I can?t explain what drives me to pick up a hacksaw and start cutting up an inherently unstable vehicle, a motorcycle, and build it into an unstable and asymmetrical one, a sidecar. 
In many ways, a motorcycle is an unsuitable vehicle to make into a racing sidecar.  The steering geometry is all wrong, the riding position is too high, the wheelbase is too short, and the wheels are too large in diameter.  Although one could bolt a sidecar platform to a stock motorcycle and go racing, I wouldn?t recommend it.  The classic and supervintage sidecars we race should be able to be driven around corners with one hand, they shouldn?t wobble uncontrollably, and they should be able to withstand at least a seasons? racing without major failures.  These are not lofty goals.  These are aspects of our class we can assume as long as those building rigs take care to adhere to sound engineering principles. 
A racing sidecar should be a purpose built vehicle with a frame structure suited to the particular stresses to which it will be exposed.  This requires quite a bit of reconstruction of the donor vehicle.  I like to use a portion of the frame which the engine came in because the engine mounts are there, the swingarm is aligned to the trans output shaft and usually some part of the front downtube or tubes is long enough to attach the new steering head to.  When I design a new rig I start with the steering geometry.  I have used rake angles ranging between 26* and 22*.  I would use steeper angles but the head tube moves further forward with less rake and becomes impractical.  I like ½? to ¾? of positive trail (see fig.1). I decide on tires and wheels because tire diameter affects trail.  I allow for some adjustment of trail to compensate for replacement tires and driver preference.
I lower the frame/engine to 3.5? or so off the ground.  Next I set a goal for the wheelbase keeping in mind the goal of a 40-40-20 percent weight distribution.  I limit the suspension travel to 2? front and 1.5? rear.  Before settling on the wheelbase, I look at the driver?s ideal position on the rig.  Ideally, the driver is positioned in such a way as to be able to weight any of the wheels by changing his/her position by leaning forward, sliding backward and/or leaning sideways with the neutral position being a reasonably comfortable one.  I set the length of the rear swingarm next. This generally means lengthening it. Now is a good time to check the squat caused by the lowered engine and generally larger rear sprocket.  I adjust the engine height and swingarm angle and location of the swingarm pivot with the goal of minimizing the squat and jacking tendencies. 
The track and sidecar wheel lead are related to each other.  I like to use 38?to 40? inches track width and around 11? of lead.  I set the sidecar wheel with zero toe in.  I?ve found the tires last longer that way.  I also set the bike portion of the frame vertical or leaned in towards the sidecar a degree or two.  Leaning the bike towards the sidecar helps keeps the rig from lifting; this can be important to a light and mildly skittish passenger.  I try to limit the distance the passenger has to travel in changing position from over the rear wheel to off the platform.  Two approaches are to lower the frame over the rear wheel and to raise the platform.  Making the sidecar fender low and close to the front of the wheel helps with this goal too.  A good passenger will make use of the space between the front of the sidecar wheel and the front of the platform to stabilize the rig in corners. I always make the sidecar platform integral with the bike frame.  I use a large diameter tube running under the rear of the engine/ trans out to the sidecar wheel.  I put the other attachment points all in different planes.  This prevents them from forming an undesirable hinge.
At this point with a rolling chassis designed and hopefully built, Spring is rolling around and you?ve used up your patience, money, and spare time.  Now the hard part begins, adding all of your own controls and cables, since you can?t just open a catalog and order them.  When you climb over the rig and start making motor noises there?s nothing but empty space to put your limbs on. In the past year or so I?ve seen the controls on USCRA rigs conform somewhat.  The shifter tends to be a straight rod with 2 pegs that your boot fits in between.  The rear brake pedal is often attached directly to the backing plate. It?s really important that the handlebars or clip-ons be very strong.
I?ve touched on some of the more salient details of building a racing sidecar rig and realize I shouldn?t try to cover the entire process in one article.  I started out by trying to illustrate the enormous amount of considerations and compromises it takes to make one of these incredibly fun to drive racers and characteristically, have run out of time.

Rake & Trail (solo bikes) - Pete Talabach

            There appears to be considerable confusion concerning the exact nature of the terms "rake" and "trail" so in keeping with the chaotic nature of the USCRA I have decided to muddy the waters even further by adding my two cents worth.  I will begin by trying to define the terms rake and trail and describe a few things the home chassis tuner can do to affect them and what to expect as a result.
            Rake, quite simply, is the angle that the steering axis makes with the vertical (or horizontal if you choose). On most vintage bikes and sidecars the steering axis is a centerline drawn through the center of the steering head bearings. Most vintage bikes have rake angles in the range of 26 to28 degrees from the vertical. Trail is a little harder to visualize. If you continue the centerline that is the steering axis down until it intersects the ground that intersection describes one end of your trail measurement. Dropping a vertical line through the front axle center to the ground will generate the other end.  The distance between these two points is the trail. If the axle center trails the steering axis the trail is positive if the axle center leads the trail is negative.
            Positive trail helps make the steering self-center. If you have trouble seeing it think of a shopping cart caster wheel, the steering axis is the caster pivot (zero degrees of rake) it is not hard to see that the axle center is stable trailing the pivot when the cart is pushed forward. A motorcycle has positive rake, as well, which up to approximately 45 degrees uses the weight of the bike to orient the axle center in a trailing position to the steering axis. This eliminates the need to push the motorcycle forward to effect that orientation, as in the caster wheel. Most vintage bikes have trail in the range of three to four and one half inches.
             Most street bikes are set up with fairly slow heavy steering and a strong rearward weight bias. To quicken steering reducing trail is often beneficial although it also reduces front-end feedback and tire feel so the order of the day is a little at a time! Reducing rake lightens steering but can also encourage wobbling (think shopping cart, zero rake). The only practical method of reducing rake angle open to the home suspension tuner working on vintage bikes is to change the attitude of the frame by using longer shocks (careful of chainlines and swingarm angles) and shortening the forks, usually by sliding the tubes up. ...This method has the added benefit of shifting weight to the front wheel. Another word of caution though, a little at a time. I never move fork tubes more than 5 mm at a time and usually only 1 or 2.
                 Changing the frame attitude to reduce the rake also reduces the trail but there are a number of ways to reduce trail without affecting rake. Probably the easiest of these is to reduce the diameter of the front wheel. Alternatively, a leading axle fork or triple clamps with more offset will also reduce trail. It is important to bear in mind though that rake and trail numbers that are stable in a modern bike with a 6061 aluminum spar frame and 43mm inverted forks will be deadly in a vintage bike with 35mm or smaller forks and garden hose for frame tubes.

                                Ride fast and take chances; Pete Talabach

A friend called and asked a question that went something like, these Dunlop's have only one direction of rotation arrow on them, what should I do with the front tire?  So, having raced these tires for ten years I gave him my opinion.

Most of us are used to having two direction of rotation arrows on a tire, one which states for front mounting and one for rear mounting. The Rule of Thumb I've heard is that if there is only one direction of rotation noted on the tire that the front tire is mounted backwards, i.e. opposite the specified direction of rotation as the braking forces take the place of the acceleration force in the tire carcass.

Well my friend's question peaked my curiosity so I contacted the very patient Phil Lamont, the Canadian importer who in turn put the question to Fort Dunlop in England. The Dunlop response was concise: "The arrow on the sidewall indicates the correct rotation for the drive wheel. When mounted on the front, the rotation should be reversed, as most of its work is in braking. ie. the arrow should be incorrect" on the front. It probably is not crucial - in our experience tread joint problems are minimal on moulded tread-patterned tyres".

So there you have it, the manufacturer's recommendation. Oh, and one other fact from Dunlop is the correct rim size for this tyre is 2.625 inch at the bead, i.e. a 16 x WM4.

End of story? Not quite.  If you walk around the USCRA pit area you'll find at least one old, balding, sidecar pilot who for ten years has been mounting the front tire "incorrectly", i.e. with the arrow in the actual direction of rotation. This racer has thought about it and sees a better water path out of the tread when mounted "incorrectly" and who really doesn't use a lot of front brake anyway. (Infamous quote: "they only slow you down").  Now before you say this sidecar racer shouldn't be allowed on the track, open up Vic Willoughby's book Exotic Motorcycles to page 182 and look at how the great British Sidecar Champion Bill Boddice mounted his front tyre.

Food for thought!!
Mark Gibson, #8 BMW kneeler

Once again this year there was a sidecar school on Friday July 23rd at the Atlantic vintage TT at Schubenacadie, Nova Scotia.  Approximately 35 people took part and by all accounts it was the best school ever. Andrew Fairbank and Tim Courts were the main teachers, but the open format encouraged input from everyone and there were many good points brought out by the participants.

This track is an exciting track for sidecars, and was the perfect venue for the school. The school started with an open discussion session, and was followed by a track tour during the lunch break, utilizing a flat bed truck, stopping in each corner for discussion. After lunch there was an extended practice session in which Andrew Fairbank and Mark Gibson each led a group of rigs around the track at low speed, demonstrating the sidecar line around this demanding circuit. Finally, a number of people who had never been on a sidecar were given a chance to passenger at low speed to see what it's all about.

Several key issues that were discussed included: Safe passing techniques, the definition of a clean pass was discussed with input from many people so that different perspectives were brought out, Left hand versus right hand rigs, differences in racing lines (entering and exiting corners), Traffic - how to deal with it, including large speed differentials, Driver Passenger safety signals, indicating passenger or machine problems, Driving in traffic, Best places to pass on the circuit, And general driving/passengering techniques. 

This school has the full support of the event organizers, and especially Martin Singleton who made sure that the time required was set aside, and also made the truck available. Thank you all! While the dead track time was minimized by using the lunch break for the track tour, thanks is also due to all of the solo riders who gave up approximately 35 minutes of practice for the extended sidecar guided tour.

Andrew Fairbank and Tim Courts did an excellent job as teachers and deserve special thanks, as well as all those participants who contributed their thoughts and ideas.  I hope that the tradition of the sidecar school at the TT continues, as it seems to get better each year with new faces and fresh ideas. 

Mark Gibson, #8 BMW kneeler.

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