Suspension sag

[Warkton Tornado No.1]

Despite the common perception, standard OEM dampers do have some compression damping, although it is not anything like the rebound damping. To my mind, that's as it should be for a base setting on a non anti-dive set-up.

Beside selecting matched pairs of springs, the variable OEM TV175 S2 were the best that I personally ever tried. Ideally, front dampers should be independently adjustable for rebound & compression, but I've yet to try any. If memory serves, there were some USA re-valved dampers (Daytona?) but I have not even seen any in the flesh.

As previously mentioned, the rear damper does affect the whole bike set up, but the engine mounts also play a part. The first of the SIL mounts were prized, as they had additional stressed, un-voided rubber in the area where they fitted in the engine case. The additional vibration was worth tolerating for the improvement in handling.

[ULC Soulagent]

Hi Storkfoot,
My front setup is Stage 3 Progressive springs with Bgm slim line 60t’s style dampers which offer i believe a middle ground of dampness Anti dive fitted also. Rear shock is a Bgm fully adjustable unit. I like too ride with a firm setup on the front end with no static sag and rear with static sag factored in for my weight, if hauling luggage for rallies then I just up the rear preload

[coaster]

Despite the common perception, standard OEM dampers do have some compression damping, although it is not anything like the rebound damping. To my mind, that's as it should be for a base setting on a non anti-dive set-up.
.

I THOUGH that OEM dampers only damped in comression and not ata ll in rebound to stop the suspension 'loading up' under braking to the point that the forks stayed bottomed out, or have I got that arse about

All interesting stuff

[Storkfoot]

Despite the common perception, standard OEM dampers do have some compression damping, although it is not anything like the rebound damping. To my mind, that's as it should be for a base setting on a non anti-dive set-up.
.

I THOUGH that OEM dampers only damped in comression and not ata ll in rebound to stop the suspension 'loading up' under braking to the point that the forks stayed bottomed out, or have I got that arse about

All interesting stuff

Arse about, mate. If you have a damper in your hand, it is very easy to compress it down to its shortest length, a lot less so to do the reverse.

I am a bit torn about this as when you have a scooter which is both used to cart loads of spares, clothes and a tent across Europe but is also used to travel around, one up, without load, that is a major difference in weight.

At the moment, I have non adjustable rebound both front and rear but stiff springs which make it feel good when loaded up. The skipping, which I know does happen, does concern me.

[Storkfoot]

Hi Storkfoot,
My front setup is Stage 3 Progressive springs with Bgm slim line 60t’s style dampers which offer i believe a middle ground of dampness Anti dive fitted also. Rear shock is a Bgm fully adjustable unit. I like too ride with a firm setup on the front end with no static sag and rear with static sag factored in for my weight, if hauling luggage for rallies then I just up the rear preload

Thanks for that I have the MB progressive springs with Escort dampers. The rear shock absorber just has adjustable spring tension which I have hard, partially to stop the possibility of the expansion exhaust touching the rear runner on very harsh roads.

As this scooter is my main rally machine, I need to invest in a rear shock absorber with adjustable rebound. I know this. I may also change to front springs that are, say, 10% firmer than standard and perhaps try smaller buffers at the bottom of the forks.

Having travelled many miles on a Vespa Rally with a standard spring and damper (both since replaced), I know that feeling of a diving front end with luggage on the front. A bit scary, to say the least.

[bsso78]

I wrote an article for scooterding a few years ago about suspension and I think Andy reprinted it in Scooternova last year. It should explain things if you can find it.

[Warkton Tornado No.1]

As we must surely now have all grasped, the subject of suspension is very much a compromise. Unfortunately, with the very limited technology inherited within the design of our forks, along with very limited space, there is not an awful lot that can be done. By comparison, anybody that has done little more than observe, or move a modern motorcycle, cannot surely be anything other than bemused by how the things wallow & float about @ the front end, yet unarguably do handle. I find riding a motorcycle a strange experience, as though not fully in touch with what is going on, yet in a car, particuarly in conditions that are uncertain, I find it automatic to feel for grip.

Multi-rate front springs are not necessarily obtainable to suit all scenarios, but would offer the benefit of soaking up most road undulations, almost unperceptibly, whilst ultimately bringing the stronger component element into play under extreme braking/road surfaces. It's all about maintaining control whilst on board, rather than feeling like you're on a scary fairground ride.

We can thank the evolution of stickier tyres & sintered pads for our desire to improve handling, particularly on the track, whereby there is the facility to brake deep into the apex of a corner, telling yourself that you are safe because the front tyre is biting into the Tarmac.

Not so many years ago, when the best tyres were probably Continentals, straight line braking from high speed was essential. No tipping in whilst still on a handful of front brake. Cadwell Club hairpin was all about maintaining corner speed for the drive back up the hill, so the braking prior was hard & would see front ends hopping but it was , erm, kind of controllable & a good way of out-psyching your opponents

[Warkton Tornado No.1]

I wrote an article for scooterding a few years ago about suspension and I think Andy reprinted it in Scooternova last year. It should explain things if you can find it.

Not heard of "scooterding"

Is it a bit like "white finger" but not actually in the fingers? In that case, I've had that....

Also "scooter-ring" after drying my wet clothed arse against a radiator. "Plukes", "Tatlocks", "Argyles" or haemorrhoids

[ULC Soulagent]

Hi Storkfoot,
My front setup is Stage 3 Progressive springs with Bgm slim line 60t’s style dampers which offer i believe a middle ground of dampness Anti dive fitted also. Rear shock is a Bgm fully adjustable unit. I like too ride with a firm setup on the front end with no static sag and rear with static sag factored in for my weight, if hauling luggage for rallies then I just up the rear preload

Thanks for that I have the MB progressive springs with Escort dampers. The rear shock absorber just has adjustable spring tension which I have hard, partially to stop the possibility of the expansion exhaust touching the rear runner on very harsh roads.

As this scooter is my main rally machine, I need to invest in a rear shock absorber with adjustable rebound. I know this. I may also change to front springs that are, say, 10% firmer than standard and perhaps try smaller buffers at the bottom of the forks.

Having travelled many miles on a Vespa Rally with a standard spring and damper (both since replaced), I know that feeling of a diving front end with luggage on the front. A bit scary, to say the least.

Have a Rally myself, dives like a sub under air attack

[ULC Soulagent]

I wrote an article for scooterding a few years ago about suspension and I think Andy reprinted it in Scooternova last year. It should explain things if you can find it.

Not heard of "scooterding"

Is it a bit like "white finger" but not actually in the fingers? In that case, I've had that....

Also "scooter-ring" after drying my wet clothed arse against a radiator. "Plukes", "Tatlocks", "Argyles" or haemorrhoids

[ULC Soulagent]

I wrote an article for scooterding a few years ago about suspension and I think Andy reprinted it in Scooternova last year. It should explain things if you can find it.

Edition No9

[Knowledge]

The adjustment I made in order to create some sag (reducing the height of the lower buffer) meant that my front dampers were not long enough to stretch between the top and bottom damper fixings, so I had to fabricate a couple of little extenders to bolt onto the top mount to shorten the distance between the two.

Although these look incredibly simple, they have taken days make them as they were surprisingly intricate.

[coaster]

And nice upcycling of the Sturmey Archer handle bar clamp

[Norrie Bodge]

too create a bit more sag
the use of the thinner type fork buffers under the links maybe?

[Knowledge]

Norrie, I cut the lower buffer down from 21mm thick to 11mm.

I sneaked out for a ride today and the whole front felt better. What I don’t know is whether the introduction of sag that helped, or was it that the dampers were always at full extension previously, and the changes to the damper top mounts has affected the apparent improvement.

I know you should only make one change at a time, but on this occasion, I had little choice.

Now go and get saggy

[Warkton Tornado No.1]

Norrie, I cut the lower buffer down from 21mm thick to 11mm.

I sneaked out for a ride today and the whole front felt better. What I don’t know is whether the introduction of sag that helped, or was it that the dampers were always at full extension previously, and the changes to the damper top mounts has affected the apparent improvement.

I know you should only make one change at a time, but on this occasion, I had little choice.

Now go and get saggy

A bit late to mention this, but I once extended (non Lamretta dampers) by cutting off the welded on rod eye, tapping the centre & fitted an extended, ball end eye ('Rose joint' type)

The principle was effective, the dampers way too stiff on rebound to be usable. Very much "PogosRus' although a lot better when the lower mount was re-attached to the axle centre, with the increased leverage. They've been assigned to the 'Experimental Department' of my garage.......