Help me with suspension setup please

[HenryDorsetCase]

Triumph Street Triple R. 2009.

Shock is fine - better than fine in fact.

Issue is the forks. When riding along on the street the small bump and ripple compliance is not good, and a sharp edged bump makes it feel like like the fork isn't compressing, so the bump is transmitted directly to the rider, and it feels like the bike pitches backwards because the forks arent compressing then the rear tyre hits the same bump and it is absorbed. Weird. That to me feels like too much compression damping or maybe oversprung. But when I land a wheelie (and yes, my technique is shit) it blows through all its travel and smashes the bump stops with a loud metallic clang.... as if it has insufficient compression damping and/or an under rate spring.

But it can't be both, right?

So, what things should I try, and in what order?

[mulletman]

Increase pre load to stop the bottoming and soften up the compression for the shitty bumps ?

Sags set ?

[HenryDorsetCase]

Increase pre load to stop the bottoming and soften up the compression for the shitty bumps ?

Sags set ?

I did set sags when I first got the bike but havent checked what they are - and I lost the bit of paper I wrote it down on.

[nzspokes]

Talk to RT, and learn how to land wheelies.

[HenryDorsetCase]

Talk to RT, and learn how to land wheelies.

Lend us your bike? I need to learn how to wheelie. For science.

[pete376403]

PM inmate Stampy here on KB and ask. He had RT do the forks on his striple. Said that plus the ohlins rear made it a diffrent bike

[nzspokes]

Lend us your bike? I need to learn how to wheelie. For science.

I would but they would be too tall for you. :bleh:

[Kickaha]

I would but they would be too tall for you. :bleh:

Everything bar a pitbike is too tall for him

[mulletman]

Dave Moss will be here at the end of next month or there abouts he'll sort it :yes:

[SVboy]

Iirc Dave Moss set This bike up a few years back? Assuming the sags are correct, then ease off your front compression to cope with road ripples. When were the forks last serviced. Fluid deteriorates
With use and becomes smelly watery piss with little damping quality. Most suspension will blow thru the stroke on wheelies, cause they aren't really designed for that!

[AllanB]

Trade it in on a brand new bike :sunny:

It's been a long year, you deserve it.

[HenryDorsetCase]

Trade it in on a brand new bike :sunny:

It's been a long year, you deserve it.

https://www.trademe.co.nz/motors/motorbikes/motorbikes/classic-vintage/auction-1493475466.htm?rsqid=5bf8aece8cf04286bedfb1111c3d7 fb8

I went in to look at this today but it was sold this morning great buying at that price.

[HenryDorsetCase]

Iirc Dave Moss set This bike up a few years back? Assuming the sags are correct, then ease off your front compression to cope with road ripples. When were the forks last serviced. Fluid deteriorates
With use and becomes smelly watery piss with little damping quality. Most suspension will blow thru the stroke on wheelies, cause they aren't really designed for that!

He did.

I am going to try and approach it scientifically -ish over the weekend.

[malcy25]

Triumph Street Triple R. 2009.

Shock is fine - better than fine in fact.

Issue is the forks. When riding along on the street the small bump and ripple compliance is not good, and a sharp edged bump makes it feel like like the fork isn't compressing, so the bump is transmitted directly to the rider, and it feels like the bike pitches backwards because the forks arent compressing then the rear tyre hits the same bump and it is absorbed. Weird. That to me feels like too much compression damping or maybe oversprung. But when I land a wheelie (and yes, my technique is shit) it blows through all its travel and smashes the bump stops with a loud metallic clang.... as if it has insufficient compression damping and/or an under rate spring.

But it can't be both, right?

So, what things should I try, and in what order?

HDC. First up, adding preload ain't worth shit when your spring rate is too light. All it does is change your ride height a bit, but mostly increases the force first required to move the suspension. When it does move, you are still stuck with whatever the spring rate is (does this sound familiar :)

Many people crank preload in to band aid not enough spring rate (thinking they will make the overall rate stiffer). What it actually does is just make the first part of the stroke very harsh. Surprisingly, when you have a better spring rate and less preload, you get better compliance.....because you are not having to over come that initial preload (eg is you have 30mm of preload on a 1kg/mm spring you need 30kgs of suspension force before it moves 1mm) . It can also cause patter in the front under hard corning load when off the throttle (ie corner entry). I was looking at one of my TZ's years ago and the rear spring rate and I asked RT what was a benchmark preload % (ie say 10% of overall free length) was an indicator the rate was too light. The 20% I had we came to the conclusion was well overdue for an increase in spring rate, and reduced preload. I've subsequently gone up a again. 5.7kg/mm to 6.2kg/mm to 8+kg/mm and each change was better.

Compression damping from there will then also have an effect, but ultimately, the bike sits on the springs and the damping controls the rate of movement. Reducing comp damping may have an effect, but could cause a compromise elsewhere , ie on the brakes as it will dive quicker and unload the back.

Apart from doing CSS, some of the biggest gains I have ever had with my racing was getting the right spring rates....Yamaha were notorious for too light fork springs for years. On my race bike I went from 0.45kg/mm stock to 0.75kg/mm with min actual preload. feel is better, small bump compliance is better, less patter, more speed vicar.

I'd look at spring rate first. Go back and redo your sag figures and see whether your laden and unladen sag figures correlate okay. Ie if to get a laden sag figure that is okay, but that creates too small a unladen sag figure, I'd say too much preload, not enough spring rate.

Remember, all bikes from the factory are a compromise on theri suspension set up - not just cost of components used, but the settings and rates as they try and make it work for 50kg lightweight and 120kg fatties. But the needs are very different.....and one size does not fit all.

[pritch]

HDC I gather from previous posts that you are not ummm over tall(?). Never seen a comment on your weight though.

Sometimes heavier riders have a problem caused by the valves in the forks being too small to pass the fluid required to deal with a sharp bump and it feels as if the forks have locked. The cheap fix is to get a good machinist to make the holes bigger. A better fix is to install Race Tech Gold Valves or similar and get springs and valves matched to your weight.

Robert @ KSS performed the latter option on my bike.

[HenryDorsetCase]

HDC I gather from previous posts that you are not ummm over tall(?). Never seen a comment on your weight though.

Sometimes heavier riders have a problem caused by the valves in the forks being too small to pass the fluid required to deal with a sharp bump and it feels as if the forks have locked. The cheap fix is to get a good machinist to make the holes bigger. A better fix is to install Race Tech Gold Valves or similar and get springs and valves matched to your weight.

Robert @ KSS performed the latter option on my bike.

Hobbit sized - 5ft 4 and 72kg - say 75 ready to ride.

I have been off work for two weeks and havent even started the bloody bike - but I am off next week and will have a crack at it then.

[pritch]

Hobbit sized - 5ft 4 and 72kg - say 75 ready to ride.


Your weight shouldn't be a problem because you are close to the weight they build the bikes for.

It's a long time since I read about the European Honda test team, they signed off on all new Honda models over 250cc. At that stage the English rider was the senior tester and he had to keep his weight close to the Honda spec weight, which IIRC was 72kg.

[HenryDorsetCase]

Your weight shouldn't be a problem because you are close to the weight they build the bikes for.

It's a long time since I read about the European Honda test team, they signed off on all new Honda models over 250cc. At that stage the English rider was the senior tester and he had to keep his weight close to the Honda spec weight, which IIRC was 72kg.

I read an article about that dude in PB last year. Dave something? Had been a road racer and endurance racer and had the most amazing memorabilia collection....

[GrahamA]

HDC. First up, adding preload ain't worth shit when your spring rate is too light. All it does is change your ride height a bit, but mostly increases the force first required to move the suspension. When it does move, you are still stuck with whatever the spring rate is (does this sound familiar :)

Many people crank preload in to band aid not enough spring rate (thinking they will make the overall rate stiffer). What it actually does is just make the first part of the stroke very harsh. Surprisingly, when you have a better spring rate and less preload, you get better compliance.....because you are not having to over come that initial preload (eg is you have 30mm of preload on a 1kg/mm spring you need 30kgs of suspension force before it moves 1mm) . It can also cause patter in the front under hard corning load when off the throttle (ie corner entry). I was looking at one of my TZ's years ago and the rear spring rate and I asked RT what was a benchmark preload % (ie say 10% of overall free length) was an indicator the rate was too light. The 20% I had we came to the conclusion was well overdue for an increase in spring rate, and reduced preload. I've subsequently gone up a again. 5.7kg/mm to 6.2kg/mm to 8+kg/mm and each change was better.

Compression damping from there will then also have an effect, but ultimately, the bike sits on the springs and the damping controls the rate of movement. Reducing comp damping may have an effect, but could cause a compromise elsewhere , ie on the brakes as it will dive quicker and unload the back.

Apart from doing CSS, some of the biggest gains I have ever had with my racing was getting the right spring rates....Yamaha were notorious for too light fork springs for years. On my race bike I went from 0.45kg/mm stock to 0.75kg/mm with min actual preload. feel is better, small bump compliance is better, less patter, more speed vicar.

I'd look at spring rate first. Go back and redo your sag figures and see whether your laden and unladen sag figures correlate okay. Ie if to get a laden sag figure that is okay, but that creates too small a unladen sag figure, I'd say too much preload, not enough spring rate.

Remember, all bikes from the factory are a compromise on theri suspension set up - not just cost of components used, but the settings and rates as they try and make it work for 50kg lightweight and 120kg fatties. But the needs are very different.....and one size does not fit all.

Perfect post. Not one herecy and a lot of good advice. RT would approve for sure.

If you want really good suspension response the factory offerings are very unlikely to be good enough for you. My last four bikes have had the KSS treatment and it has been money well spent.

[F5 Dave]

Huh! Never saw this thread till now.
On my 11 we made some mods which transformed the STR. I rode a mates one and was reminded how bad they are std. Last couple of posts on the money.

The fork Springs for my 80kg are too soft. The valving is primitive. I went Racetech valves on my Tiger and was going to again but a mate does Wellington KTech so he convinced me to try their valves. Big improvement with 0.95 Springs .
The rear shock is quite good but had a stupid 12kg rear spring. Changed to a 10 but also stk valving is wacko. Some new shims and now it doesn't skate over stutter bumps yet hard enough for sport riding. Don't underestimate how much the rear affects the front.