Suspension tuning tips- Mtbr.com
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  1. #1
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    Suspension tuning tips

    Hello All,
    I'm new to this area of MTBR, but I think this forum will lead me to feel I am looking for. I have been doing a lot of searching, and watching, and reading about suspension setup. No one talks about setting your bike up to climb. How do you tune out pedal bob? If your front wheel is constantly trying to stop and throw you OTB, how might you combat that with adjustments available to you? I am also interested in where you folks find the balance between firmness and suppleness. Have you found a way to get both?

    I understand preload, compression, rebound, and adding spacers. There are a billion videos and articles explaining them. But there are very few resources giving you specific examples of if you feel x, then you may want to try y. I'll start with a few examples. Tonight I used the 10% grade and steps in the path that goes to the bottom in my backyard for setting up my old '98 ProFlex with updated suspension, drivetrain, and new wheels. I did the curb test where you ride off a curb at walking speed and feel for how much your rear shock oscillates before settling in. I ended up at 9 clicks out of 10 to control 250psi. Since all I have is rebound and preload to adjust (its an RP23 and the propedal switch is just a switch with 3 settings I'll settle on later) I moved onto the fork. I did the bracketing thing to help narrow the setting down, trying to feel if it was packing or bouncing me around like about 50 videos have said. I didn't really feel either as I feel the modern suspension is so good that feeling for packing or bouncing on anything that isn't high speed is quite hard. What I did notice is that the bike steered where I wanted it to go much easier in the closer to the right rebound setting I got. But it wasn't the descent and steps that made up my mind. It was the climb! It is just in my backyard, but it is steep and my lawn has all of those hidden little micro ruts I guess you'd call them. While climbing under power there was a definite difference in how the wheel tracked with just one click either way. I ended up on the third click, 1 being wide open. I tested the settings down the hill again, and over a section that sent me OTB last week on this bike. It felt a bit harsh, so I tired one click less, and then the front wheel was hooking on one or two dips. #3 let the wheel roll through it, the uphill told me what I needed to know. Now that I have thought about it I am going to try taking a few psi out of the tires and see if I can tune out the harshness a bit and hopefully get even more grip.

    I now feel confident enough to hit the trail with some speed on the XC bike now. Maybe I'll report in as I get the chance. But the thing I am looking to do is get my GT Sensor to accelerate and climb when out of the saddle. I did get some advice from a suspension business that is touring the country promoting SR Suntour's new stuff. They recommended, and I bought, few unofficial volume spacers for my UnAir shock. But I have yet to put them in. Mostly waiting for the ol' ProFlex to get back and running so I had something to ride. But now that is a thing I'll have to do it. The shock is just rebound and a lockout, but I have a TA Auron on the front with all kinds of dials. I feel I have a good baseline. Anyone have any suggestions?

    Does anyone have any real-world examples of when x happens do y? Or here's how to combat z. I'm interested, thank you.

  2. #2
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    So judging by the 250psi in your rp23 and the fact the rebound is near fully closed, I'm assuming you are around 210lbs?

    If you are running the Auron 3 clicks from open on the rebound then you are probably running way too little rebound dampening at that weight. Your rebound setting will depend on a few factors, but mainly your spring rate (so your weight) and riding style. The higher your spring rate is, the more rebound dampening required to slow it down. I'm the same weight and run about 3-4 clicks from CLOSED, which feels appropriate. If you are doing that from open, then I'd venture you are too fast. If you are considerably lighter, then you could probably get away with that, but you may want to experiment with it having more dampening. I feel like the fork rebound is a bit tricky to set if you aren't used to what is correct.

    The HSC, LSC dials will be a little more of preference. I can go hunt down my settings if you like (I weigh similar), but your LSC setting will adjust things like brake dive, corner dive, weight shifts, and pedaling efficiency. HSC will be bigger, faster hits that cause the fork to compression at a faster rate.

    I always prefer to start on the stiffer side of all compression settings, if your fork is harsh then you probably aren't gonna get into trouble, but if it's too soft and dives at the wrong moment, then you can end up OTB. If you are on a smooth course, then you'll be able to run more which will give you more efficiency in pedaling, pumping, etc. Suntour doesn't really offer a baseline for their compression settings, so I started in the middle and worked around in the parking lot some getting a feel for brake dive and weight shifts. On the trail, I continued to adjust it and make some tweaks based on how it absorbs bumps and to avoid dive.

    For HSC, there are only 5 clicks and I find myself at 2-3. The internal tune for the HSC is pretty stiff IMO, I wish there was more adjustment range and the internal tune was softer, the current options aren't granular enough and even doing a fair number of big hits results in me being at the low end of the adjustment range.

    I also hooked up a Shockwiz, but all my settings except HSC were right on according to that. It wanted lighter HSC, but when I dialed in the HSC to the lowest setting, it went the other direction, which more or less confirmed what I felt.

    I also find the Auron works best ~25% sag, which is about 3-4% more than most forks I've used. I run 3 spacers, but I do a lot of technical riding on steep terrain and the fork staying high in it's travel is really important to me, moreso than anything else. Even with 3 and being 210-215, I don't think I've ever used more than 90% of my travel except on one really bad near miss where I ran into a rut wrong and it bottomed out, which is exactly why I run it that way. Normal riding, I use maybe 70-80% of travel, at worst.

    As for tuning it to climb, I would set your rebound to be fairly consistent and based on keeping it from bucking. If it's too fast, even on technical climbs it can cause the fork to buck and make the front hard to control. I think that's gonna be more of a weight / spring rate setting that remains consistent. You can increase your LSC to help with out of the saddle climbing, as well, but I find I don't adjust it very often. If you are bobbing a lot out of the saddle, then it might be worth examining your technique, as well, and smoothing out your pedal strokes. My experience having been that once the fork is set up, it doesn't need a lot of tweaking.

  3. #3
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    Haha, no I'm not lighter and faster, I'm heavier and slower. 235lbs. But great tips on the compression.

    Now I have 2 bikes. A GT Sensor with SR Suntour Auron ans UnAir shock. And my '98 ProFlex 5500c which I have upgraded with Fox Float RP23s front and rear. Its a linkage fork, and I didn't mention this before because I didn't to distract from the my main focus.

    I was looking at my notes, and on the GT I am running 110psi for 25% sag in the fork, and rebound is 8 clicks out of 12, HSC is 3 of 12, and LSC is 1 of 10. Also keep in mind I have the travel adjust version, and I run it at 130mm, instead of 160mm. Once in a while I let it out, but its rare. So that firms things up a bit. The ProFlex is at 250psi rear with 9 of 10 on the rebound. But the front shock running only 70-75psi, hence why I am only running 3 cicks of rebound. I do feel I need some a volume spacer, but I can't find any to buy.

    I found that if I run too much more LSC that the front tire starts to wash out. But, I haven't played with it much after getting my current settings. However, I have found that setting up the rebound on any fork to the ball park of where it needs to be gets rid of a lot of pedal bob. After that its comprsession. But I found that LSC did nothing to tune out the bob. It was high spoeed compression. And I beleive the Vorsprung Tuesday Tune videos confirmed that. But I would have to confirm that. I am just trying to get enough of a platform (for lack of a better term) that when I get out of the saddle the bike accelerates smartly. I bought a Sensor because I don't do a lot of fast technical riding. I do encounter tech, but its slow speed. But I know I can pop the fork out, and its more than enough bike for what I can handle should things get steep and rowdy. Its mostly my chill/upright/relaxed/play bike, vs the all business ProFlex.

    Thank you for the compression tips. And I will work on my out of the saddle technique. I have ridden Sensors with the factory tuned shock, and I know I should be getting better "snap" out of the frame. I am going to try some volume spacers. The frame is a 2.7 ratio and the shock is tuned for 2.4. I talked to the guys who are tuning the SR stuff, and they are sending me in that direction, before breaking down and sending the shock in for a custom tune.

    Thank you for your reply!
    Last edited by jazclrint; 02-12-2018 at 10:42 AM.

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