Two big questions I am regularly asked is how to set your up your suspension and what tire pressure to run for mountain bikes. In this article, I’m going to give you some basic guidelines for setting up your mountain bike suspension. In Part II, we’ll tackle tire pressure. I change my suspension and tire pressure based on conditions, but learning how to set the baseline and adjusting from there is both empowering and it drastically improves your ride experience.
For years, I was afraid to touch my fork and shock. I honestly didn’t really know how all the little knobs would affect my ride. I set up my shock and fork pressure based on the range suggested to me in the instruction manual and never touched it again. It’s a great place to start, but not a good place to finish. It wasn’t until I moved to BC 5 years ago that I really spent the time to figure it out and it was one of the best things I’ve learned! Let’s talk about sag first. Sag is how much the suspension squishes down when you sit on your bike.
Here are the tools you’ll need:
1. Tape Measure if sag percentages are not on the shock stancion
2. Shock Pump. I’m using the Topeak PocketShock DXG
First, grab a friend and get geared up. We are talking everything – what you normally wear on your rides, helmet, pack with water, tools, etc. You want to set up your bike based on your ride weight, not your body weight.
Set your Sag
Look at the chart printed on your fork and put air into the fork to set an initial pressure with your weight (including all your gear) as a baseline. Measure the amount of travel is you don’t know how much travel you have. Ideally for an XC set-up, you want to start with 25% sag. Push the rubber O-Rings down the base of the shock and fork. Have your friend hold up your bike facing you and holding the handlebars with the front tire between their knees. Gently get on the bike with the shock and fork open (put both feet on the pedals) and then gently step off. Measure the sag based on the distance of the O-Ring from the base. If you less than 25%, let some air out. On my shock pump, there’s a little button so I can let very small increments of air out.
You can see the O-ring in the photo.
If you like things a bit more plush or are doing more enduro style riding, start at 30% sag. If you ride and notice that you aren’t cycling through your suspension, you might need to take a volume spacer out of your suspension, especially if you’er a lighter rider. I use FOX for all of my suspension. I weigh 130lbs without my gear, and I usually have to take one volume spacer out of the fork. After I do that and continue to play with the pressure, I can usually get full travel.
Use trial and error. The instruction manual isn’t always accurate. Start with where you should be in the manual, assess how much travel you’ve used after a typical ride. If you are not cycling through your suspension, let out 5 psi at a time per ride.
Set Your Rebound
Yep, that little knob on the bottom with a + and a -. My Fox fork has a turtle and a hare. Don’t be afraid to play with it. First, turn it all the way to one side. Compress the shock and watch how fast it comes back up. Then turn it all the way to the other side and observe. Then count the total clicks from slowest to fastest and start in the middle. When it’s colder, you’ll want to go a little bit faster with the rebound. If the shocks don’t feel quite right, your rebound might be set wrong. You’ll want to again use trial and error to see how it feels for you. Once you can get a feel for what rebound that’s too fast feels like and rebound that’s too slow feels like, you can start adjusting on the fly. I change my rebound based on temperature, terrain, and what type of riding I’m doing. For jumps or smoother trails, I’ll favor a slower rebound. For really rocky, bumpy terrain, I like to set it faster so it can rebound fast enough to take the next hit. Ride the same section of trail over and over with different adjustments to your rebound so you can feel it too.
Ideally, you want your front and rear shock to work together as a team. If one is really stiff (a lot of air pressure) or one has fast rebound while the other has slow, your bike won’t work properly. Ride your bike slowly and push up and down into the suspension and see how it feels. Ideally, you’ll want them to feel balanced and come up together at the same rate.
There’s a whole other level of suspension we can get into, but I think that would be best done in a video. It’s about how to push into, pre-load, and pump your suspension to navigate terrain. Also, thinking about how your suspension is loading and unloading in corners or at the bottom of a steep roll can help you adjust your pressure and rebound.
One last note if you’re using the same Topeak shock pump. One feature I like, but want to make sure you know how to use is the 2 stage air valve. When you put the pump on and off the air nozzle, air can leak out. This 2 way valve prevents that! You can see in the first photo, I have screwed the pump onto the nozzle, but the second part of the pump is open. In the second photo, you can see that I screwed down the second portion of the pump which is the part that makes contact with the core of the nozzle to allow air in and out. To remove it, make sure you do this in reverse order.