Lowering links vs sag numbers

[TexasT700]

Questions for some of you knowlegable suspension brains!

I have 1 inch lowering links by Kouba.

I weigh 225 in street clothes.

I have a topbox on T7 that might weigh 10 pounds.

Just upgraded from factory rear spring to a Rally Raid 85nm spring.

First 40 mile ride felt like I used to have a vw bug and just turned it into a cadillac ride.

Nice ride, little bumps hardly noticed anymore, altho front end still a little brash. Work to be done on front, but just concerned about sag numbers on rear shock for now.

So, did a lot of studying online,  adjusted the preload up and up to get to about 30% sag. (As I understand, that is static sag added to the rider sag. )

At full preload, about 24 turns or clicks, I acheived 58mm sag, difference of totally extended rear suspension and me sitting on bike measurement. Went for a ride. It felt like an overtightened guitar string. Waaay too "taught", way too tall, and no longer the nice plush ride I felt before trying to get 30% sag.

Am aware that lowering links change the dynamics and design intentions of the suspension.

My first question is: Is 30% sag really correct for a bike with 1" lowering links? If not, is more sag necessary?

When I measured the sag before adjusting preload, when it rode so nicely, the sag was about 83 mm, or 40%.

I can easily put the oem shock links back in. I also can buy a 90 or 95nm spring.

With the preload cranked all the way up, the bike is back to making it a reach to the ground, so the lowering links hardly help if they demand high preload!

Any and all thoughts on this are greatly appreciated!!

 

 

[TexasT700]

I know, I searched the www for many hours and can't find ANY info on sag numbers for a lowered suspension. Guess will relax the preload back to where it rode nice and assume that lowering links require more sag. Should end up around 80mm sag or near that.

[DuncMan]

I need to adjust mine with the new links and also am struggling to find the sag numbers. Guess I'll just tweak and see how she rides.

[TexasT700]

Awesome! Let me know if you find the magic sag numbers

Thanks

[Quercus Petraea]

You need a stiffer spring. Lowering links are longer than the oem, so more levering is applied to the shock. For 18mm lowering links a +5nm spring us recomended, so may be for 1 inch (25,4mm) lowering links you'd need a +10nm spring (95nm).

 

The right spring feels way better than a softer spring with a lot of preload to reach the same sag.

Edited January 6 by Quercus Petraea

[TexasT700]

Thanks Quercas,

I think that might be a very good suggestion. Going to back off the preload to experiment a little, but I am thinking you are correct. I used the 3 ratchet straps with floor jack method to install this spring, but think I  shall buy the Unit spring compressor for a safer and more efficient change. I saw a video of it in operation and for less than 40$, it looks to be a breeze to use.

I know the 85nm spring was amazingly better than oem at around 68nm, so going to 95 makes perfect sense, to offset the links leverage. It may take a few weeks to get the 95nm spring, but I shall post up here if that is THE answer.

Thanks!

[Uncle M]

If you're using a Rally Raid shock spring, I'd suggest contacting @Ktmmitchat Rally Raid for advice in which spring would be right for your use. He's excellent.

As @Quercus Petraea said, the 85Nm spring is too soft if you have to go 24 clicks to get 30% sag. My understanding is that you want to use a "stiffer spring" so little shock preload is required to keep the shock high up in its stroke for maximum performance. I don't have lowering links and I weigh less than you but I get 30% sag with 3-4 clicks of preload with a 90 Nm Rally Raid spring.

Good luck!

[TexasT700]

Thanks! Great idea to run this by Rally  Raid. They are experts and know what is going on.

[TexasT700]

So, I think I have answered my own question. Some of ya'll are right on. I installed a 95nm spring, rode 65 miles today, in warm Texas. Very nice results. I also cranked up the compression and rebound around 3 to 4 clicks each. That calmed down a bit of bounciness and made the rear suspension feel just about perfection on the road. The rider sag came in at 73mm, 36%, with zero preload. I believe I will leave preload at zero, cuz it feels so right. I got on the lying scale when returned from ride today, and it said 240 with jacket and helmet. Guess I am trying to kid myself that 225 was all I had. Also, have 1" lowering links and a Givi topcase. With this config, the 95nm seems to be right.

Now, the front seems to be a bit brash on edges. Clunks when I hit a 2" edge at speed. I measured it today, came in at 27% rider sag at 57mm. However, interestingly the static sag was 21% at 44.45 mm.

I am guessing a 6.2 or 6.3 spring set for front might solve this. Maybe even 6.4???

Any suggestions welcomed!

PS The Unit spring compressor does NOT work with the T7 shock. Not possible to use it due to config of top end of shock. I will put this one up for sale for someone who has something other than T7.

[Uncle M]

@TexasT700  I would try adding a bit of preload til your rider sag is closer to 30% and compare it with your current 36% sag. 

[TexasT700]

Thanx. Good suggestion, nothing to lose trying! Will give that a try. Unfortunately, high temp tomorro is about 40 degrees here. But will try your suggestion asap.

[TexasT700]

Uncle M,

I did as you suggested and you are correct!!! Added 4 clicks to preload on shock and the ride is actually even better. I have not measured the sag again, but am guessing it is very close to 30%. Thanks for the great advice!