Roger Walton said:
On the dirt tracks on the way to work there a some horrible corrugations starting to appear and my Adv is struggling to keep the back wheel planted and gripping in any gear or speed.
If I soften the rear suspension some will this help keep the back wheel in contact with the road instead of bouncing hard?
Hi... hope this helps, cos the more you delve in to suspenders (?) the more it becomes a 'black art' (can I say that?)
Standard suspension's a compromise... and naff anyway! We checked out BM's suspension some time ago and while the spring rate is usually OK the damping is err mmm well it leaves a lot to be desired!
Good suspenders is worth 10bhp at least.
You need as little rebound damping as you can get away with. Suspension units with only one adjuster for damping are nearly always 'rebound' damping adjustment... BUT
Before adjusting the damping you need to adjust the spring pre-load!
Compromise remember... the suspension on your 'bike has to cope with the eight stone lady rider, and/or the twenty stone rider with eighteen stone bride and campng gear... it can't be done!
Rough guide (as ever)... with the 'bike standing upright on it's wheels, no load, measure from a fixed point (seat base or whatever) to the ground... note measurement. Now sit on the 'bike with your gear on etc. and have someone take the same measurement... it will be less, the 'bike will have sagged. The sag should be approx 25% to 30% of the overall wheel/suspension movement!
If the total wheel movement, up and down (and front and rear want doing seperately) is, say 4", and the sag was 1" then great. (25%) But if the total wheel movement is 4" and when you sit on the 'bike it drops/sags 1/4" then this represents errr mmm lets see... a sixteenth of the total movement, ie 6.25% then you'll be bounced out of the saddle with every bump! Toooo hard! Back off the pre-load.
If you sit on the 'bike with the bride and it drops 2" (now this is easy) then the sag is 50% and every time you hit a bump the suspesnion will bottom out.... boing boing boing hellow Zebedee! Wind up the pre-load.
SO we adjust the preload to give us that 25 - 30% of sag! Can't do it? ... we need Öhlins or Wilbers
NOW we adjust the rebound... as little as we can get away with remember! Standard BM shocks, adjust the rebound... no fffffng difference! Go over your undulations and if the 'bike squats at the back end and you feel every ripple then too much 'rebound'. Back it off too much and the 'bike will bounce along as if on the Magic Roundabout.... get it right and perrrrfek! But you probably won't with standard units!
Or, as my mate says.... shut your good eye and go for it, tackle it flat out and you wont feel a thing
Hope this helps... sorry to go on a bit, but it's what I'm good at errr mmm OK then maybe not!
Time for a
. I will have a tinker
