Lowering GSA with Hyperpro springs?

Has anyone lowered a LC GSA fitted with ESA using the appropriate -20mm Hyperpro springs?

I'd expect it to improve the handling a little but am mainly looking to lower the bike to about the same as a standard GS without it becoming cramped with a too low seat.

You're going to need to think about the stands too.

I fitted Wilburs lowered suspension

In terms of foot down its fine for me 28" inside leg / low seat.

However as Chazzy says

You will need a new or modded centre stand & bushing (you transfer the other parts off your old stand)

You also need a modded side stand, you can either cut and weld your old one, or you can purchase a new one

Be aware that if any of the bushes need replacing the cost starts to add up.

if you look in the HH threads there is my previous thread on this which covers everything.


and just when you though it was all over


with the lowered suspension, the seat / Hip / Knee / Ankle to peg relationship, all changes

So whereas before you may have had straight calves , now you will have a bend ...


Use www.cycle-ergo.com to see what the effects of changing the suspension will have

Hi Santa-2512

According to Hyperpro there is no need to modify the centre or side stands. As I'd only be changing the springs and keeping the shocks the same the unladen height of bike remains the same, I'm not totally convinced though.

What do you mean by HH threads?

The reason for lowering the suspension rather than the seat is to keep the ergonomics the same, I don't see how just lowering the suspension can alter the ergonomics

Bob Jeffries said:

Hi Santa-2512

According to Hyperpro there is no need to modify the centre or side stands. As I'd only be changing the springs and keeping the shocks the same the unladen height of bike remains the same, I'm not totally convinced though.

What do you mean by HH threads?

The reason for lowering the suspension rather than the seat is to keep the ergonomics the same, I don't see how just lowering the suspension can alter the ergonomics ��

Click to expand...

HH Hex Head forum

I thought changing the spring length wouldnt have any effect, but it does

The spring is held in place by the top collar and the lower part of the suspension, fitted to the bike this will expand to full extension when the bike is on the centre stand

For example, and these are hypothetical figures lol The full extension of the shock with normal spring is 500mm so bike on centre stand, and the wheel can only drop as far as the extended suspension will allow - 500mm

This will leave say 100 mm between the wheel and the ground

Now fit a shorter spring, and the extension is 480mm (the spring is 20mm shorter) now when the bike is on the centrestand it has 120mm between the wheel and the ground, because the shock can only extend to 480mm

With me so far?


Now if you drop the bike off the centre stand , with normal suspension,

the distance between the centre stand and the pivot point is calculated to give you enough leverage to bring the bike onto the centre stand by standing on the lever arm of the centre stand.

It's fulcrums and levers and i cant explain it propperly

However with the bike sitting 20mm lower this changes the pivot point of the centre stand, so you effectivly have to lift the bike onto the centre stand. instead of physics and fulcrums making it easy ...


The side stand needs to shorten as the lean angle of the bike changes

With the bike having normal suspension the lean angle is say 45 degrees, lower the bike and the side stand wont give enough lean so the bike ends up at almost 80 degrees one small push and its tipped the other way


You have to lower the centre stand by about 30mm, and the side needs about the same, but due to the angles involved needs 30mm removing and the foot angle changing by 9 degrees

If you have the bike fully panniered with the low set up, it becomes a heave and a half to get it on the centre stand moreso when lowered

HTH

I did expect to have to shorten the stands and am doubtful about Hyperpro's assurances.

If they are wrong I'd probably be ok with the centre stand even if I have to use a 20mm block under the back wheel but there would be no option other than to shorten the side stand - I'd probably buy a s/h one and shorten that.

I do have a low seat but it cramps the riding position and I'd rather not do that.

I fitted the lowering springs on my 1250 GSA. Excellent solution for my short instead of 29 inches. You can leave the side stand but I was unconvinced. I first bought a nos low chassis side stand but that lies over too far for liking as I struggled to get it upright whilst sat on it.

I have had the original stand shortened by 10mm and it's due back tomorrow so I will update when its refitted.

10mm is not going to be enough.

I have the measurements of the short and long stand, and if i recall its 30mm or so,

Also where you take the material out is important too.

if it stops pissing down i'll go and thake some pics of mine

I decided to start at 10mm. Weld ground away at foot. Stand shortened at bottom at same angle as original and then rewelded.

I think it will be enough for me but it's easy to take another bit off and very difficult to put some back.

Low chassis GS is something like 70mm lower at the seat than std chassis 1250 GSA but the stand is only 30mm less so I reasoned that as I am only lowering 1/3rd of low chassis then removing 1/3rd of the stand length difference would be a good start point ?

however short or long the springs are it makes sod all difference to the knee hip angle

RSiconic said:

I decided to start at 10mm. Weld ground away at foot. Stand shortened at bottom at same angle as original and then rewelded.

I think it will be enough for me but it's easy to take another bit off and very difficult to put some back.

Low chassis GS is something like 70mm lower at the seat than std chassis 1250 GSA but the stand is only 30mm less so I reasoned that as I am only lowering 1/3rd of low chassis then removing 1/3rd of the stand length difference would be a good start point ?

Click to expand...

There is no difference in the chassis of the "low" version, all the lowering is done via the suspension and if required seat.

Your 70mm is a bit out btw

For a std gs normal seat height is 870mm dropping to 850m with the std seat in the low position

Fitting a low seat gets this to 820mm. fitting low suspension & low seat will get it to anywhere between 790mm and 800mm (and you can get this lower as well ) 30mm spring reduction & preload backed right off


We cut the stand between the foot and first bend, its far easier plus you can rejoin and sleeve in this area if needed

I think the hyperpro springs are progressive and the length is the same.
The difference being that the spring gets stiffer as its compressed thus enabling the bike to sit lower when your sat on it. I would ring Cal sport and ask there opinion before spending the cash..

I’m in the same camp as Bob at the minute looking to find a lowering solution.

The Hyperpro springs are as they describe progressive so same length as standard spring, but as described to me by I think by Fox racing the progressive spring let’s the bike sit lower under it’s own weight then the spring progressively stiffens up to counter this initial compression, what I don’t know is can you also get the spring to match rider weight, and is it also worth changing the front spring at the same time. They also sell the springs for ESA and non ESA but struggling to find anyone that has experience of fitting them to see what they think of the result.

This is a £200 option plus fitting so a lot cheaper than the full shock change, and possibly not as good but it’s in the price range I’m willing to spend rather than the couple of grand alternative.

If your bike has dynammic ESA ( post 03/17) it won't work as the auto preload will compensate for the reduced ride height and lift the bike back up again.

CPJS said:

If your bike has dynammic ESA ( post 03/17) it won't work as the auto preload will compensate for the reduced ride height and lift the bike back up again.

Click to expand...

But will it though?

The preload adjusts to the weight applied?

So if the bike on the existing shock sits that bit lower because the spring compresses a bit further will the sensors jack it back up, no more weight applied to the bike, how does the sensor detect and adjust?

I honestly don’t know the answer, just my thoughts?

Luke aka Denzo of this parish is your man to ask about springy stuff...

Me i purchased a set of wilburs 30mm lower shocks

Do they make a difference ... undoubtably yes. Ive gone from tippy toes to one foot flat

handling is easier, as i dont have to worry about if i can get a toe on the deck. i'm happier throwing it into a corner .

Yes you need to be aware it sits lower, so cleaeance is reduced. but use common sense and all will be OK

Are the Wilburs lower than stock... definatly, but they need careful setting up, and you will need to lower the centre & side stands

otherwise , enroll in a gym, your going to need to build up those muscles & pack on a few lbs

Roadrash Rider said:

But will it though?

The preload adjusts to the weight applied?

So if the bike on the existing shock sits that bit lower because the spring compresses a bit further will the sensors jack it back up, no more weight applied to the bike, how does the sensor detect and adjust?

I honestly don’t know the answer, just my thoughts?

Click to expand...

The D-ESA adjusts according to the swingarm movement in relationship to the frame measured by this.

https://www.realoem.com/bmw/enUS/sh...-BMW-R_1250_GS_Adv_0J51,_0J53_&diagId=33_1712