The Robert Taylor suspension thread

[FROSTY:Me]

Who is Ryan??

[HDTboy]

Cowpoos .

[imdying]

I'd like to go to something like that, but I'd feel like a right twat taking a place away from a racer that would actually use it. Make sure you have a 'cancellation' list that a pleb like me could fill if available.

[Skunk]

I'd like to go to something like that, but I'd feel like a right twat taking a place away from a racer that would actually use it. Make sure you have a 'cancellation' list that a pleb like me could fill if available.

I was thinking the same thing about myself. Love learning this stuff - no 'real' use for it.

[Robert Taylor]

I'd like to go to something like that, but I'd feel like a right twat taking a place away from a racer that would actually use it. Make sure you have a 'cancellation' list that a pleb like me could fill if available.

Racers and road riders, same basic principles but slightly different emphasis. The main thing is to have interested people willing to learn.

[Sanx]

Definitely be in for a place at the Auckland workshop. Would love to get a better understanding of this mythical suspension thing.

[Robert Taylor]

Definitely be in for a place at the Auckland workshop. Would love to get a better understanding of this mythical suspension thing.

Its not that mythical! I am saying that riders/ mechs should have a better base understanding so that they shouldnt have to always seek out a capable and sincere suspension engineer for the most basic set up.

There are those who would like people to be almost totally in the dark, I think that is a mentality that is open to flagrant profiteering. Whilst a charge is appropriate for any detailed time consuming external set up work the amount should be appropriate and fair.

Two things I hate with a vengeance are people being ripped off and also the shoddy workmanship that I commonly come across. It is too easy for anyone in this country to set themselves up as a ''specialist'' when the truth all too often is that their equipment is worse than minimalist, as is their background and product knowledge / experience.

The bar needs lifting and MNZ share in that opinion.

[warewolf]

Robert, appreciated the commentary so far...as always.

My KTM 640 Adventure carries 20kg of fuel (on a 158kg half-dry bike) and there is a dramatic difference in suspension performance between full and nearly-empty tanks. On a full tank, it gets harsh/choppy; IIRC a couple of clicks extra rebound damping on a full tank helps smooth things out again. There are no (external) spring preload adjusters, but these can probably be retrofitted from other similar forks.

The Triumph Trophy has a similar sized tank. Although there is a noticeable difference between full and empty - specifically the bike feels more planted with a full tank - it doesn't develop the harshness like the Adventure. I suspect this is for two reasons: firstly the Trophy is much heavier at around 220kg+ dry so the fuel load is a much smaller percentage of the bike's mass, and secondly the front suspension is firmer with shorter travel.

Could you explain (briefly) the effect on the suspension between heavy and light fuel loads, please? Also, which direction the compression and rebound clickers should be tweaked to compensate - if it is consistent - otherwise why it is not?

My plan is to aim for good settings for say 1/4 and 3/4 tank-fulls, swapping between the two as needed. Previously I'd always tuned for a half-tank, but having two settings for the Adventure may be advantageous. At 500km per tank, stopping to tweak the clickers would take the place of fuel stops as an excuse for a stretch.

TIA!

Oh and PS I would travel to CHC to do a suspension workshop.

[F5 Dave]

Why the answer is simple. Have your manservant ride the 640 for the first 1/3 of a tank &/or until the going gets a bit rough then swap out the Trophy for the KTOOM.

I'd be keen on a wgtn class if there is the numbers.

[Robert Taylor]

Robert, appreciated the commentary so far...as always.

My KTM 640 Adventure carries 20kg of fuel (on a 158kg half-dry bike) and there is a dramatic difference in suspension performance between full and nearly-empty tanks. On a full tank, it gets harsh/choppy; IIRC a couple of clicks extra rebound damping on a full tank helps smooth things out again. There are no (external) spring preload adjusters, but these can probably be retrofitted from other similar forks.

The Triumph Trophy has a similar sized tank. Although there is a noticeable difference between full and empty - specifically the bike feels more planted with a full tank - it doesn't develop the harshness like the Adventure. I suspect this is for two reasons: firstly the Trophy is much heavier at around 220kg+ dry so the fuel load is a much smaller percentage of the bike's mass, and secondly the front suspension is firmer with shorter travel.

Could you explain (briefly) the effect on the suspension between heavy and light fuel loads, please? Also, which direction the compression and rebound clickers should be tweaked to compensate - if it is consistent - otherwise why it is not?

My plan is to aim for good settings for say 1/4 and 3/4 tank-fulls, swapping between the two as needed. Previously I'd always tuned for a half-tank, but having two settings for the Adventure may be advantageous. At 500km per tank, stopping to tweak the clickers would take the place of fuel stops as an excuse for a stretch.

TIA!

Oh and PS I would travel to CHC to do a suspension workshop.

Okay, forgive the way I am describing this, as I am so busy with Ohlins suspension I have largely been ''spared'' from working with WP, if that is what is fitted to it? Irrespective, adventure bikes tend to be softly sprung. When you have a full fuel load it is precompressing especially the front end a little further and dynamically it is riding lower. That means that especially under brakes the forks are riding lower in their travel otherwise earlier, in the compressed part of main spring and also secondary internal air spring effect.

Because its soft it feels hard! What you need to do is to fit slightly firmer fork springs which will allow the bike to ride higher in its stroke and also precompressing those very springs less. It will actually feel plusher but will also resist blowing through its stroke too readily. If you can graft on adjustable preload caps then all the better. The compression damping could be a little firmer and the rebound needs to be just fast enough that there is the faintest hint of overshoot when it returns freely after a static push. Do resist the temptation to tie the bike down with ''lethargic'' rebound speed, that is the biggest mistake everyone makes and also a big cause of crashes.

Similiar changes may need to be effected to the rear to keep the supension action balanced and therefore free of ''seesaw '' motion.

[Robert Taylor]

Okay, forgive the way I am describing this, as I am so busy with Ohlins suspension I have largely been ''spared'' from working with WP, if that is what is fitted to it? Irrespective, adventure bikes tend to be softly sprung. When you have a full fuel load it is precompressing especially the front end a little further and dynamically it is riding lower. That means that especially under brakes the forks are riding lower in their travel otherwise earlier, in the compressed part of main spring and also secondary internal air spring effect.

Because its soft it feels hard! What you need to do is to fit slightly firmer fork springs which will allow the bike to ride higher in its stroke and also precompressing those very springs less. It will actually feel plusher but will also resist blowing through its stroke too readily. If you can graft on adjustable preload caps then all the better. The compression damping could be a little firmer and the rebound needs to be just fast enough that there is the faintest hint of overshoot when it returns freely after a static push. Do resist the temptation to tie the bike down with ''lethargic'' rebound speed, that is the biggest mistake everyone makes and also a big cause of crashes.

Similiar changes may need to be effected to the rear to keep the supension action balanced and therefore free of ''seesaw '' motion.

A very learned colleague correctly pointed out that my comment about increasing compression damping was a little misleading. It needs a slight increase in low speed compression damping to help hold the bike up in the more compliant part of its stroke. ( That, allied with the spring rate increase I suggested ) BUT, it possibly needs a complimentary reduction in high speed compression damping. When the fuel load is increased the extra weight will make the forks move at higher velocity, especially under brakes. Damping force increases with velocity, if as is possible the high speed compression damping is too progressive then that will in part contribute to the harshness you feel.

More spring and low speed damping force to arrest the train before it becomes runaway and then softer high speed calibration so it retains compliance at the higher velocities. Its all about combinations. Someone abundantly familiar with WP that has worked with this model may be able to offer a comprehensively tested / verified mod.

[warewolf]

Thanks Robert, sorry for the delay in responding. I've been hoping to get some actual sag measurements... not yet, but soon!

Okay, forgive the way I am describing this, as I am so busy with Ohlins suspension I have largely been ''spared'' from working with WP, if that is what is fitted to it? Irrespective, adventure bikes tend to be softly sprung.

You're forgiven, yes it has WP, 4.6N/mm springs. In lieu of actual measurements I've crunched some numbers for my own education. There are a couple of fudge factors in there, such as percentage weight bias to the front, and allowance for the steering rake vs gravity vectors.

The fudged numbers show the rider sag with empty tank to be 32% of travel, which explains why it works better with a low fuel load. A full tank only adds 7.1mm to the front sag, 35% travel. This is less difference than "gut feel" suggests. So in theory it is undersprung for a full tank, marginal for empty. We will see what the actual measurements say. I'll talk to your man in time.

Of course it is impractical to change springs when the fuel load changes on a touring bike, adventure being off-road touring. So it's going to be sub-optimal at some load or other. Hence my question, which you've answered, thanks.

the rebound needs to be just fast enough that there is the faintest hint of overshoot when it returns freely after a static push. Do resist the temptation to tie the bike down with ''lethargic'' rebound speed, that is the biggest mistake everyone makes and also a big cause of crashes.

With the road bike, I tend to back out the rebound until the bike wallows or porpoises, then just eliminate that (or be one click on the soft side).

Re: the 200EXC we wrote about, I checked it today. Umm, I did a bad thing: the shock rebound clicker was fully closed. I must've wound it all the way in to count out from zero, and forgotten to take it back out...oops! A static push took maybe 2 seconds to return. KR suggest pos 14, that's not too bad, maybe 0.5s return time with no overshoot. As a test, I wound it fully out (to pos 18?) and it is hardly any faster, and still no overshoot. I'm gonna have to talk to your man about this shock!

[Drew]

Yea it hurt.

I went for a hoon today, on a friends ZXR400, (It's got blown fork seals, and what feels like no shock at all in the rear), and gave my younger brother, and a very competent mate the learn over the Rimutaka hill. Dont get me wrong, it was hardly race pace, or anywhere near it, but it got me wondering...

The front forks diving to the end of thier travell under brakes, decreases the fork rake, making the stearing quicker, then as you pitch the bike over, the bike levels off, but not completely, which still leaves you with more feel, then on the exit they extend fully, giving a far less twitchy bike than when they are steep. Also, the freedom of movement allows more traction than a stiff shock. So how are all these things bad?

This is not a piss take, to my mind these things all make sense, but I FULLY enjoy the benefits of a decent damoing system, and I'm quicker with them than without, I just want to know why.

[Robert Taylor]

Yea it hurt.

I went for a hoon today, on a friends ZXR400, (It's got blown fork seals, and what feels like no shock at all in the rear), and gave my younger brother, and a very competent mate the learn over the Rimutaka hill. Dont get me wrong, it was hardly race pace, or anywhere near it, but it got me wondering...

The front forks diving to the end of thier travell under brakes, decreases the fork rake, making the stearing quicker, then as you pitch the bike over, the bike levels off, but not completely, which still leaves you with more feel, then on the exit they extend fully, giving a far less twitchy bike than when they are steep. Also, the freedom of movement allows more traction than a stiff shock. So how are all these things bad?

This is not a piss take, to my mind these things all make sense, but I FULLY enjoy the benefits of a decent damoing system, and I'm quicker with them than without, I just want to know why.

Attend a forthcoming suspension set up seminar and ask me. I dont have the inclination to type 10,000 words of text with 2 fingers!

[Drew]

Attend a forthcoming suspension set up seminar and ask me. I dont have the inclination to type 10,000 words of text with 2 fingers!

Fair enough, with said two fingers, tell me if it's a dumb question though, I'd rather not ask it in public where people can SEE me go bright red as I proclaim myself an idiot.