Long time lurker - first time poster...
I picked up a 2022 GasGas MC350F that I put about 20 hours on with just spring rate (5.2) change and air for psi (163) but stock valving. It was ok but not great and to get enough compression to handle the occassional over jump I really had to increase the compression towards the limits and it would cause the forks to be harsh everywhere else. Note that the manual calls for 35 static 105 race sag on the rear.
Long story short I decided to revalve both ends and went the racetech route. The valving the suggested absolutely fixed blowing through the forks on big hits without hurting plushness, I'm happy there. However the suggest running 98mm of sag in the rear, which is way higher than I'm used to running on KTM's historically (lets call it 103ish) and definitely gives the bike too much turn in. After knifing the front end a bunch I dropped the forks down to flush which helped, but it still feels stink bug and I have to think about sitting further back on the seat to lengthen the bike out in a g-out rut.
I called racetech to ask why they would suggest 98 on the gasgas but 103 on the ktm, thinking it might be a simple mistake in their database. The tech was helpful but I'm not buying their explain and suggestion.
He said there is a note in the system claiming it uses a low leverage link, thats why its different. I didn't think there was anything diff physically in the swing arm/knuckle/link/frame on the GasGas, and I cross referenced the knuckle and link parts as the same while we were talking. After that he went and asked someone else and then came back saying that the subframe on the GasGas sits lower at the fender so they suggest running less sag on them to prevent fender rub. Which of course I've gotten on my last 2 KTM's as well as this GasGas, along with pretty much everyone else it seems. I
However I don't know if there is any actual diff in this subframe/fender, I thought tanks and colors were the only differences in plastics between the two brands basically which is part of why I picked up a GasGas in the first place just to be a little diff.
I'm going to move to more like 101 sag and see how it feels, but the engineer in me wants to get to the bottom of why racetech would suggest such a big difference.
What say you vital experts?
I’m no expert but I would put the forks back to the normal position and test the suspension at different sag settings. Go back to 105, test then put in 3 turns stiffer test, 3 turns softer. No need to measure. You will find the sweet spot easily. Then measure. Who cares about fender scrub?
That's a lot of bullshit from RT. I would not trust them with anything after hearing that explanation.
104-105 on Austrian bikes. 35-40 static depending if you prefer a soft or stiffer rear spring. Anything under 103 sag is unrideable.
Depending on your line of work as an engineer, you know how sometimes a little mistake can propagate. Hold it where you have it and slowly take some tension out of the spring until you like it, all parameters held constant. It’s probably just a mistake on their end, no big deal.
definitely doesn’t mean they’re totally useless from here on out…
According to Motorsport’s OEM parts listing gasgas and KTM are the same. Husky is different tho. Also I had to pick the 250 as Motorsport doesn’t have a 350 listed for the gasgas
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Yup - I found the same on rocky mountain. That’s why I’m confused about it, now it makes me wonder if they have the same valve stacks in it as the ktm 350 setup or not too.
Isn't it crazy. I don't understand how suspension can be subjective and objective at the same time?
Some say static sag on ktms should be measured, WP say use spring length and preload. At the same time, but put a light kid on a ktm, and the spring is loose to get the right sag, and for big blokes, you need more damping and a lot more spring.
And the ktm manual shows how to measure sag off the molded sag mark on the rear fender…
You need to use all of the measures. 105/40 with 3mm preload is to stiff spring.
105/35mm with 9mm preload is to soft spring.
So even if you can make sag work, you need preload to determine if spring is right.
That was my point. I skip free sag, and just set spring length to 7mm. Then make small adjustments to 105mm sag or find another spring.
Even setting 105mm rider sag isn't trivial... with the linkage ratio, its a narrow window and sag changes significantly by how you sit on bike. I set sag standing up.
Thanks for all the responses guys. It sounds like we're pretty much in concensus that RT has made a mistake in their database, which is interesting.
For kicks I left the forks flush and increased the sag, the bike definitely turned slower, too slow.
Has anyone played with difference in running the bike forks down/up in relation to sag? Moving the forks up 5-10mm (from flush) doesn't change where they sit in their stroke, but the sag change does change where things will sit in the stroke.
What would be the expected feel on the bike of running flush and 98mm of sag versus forks down 5mm and 103mm of sag (same 5mm diff front and rear for bias, or even 10mm down and 108mm of sag (same 10mm down for bias)?
It will be harsh in both rear and front with 98mm sag. Easier to get armpump. Works on flat and smooth tracks, SX style surface. Fork height compensation don't help much/any with that part. Bike will also tend to kick sideways over uneven jumpfaces
108 will be plush in front and rear, even on third line or further up. Can go way faster over braking bumps. Also with right amount of HSC it will be rock solid over broken down track segments like jumpfaces with both deep ruts and kickers.
But you will lose front tire pressure and you will not be able to compensate that with moving forks. Most noticeable on flat corners with less traction and no ruts to bank against but also in sweeping fast corners where it will want to drift put.
It's also big difference between 98/40 and 98/35, as well as 108/35 and 108/40.
Assuming you are on the right spring and you can get 105/35-40 my comments apply.
what's your weight in gear ?
I have a 22 MC250 and run a 5.2 for 210 lb w/o gear
spring conversion in the forks so nothing to compare with
Thanks for continued advice guys - not a lot of riding TX ice last week to try out new settings
I'm 215 naked - so pretty close to you and also have a race tech 5.2 on it. With the 5.2 I can set sag (wearing gear) using ~2 turns on the preload adjuster that goes from sag range of 31 static / 98 sitting and 96 standing, to 35 static / 105 sitting and 102 standing. Everything else is in between obviously. I try and split the difference standing and sitting if they change when setting it.
I haven't backed it off completely and tried to get a set of calipers in there to measure uncompressed length versus compressed (per a post above) but I'd be surprised if I'm not in the 5-10mm range for within that 2 turn window. It gets pretty easy to turn by hand down at 105, by 108 there probably wouldn't be much if any preload tension on it.
I'll play a bit next week with going back to 5mm fork height vs flush with a higher sag number to see if feel I can feel improvement without the negative cornering issues.
I did a little more part cross referencing - the engineer in me still is annoyed racetech can't give me a reason why settings would be diff. The front forks are identical parts aside from valving, obviously the triples are not the same. But interestingly, the swing arm is actually a different part number. The 2022 husky and gasgas share a swingarm that is labeled 2018 complete but the KTM has an arm labeled 2019 complete with a diff part number. Anyone know what the diff in swingarms actually is?
Looking in detail at the sxf vs mc350 settings for same 40 vet B rider - race tech actually has a 164.56PSI suggestion front and 5.16kg rear, 6mm preload for 103 sag for the SX-F, 162.62psi with 5.26kg rear and 5mm preload for 98 sag.
I run my forks at 163 and I'm not good enough to tell the difference beteen 162 and 164 from 163. Drop it 5psi and I notice, but definitely not 1.
RT has husky 350 at 167PSI, same 5.26 spring with 5mm of preload, and 98 sag. Interesting that with the difference in linkage + forks to achieve overall reduction in seat height that the rear is the same suggestion but the front is not.
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