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.
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:
Remove the dust covers
from
the cranks.
Remove the nuts/bolts from
the centre of the cranks
Remove the cranks using a
crank extractor (see instructions).
Be sure to screw the
extractor fully home before you start to extract the cranks.
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.
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).
Once bearing have been
removed clean the hub shaft with wire wool and little oil to remove any
rust or dirt.
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.
Clean the bearing holders to be
sure that there is no dirt or rust.
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.
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.
Place the unicycle on
your scrap of wood and use a rubber mallet to hammer the cranks home.
Tighten the nuts/bolts in
the end of the hubs, these must be secure. Tighten
well but do not over tighten.
When you are building a wheel (or if you would like to find out how to do it)
it is
very important to have the correct length of spokes to match your chosen hub and
rim combination. On this site we have a spoke calculator to help you to find the
length of spokes you need. Please click here.
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.
7. 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.
Kris Holm hub, Summit hub Features
20mm hardened CrMO spindle.
Large 8 crank splines.
6 Splines holding hub body.
Aluminium hub body pressed on to spindle.
CrMO hollow cranks in 170 and 140mm with zero off set.
25 x 8mm hardened crank locking bolt.
20 x 8mm spline locking bolt.
Aluminium bearing shield.
6004 bearings (42x20x12mm), 96mm spacing (centre to centre).
How to Assemble 1. Insert large spacer.
2. Insert bearing.
3. Insert bearing shield - the tapered side goes towards the bearing. (Note that
the hole in the washer needs filing out to allow it to fit on replacement units.
If fitting on any frame other than the Kris Holm frame it should be fitted next
to the crank.)
4. Insert small spacer.
2. Grease the spline liberally, both on hub and crank.
3. Slide on the crank
4. Tighten the crank using the crank locking 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. Tighten the spline locking bolt tightly.
7. Repeat with the other crank, be sure that the cranks are 180 degrees from
each other.
8. When both cranks are on Tighten the bolts fully, very tight.
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.
When both bolts are loosened it should come off easily.
2. Remove the spacers and bearing shield, clean and put aside.
3. Remove bearings, 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. Insert large spacer.
7. Insert bearing.
8. Insert bearing shield - the tapered side goes towards the bearing.
9. Insert small spacer.
10. Grease the spline liberally, both on hub and crank.
11. Slide on the crank
12. Tighten the crank using the crank locking 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.
13. Tighten the spline locking bolt tightly.
14. Repeat with the other crank, be sure that the cranks are 180 degrees from
each other.
15. When both cranks are on Tighten the bolts fully, very tight.
Qu-Ax Hub Features
20mm hardened CrMO spindle.
Large 10 crank splines.
Aluminium hub body pressed on to spindle.
CrMO hollow cranks in 170, 140 and 125mm with slight set.
25 x 8mm hardened crank locking bolt.
20 x 8mm spline locking bolt.
6004 bearings (42x20x12mm), 100mm 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 the crank using the crank locking 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. Tighten the spline locking bolt tightly.
6. Repeat with the other crank, be sure that the cranks are 180 degrees from
each other.
7. When both cranks are on Tighten the bolts fully, very tight.
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.
When both bolts are loosened it should come off easily.
2. Remove the spacers 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. Insert small spacer.
7. Grease the spline liberally, both on hub and crank.
8. Slide on the crank
9. Tighten the crank using the crank locking 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. Tighten the spline locking bolt tightly.
11. Repeat with the other crank, be sure that the cranks are 180 degrees from
each other.
12. When both cranks are on Tighten the bolts fully, very tight.
Profile Hub
Features 3/4" hardened CrMO spindle.
Fine 48 crank splines.
1 x 3/16" Woodruff keys to hold the central hub body.
T3 Aluminium hub body pressed on to spindle.
CrMO hollow cranks in 145, 160, 165, 170 and 175mm with 12.5mm offset.
15 x 8mm hardened crank locking bolts.
6203-3/4-2RS bearings (40x19.03x12mm) or 99R12 bearings (1 5/8" OD), Min 92mm,
Max 108mm spacing (centre to centre).
Comes with a life time warranty
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 spacers on until you have right width for your frame,
note it is advisable to have the frame slightly narrower than the bearings so
that they force the bearing on.
3. Slip on the bearing.
4. Slip on the remaining bearing spacers.
5. Slide on the crank until it is on by 10mm, note that you may need to tap this
on with a mallet, but use a rubber mallet or a block of wood to protect the
crank top.
6. Tighten crank using the hardened steel bolt (do not forget the aluminium
tapered washer), 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.
7. Repeat with the other crank, be sure that the cranks are 180 degrees from
each other. Check that the hub spindle is central in the hub body as it
can be pulled through from one side or the other using the crank locking bolt.
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. Remove the crank locking bolt using a long allan key or adaptor on a socket
set.
2. Insert the Profile extraction tool and tap while holding the crank or use the
Evercraft bearing puller when using this use the small side of the puller
and place it over the bulge of the crank.
4. Remove the spacers, 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 spacers on until you have right width for your frame,
note it is advisable to have the frame slightly narrower than the bearings so
that they force the bearing on.
8. Slip on the bearing.
9. Slip on the remaining bearing spacers.
10. Slide on the crank until it is on by 10mm, note that you may need to tap
this on with a mallet, but use a rubber mallet or a block of wood to protect the
crank top.
11. Tighten crank using the hardened steel bolt (do not forget the aluminium
tapered washer), 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.
12. Repeat with the other crank, be sure that the cranks are 180 degrees from
each other. Check that the hub spindle is central in the hub body as it
can be pulled through from one side or the other using the crank locking bolt.
Refurbishing Hubs
After considerable use, wear can sometimes be detected in the interface between
the hub body and the spindle. By the time this occurs the splines and
cranks have often worn to the point where it is not worth repairing, but if if
this is not the case here is how to proceed.
1. Remove cranks and bearings.
2. Remove spindle from the hub, this is best achieved by supporting the hub body
between 2 blocks and then tapping the spindle out with a rubber mallet or a
hammer and a block of wood to protect the spindle. If your hub body is really
worn this should be very easy.
3. Remove the keys using a screwdriver and hammer. Be very careful not to
damage the spindle or key.
4. Clean all parts thoroughly, the ideal is Loctite Klean 'N Prime, although
lighter fluid does a pretty good job in my experience.
5. Reassemble the keyways using a product like
Loctite 660 and 7240 or similar to fill in the wear.
6. Apply the Loctite to the inside of keyway (but not the inside of the spindle
shaft) and the shaft exterior being careful not to get any in the splines.
7. Re-assemble the spindle into the hub, clear away any excess Loctite. Be
sure that the spindle is central in the hub.
8. Re-assemble the spacers, bearings and cranks.
9. Put aside and do not use for 48 hours.
Compiled by Roger Davies with the help of Kris Holm and Tony Melton
The shortest seatpost we offer is 220mm. Any seatpost length will give you a
range of 100mm in height. While this will be suitable for many people it may not
be suitable for you. If you are too tall you can order a
longer seatpost, if you are too short and don't want to reduce your wheel
size a good option is to cut down your seatpost. By cutting down your seatpost
you shift the range of heights available downwards.
The simplest and cleanest way of doing this is with a seat post cutter. Measure how
much you need to cut off (keeping this to a minimum) and mark. Gently tighten
the blade of the seat post cutter to your mark, clamping it in place before rotating
the seatpost. ( Holding the handle of the seat post cutter turn the seatpost towards
you otherwise it can spiral and damage your seatpost.) Tighten the blade gently
every 360˚ until the unwanted section
falls off. This method should give a clean cut, reducing the need for filing.
If you don't have access to a seat post cutter then you can use a hacksaw. Clamp the
seatpost still (being careful not to bend it) and carefully saw where you have
marked. This tends to give a much rougher edge and will probably need filing.
Take care when cutting down not to cut too much off . You can always cut some more
off later but you can't reattach it if you cut too much off first time!
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 (yes Simon and Will!)
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.
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.
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.
Copyright 2001, Unicycle.Com. For our Customer
Service Policy and Privacy Statement, see Customer
Services.
Unicycle.Com, The Grange Business Centre, Belasis Avenue, Billingham, Stockton. TS23 1LG United Kingdom.
Tel: 0800 980 0711 Email: contact@unicycle.uk.com
Unicycle maintenance
