when measuring fork and shock ride height, is it supposed to be on stands or on the ground? i've heard both and not sure which to follow. for reference, it's a GSXR 600. i have 525mm from the center axle, to the top of the lower triple...on a pin stand. shock is 316.5mm on a spool stand.
I measure the front end fully extended. You may need to push the front wheel down some to collapse the top-out spring. I don't measure rear ride-height directly. I measure the shock length off the bike and adjust with spacers. I can't change my swingarm pivot or shock linkage, so there isn't much need for knowing ride-height. I'm also not worried about the small ride-height changes caused by axle position. If I needed to measure rear ride-height, I'd do it fully extended as well. One goal of any measurement is to minimize variables. Measuring shock length in the bike on a stand adds plenty of variables compared to when it's off the bike.
you're right. i measure the shock in length...not on the bike. so it's just the fork height i need to focus on
On the ground. "Ride height" is the bike sitting upright, unloaded, on it's wheels. Depends on what you're doing but semantics matter. If you are trying to match a Suzuki "ride height" number, it's meant to be on its wheels, not any stand. Suspension extension, as measured above^^^ is a different spec, and good starting measurement to know and calculate ride height or sag from there. Strangmx13 makes a good point about eliminating variables. Street bikes typically have very limited suspension travel, so its all about sag (ride height including load) to get the suspension in the correct starting point to begin damping adjustments.
What have you tried to fix this issue? You need to experiment. Identify exactly where the bike won't turn and under what circumstances, then make a change. For ex. if the bike doesn't turn on the brakes on entry, change the front height. If the bike doesn't turn on exit on the throttle, change the shock length. Record and repeat until you teach yourself what each change accomplishes and what you like best. Or you could identify where the bike won't turn, present a suspension tuner with your entire setup, and pay them for help. Sag is not a starting point, it's a result. And IMO, it's one that isn't worth measuring on a race bike. This is especially true if you paid someone for good knowledge of spring rates and preload that are within range.
I think we're saying the same thing. Sag is a starting point, always, as in the first thing to get correct. A result of being properly adjusted, first. It sets the suspension in the correct part of its stroke so it doesn't top out or bottom out, then you can start to set damping. Sorry but I wholeheartedly disagree with not checking sag, and doubly so on any race bike!?! There are just too many variables to guess. Guessing isn't a good way to win races and frankly dumb when a tape measure and 30 seconds is all it takes. If you bought a pre-built shock or fork springs or whatever 'for your weight' and installed them, you're probably close... but you still need to set sag after they're installed on the bike. Especially on a race bike. Besides, why wouldn't ya? It's super easy! Sorry it's that important OP, It's important to know if Suzukis measurement of "ride height" you are trying to get is a starting measurement (unloaded/static) before you set sag, or a finished measurement after you add the load. But off the stands either way
Set the sag to what? What magic number is "correct"? Why is it "correct"? If you have a range, why did you pick the #'s that you did? Did you set that # with the gas tank full or empty? What is "correct part of the stroke"? Why is that part correct and under what riding conditions is it correct? I suspect many of your answers will be arbitrary or vague. My usable fork springs range from 8.75-9.5 N/mm. My fork preload adjustment range is 6-16 turns for 8.75 and 6-10 turns for 9.5. Each track may require something different. Each preload turn is 1mm and near 1mm of sag difference. With my shock, I run 90-97.5 N/mm springs and 8-10mm total preload. Some of those setups produce very different sags. Which one is correct? Here's what I meant by sag is a result.... Springrate + Preload + Weight == Sag. When going to new tracks or trying to resolve issues, my suspension tuner recommends a springrate for my riding style, my weight, and the track. We then pick a preload based on previous data/experience and adjust to find what feels best. Often when changing springs in the middle of the day, we do not change preload. In these scenarios, I literally know every variable on the left side of the above "equation". The fork and shock are aftermarket and designed by people that know their stuff, so using a recommended range of springs and preloads will produce good results. So there is no point in measuring sag. It's a meaningless number that gives no benefit to my setup or my lap times. If you've paid a top-tier suspension pro for their setup, they've hopefully seen you ride, know your weight, know your bike, know your track, and have set the springs, preload, and damping to a good baseline. Don't mess with it until you can identify an issue. If they didn't set the preload or damping at all, you can probably find a better tuner. Sag is useful for street riders or inexperienced track riders and tuners working on their bikes because all or most variables on the left of that equation are unknown. So the tuner must "guess" at a good setup. Sag provides at least one data point to reduce the amount of guessing. But once you put in aftermarket components and/and know everything else, there's no point.
Sag is so insignificant that suspension shops never recommend it and it's also never brought up within entire book chapters that are dedicated to the topic. The secret is to start shooting from the hip with any settings you feel like and go from there.
Remove shock and measure. Or fully extend swingarm with stands under foot pegs and measure eye to eye on shock. What year gsxr? If it's 06-09, your rear shock is too short likely. Needs to be 325mm at least up to like 332 or so. I always found my sweet spot at 328mm e2e. Front is a good starting point. Once you raise the rear it'll turn. Then continue to raise the front so it transitions easier. Raise front til it running wide again and decrease front back to where it transitions but doesn't run wide. Assuming it's 06-09. But I thought you already knew these numbers. Maybe I typed all that for nothing.
06 GSR 600. shock length was measured when it was out for service at the track last season. my height was lowered for Dayonta, but it's back to 319mm. i may put it to 325 this weekend. this is my first time messing with rear height. i was trying fork height, which cleaerly wasnt helping me.
Leave the shock length as-is for the first 2 sessions, one to warm-up and one to feel it. Then add 2mm for the next session. Add 2 more for the session after that. Keep going with 2mm until the feeling doesn't improve anymore. Once you get too tall, the tire will probably spin easy on exit or slide too much on entry. The point of this is to learn what that adjustment feels like and to find your favorite setting for that track. Shock length is the thing that I change most often. My range is 4mm. Generally, I run short for flowing track and tall for tracks that need flick-ability. That 4mm is closer to 8mm at the wheel, so it can be a large change. The front ride-height range is 5mm, but I like my current setting everywhere at the moment.
it's been awful for a while at 319. so i'll take your advice and go up in 2mm increments. i'll do practice 1 at 321mm. i only just raised it to 319mm, because i lowered it for Daytona to fix a wobbling issue on the banking. i've been riding at 319mm and unhappy with it
so it looks like mine will max out at 323mm, and people add shims/washers to make it taller. 323 will be the tallest i can run it, without adding spacers. https://www.ohlins.com/product-item/62195/
There's so much information on 06-09 gsxr. Hundreds of pages on other forums. Yes you'll have to add spacers or get a shock that will adjust. Penske's would go up to like 330 iirc. Do what you want and go up 2mm at a time if you want, but you'll want 325 or more depending on the tires you run. I was on a taller dunlop 190-60 running 326-328mm at barber, Jennings, roebling, road atl and little tally. If you aren't committed to raising the rear, lower the front back down. Some guys were going as high as 334mm. Do what you want, but you'll be over 325 in the end likely. Depends on your tire heights as well. So much info on gsxr forum and gix xer.com
