BMW motorcycle wheelbase, SWB, and LWB
The question keeps coming up, “What is this long wheelbase, and how do I know if I have one?” A very good question, and the answer is simple. When BMW came out with the /5 series in 1970, the bike had some stability problems. See my page on wobbles for more info on this subject. In the middle of 1973 production, BMW started using a longer swingarm to get more wheelbase and, therefore, more stability. It worked. If you inspect the swingarm (drive shaft housing), you can see what you have. The difference isn’t subtle.
This wonderful sketch shows three types of swingarms. The upper one is a SWB from 1970 to mid 73. The middle one shows a mid 73 piece that is “welded in” to make it longer. The text is in error on the lowest swingarm. It should say, “/6 LWB ’75 ON.”
A SWB swing arm
A mid-73 LWB with the welded in 2″ piece.
The 75 and later type LWB.
The result of the longer swingarm is a BMW motorcycle that is far more stable. One could load it up with more junk and still not wobble. The price paid is much slower handling. The SWB is better for solo sports riding. The LWB is better for two-up touring with luggage. It is certainly possible for the LWB to wobble, but is less likely.
Updated 7 Nov. 2019