Skip to content

USCA Sidecar Forum

For some extra information about navigating the forum you can go to Forum Tips

Please to create posts and topics.

1/3 sidecar weight rule

PreviousPage 2 of 2

The 1/3 sidecar weight rule - and also the standing on the left footrest while lifting up on the right handlebar and pushing down on the left handlebar and swinginging your weight outwards away from the bike as you do so were all part of the USCA suggestions for the very first organized sidecar training classes developed by and taught by the USCA sidecar schools in Chicago back in the mid 1970s, and were part of the sidecar manuals developed by Hal Kendall and still available for just downloading them.

But we did not originate the 1/3 rule. They are part of the sidecar development articles published in the british motorcycle magazines of the mid 1950s. And should you go back even further, they were in public domain by authors in the 19302 and even the 1920s.

The rule is a general commonsense rule. It was based on many driving experiences. Some have tried to make it very complex. It is a drive it and see. For most applications. But if you have a 250 pound momma on the pillion with a 300 pound dadda on a 350 cc Royal Enfield with an American Eagle sidecar - they will probably not even make the first right hander. This is where the standing on the left footpeg rule will show the unworthiness of the rig.

In the late 70s and early 80s when I attended most USCA rallies, many would come up to me and ask me to try their rig out. The first thing I would do is the left footpeg guideline. If their rig rose suddenly in the air - I would not attempt to drive. Too dangerous for me. Put enough ballast in it so that it behaved more normally then perhaps. But ballast alone will not do it. A light chair with ballast on a heavy bike will put undue stress on the flimsy wheel, spokes, bearings, frame and struts. It all must balance.

A good example is given by our Canadian friend - Bruce - who had a GW1800 with a wraparound british frame - a solid rig. But it took the filling of the entire frame with lead shot, plus a substantial lead sheet under the sidecar body to offset his 350 pound weight. Even so he could still lift the rig on sharp righthanders.

Note - there is a BIG difference between lifting the sidecar wheel on aggressive righthanders and flying the rig. True flying is when the sidecar has been lifted so high that the center of gravity now lies directly over the line between the front and the rear wheels of the bike so that the rig behaves as a lopsided single track machine in a manner similar to a solo bike. This type of driving is usually left to the circus or for parades covered by a police permit. Like stoppies and wheelies, it is banned from normal public street drining.

Lifting the sidecar wheel on the other hand is normal and typical although some sidecarists have been given tickets for dangerous driving - most of which have been beaten if taken to court.

PreviousPage 2 of 2