OK, so I'm an idiot

[lil4399]

Well, total confession, whilst I'm ok with my hands and able to follow instructions, it doesn't mean I know what I'm doing.

I have followed all the guidance on rebuilding the suspension and installed progressive springs. I now have to set up the suspension, I have three points to adjust:

Pre load

Rebound

Compression

But what exactly do they mean? In simple words (for me) what do they mean in the real world? My biggest driver in rebuilding the forks was when I braked, the front dived WAY too much. I found the compression dampers were seized, one 6 clicks out, the other 12 clicks out. But was this the problem? (I also had uneven tyre wear)

I have set everything to factory settings, I also have the MCN Settings but neither are set for progressive springs so I need to understand the terminology before setting off with tools in pocket to set the bike up.

For info, I am 95kg and ride solo so if anyone has a similar set up and can give me a starting point for set up it would be much appreciated.

I have looked at suspension gurus but can't find one in France.

[Hooli]

Pre-load is how stiff the spring is, you need to use that to set your static sag. I can't remember the figures but I think it's about a third of the travel when you're sat on the bike.

Compression is how much the damping resists the suspension being compressed, ie the wheels going up.

Rebound is how quick the wheels go back down after the suspension is compressed.

If you don't get the last two balanced then you can end up with the bike running out of travel because it's moving more one way than the other - ie soft compression & stiff rebound the bike with get lower over a series of bumps as the suspension can't recover as much as it absorbs the bump.

[grog]

Lil, im around 90 kg. K7 with progressive Wilbers. Preload is set at 7 rings showing. Will check the other two for you, no idea where set. Brake dive was my reason for changing, once set its far more than just that, just more compliant, diff bike feel. Far better.

[Hooli]

Years ago I put hyperpro progressives in one of Moth's 14s. Having thought about it I think I remember using MCN damping settings and less preload. She was/is small n light though.

It did cure the diving under braking without affecting ride quality.

[lil4399]

Lil, im around 90 kg. K7 with progressive Wilbers. Preload is set at 7 rings showing. Will check the other two for you, no idea where set. Brake dive was my reason for changing, once set its far more than just that, just more compliant, diff bike feel. Far better.

Thanks, that should be a great start.👍

[Batkwaka]

I agree Hooli except for one point and that is preload. You have changed to Progressive Suspension which does alter spring tension when wound up.
Standard springs tension does not change as you wind it up, it just requires more weight before it starts to move.
I have always set the sag at 20-25mm.

[VladTepes]

@lil4399  suspension is definitely a dark art as far as I am concerned too.
A complete mystery.

Sure I can feel when a bike suspension is trying to kill me, but short of that - no idea.

[Hooli]

I agree Hooli except for one point and that is preload. You have changed to Progressive Suspension which does alter spring tension when wound up.
Standard springs tension does not change as you wind it up, it just requires more weight before it starts to move.
I have always set the sag at 20-25mm.

You could well be right, I'm no expert in it at all.

[steve porter]

Colin chapman famously said
" Make the suspension adjustable and they will adjust it wrong"

[lil4399]

@lil4399  suspension is definitely a dark art as far as I am concerned too.
A complete mystery.

Sure I can feel when a bike suspension is trying to kill me, but short of that - no idea.

That's exactly how I feel, but not understanding what each adjustment means and therefore does just makes it worse. I may have to do a 1000 mile run to the nearest guru 😅

[steve porter]

@lil4399  suspension is definitely a dark art as far as I am concerned too.
A complete mystery.

Sure I can feel when a bike suspension is trying to kill me, but short of that - no idea.

That's exactly how I feel, but not understanding what each adjustment means and therefore does just makes it worse. I may have to do a 1000 mile run to the nearest guru 😅

set everything on the middle settings and go for a ride, if it feels good leave it alone, if you want to experiment just go one click at a time either way and see how it feels, having someone set it up for you can be a good start,BUT just remember 2 people of the same weight but with different riding styles will need different settings to achieve the same result

[Batkwaka]

Really you need two people to do it easily but basically:

Set the Sag:
Lift the rear of the bike so the spring is at full extension.
Measure a point between the top and bottom of the spring for length.
Sit on the Bike and take the same measurement.
Ideally it should sit 20-25mm under full extension.
Do the same at the front.
Check both again once done.

Compression damping:
Get a cable tie and tie it around the fork slider as a measuring device.
Set the damping to half (or standard setting).
Go for a ride, see where the cable tie stops.
If it has barely moved you have too much damping.
If is at the very end of it he slides not enough damping.
The cable tie should be at about 2/3 of its travel unless you've done an emergency stop.

[SpongeBob]

jumping in a bit late, sorry for that.

The basic issue you have, I guess, is actually the starting point: it is... the progressive springs. Progressive springs may seem more comfortable at first (that's the goal...) but make proper suspension setup pretty difficult, if not impossible -- just talk to some suspension specialist/manufacturer, such as EMC suspensions in France, Maxton in the UK, etc., and ask them what they think about progressive springs and if they sell such things. Check also sports bikes: no progressive springs... neither on the '14, originally, by the way.

The first thing to think about when changing/installing springs is the spring rate (measured in Kg/mm); Choice all depends on the bike's weight, your weight, the front/rear balance (e.g. if you've dropped the front end or lifted the back end), and also your riding style. And how surprising, progressive springs are not sold with a spring rate specified -- which seems logical as they are, indeed, progressive. Note by the way that '14 OEM spring rate is quite low (less than .8Kg/mm if I remember correctly), they are very soft for this bike weight.

Then you have to set the 'Static Sag', i.e. how much the suspension compresses under the bike's own weight. This is done with the preload setting, and should be around 15-25mm front and 5-15mm rear -- with linear springs. Setting the static sag with progressive springs, is, obviously, closer to a gamble.

Then you can start to play with hydraulics, i.e. compression and rebound settings. There is no defined or perfect setting, it all depends on the bike's weight, your weight, your riding style and, obviously quite importantly on the fork oil used.
At a starting point you can set both at a conservative 50% (which should be close to factory settings anyway), and from there start testing, and adjusting. The cable tie trick as @Batkwaka suggested is perfect for that. Basically then, if the forks plunges too much/quickly add more compression damping (gently), if it seems to bounce, add a little rebound damping.
Note that the forks *must* plunge, reasonably, to help cornering and braking. All the same both compression and rebound should be 'soft enough' to help the bike keeping its line/trajectory.
Finally,there is some less obvious things such as if the rear seems to collapse too much when accelerating hard at corners exit, that may be that rear compression is too soft, but also that forks are expanding too quickly and in that case adding a little rebound damping would help.
So it's all a matter of balance between all that, but reasonably, on regular riding (and with appropriate oil) I'm quite sure you should keep not very far 50% settings.

Et voila! ;-)

Once suspensions are setup nicely, this bike is quite capable, as you can see :-)

[Batkwaka]

The advantage I found with progressive springs is they cover a wider range of conditions than standards springs. If you have a pillion or load the bike for camping, I believe a progressive spring offers a better choice of suspension but if it the bike is only ever for solo riding the right weight standard spring is definitely the way to go.

[GSXKING]

If as an experiment you had 100 GSX1400 owners together at a racetrack and asked them to all set the settings to standard 80 of them wouldn't notice a big difference IMHO.