterless and ISIS cranks.

ISIS is the International Spline Interface Standard.  The ISIS standard is a standard for 10 spline hubs and cranks. Products from manufacturers who use this standard are compatible and ISIS hubs and cranks have a distinct advantage over square tapered hubs and cranks. They provide better transmission of power through the interface and require less maintenance than the square tapered setup. Click here to have a look at the ISIS link to help understand further questions.

Splined Cranks
Splined cranks are stronger than cotterless cranks and therefore are more suitable for muni or trials unicycling, but require slightly more maintenance. 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 our section on maintenance of splined cranks. Never ride with the cranks on the wrong side or you will destroy them.


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). ISIS Cranks: tighten bolt with 8mm Allen Key

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: 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 10mm spanner or socket to tighten.

Frame Bolts: 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.


Changing Bearings

Bearings on unicycles generally last a long time; even when you take your unicycle in a fountain, or the sea, or just splashing around in the mud. They do give up in the end though; normally at the worst moment possible (the middle of a Polaris Challenge event for me). You hear them grinding first, then when you turn the wheel slowly by hand you can feel the restriction in the movement.

This document is to give you a guide of what to do if you are brave enough to try and replace them yourself. Be warned this is not an easy task and requires special tools, most bike shops will be able to do this for you.

What you will require:

Replacement bearings - see our catalogue for quality replacement bearings. Crank extractor - again we sell these. Socket set - not really necessary, normal spanners can do but makes it easier. Rubber hammer/mallet - again not really necessary, a little imagination can find other things that will do. Bearing puller - either as small 3 leg bearing puller or a special DM bearing puller - this is essential. Scrap Wooden Block - not really necessary but it helps to prevent damage.

To remove and fit bearings:

1.   Remove the dust covers from the cranks.

2.   Remove the nuts/bolts from the centre of the cranks

3.   Remove the cranks using a crank extractor (see instructions). Be sure to screw the extractor fully home before you start to extract the cranks.

4.   Remove the wheel from the frame, in most cases this involves removing
4 bolts from the bracket that surrounds the bearing. In the case of the Pashley the screws are in the side of the fork legs and the bearing holder stays with the bearing.

5.   Fit 3-leg bearing puller over bearings and use a spanner to pull the bearing from the hub. Be sure to seat the legs of the bearing puller securely under the bearing so that it is not destroyed before it is removed from the hub. On a Pashley you need to extract the whole bearing holder. Do not try to remove with a lever or screw driver behind the bearing, it will damage the hub. For ISIS hubs use the ISIS cap from the crank extractor or something similar to prevent the bearing puller damaging the threads in the hub. (With Pashley and Dodger bearings they will require pressing out from the bearing holder and then the new ones pressed back in before refitting to hub. It is recommended that this is done by a machine shop).

6.   Once bearing have been removed clean the hub shaft with wire wool and little oil to remove any rust or dirt.

7.   Fit new bearings over the shaft (be sure to fit spacer on first if one was fitted) and gently push, ensuring that it is square with the shaft. When it can not be pushed any further by hand place the old bearing on top of the new one and slip a pipe or socket on top. Ensure that the pipe/socket is pressing on the centre of the bearing, not the outer ring or rubber seal. Place the wheel on a piece of scrap wood to protect the other side of the hub shaft. Hit the pipe/socket with a hammer until bearing is seated home. Remove old bearing.

8.   Clean the bearing holders to be sure that there is no dirt or rust.

9.   Re-fit the wheel in the frame. Be sure not to over tighten the bearing cups as this will impede the performance of the bearing.

10.  Re-fit the cranks on the hub. Be sure to check that the cranks/pedals are on the correct side. On the end of the pedals there is a letter L or R for left and right and a letter on the back of the cranks.

11.  Place the unicycle on your scrap of wood and use a rubber mallet to hammer the cranks home.

12.  Tighten the nuts/bolts in the end of the hubs, these must be secure. Tighten well but do not over tighten.

13.  Replace the plastic dust caps.
 


Maintenance Splined Cranks

It is very hard to actually break a set of splined cranks but unless they are regularly maintained they will wear and show movement on the spline. This goes for all types and makes of splined crank sets. This is because the splines are not tapered but are straight and rely on the precision of the fit to keep them from moving.

Features 20mm hardened CrMO spindle. Fine 36 crank splines. 2 x 1/4" keyways over the whole length of a central length. T3 Aluminium hub body pressed on to spindle. CrMO hollow cranks in 165 and 140mm with 12.5mm offset. 30 x 8mm hardened crank locking bolts. Self extraction ring. 6004 bearings (42x20x12mm), 108mm spacing (centre to centre).

How to Assemble They come assembled with the Bearings already fitted. 1. Grease the spline liberally, both on hub and crank. 2. Slip on the bearing spacer. 3. Slide on the crank 4. Tighten crank using the hardened steel bolt, use a long allan key or adaptor on a socket set. Do not tighten fully until you have assembled both sides then you need a very high torque on this. 5. Insert nylon washer on to bolt 6. Insert extractor ring - look out though, the thread goes the opposite direction to normal. Tighten fully until locked. 7. Repeat with the other crank, be sure that the cranks are 180 degrees from each other.

General Maintenance You should be aware of any change in the condition of your cranks when you are riding your unicycle. If they start to creak or movement is detected then stop immediately and investigate. Creaking - this is the sign of movement check the pedals are tight, crank bolt, spokes. Tighten if found loose. Movement - Check that the right crank is on the right hand side - if not swap the cranks over. If you are detecting movement tighten the crank bolt TIGHT. If there is still movement detected then give the crank assembly a full service.

Service Crank assemblies should be serviced on a regular basis to help eliminate any wear . If you have detected movement and it has not been fixed by tightening the crank bolt then try servicing the whole assembly; this can reduce or even eliminate this movement.

1.   Extract the crank using a long allan key or adaptor on a socket set. To do this just unscrew the bolt and it will pull off the crank.

2.   Remove the spacer, clean and put aside.

3.   Remove self extraction ring (remember the thread goes the other way), the nylon washer and bolt. Clean and put aside.

4.   Clean the hub splines and those inside of the crank thoroughly using a solvent and cloth.

5.   Inspect for wear, if wear is bad consider replacing the parts.

6.   Grease the spline liberally, both on hub and crank.

7.   Slip on the bearing spacer.

8.   Slide on the crank, but select a different position to where it was originally. Select a position at least 20degrees from the original position.

9.   Tighten crank using the hardened steel bolt, use a long allan key or adaptor on a socket set. Do not tighten fully until you have assembled both sides then you need a very high torque on this.

10.  Insert nylon washer on to bolt.

11.  Insert extractor ring - look out though, the thread goes the opposite direction to normal. Tighten fully until locked.

12.  Repeat with the other crank, be sure that the cranks are 180 degrees from each other.

 


Frame Straightening

Frames can get bent by various means or sometimes they just need fitting to a new hub. A bent frame can be caused by doing kick-up mounts in the gym or by jumping down loads of stairs and landing badly. On the larger frames the forks can widen after doing lots of turning, this then causes the bearings to be pulled off towards the cranks. Sometimes it can be that the frames when supplied from the manufacturer are just not straight or are too wide for the bearings and just need some tweaking for optimum performance. This is not a hard process but does require 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.

1.  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.

2.  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.

3.  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.

4.  If the wheel is consistently closer to one side than the other after you have done three tests above then your frame needs tweaking.

5.  Place the wheel in the frame and mark the side that is closest to the wheel with a marker or tape.


6.  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.

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

8.  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


Changing Cranks

There are four types of cranks: cotterless, ISIS, splined and 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. Some extractors have a removable ISIS head so you can use them on cotterless and ISIS cranks.

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 our section on 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 but we do sell replacements for them. 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.

 


Spoke Calculator

Unicycle.com United Kingdom has a great little tool for when your building wheels; their Spoke Calculator calculates what spokes you will need for the rim and hub you will be using. Simply select your Hub and Rim from the drop downs and it will tell you the size of spokes you are going to need.

 


Using a Crank extractor - Allen key ISIS-Octalink

 
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