There are three major parts to a wheel – the rim, the spokes and the hub; together these can bear loads of many times their own weight and transport them over enormous distances with ease. You should check each part regularly to ensure it is secure and in good condition.
There are four main types of rim : Endrick, high pressure, Westwood and sprint.
This rim is the most commonly used; it is of a heavy, durable section. Usually made of steel, and has braking surfaces on its sides to accept caliper-type brakes.
This is of a lighter, smaller ‘U’ section than the Endrick type and is usually made in either steel or alloy. Like the Endrick, it accepts brake blocks on its sides.
Resembling a ‘W’ in profile, the Westwood rim is made of steel. Braking is with rod (or roller lever) brakes; the brake blocks are drawn up from beneath the concave curves of the rim. With this type of braking system, it is difficult to remove the wheel without releasing the brake guides and stirrups and this has led to the phasing out of the Westwood rim.
This type, which accepts tubular tyres. Is almost always made of alloy and, apart from the concave bed in which the tyre sits, is a hollow box shape. Again braking is on the sides. The sprint rim is becoming increasingly popular with club and racing cyclists.
Unless a bicycle is fitted with hub brakes, the rims provide the means of stopping. The surfaces of the rims should always be absolutely clean and free from grease and oil, otherwise braking will be greatly impaired.
The spokes hold the rim in place relative to the hub; they fit into holes at the hub flanges and into nipples at the rim so they are adjustable. Half of the spokes attached to the rim go to one of the hub flanges and half to the other: in each hub flange half of the spoke heads face outwards and half inwards. The holes in the rim are usually staggered (offset) and no two spokes from the same flange are side by side when they reach the rim: if they are, the wheel has been built incorrectly or repaired badly at some time. The spokes should radiate from the stagger to the hub flange which is closest to them.
Spokes require little general maintenance other than regular cleaning. Remove dirt with warm water and washing-up liquid and a soft brush, then rinse with clean water and dry.
Hubs come in a wide variety of types. On ordinary roadster-type bicycles the hubs are usually made of steel and the wheels are fixed to the frame with nuts; on lightweight racing or touring machines they are usually made of alloy and have quick-release, cam-operated levers to secure the wheel.
Carrying out repairs
Damage to the wheels of your bicycle should be made good as soon as possible, otherwise the machine could become dangerous. In some cases you can make repairs with the wheel on the bicycle, but it i8 often necessary — and much easier — to take the wheel off. The method of removal and replacement depends on the type of bicycle and on whether the wheel is at the front or the rear.
Front wheel To remove the front wheel, loosen the axle nuts with a spanner and take the wheel out of the fork drop-outs; if you have quick-release hubs, simply flip the lever.
To replace the wheel, slip the axle back onto the fork drop-outs. If the wheel is held with nuts, tighten these a little and check the rim is centred between the fbrk arms before tightening them fully. With quick-release levers, turn the lever until it is just finger-tight, check the rim is centred and tighten the lever so it points up and backwards.
Some front hubs do not have lock nuts to hold the cone in adjustment and these must be fitted into the fork with the plain cone (the one without spanner flats) on the right-hand side as viewed from the saddle position. The fork arms will have to be sprung open to remove or insert the wheel and the shoulder on this cone must locate in the keyhole slots in the fork ends.
To remove a rear wheel on a machine with Derailleur gears, run the chain to the smallest sprocket, undo the axle nuts or flip the quick-release lever as for the front wheel and slide the wheel forward out of the frame.
To replace the wheel, ease the axle into the fork drop-outs, slipping the chain onto the smallest sprocket on the freewheel, then slightly tighten the axle nuts or quick-release lever. Pull the wheel towards the rear of the machine until the right end of the axle touches the back of the Derailleur clamp plate slot. Ensure the plate is securely fixed then, using this as a pivot point, centre the rim and tighten the axle nuts or levers. This procedure also applies to single speed bicycles except that, when refitting the wheel, chain tension will locate the wheel initially in the fork end slot.
On some older roadster and junior models you may have to slide the wheel back to remove it. First loosen the nuts and disengage the wheel locators, if fitted; slide the wheel forwards to slacken the chain and remove the chain from the chain wheel. Pull the wheel back until the axle is clear of the slot, remove the chain from the freewheel and lift the wheel clear. To refit the wheel, thread the chain over the freewheel and place the axle in the slot. Refit the chain and pull the wheel back until most of the chain slack is taken up; slightly tighten the axle nuts, refit and tighten any wheel locators and secure the axle nuts.
If you have hub gears, you will have to disconnect the gear cable at the hub before removing the wheel and reconnect it after replacing the wheel (see below).
Removing rim bulges
Bulges in the rim caused by running over pot-holes or into kerbs should be removed at once; they can contribute to increased tyre wear at a particular spot due to the brake snatching as it meets them, and they can ruin the head set bearings and their housings by setting up a constant juddering movement when the brake is applied.
These are difficult to remove and you should go to your local specialist dealer for advice.
If the rim is beyond repair, it will be necessary to have the wheel rebuilt or even replaced.
First mark the position of the bulge by rotating the wheel slowly and looking along the rim at its movement between the brakes; any bulges will show up clearly as they pass between the blocks. Running the rim between your thumb and forefinger can also pin-point any corrugations.
To remove these bulges you will have to take the wheel off the bicycle; you can then ease the tube and tyre off the rim. You will need a flat piece of metal about 100mm (4in) square and 6mm thick, with a flat smooth edge. Place this vertically in a vice with at least 50mm (2in) protruding and place the inside edge of the rim squarely on the metal so it is supported. Using a rounded planishing hammer, very gently tap the rim back into shape.
Truing the wheel
Once you have tapped the rim into shape you may find the wheel is slightly out of true or eccentric; you can bring it back into shape as long as you are prepared to spend some time on the job. You will need a very good quality nipple key to turn the spoke nipples; don’t use a poor quality type and never use pliers on the nipples since they can be damaged quite easily.
Put the wheel back onto the machine without the tyre and tube; leave the rim tape in place to stop any spokes shooting out if they break under tension. If the wheel is a rear one, don’t engage the chain on the sprocket since the wheel must spin freely both ways and it cannot do this if the freewheel is driving. It is very useful to have someone to hold the machine steady at this stage.
Spin the wheel and watch its movement between the brake blocks. If, when looking down the rim, the braking surface touches the left-hand brake block, use the nipple key to give half a turn to one or two spokes coming from the right-hand flange of the hub; if the braking surface touches the right-hand block, adjust the spokes from the left-hand hub flange. If the wheel moves up and down, adjust one spoke from each side of the hub. Tighten spokes to remove a bump in the rim and loosen them to remove a dent or depression.
Getting the wheel up to the correct tension is almost a matter of taste; there is, however, an optimum tension for every type of wheel, but you will only learn this by experience. Pressure against the nipple key indicates the tension is too high and the spokes may break; rattling spokes indicate the tension is too loose.
If spokes have become weathered or ‘frozen’ and the nipples will not turn, apply a little penetrating oil to the threads and turn the nipple backwards half a turn to release it. If this fails, you will have to replace the spoke.
This can be very difficult if the wheel is under extreme tension. You will have to cut out the spoke and apply adverse pressure to the rim by hand to hold it in position while a new spoke is fitted; if you do not do this, the rim will warp or buckle — or even collapse. You should have a nipple and spoke of the correct length ready to fit as soon as the old one is removed.
First take the spoke and nipple out of the hub and the rim, then push the new spoke, rim end first, through the hole in the hub from the opposite side to the two adjacent spokes and weave it through the other spokes in the same way as the original one. Fit the spoke through the hole in the rim and screw the nipple onto the end; tighten with a screwdriver.
You will now have to true the wheel as previously described, then file down any protruding spokes and refit the rim tape, tube and tyre.
Adjusting hub bearings
Correct adjustment of the bearings is probably the most important aspect of hub maintenance. It is not easy to tell if the hubs need adjusting, so make regular checks to ensure they are secure.
With the axle nuts tight, hold the axle firmly in place and move the wheel from side to side; if play is apparent or the wheel will not spin freely, the cones need adjusting. Remove the wheel from the machine and slacken the cone lock nut using a spanner to hold the cone; then screw up the cone and tighten the lock nut. With the wheel back on the bicycle check it spins freely and there is no side to side play at the rim or at the hub.
The most popular hub gear, the Sturmey-Archer, has a definite sequence of adjustment which must be followed to ensure all the internal parts are kept in mesh. First engage third gear then disconnect the indicator rod on the right-hand side by undoing the long knurled sleeve and small knurled lock nut then remove the indicator rod by rotating it anti-clockwise. Undo the axle nuts and remove the wheel. Undo the left-hand lock nut and cone about three turns and, with the spindle clamped sprocket uppermost in a soft vice, undo the lock nut a few turns so you can lift up the double-pronged tab washer which stops the cone rotating. Turn the cone clockwise until it is finger tight then turn it anti-clockwise three-quarters of a turn. You can now lock it back in position with the tab washer and lock nut and adjust the left-hand cone in the usual way to eliminate any shake in the bearings.
Put-the wheel back onto the machine, screw the indicator rod fully into the hub, then turn it back half a turn. Reconnect the indicator rod to the gear lever cable using the knurled sleeve, select second gear and check the two small flats adjacent to the chain are flush with the end of the hub spindle when viewed through the hole in the cable housing. Having set this you can lock the sleeve with the lock ring. If, when you operate the gear lever, this fails to engage all gears, seek specialist advice. Hub dynamos Modern Sturmey-Archer hub dynamos are relatively easy to adjust. Before removing the wheel, release the two terminal tags which are connected to the armature in the centre of the hub; otherwise they may be pulled off their connecting wires. Grip the small flange side of the hub spindle in a soft vice and check the lock nut on the armature side of the hub is secure. Turn the wheel over and adjust the opposite side in the usual way, again ensuring there is no excessive play in the bearings. Never remove the keeper plate on the dynamo body since this would break the magnetic field and render the dynamo unit useless.