afm199
Well-known member
make sure u buy those forks w/ Ohlins carts and extenders in the For Sale section
Right? That's a screaming deal and that's a really good setup.
make sure u buy those forks w/ Ohlins carts and extenders in the For Sale section
Haha grad student budget + $350 into revalving the forks I have this spring = no more suspension budget. But I'm sure I'll regret it in a year when I have the money.
Though if I go with extenders then that's $200 plus install anyway...
This is a little tangential, but I also feel like it's extremely difficult or nearly impossible to turn in if I'm braking beyond ~30%. Is that normal behavior, or do I need some suspension fixin'? Only shows up if I'm cooking a little hotter than I should on weekend rides (so yes, the non-moron answer is to slow down. I know).
LOL. If you are riding with Keigwins this year, come by and say hello. I'll be glad to do some laps with you and give you some feedback.
I'm always pitted with the other instructors under the first canopy at Thill East.
#199
why would u need extenders if u dont like the front end taller than flush?
if u think raising the whole bike would help, why didnt u leave the forks sunk in and add shock length?
did the tuner do anything w/ preload?
what track and which corners did the bike feel like a boat?
how much brake pressure were u holding to the apex? is there any correlation btw brake pressure and the boat feeling? ie did the bike turn in better on the brakes or no?
Pirelli sc2 180/55. The new DOT V2 tire.
Sorry, I got mixed up - this last four days I've been running the new rear 180/60, I forgot that Daredevil got me on the new one when I changed it over. Pirelli does have a 190 rear now in the DOT, should I give that a shot? These are almost toast anyway...
I'd like to come to Laguna but I doubt this bike will pass sound with an M4 slipon on the right side. Also generally outside of my budget... if I can pick up a cheap last minute ticket I may give it a shot.
It's weird that the bike has so little rear sag since I think this spring is pretty close for me... There is a lot of threads showing above the hydraulic preload on the ohlins shock (su647). Wonder if the collar is just set really low. Ohlins gave me a spec for coil length with zero preload but not the amount showing above the collar.
In order:
1. I was implying raising the whole bike, not just the front - I was under the impression this would make the bike transition easier from side to side
2. I couldn't adjust the rear ride height because I don't have two of those super thin 24mm wrenches. So I dropped the front instead, since my goal this weekend was to experiment - how else am I going to find out what's wrong?
3. I went to 4 turns (of 14) from full out on the front. Tuner backed it off to 2 turns. Felt fine, not bottoming (zip tie about 3/4cm from bottom of stanchion).
4. Rear has no preload. Tuner claims its still way too stiff, and it needs more sag. I can't remember the number he gave me but it was apparently less than ideal, he said that might be screwing with the whole bike. It sort of chops at high lean angles and he said that's why. Racetech and the GSXR forums seem to say 100 N rear spring is pretty close to spot on but he would rather back it off to a 95.
5. Thill East. Mostly turn 1 and 8 I felt it the most that it was boaty. It wasn't unrideable but it was really hard to turn in and vague.
6. I played with it, it felt better with more brakes to the apex for sure now with less compression in the front it was better. I think one leg was all the way closed (!) so that probably explains why it wouldn't pack down for me on the brakes previously.
6 cont'd. If you wanted some reading, there's a great thread from an AMA racer here that outlines his and east coast suspension guru Thermosman's experimentation on this bike's setup.
7. the tuner's sheet he just emailed me said the rear sag was 20mm. I will try to remeasure myself because every resource I've found online says that this is the right spring for my weight.
big rear tires seem to require tons of front ride-height. the tire height pitches the bike forward and takes away swingarm angle, making the bike not finish corners. adding more shock length steepens the forks too much, removing front stability and causing the tire to tuck easily. so the answer is tons of fork length to get the stability and swingarm angle back. some bikes need shock length too, others dont.
1. ahh. sounds like u are 6-8mm away from max front ride height right now. so u can add 3-4mm of shock length and not need extenders. its prob worth trying there before spending the $$ on extenders.
2. the GSXR all use a shim under the top clevis, correct? a lot of racers dont bother changing the shock length. they set it at their minimum, then swap shims. that way your changes are accurate, u dont need to mess w/ funny wrenches, you dont round the shock nuts, and u dont burn your hands. it takes an extra 3min on the R6 to swap shims.
3. its funny you are running so little external preload. i think before i had assumed the shop that worked on it would have cut the preload spacer so that the adjuster was near the middle of the range. prob didnt happen that way. i think we also agreed previously that your fork springs are too stiff. lots of things still to sort out w/ the front end. a spring w/ very little preload has some interesting side-effects, so its prob a good idea to measure if/when u swap springs.
4. i hope not. "no preload" is bad news bears. springs arent linear w/ no preload. if u have an Ohlins, theres a topout spring in there and u need preload to deal w/ that too. dont listen to Racetech. their springrate calculator is way off for every racer i know. and who knows about yahoos on a forum :laughing. change the springs so u can stop "wasting" trackdays on an ill handling bike.
5. both of those turns are easy to get into completely off the brakes. so your dynamic ride height is taller and the bars are difficult to turn. but thats how setup works. we very often sacrifice one corner to make up time in the other 14 turns.
6. in a normal braking zone, where u brake for at least 1sec with the bike upright, compression damping has very little effect on the fork position. the shorter the braking zone, the more effect it has. damping controls the speed of fork movement, springrate/preload/oil height controls the position of it. any overlap btw those 2 concepts all depends on time/duration of the input to the suspension. i fully expected u to say the bike was better on the brakes, because the front is/was taller. the brakes lower the ride-height, reduces trail, shortens wheelbase, and lets the bike turn easier. can u use that to go faster? (u should def say yes )
6 contd. IMO, the main reason why racers run shit tons of fork length is because theres plenty of time to be made up on the brakes. modern tires can support A LOT of brake pressure all the way to the apex. 40% brake pressure with a knee on the ground is borderline normal. getting off the brakes before turn-in is slow obviously. so the front end is statically very long and they control front ride-height w/ the brakes. u arent riding like that... yet. so the setup that works for an AMA pro might not work well for u. i just rode a 2016 Graves R6 last weekend for one session. the front end was practically immobile at fast A group pace when i was hardly using the brakes. but as i started to use my racing markers and brake harder, it was money. there is some discussion to be had about how to setup a bike for a rider thats learning... set it up how fast guys use it, then hope u learn to ride like that. or set it up best for u now and hope that u realize when it needs to be adjusted. hmm.
7. see above for online calculators - they are shit. if u want the best suspension experience, find a tuner that has personal experience setting this bike up for racing. not just building parts and sending it out. literally working at the track w/ a racer. then get them to watch u ride and pay them for their recommendations. normally, i dont care one bit about sag. but u arent in range so we'll use it. and its telling us u need a new spring. also, def verify how much installed preload u have. measure the spring length now w/ the rear tire off the ground and get back to us.
1. ill defer to afm199 on the shock length u need.
2. the shims i use on the R6 are slotted. they just slide in. remove seat (2 bolts), lift the tank (3 bolts), loosen the shock nut, lift up on footpegs and slide in shim, put everything back. i guess that doesnt work for your GSXR, oh well.
3. i still dont care about sag . all the way closed on compression doesnt mean the fork doesnt move. the oil still flows past the shim stack for all fork velocities and u might have a bleed hole in the valve body. and only one leg, psh :laughing jk. ya im sure riding that sucked, esp if u werent pushing that hard on the brakes.
4. 11-12mm preload is great. a good range for preload on almost any shock is 8-16mm total preload. obviously, putting the adjuster so that full soft is at 11mm ruins your ability to get down to 8mm. the tuner saying "no preload" threw me off, an odd thing to say. dont forget, preload has nothing to do w/ spring stiffness as well.
i dont know what u mean by "chopping". can u explain?
6 cont'd. the travel isnt the same on most pro setup bikes, at least on the ones ive seen. a good tuner can use an aftermarket fork cart to extend the travel by 10-20mm. the extra travel allows for a wider range of useable springrates before hard braking causes bottoming. this in turn moves the dynamic ride-height around a lot, for better or worse. ive heard the whole reason GSXRs "need" extenders for race pace is because the fork bushings only allow for 10mm extension (or something) and u still gotta go higher.
but rly, that part ^ doesnt matter much for your actual question. say uve found some dynamic* ride-height, some ideal fork position, that allows the bike to turn as good as possible on the brakes... but now u want to brake harder. u must add fork height, add preload, or increase springrate to maintain that ideal position given the stronger input. the same goes for midcorner too. faster riders load the suspension more w/ higher corner speeds, so they might run a taller dynamic ride-height to deal with it. im sure u can think about how all this relates to my prev paragraph for #6 w/ compromises and pace.
funny thing... RaceTech recommends .875 fork springs for me and "roadracing". with the stock fork travel, i can bottom .925 in any hard braking zone. so why the hell would they recommend .875!?!?!. however, that Graves bike i rode 2 weekends ago had the longest R6 forks ive ever seen, 8mm longer than my extended forks. they had .90s and i couldnt bottom them. midcorner grip felt good too.
7. heres the manual for your shock. its interesting that they recommend 14mm installed out of the box. sounds like the adjuster is setup to allow ~10mm at minimum. its all making sense now. https://www.ohlins.com/app/uploads/world/documents/2006/03/MI_SU647.pdf
*i say "dynamic" because u are riding the bike when u need this ride-height. its not static ride-height when the bike is on a stand.