I’m starting this thread to document my bike setup, to share with those who may benefit from it, and to get feedback during the process. The bike has GP fork cartridges, a K-Tech 35DDS Pro shock, and has the kit ECU/harness. I’m racing mostly tight and technical tracks in CO, NM, and AZ at the Expert level. The 2021 season was my first on this bike and it was very busy. I did some brief setup work early in the season and then just focused on getting used to the bike and finding the right TC settings. Overall, me and the bike did alright together. Over the next month I’ll have the chance to dedicate a few weekends to setup so I can start the 2022 season with a dialed bike. I should be able to get in at least 4 days of testing I think. Here are my current settings: - Fork tubes 3 mm above triple clamp (cartridges add 7 mm from stock), ~519 mm from top of lower triple to center of front axle - Shock @ 310 mm stretched, 5 mm spacer + 7 mm additional = 322 mm total - Using MSS -0.5 degree, +5 mm (forward) head inserts - Stock position swingarm pivot - Swingarm length ~602 mm - 105 shock spring, 13 mm preload - 10.5 fork springs, 4 turns preload (so 4 mm + whatever installed preload is, this is just enough to compress the topout spring), 180 mm oil level Before I put the head cups in I was running the rear @ 324 mm total length to get the bike to steer. After install that was too high so I dropped it 2 mm, but one of the first things I’ll be testing is dropping it more. Based on measurements I’ve seen on stock bikes, the stock swingarm angle is around 12.2 degrees (where ideal is around 12.6 - 12.8) and that is using the stock 309 mm shock length + 5 mm spacer = 314 mm total. Because the bike tracked better mid corner after dropping the rear a bit, I suspect I will end up going down quite a bit more. Any thoughts on shock length/swingarm angle? I currently have about 22 mm of unused travel in the forks. That has gone up since earlier in the season and I wonder if I’m just braking less now. I plan to test with lighter fork springs. Let me know what you think about spring rates, I’m 195 in street clothes. Regarding fork length/front end height, I think the stock setting is 7 mm of tube showing above the triple, so I’m somewhere around 12 mm higher than stock at the front. Based on that and the longer shock length my CoG is quite a bit higher than stock, but by how much I’m not sure. The bike isn’t doing anything in particular that I’m trying to fix, but it doesn’t seem to lock into turns the way I’ve experienced on other bikes. I guess I’m looking for that feeling where you can let both hands off the bars mid corner and have the bike track all the way through on its own, holding it’s line perfectly. This is currently not how the bike feels. That combined with nice quick steering and this bike will be a real weapon, although I know this combination might not be easy to find! I wonder if just dropping the rear might get me there and with softer springs it may settle into the corner better but I guess we’ll see. I hope to get some testing in next week but it may not be until early January. Any feedback on my current setup and direction I’m trying to head would be appreciated.
I don't have any suggestions, but im in the same boat as you. I'm doing the same thing with a 2020 zx10. I rode it completely stock last season, and i have a ttx shock coming this January and am hoping to get it setup properly for the upcoming season. I will be following this closley. Thanks in advance for everyone's knowledge and help. It's very much appreciated!
When I really want to accomplish something during testing, I head to a trackday with a written plan. I'll write down changes I want to make/explore throughout the day, including which session I'm going to do it. My initial list of changes will probably cover half the day, as something always comes up that adds more to the list. And I still want time to finish everything on that list. One change at a time can fill up a day real fast. For example, if I want to explore a fork spring change, ill do something like this: Session 1: Warm-up, set tire hot pressure S2: Spring change S3: Preload change x2* S4: Using best setting from prev sessions, explore something else Etc etc *For that "x2", I'll leave a tool on the hot pit wall and make the 2nd change mid-session. It's really helpful to feel those smaller changes back to back. Aside from all that, don't get too attached to settings - yours or anyone else's. You've already discovered that you like the bike better with less swingarm angle than what someone else said is "ideal". So either that higher SA isn't actual ideal for your riding/tracks/tires/bike, or something else is out of range with your setup. On top of that, you likely have some bias for some setting that you should change, but won't think to because "you've always ran it like that". Im sure you can imagine how those two issues could make it very hard to find the best solutions for setup issues. The more open you are to trying things based on how it all feel on track instead of preconceived notions, the faster "developing" your own bike can go. I like this thread idea. It'll be cool to follow along as you learn things.
It's more than just trail, I've been on bikes with 10mm+ less trail than this bike and they have railed. Wish I knew what it was, but I will work on getting the front and rear more balanced (instead of having it more on its nose like it is now) and hope this might get me closer. I have 3 specific setups that I will be testing which I already have modeled on MotoSPEC, then I will go from there based on results. They consist of dropping rear first to see if I can get a more balanced feel, then dropping both front and rear while keeping the rake constant to see what effect the GC has. I figure this should show me a lot about this chassis works. Luckily for me I am friends with the owner of the track so no sessions, no other riders, complete focus this weekend. Unfortunately I don't get the bike back until tonight (hopefully) and the weather is getting worse, testing may happen under 40 F with possible showers so that should be fun...
If you are somewhat far from the bottom of the fork travel, is the bike really on its nose? Rhetorical question. Can you change the swingarm pivot to really isolate a CG change? If not, I wonder how much you'll feel the SA change over the CG change when lowering the whole bike.
Spent most of the morning with some cooling issues, then it rained later in the afternoon so I didn't get as much done as I hoped. I did test some lighter fork springs but preferred the heavier ones. I dropped the rear 5mm for a total length of 317mm shock and spacers which was a huge improvement, especially on one particular bumpy corner exit where the power was getting down and I was not getting bucked nearly as much. I'm going to be able to throttle harder there now which is awesome. The steering quickness did decrease as expected but not too bad, I will be dropping the front about 3mm too but I ran out of time. I'm am waiting for a cold and wet day tomorrow, it's supposed to rain all day so I already swapped my rains on. Not sure how much meaningful geometry work I can do in the wet but we'll see. I know what you're saying, but regardless of the bottom of the stroke the geometry "hard" settings are biased with a high rear. Yes, if you flip the pivot it will drop 2mm and I think you could do that to isolate the CG change without also changing SA angle. To the larger point though, I think the CG change is going to have most of its effect on the feeling when flipping the bike over in the esses and to a lesser extent mid corner, where the SA angle is going to mostly be on corner exit. So I figure it's discernible between the two, although a higher CG will transfer more weight on the rear so it does make sense to try to isolate the change with the pivot to really understand the effect. Good point. It was high 40s, I was 1.5 seconds or so off my race times.
