Hagon manufacture a single spring 420mm unit exclusively for BMW Boxer models which have had the rear subframe removed and the top shock mount relocated to the rear of the frame cradle meaning the shocks need to be significantly laid over to enable mounting which creates a number of problems.
Normally a 420mm shock will be an off road shock, with maybe 120mm of travel instead of only 80mm that a road shock would have. So – far too much wheel travel as a result of the extra shock stroke! Also, because of the leant over shock angle you will get even more travel that you don’t want at the wheel spindle, so 10mm of shock travel could be 20mm of spindle travel. On a lot of bobber projects with the leant over shock you only want 50mm or 60mm of travel, otherwise tyre collides with bodywork!! Hence the need for specially designed shocks.
Another problem is that longer shocks often have softer springs to allow the extra travel required off-road. Not something you want on your bobber with a fork sometimes running only 3 inches of travel!
So these Hagon shocks have single springs with 80mm of travel and a means of restricting the travel down to as little as 50mm.
We would strongly recommend carrying out the following procedure which has to be done when the bike is nearly rideable and all mudguards and bodywork is installed.
With the bike safely supported remove the rear shocks. Once removed, slowly lift the rear wheel and swing arm upwards until travel is stopped. This may be because of tyre to rear mudguard, swingarm to frame etc, so be careful to avoid possible paint damage. Once the wheel is at its maximum height measure the shock mounts centre to centre. Depending on your measurement, if your mudguard hits the seat when the shock mounts are more than 340mm apart, the shocks will incorporate restrictors ensuring the bike is safe.
Use FIND MY BIKE to check which shocks are right for your bike.