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Re: ST rear suspension sag
- Subject: Re: ST rear suspension sag
- From: Erik Miner <Axeis@xxxxxxxxxxxxxx>
- Date: Mon, 19 Feb 2001 21:29:53 -0500
Simple answer Blake is that the ST is set up from the factory for a
single rider, NO bags ( they add about 25 lbs) and with the rider
about 160-180lbs. So if you figure you weigh 185 dressed, and the
bags add another 25 you are a good 25lbs past what the stock rear
spring is spec'ed for. FYI the stock rear spring according to the
Racetech site is13.75kg I've got a 15kg on my Ohlins and I can get
the preload right on the money with the adjuster about half way
through it's range.
Erik
>Hi all,
> As I threatened earlier this weekend, I found a willing
>accomplice to help me set the sag on the rear of my ST. The process
>and results were quite the eye opener, and left me with a few
>questions.
>
>Background: I weigh 165 lbs (sans clothing), but 186 lbs in full
>gear. I did all the suspension measurements in full gear and with my
>saddlebags loaded with my typical junk: a laptop computer and some
>papers in the left bag, an extra helmet in the right bag. The gas
>tank was about 1/3 full. (Yes, it probably should have been 1/2
>full.) As setup from the dealer, the preload was 13 turns out -- not
>the 12 as specified in the Owners Handbook.
>
>I reviewed my notes from Freddie Spencer's school regarding
>suspension setup, and I also read the RaceTech setup information at
><http://www.triumphnet.com/st/acc/racetech/setup.htm>. Freddie
>recommends between 3/4ths and one inch of sag at the rear, while
>RaceTech recommends 30 to 35 mm (1.17" to 1.365"). Both sources
>recommended the following formula:
>
> Static Sag = L1 - ( (L2 + L3) / 2 )
>
>where:
>
> L1 is the unloaded suspension extension (tire off the ground),
> L2 is the loaded suspension extension after compression,
> L3 is the loaded suspension extension after extension.
>
>I decided that one inch of rear sag would be a good place to start,
>as a compromise between the two recommendations.
>
>I already knew that 13 turns was way too soft. As Erik Miner had
>pointed out to me several months ago, the head shake I experienced
>when WOT in lower gears was likely a symptom of not enough rear
>pre-load. Remember that I have RaceTech'd my front forks, so they're
>stiffer than stock. The imbalance between the front and rear is
>likely the cause of the head shaking. So, I started with Triumph's
>recommended eight turns for a firmer ride and worked from there.
>Here are the results, with the measurements taken from the top of
>the seat lock cylinder down to the top of the rear hub:
>
>8 TURNS:
> L1: 14 12/16"
> L2: 13 4/16"
> L3: 13 4/16"
> SS: 1.5"
>
>7 TURNS:
> L1: 14 12/16"
> L2: 13 4/16"
> L3" 13 5/16"
> SS: 1.46875"
>
>4 TURNS:
> L1: 14 12/16"
> L2: 13 7/16"
> L3: 13 7/16"
> SS: 1.3125"
>
>0 TURNS:
> L1: 14 12/16"
> L2: 13 8/16"
> L3: 13 9/16"
> SS: 1.21875"
>
>Is this typical of what others have found? I'd heard that the stock
>shock was supposed to be pretty good and that the range of
>adjustment covered most loading scenarios. I'd hardly call my
>loading extreme -- I'm not even trying to set up the suspension for
>two-up traveling -- yet I couldn't get the sag to where I wanted it.
>Are my sag recommendations extreme?
>
>At least it was nice to see that the rear shock didn't show much stiction.
>
>I took a quick spin in between the rain showers to see what the new
>settings felt like. Although the conditions wouldn't allow any WOT
>runs, even the half (OK, OK, 3/4) throttle runs felt much better. I
>felt very little squat on acceleration, and there was no perceptible
>head shake, either.
>
>I'll try this pre-load for a few weeks and see how it feels, but it
>looks like I need to get a heavier rear spring. If this was the max
>loading I ever planned I might be content, but I hope to take a
>girlfriend for some weekend escapes on the back. In that case, I'll
>need some more adjustment room.
>
>--
>Blake "Dawgbert" Sobiloff <sobiloff@xxxxxxxxxxxxxx>
>Burlingame, CA, USA
>
>
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