Fitting a sidecar
Having chosen the motorcycle and a suitable sidecar you have first of all to make the firm decision that all work done on the combination will be of the highest quality, particularly with respect to safety. This cannot be stressed too highly.
Starting with the two components you must decide just where to put the sidecar in relation to the motorcycle. The parameters used to describe this are Lead, Lean-out and Toe-in.
1. Sidecar wheel lead
The distance straight forward from the rear axle of the bike to the sidecar wheel spindle is known as the lead. The value can be anything from zero on some vintage outfits to as much as 500mm.
As lead is increased the weight distribution improves until a point is reached where the steering becomes too heavy and tyre wear becomes excessive. A good rule of thumb is to set the lead to about 20% of the wheelbase of the motorcycle. It is not critical and may in any case be dictated by where the fittings can be positioned.
2. Motorcycle lean-out
When fully laden it is important that the bike should not lean towards the sidecar; if it does the steering will be heavy particularly when turning away from the sidecar. The amount of lean-out is measured at the steering head of the unladen motorcycle and is usually less than 30mm. Outfits with car tyres, particularly wide, low profile ones, should be set close to zero lean-out, but not usually leaning in.
3. Sidecar wheel toe-in
Toe-in is defined as the amount by which the track width at the front wheel is narrower than at the rear wheel. It is measured using a pair of straight edges, one along the motorcycle wheels and one along the sidecar wheel extending forward to the front wheel. If the front and rear wheels differ in width this should be allowed for.
Too much toe-in will scrub the tyres on turns toward the sidecar and let the outfit drift towards the middle of the road under neutral steering. Too little toe-in and the outfit will favour the gutter.
In practice it is usually found that a well set up outfit will move slightly towards the kerb under acceleration and slightly away on the over-run. A typical value would be 10 to 20mm, rarely, as much as 35mm. This measurement can be critical to the steering bias of the combination and the more lead you have the less toe-in you need.
Fitting the Sidecar
Having decided where the sidecar wheel should be positioned it remains only to bolt it on and wire up the lights.
Apart from Ural and Jawa, very few motorcycles today have any provision for the fitting of a sidecar. With the increasing use of aluminium frames, square section tubing, integral fairings and the absence of lower frame tubes, it is likely that you will need the help of a sidecar manufacturer.
Wasp, Watsonian/Squire, Merlin and Lumley Engineering all offer a fitting service and it is well worth enquiring to see if one of them has tackled the particular bike you have in mind.
All fittings should be attached securely to the main frame of the motorcycle; do not use passenger footrest hangers as these are seldom strong enough. The rear subframe on some machines is only a lightweight affair to carry the saddle and should be avoided or strengthened as necessary.
If a sidecar lug is incorporated, (rare after about 1965) use it; these are typically found at the steering head and top or bottom of the saddle tube. The recent fashion for "retro" bikes does provide frames with round tubing to which it is relatively easy to fit traditional clamps.
In the absence of lugs, try to position the fittings near cross-members so that loads are transmitted to both sides of the frame and advantage can be taken of any triangulation offered by it.
The usual four points for fittings are generally arranged as follows:
1. Top front
There are, broadly speaking, three types of frame to be encountered: single down-tube, twin down-tube and no down-tube. Fitting to the first type should be by means of a substantial clamp as high as possible on the down-tube; this gives less chance of frame flexure and less likelihood of the fittings interfering with the front mudguard on heavy braking.
Twin tubes give three possibilities: a single clamp on one tube as high as possible, a pair of clamps across both tubes sharing the load of the fitting, and thirdly, if there is a convenient cross member near the top this may be used with a single clamp.
Frames lacking a front down-tube or engine cradle are very common today. Sub-frames are available for most of them as part of the fitting kit. Sometimes it is possible to pick up on the frame under the tank, or the top engine mount may be used, modified or replaced with one suitable for hanging a sidecar. In any case the sidecar manufacturer should be consulted.
2. Bottom front
On older machines this may be a single frame clamp or the engine plates may be used or an engine bolt may be replaced with an eyebolt of appropriate dimensions. Panther and Vincent machines, being without down-tubes, used a lug directly into the crankcase. Think very carefully before doing the same on an engine not designed for it. The bottom front fitting will be part of the sub-frame for many modern motorcycles.
3. Top rear
This should be fitted to the main frame under the saddle nose or at the top of the rear shock absorber on a twin-shock machine. Monoshock frames usually have very light rear subframes designed only as saddle supports and either additional gusseting or a special subframe will be required. If it is possible to take this fitting through the sidecar body to somewhere near the sidecar wheel this will vastly improve the rigidity of heavy or powerful outfits. Finally, remember that a pillion passenger, if carried, will want somewhere to put both legs!
4. Bottom rear
A clamp can be fitted anywhere from under the gearbox to as far back as the pillion footrest. If gusseting and accessory mountings prevent use of a clamp, a bridging plate must be made to attach to bolts on the frame, e.g. longer footrest or engine mounting bolts. The bolts can be the next size up without spoiling the appearance if more strength is required. Another possibility is to use the centre stand mounting as the stand itself is likely to be redundant.
Having four good attachment points, position the bike (without stand) and sidecar next to each other, with enough space between them for your legs, using bricks, blocks, axle-stands etc. according to the recommended toe-in, lean-out and lead. Classic sidecars look better slightly nose up (say 20mm), modern ones usually level and of course level side to side for all types.
For most combinations it will be easier to attach the two bottom fittings first and then add the two top struts. For combinations with an old-fashioned "swan neck" this will not be possible and the top front (ie the swan neck) and rear bottom pair should be tackled first. Adjust the length of each fitting as appropriate.
Next, fit all clamps, nuts and bolts but do not fully tighten them until you are sure everything is in position. It should be possible to remove any single bolt with the fingers. In other words no connection should have any stress or preload; if force is needed to take a bolt out then the plot is not correctly set up. Finally tighten all nuts and bolts so that the outfit is now a rigid unit; NO play between bike and chair is acceptable.
A lamp of at least 5 watts is obligatory but it is recommended that a brake light be fitted and that the indicators be moved over to the nearside of the sidecar.
It is also recommended that a sidecar brake be fitted. It is not possible to go into detail here but it is a job for an expert and a sidecar specialist should be consulted.
For further details contact the Technical Officer.
While the advice contained herein is given in good faith, the Federation of Sidecar Clubs and its officers, committee members and helpers have no control over the use or application of these Guidelines and cannot be held responsible for any consequential circumstance.
Having chosen the motorcycle and a suitable sidecar you have first of all to make the firm decision that all work done on the combination will be of the highest quality, particularly with respect to safety. This cannot be stressed too highly.
Starting with the two components you must decide just where to put the sidecar in relation to the motorcycle. The parameters used to describe this are Lead, Lean-out and Toe-in.
1. Sidecar wheel lead
The distance straight forward from the rear axle of the bike to the sidecar wheel spindle is known as the lead. The value can be anything from zero on some vintage outfits to as much as 500mm.
As lead is increased the weight distribution improves until a point is reached where the steering becomes too heavy and tyre wear becomes excessive. A good rule of thumb is to set the lead to about 20% of the wheelbase of the motorcycle. It is not critical and may in any case be dictated by where the fittings can be positioned.
2. Motorcycle lean-out
When fully laden it is important that the bike should not lean towards the sidecar; if it does the steering will be heavy particularly when turning away from the sidecar. The amount of lean-out is measured at the steering head of the unladen motorcycle and is usually less than 30mm. Outfits with car tyres, particularly wide, low profile ones, should be set close to zero lean-out, but not usually leaning in.
3. Sidecar wheel toe-in
Toe-in is defined as the amount by which the track width at the front wheel is narrower than at the rear wheel. It is measured using a pair of straight edges, one along the motorcycle wheels and one along the sidecar wheel extending forward to the front wheel. If the front and rear wheels differ in width this should be allowed for.
Too much toe-in will scrub the tyres on turns toward the sidecar and let the outfit drift towards the middle of the road under neutral steering. Too little toe-in and the outfit will favour the gutter.
In practice it is usually found that a well set up outfit will move slightly towards the kerb under acceleration and slightly away on the over-run. A typical value would be 10 to 20mm, rarely, as much as 35mm. This measurement can be critical to the steering bias of the combination and the more lead you have the less toe-in you need.
Fitting the Sidecar
Having decided where the sidecar wheel should be positioned it remains only to bolt it on and wire up the lights.
Apart from Ural and Jawa, very few motorcycles today have any provision for the fitting of a sidecar. With the increasing use of aluminium frames, square section tubing, integral fairings and the absence of lower frame tubes, it is likely that you will need the help of a sidecar manufacturer.
Wasp, Watsonian/Squire, Merlin and Lumley Engineering all offer a fitting service and it is well worth enquiring to see if one of them has tackled the particular bike you have in mind.
All fittings should be attached securely to the main frame of the motorcycle; do not use passenger footrest hangers as these are seldom strong enough. The rear subframe on some machines is only a lightweight affair to carry the saddle and should be avoided or strengthened as necessary.
If a sidecar lug is incorporated, (rare after about 1965) use it; these are typically found at the steering head and top or bottom of the saddle tube. The recent fashion for "retro" bikes does provide frames with round tubing to which it is relatively easy to fit traditional clamps.
In the absence of lugs, try to position the fittings near cross-members so that loads are transmitted to both sides of the frame and advantage can be taken of any triangulation offered by it.
The usual four points for fittings are generally arranged as follows:
1. Top front
There are, broadly speaking, three types of frame to be encountered: single down-tube, twin down-tube and no down-tube. Fitting to the first type should be by means of a substantial clamp as high as possible on the down-tube; this gives less chance of frame flexure and less likelihood of the fittings interfering with the front mudguard on heavy braking.
Twin tubes give three possibilities: a single clamp on one tube as high as possible, a pair of clamps across both tubes sharing the load of the fitting, and thirdly, if there is a convenient cross member near the top this may be used with a single clamp.
Frames lacking a front down-tube or engine cradle are very common today. Sub-frames are available for most of them as part of the fitting kit. Sometimes it is possible to pick up on the frame under the tank, or the top engine mount may be used, modified or replaced with one suitable for hanging a sidecar. In any case the sidecar manufacturer should be consulted.
2. Bottom front
On older machines this may be a single frame clamp or the engine plates may be used or an engine bolt may be replaced with an eyebolt of appropriate dimensions. Panther and Vincent machines, being without down-tubes, used a lug directly into the crankcase. Think very carefully before doing the same on an engine not designed for it. The bottom front fitting will be part of the sub-frame for many modern motorcycles.
3. Top rear
This should be fitted to the main frame under the saddle nose or at the top of the rear shock absorber on a twin-shock machine. Monoshock frames usually have very light rear subframes designed only as saddle supports and either additional gusseting or a special subframe will be required. If it is possible to take this fitting through the sidecar body to somewhere near the sidecar wheel this will vastly improve the rigidity of heavy or powerful outfits. Finally, remember that a pillion passenger, if carried, will want somewhere to put both legs!
4. Bottom rear
A clamp can be fitted anywhere from under the gearbox to as far back as the pillion footrest. If gusseting and accessory mountings prevent use of a clamp, a bridging plate must be made to attach to bolts on the frame, e.g. longer footrest or engine mounting bolts. The bolts can be the next size up without spoiling the appearance if more strength is required. Another possibility is to use the centre stand mounting as the stand itself is likely to be redundant.
Having four good attachment points, position the bike (without stand) and sidecar next to each other, with enough space between them for your legs, using bricks, blocks, axle-stands etc. according to the recommended toe-in, lean-out and lead. Classic sidecars look better slightly nose up (say 20mm), modern ones usually level and of course level side to side for all types.
For most combinations it will be easier to attach the two bottom fittings first and then add the two top struts. For combinations with an old-fashioned "swan neck" this will not be possible and the top front (ie the swan neck) and rear bottom pair should be tackled first. Adjust the length of each fitting as appropriate.
Next, fit all clamps, nuts and bolts but do not fully tighten them until you are sure everything is in position. It should be possible to remove any single bolt with the fingers. In other words no connection should have any stress or preload; if force is needed to take a bolt out then the plot is not correctly set up. Finally tighten all nuts and bolts so that the outfit is now a rigid unit; NO play between bike and chair is acceptable.
A lamp of at least 5 watts is obligatory but it is recommended that a brake light be fitted and that the indicators be moved over to the nearside of the sidecar.
It is also recommended that a sidecar brake be fitted. It is not possible to go into detail here but it is a job for an expert and a sidecar specialist should be consulted.
For further details contact the Technical Officer.
While the advice contained herein is given in good faith, the Federation of Sidecar Clubs and its officers, committee members and helpers have no control over the use or application of these Guidelines and cannot be held responsible for any consequential circumstance.
Simply Sidecars also has a good guide here.