iconic558 Posted December 22, 2014 Report Share Posted December 22, 2014 (edited) Hi guys, bit of back ground first... now I'm actually doing some trials with my SWM TL320 I have been playing with suspension. But coming from enduro's I've come to the conclusion that I may be out of my water a little? She has Magicals springs up front and Sammy Miller gassers up the blunt end. When she came to me the front and rear were set up for a erm' heavier rider (well built Steve, all muscle!) with 50lbs/in rear springs and 135mm of preload in the front springs, I weigh 11 stone. I had very little front and rear sag. First trial I just rode her as was. She rode very high too, I could of rolled over a 45 gallon drum without scraping the bashplate! Since the first trials I've reduced the front preload spacers by 25mm and this gives me around 2" front sag and a very nice progressive front end. The rear springs were on the middle pre-load position and I dropped this to the lowest and got a little bit of sag but still felt hard and lifeless compared to my Beta REV3 which felt lovely, compliant, progressive and soft. I also had an issue with the shocks 'binding' on the shock top mount due to powder coating and this made the action stiff too, removing the powder coat made them a lot better....not sure why as the movement should be on the rubber bush shouldn't it? I bought a pair of SM 40lb/in springs and set the sag to around 1/3 rear end travel (3rd stop on preload) using the MK eyeball and a cable tie method, felt lovely, plush and soft. I left tell-tale cable ties on the front and rear. Bouncing her up and down as hard as I could in my unit I could get the rear end to be around 3/4" off the shock bump stop and thought thats fine. Did a trial yesterday and she felt much better all round, front much more planted, rear end working, still a bugger on climbs though with a light front end....most of which could be my poor body positioning. The trial wasn't very difficult per se but a good mix of hard/soft climbs and drops. During the lunch brake and I looked at my 'tell tail' cable ties and the rear end was up to the bump stop and the front was high too but not 'blown-thru', all of which alarmed me somewhat...I hadn't been jumping or getting air! Got home and found the rear springs had sort of 'run themselves in' and now I had to raise to top setting on preload to get my 1/3 total movement sag, this is LOT of pre-load...I think, but if it's adjustable why not use it? Now, in the above I'm assumed quite a lot, taken a few guesses too so I would like to ask if I'm 'getting there' or 'out to lunch' on twinshock suspension. So my questions are: 1/ If I'm using all my suspension movement this could be a good thing....its there to be used...one could assume? 2/ Should twinshock trials bikes be very soft like my old Beta REV3, she felt lovely to me and bouncing her up and down helped me balance...in between putting my feet down 3/ Is a softer spring with more preload worse than a harder spring with a lot less preload?....I know that the spring rate isn't changed by preload on a straight rate spring but the SM springs look very progressive, so I could be getting a harsher ride with the softer springs than the hard springs, as I'm getting off the softer part of the spring onto the stiffer part..are you with me? 4/ The shocks on a SWM are slanted over (to me) and this would reduce the spring rate of the rear spring...but they aren't slanted over like a Gripper! I have two bottom mount positions on my SWM swing arm and I've have been using the mounts nearer the end of the bike to get the ride height down a little by introducing a tad more slant..only makes 1/2" difference but all helps....Martin 'SWM' M tells me that the front mount is the std position and the rear mounts were for when the pillion mounts were used thereby giving a little room for the rear shocks but I thought I'd experiment...it was all I could do to drop my trans oil in my Beta, aren't twin shocks addictive Seasons greeting and thanks for any help Edited December 22, 2014 by iconic558 1 Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 22, 2014 Report Share Posted December 22, 2014 Not an expert by any means, but I can bottom rear shocks easily by kicking down on the pegs. However, they very rarely bottom when riding a section. I have the shocks laid down a bit, and lengthened to 400mm (centers) I use 50lbs springs and have reduced the damping both ways to suit. The swinging arm runs in needle bearings, as opposed to silent block which must affect action, even if only marginally. This setup works well for me, and finding grip is not an issue. Trouble with moving shock mount back is its effect on steering (hence lengthening mine, I have also dropped forks by 20mm) 1 Quote Link to comment Share on other sites More sharing options...
lbhbul Posted December 22, 2014 Report Share Posted December 22, 2014 Certainly no expert here, just a lot of running thru the rocks & such (Bultaco mostly), B40 has the experience on SWM. That said, you could certainly benefit from experimenting with the shock mounting, we stood them up nearly straight on earlier bikes which made for more softness with stock springs(maybe 50 lb) which also changes the geometry slightly. You will be hard pressed to get it to feel like your Beta, but it is a twin shock and as such enjoy & learn as you go. Larry 2 Quote Link to comment Share on other sites More sharing options...
iconic558 Posted December 22, 2014 Author Report Share Posted December 22, 2014 Whoops....forgot to add, I have raised my forks in the yokes around 15mm. I may have another 5mm left before interference with handlebar bottoms. cheers guys Quote Link to comment Share on other sites More sharing options...
bisby Posted December 22, 2014 Report Share Posted December 22, 2014 I was once told you should only be able to bottom out the rear shocks when hitting a rock step. when I first started out on my gripper I was happy with the compression but wanted a quicker rebound (as my then modern monoshock bike) I had them altered but I was still not happy. Then a friend of mine said he had worked on a shock and knew what to do (mine are Falcons) he asked me how much faster I wanted them to rebound and I said at least 25%, so there were three small holes in the damper piston on the rebound side so we drilled another the same size and I love the result I also grease the rubber bushes this seems to make them feel more plush? Stephen. 1 Quote Link to comment Share on other sites More sharing options...
iconic558 Posted December 22, 2014 Author Report Share Posted December 22, 2014 Thanks stephen Quote Link to comment Share on other sites More sharing options...
dadof2 Posted December 22, 2014 Report Share Posted December 22, 2014 Sounds as if you have got it about right. If it does not track well on slippery cobbles in streams, maybe soften it off a shade more. Quote Link to comment Share on other sites More sharing options...
stan wellback Posted December 22, 2014 Report Share Posted December 22, 2014 Hi, the shocks you have look like re-badged Betors. The end bushes have the tube through the middle,this means less rubber for the bush.when you tighten them up they go solid.take one shock off,re-mount it one end only.tighten the nut and try to move it. Bisby is quite right in greasing them, but the betor rubbers get stuck solid to outer ring they sit in. add the fact that the swing arm mounts are wider apart than the top mounts on the swm,[steel swing arm at least,not measured an ally one],the dampers have very restricted movement even before you add the springs. i use falcons which i keep well lubed.Their web site give good info on setting things up. 2 Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 22, 2014 Report Share Posted December 22, 2014 Hi, the shocks you have look like re-badged Betors. The end bushes have the tube through the middle,this means less rubber for the bush.when you tighten them up they go solid.take one shock off,re-mount it one end only.tighten the nut and try to move it. Bisby is quite right in greasing them, but the betor rubbers get stuck solid to outer ring they sit in. add the fact that the swing arm mounts are wider apart than the top mounts on the swm,[steel swing arm at least,not measured an ally one],the dampers have very restricted movement even before you add the springs. i use falcons which i keep well lubed.Their web site give good info on setting things up. Might be worth removing back wheel and springs. Reassemble and see/feel exactly what's going on. 4 Quote Link to comment Share on other sites More sharing options...
lbhbul Posted December 22, 2014 Report Share Posted December 22, 2014 I don't know SWM well but if as Stan pointed out, if they don't maintain a straight line top to bottom, then you will probably need to spacer them to get as near as possible to straight alignment. The help here is great, (knowledge) stuff you can use, it will help, and rear will be better smooth & easy than harsh. Larry , Quote Link to comment Share on other sites More sharing options...
jon v8 Posted December 22, 2014 Report Share Posted December 22, 2014 Dunno what all the fuss is about - real trials bikes don't have rear suspension... My tip is to get someone to video you riding over rough ground,you can then see exactly how well its working and alter it to suit.Its amazing when I'm observing how many bikes I see where the suspension is virtually solid - they had just as well join me in the rigid class for all the good its doing... 3 Quote Link to comment Share on other sites More sharing options...
pschrauber Posted December 22, 2014 Report Share Posted December 22, 2014 There is a rule of thump for setting the forks and rear shock(s) on a trials bike, the negative compression of the fork and the rear shock without the rider should be at the front around 5mm and to the rear the shock should - after a repeated gentle compression - allow to swing back in his neutral position which means decompress fully but not hit hard against the upper spring limiter. This can be adjusted if possible by the pre-load adjuster. To the sag (negative spring travel while the rider is standing on the bike), this should be around 30 - 50mm at the rear and 20 - 40mm at the front, if you have less the springs are to hard if you have more the springs are too soft. The springs are the key for a proper suspension not the adjustment of pre load or any spring compression. There are two very good "in depth" article about the adjustments of the suspension for trials machines in the German "Trialsport Magazin" issue 360 and 361. 1 Quote Link to comment Share on other sites More sharing options...
b40rt Posted December 22, 2014 Report Share Posted December 22, 2014 (edited) I don't know SWM well but if as Stan pointed out, if they don't maintain a straight line top to bottom, then you will probably need to spacer them to get as near as possible to straight alignment. The help here is great, (knowledge) stuff you can use, it will help, and rear will be better smooth & easy than harsh. Larry , re alignment. With help and info from John Bull I have fitted plastic rose bearings to top mounts, not sure if they improved the action, but can't do any harm. Edited December 22, 2014 by b40rt 1 Quote Link to comment Share on other sites More sharing options...
iconic558 Posted December 22, 2014 Author Report Share Posted December 22, 2014 Cheers guys, thanks for the advice Quote Link to comment Share on other sites More sharing options...
iconic558 Posted December 23, 2014 Author Report Share Posted December 23, 2014 (edited) Looked into my shock mounts and yes stiff as a pornstars....well you know the rest. Removed and greased the rubber bushes, spaced out the large washers with small spacing washers and action now much plusher. .....with result that I'm back on the 50lb springs! Free sag and 'race' sag spot on. Took her for a ride today and riding over tractor tyres she is close but not botttoming out. thanks for the great tips, help and advice. PS pair of 3 hour 40lb/in springs going tweet! Edited December 23, 2014 by iconic558 Quote Link to comment Share on other sites More sharing options...
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