CHOOSING THE RIGHT MOTORCYCLE

Some motorcycles are easier to fit a sidecar to than others. Our sidecar fitting system is only designed for tubular steel cradle frames. That is a frame made entirely of steel tubes which form a complete cradle round the front and under the engine. Ideally this should have two tubes in front of the engine, although some lighter bikes such as the Royal Enfield 500 may only have one tube. Most twin shock bikes and most custom cruisers would have this type of frame. The frame steering geometry of the original bike should not be at all sporty, so again most retro or classic twin shock bikes as well as most cruisers are correct. A long bike will generally be more stable in a straight line than a short one. A low center of gravity is more stable when cornering, so again cruisers win. It's good to have an under stressed engine with plenty of torque. So for ease of fitment and a very stable easy ride a cruiser would be a good choice. There is however one potential issue to look out for when choosing a cruiser, this is trail. Some cruisers have excessive trail as standard, great for stability but it can make the steering very heavy. Before buying a cruiser quickly check on line and find out the manufacturers rake and trail figures, ignore the rake, but look at the figure for the trail, 100 mm to 120 mm will be stable and light to steer, 121 mm to 140 mm will be very stable but starting to get heavy, 141 mm to 160 mm really will be heavy unless you have very wide bars, above 161 mm and you should probably pick a different bike. Retro and Classic bikes make a good choice, offering straight forward fitment and slightly livelier handling usually having between 100 mm and 115 mm trail

The first measurement to look at is how much the sidecar axle is in front of the rear wheel axle of the motorcycle as shown at C and D on this picture. This needs to be between 20 and 30 cm, less axle lead (20 cm) will produce a sidecar outfit which turns quickly but is less stable at speed. It will also require slightly more toe in. More axle lead will produce a sidecar outfit that is slightly heavier to turn but it will be more stable at speed. It will also require less toe in.

Arrange the sidecar chassis on blocks of wood next to the motorcycle so it is level and the axle lead is correct. Loosely attach the two lower mounts. The front lower mount should be as low as possible and as far forward as possible, This can usually be attached to the main horizontal frame tube just before it turns to go up towards the headstock. The rear lower mount should be as far back as possible. This one often needs an additional subframe making to take the mounting point as far back on the motorcycle as possible.

You will need four bricks and two straight lengths of steel. Place the two straight edges on the bricks either side of the bike and sidecar. On the bike side measure accurately and adjust the straight edge so it is 25 mm away from the wheels rims. You should be able to measure this at four points. Rear of rear wheel, front of rear wheel, rear of front wheel and front of front wheel. Then do the same on the sidecar wheel but as you only have one wheel you will have to rely on two measurements. Finally measure the distance at right angles to the bike just behind the rear wheel (marked A) and again just in front of the front wheel (marked B). This is the amount the vehicle toes in over the whole length. There are no hard and fast rules for this but a good starting point is 15 to 25 mm. So to be clear the distance between your two straight edges should be 15 to 25 mm greater at the back than it is at the front. (These measurements do assume that the wheel rim is the same width front and back even if the tyres are not the same size). If you had near 30 cm axle lead set the toe in close to 15mm and if you had near 20 cm axle lead set the toe in close to 25 mm.

TRACK WIDTH

This is the distance between the centre line of the tyres on the bike to the center line of the sidecar tyre. Measure this just where the the front edge of the sidecar tyre touches the ground, or roughly half way between the front and rear wheels of the bike. Generally the width of the track will be governed more by practical considerations such as can you still operate the gear change if the sidecar is too close, or will it actually fit through your gates at home if it's too wide. Mounting further away makes the sidecar outfit more stable when turning left, but means the sidecar will push and pull more on the bike as you accelerate and brake. So it's a compromise. As a guide a track of about 110 cm seems about right for a light bike with a Velorex and about 135 cm for a heavier bike with a Velorex.

CAMBER

This is less important than axle lead, toe in or lean out but still worth considering. As the bike turns right the suspension on the sidecar will compress and the suspension on the bike will lengthen causing some body roll. In turn this will mean in hard right turns the top of the sidecar wheel will move away from the sidecar as the bottom moves towards it. At rest the sidecar wheel should be set to either upright or slightly leaning in towards the sidecar. It should not be set leaning away at the top as this will increase when cornering. When set slightly leaning in at the top the outfit will be more stable in corners and the forces will go through the wheel and bearings in a straighter line putting less stress on the spokes and bearings.

ELECTRICAL CONNECTION

Lights usually fitted are front white marker, front amber direction indicator, rear red marker, rear red brake light and rear amber direction indicator. If your bike does not have indicators there is no requirement to have indicators on the sidecar.

Most motorcycles have a main wiring loom going to the rear lights and indicators located under the seat. This is the best place to connect the wiring. Our sidecars are all supplied pre-wired with plenty of spare length. A waterproof connector is supplied and this should be connected in a place which makes it easy to unclip in the event that the sidecar needs to be removed.

The original left hand direction indicators should be removed from the motorcycle if possible. If it is not possible to remove them completely the bulbs should be removed so they no longer flash.

STEERING DAMPERS

To fit or not to fit that is the question. Whether it is nobler in the mind to suffer the low speed shakes of an undamped outfit. Or strengthen thy arms against the opposing forces of a damper. (sorry couldn't resist).

At simply sidecars we prefer not to fit them. If the original bike is in good condition with no play in any wheel bearings, if the correct tyres are chosen, if these are at the correct pressure and if the sidecar is fitted and aligned correctly there should be little or no handlebar shake other than a small amount as you pull away, which can be corrected by correct riding technique. However some people like steering dampers, and if you do, then go ahead and fit one. If you are fitting one it should be as near parallel to the ground as possible, mounted securely on high quality rose joints to allow for the up and down movement of the forks and obviously it should not limit the steering lock in either direction.

Pros. If fitted correctly they will eliminate steering shake completely unless there is something seriously wrong with the bike or setup. If you have leading link forks with very little trail because you wanted lighter steering but now find it is so light it wobbles all over the road they are a useful way of adding some weight and feel to the steering.

Cons. They will make the steering heavier in all situations but most noticeable in traffic and at lower speeds when the steering would otherwise be pleasantly light. They can go wrong, not often, but they can. The can disguise small faults such as wear in the wheel bearings or bad set up which may lead to lack of correct maintenance.

WARNING AND THE SMALL PRINT

Our sidecars are designed to be fitted by competent home mechanic. We are happy to offer advice. BUT ultimately it is your responsibility to ensure all work is carried out to a safe standard. We strongly advise that any welding, or specialist bending is carried out by a professional fabricator.