Static Sag v Rider Sag

[bass gt3]

clen666 said:

bass gt3 said:

No, TEN means TENSION. Rebound in other words
Apart form Big Piston Forks or separate leg items like newer Yams, Preload and Rebound are at the top of each leg, Compression is at the bottom

Ah I see, that's a shame as according to the race tech suspension website, 10N/mm would be pretty much bang on what is recommended for my weight (according to their calculator).

Hahaha!!
Is that the RaceTech USA spring calculator? if so, it can be a little bit out at times.
Springs weights required are determined by a combo of bike and rider weight plus use.
For example, my Duc is light and I weight 95fully kitted so the correct spring is around a 9.5
But I prefer a 10 in each leg with less preload and open compression rather than a lighter spring wound in a bit more. Bu that's a track bike obviously. On the road, it's better to have good compliance due to the road conditions

[Mr OCD]

bass gt3 said:

Try slowing the rear comp or opening the front comp to get better balance. Remember that compression adjustment will only affect the SPEED of change not the amount.

I've opened up the front comp ...

Now ...

Rebound - 2 1/4 turns
Comp - 2 1/4 turns

Feels proper soft

It's balanced though ...

[Mr OCD]

Even funnier they are closer to standard settings in the manual ...

[bass gt3]

Mr OCD said:

bass gt3 said:

Try slowing the rear comp or opening the front comp to get better balance. Remember that compression adjustment will only affect the SPEED of change not the amount.

I've opened up the front comp ...

Now ...

Rebound - 2 1/4 turns
Comp - 2 1/4 turns

Feels proper soft

It's balanced though ...

Cool,

Now it might be a tad soft, (we've been setting it up stone cold so it may get softer) but if you feel it's too soft once warmed up, add compression damping (clockwise) to front AND back in the same amount. DON'T touch the rebound unless it's too fast once warm.
However, if the suspension is compliant it'll ride much nicer and get better traction rather than if it feels all stiff and heavily controlled.
Ultimately, there's no magic bullet. You will like what you like and it might not be this. However, if you let the suspension do its job, the bike becomes much better to ride.
I did this with a good racer 2 weeks ago and despite his scepticism he ended up 3 seconds a lap quicker on a bike he felt was "looser'. Bottom line was the tyres had much better traction, and once he got used to the slight squirming under power, the grip off corners was much better, hence the massive drop in times

[bass gt3]

Mr OCD said:

Even funnier they are closer to standard settings in the manual ...

hahahahaha!!

Really???

How good am I

[clen666]

bass gt3 said:

Hahaha!!
Is that the RaceTech USA spring calculator? if so, it can be a little bit out at times.
Springs weights required are determined by a combo of bike and rider weight plus use.
For example, my Duc is light and I weight 95fully kitted so the correct spring is around a 9.5
But I prefer a 10 in each leg with less preload and open compression rather than a lighter spring wound in a bit more. Bu that's a track bike obviously. On the road, it's better to have good compliance due to the road conditions

Yes, RaceTech USA. I just saw a link to it on another forum when searching for spring rates. Their calculator adds in the weight of the bike but for some strange reason asks for rider weight without kit.

My recommended spring rate comes out at 1.018Kg/mm, basically 10N/mm, and the standard spring is 0.870Kg/mm (again, according to the RaceTech website)

[Mr OCD]

Ok so more questions despite me being done in the garage tonight.

The Fireblade runs more travel at the rear than the front therefore with this in mind would we not run more sag at the rear as opposed to the front?

Just seems odd that most superbikes run a nose down stance which would suggest less sag at rear (cos it's ride height init!? )

As first for me as all my R1's had less travel at rear than front hence me setting 30-35mm rear, 35-40mm front for road work ...

I'm on 38mm front, yet 9 turns from fully out with 1.1NM/mm springs ... Bit odd no? I'm 90kg kitted.

Thanks for all your help fella. Really interested and goes someway to supporting never trust everything you read on forums ...

[Mr OCD]

bass gt3 said:

Cool,

Now it might be a tad soft, (we've been setting it up stone cold so it may get softer) but if you feel it's too soft once warmed up, add compression damping (clockwise) to front AND back in the same amount. DON'T touch the rebound unless it's too fast once warm.
However, if the suspension is compliant it'll ride much nicer and get better traction rather than if it feels all stiff and heavily controlled.
Ultimately, there's no magic bullet. You will like what you like and it might not be this. However, if you let the suspension do its job, the bike becomes much better to ride.
I did this with a good racer 2 weeks ago and despite his scepticism he ended up 3 seconds a lap quicker on a bike he felt was "looser'. Bottom line was the tyres had much better traction, and once he got used to the slight squirming under power, the grip off corners was much better, hence the massive drop in times

Ok, so play with compression only ... Got ya! ... Half a turn at a time?

But yep the bike is pretty much on standard settings now ignoring preload !

I should have just done that first!

[bass gt3]

clen666 said:

bass gt3 said:

Hahaha!!
Is that the RaceTech USA spring calculator? if so, it can be a little bit out at times.
Springs weights required are determined by a combo of bike and rider weight plus use.
For example, my Duc is light and I weight 95fully kitted so the correct spring is around a 9.5
But I prefer a 10 in each leg with less preload and open compression rather than a lighter spring wound in a bit more. Bu that's a track bike obviously. On the road, it's better to have good compliance due to the road conditions

Yes, RaceTech USA. I just saw a link to it on another forum when searching for spring rates. Their calculator adds in the weight of the bike but for some strange reason asks for rider weight without kit.

My recommended spring rate comes out at 1.018Kg/mm, basically 10N/mm, and the standard spring is 0.870Kg/mm (again, according to the RaceTech website)

Yeah, not sure why they refer to weight without gear.
But In truth, a 10 is generally a good bet for the average 90to 95 kg rider including gear and most modern sports bikes.
But there's no reason not to fit asymmetric springs, say a 10 in one leg and a 9.5 in the other to achieve a value of 9.75 across the front. it's why k Tech supply 3 sets of springs so you have many permutations to fine tune the sag. It matters that much

[Mr OCD]

Standard settings for you to smile smugly at ...

Fork PL - 6 turns from out
Fork comp - 2 1/4 turns in
Fork rebound - 2 1/4 turns in

Shock PL - 4 notches from 10
Shock comp - 2 1/2 turns in
Shock rebound - 2 1/4 turns in

[bass gt3]

Mr OCD said:

Ok so more questions despite me being done in the garage tonight.

The Fireblade runs more travel at the rear than the front therefore with this in mind would we not run more sag at the rear as opposed to the front?

Can you elaborate? if the front is 124mm total stroke what's the rear? I would expect it to be around 130mm total wheel travel

Mr OCD said:

Just seems odd that most superbikes run a nose down stance which would suggest less sag at rear (cos it's ride height init!? )

Remember sagis not related to ride height. regardless of getting the sag right, there's nothing stopping you setting the bike up with a steeper rake, say by changing the fork height. But here's the oddity. Adding preload to the front effectively lengthens the forks yet the same isn't true as much for the rear shock. It's why good rear shocks have a separate shock length adjustment as you typically want 12mm of preload on the rear spring when assembled. If the sag isn't right, you get a stiffer spring.

Mr OCD said:

As first for me as all my R1's had less travel at rear than front hence me setting 30-35mm rear, 35-40mm front for road work ...

5mm isn't anything to worry about. But 45mm front and 30mm rear isn't good for example

Mr OCD said:

I'm on 38mm front, yet 9 turns from fully out with 1.1NM/mm springs ... Bit odd no? I'm 90kg kitted.

Indeed, which is why I'd question the quoted value. But there's other factors possibly in play. But 38mm on a road bike is on the firm side of good considering the target is around 1/3rd of total stroke as sag.

Mr OCD said:

Thanks for all your help fella. Really interested and goes someway to supporting never trust everything you read on forums ...

Absolute pleasure mate. definitely never just accept forum facts as truths!! Your bike is unique to you and how you like it to feel. There's no "One Size Fits All" magic bullet.
If you understand the basics of suspension there's no reason why you can't tailor your bike to YOU rather than accepting some strangers word for it. But I do believe peeps run their bikes much to stiff. If you loosen the suspension and let it do its job, the bike feels much better and goes well. It might not feel as "controlled" but the goal is traction and compliant suspension aids traction

[Mr OCD]

Just about to head out ... Will reply to rest later on but according to manual...

Front travel - 120mm

Rear travel - 135mm

[bass gt3]

Mr OCD said:

Just about to head out ... Will reply to rest later on but according to manual...

Front travel - 120mm

Rear travel - 135mm

Not enough to worry about. As measured you found 124mm in the front which is normal. Some Ohlins can be adjusted to 135mm travel but 125 is the standard.
Go ride her and see how it feels. If you need comp, add it in 1/4 turn increments.

[Mr OCD]

Mr OCD said:

I'm on 38mm front, yet 9 turns from fully out with 1.1NM/mm springs ... Bit odd no? I'm 90kg kitted.

suspension wizard said:

Indeed, which is why I'd question the quoted value. But there's other factors possibly in play. But 38mm on a road bike is on the firm side of good considering the target is around 1/3rd of total stroke as sag.

Afternoon

Just had a look round online...

RaceTech are reporting the front spring rates as 1.040kg/mm standard...

Not as stiff as originally thought... although spring rates seem to differ looking around on line! So I've dropped both KAIS and K-Tech an email this morning.

Initial impressions on riding the bike today... I'm not convinced it is as soft as expected. Feels rather compliant but I haven't pushed the bike hard enough to judge properly. It does however feel as though the rear is sitting a little low when I sit on it fully kitted. Or possibly the front is a little high...

[bass gt3]

Mr OCD said:

Mr OCD said:

I'm on 38mm front, yet 9 turns from fully out with 1.1NM/mm springs ... Bit odd no? I'm 90kg kitted.

suspension wizard said:

Indeed, which is why I'd question the quoted value. But there's other factors possibly in play. But 38mm on a road bike is on the firm side of good considering the target is around 1/3rd of total stroke as sag.

Afternoon

Just had a look round online...

RaceTech are reporting the front spring rates as 1.040kg/mm standard...

Not as stiff as originally thought... although spring rates seem to differ looking around on line! So I've dropped both KAIS and K-Tech an email this morning.

Initial impressions on riding the bike today... I'm not convinced it is as soft as expected. Feels rather compliant but I haven't pushed the bike hard enough to judge properly. It does however feel as though the rear is sitting a little low when I sit on it fully kitted. Or possibly the front is a little high...

Afternoon,

If you really feel like the front is a tad high, try taking2 or 3 turns of front preload out. That'll drop the front a tad.
As for the perceived softness, they never are as soft as you'd think.
But once you have the front height where you're comfortable, try dialling in a tiny (quarter turn) of compression front or back and se how it feels. But now's the point where you need to start making notes and only change ONE thing at a time.

[Mr OCD]

bass gt3 said:

Afternoon,

If you really feel like the front is a tad high, try taking2 or 3 turns of front preload out. That'll drop the front a tad.
As for the perceived softness, they never are as soft as you'd think.
But once you have the front height where you're comfortable, try dialling in a tiny (quarter turn) of compression front or back and se how it feels. But now's the point where you need to start making notes and only change ONE thing at a time.

But that will increase rider sag to over 40mm?

IIRC 7 turns from fully out (soft) is 42mm with me on it ... standard is 4 turns from fully out (soft) (out of 15)...

After reading back through this thread last night one question I did raise is given the preload has no affect on spring rate, i.e. preload changes suspension height not stiffness. Why does increasing preload reduce sag?

[Mr OCD]

RACETECH

FRONT FORK SPRINGS
Recommended Fork Spring Rate: 1.007 kg/mm (use closest available)
Stock Fork Spring Rate: 1.040 kg/mm(stock)


Something is wrong ... got to be. Fork springs on the bike should be perfect (unless they have been changed) for my weight so why am I needing so much preload to get the sag in the right area?

I assume I'm measuring it correctly?!!

Fork seal/lip to base of fork?

[bass gt3]

Mr OCD said:

bass gt3 said:

Afternoon,

If you really feel like the front is a tad high, try taking2 or 3 turns of front preload out. That'll drop the front a tad.
As for the perceived softness, they never are as soft as you'd think.
But once you have the front height where you're comfortable, try dialling in a tiny (quarter turn) of compression front or back and se how it feels. But now's the point where you need to start making notes and only change ONE thing at a time.

But that will increase rider sag to over 40mm?

IIRC 7 turns from fully out (soft) is 42mm with me on it ... standard is 4 turns from fully out (soft) (out of 15)...

After reading back through this thread last night one question I did raise is given the preload has no affect on spring rate, i.e. preload changes suspension height not stiffness. Why does increasing preload reduce sag?

It's an illusion If you wound full preload in, you see your total stroke was longer as the preload is overpowering the neutral spring. So the spring will always sag the same amount for a given weight. Preload just moves the range up a bit. It's why springs come in half newton increments, otherwise if preload was able to cover a broad range of springs, there'd be no need for such fine increments.
But given that we're stuck with the springs we have, we can't actually change true sag. The preload will only adjust ride height so it's ok to take a couple of turns out to lower the front. Now you can add a smidge of compression in the front to slow the forks a bit.

[fergus]

there are several iterations of this tyre wear guide on the web http://biketrackdayshub.co.uk/motorcycle-tyre-wear... all originally taken from Dave Moss' website http://feelthetrack.com/

There is a small section on fine tuning your rebound rate. As Steve says, the base setting for the rebound is to ensure the bike returns to it's neutral state as smoothly as possible, without oscillating (i.e. the spring isn't sufficiently damped in rebound). The guide can really help tyre wear issues.

check out his site, it's got some really interesting stuff on it : http://feelthetrack.com/free-vidoes/setting-sag-2/

you could do a lot worse than to buy this book: http://www.amazon.co.uk/Suspension-Tuning-Handling... It's very easy to read and explains things in an accessible way.

Edited by fergus on Monday 30th March 14:39

[Mr OCD]

bass gt3 said:

It's an illusion If you wound full preload in, you see your total stroke was longer as the preload is overpowering the neutral spring. So the spring will always sag the same amount for a given weight. Preload just moves the range up a bit. It's why springs come in half newton increments, otherwise if preload was able to cover a broad range of springs, there'd be no need for such fine increments.
But given that we're stuck with the springs we have, we can't actually change true sag. The preload will only adjust ride height so it's ok to take a couple of turns out to lower the front. Now you can add a smidge of compression in the front to slow the forks a bit.

Thanks for the explanation...

I'm actually considering changing the springs if I need to do so as I plan to keep the bike a couple of years so want it riding well. As always it is a compromise... the standard Fireblade suspension is supposed to be very good and as a road bike for 95% of the time commuting spending thousand of pounds on suspension upgrades just isn't justified.

Don't mind spending a couple hundred quid on springs though...

I will change the preload to 7 turns from soft that puts is back to pretty much how it was!

So we've come round full circle...