RST First 120mm 29″er Fork:Take 2 – by Grannygear with JeffJ

We first talked about a sampling of RST forks we had in house spread out across Guitar Ted, Grannygear, and JeffJ earlier last year.  JeffJ had the most difficulty getting the fork to react the way he wanted to when mounted to the Giant Anthem X 29″er and speaking with RST after the review, they made some suggestions as to how to tweak that fork for a bigger, heavier guy.  The mod takes about 10 minutes tops, but it took us forever to actually get around to doing it.  Still, if you are a Clydesdale looking for a stiff and solid steering fork on a budget, here is a mod that could get it working right for you.


From the extremely well organized garage of JeffJ:

RST First Air 29 Revisited

I had a chance to run the RST First Air for a bit back in August, and for me, it just wasn’t working. When I got the sag to any less than about 40%, the air spring was way too progressive and I could not get close to full travel, and even with the rebound opened up all the way, it was too slow for my liking.

After talking it over with grannygear and Mike Dunn from RST, we felt like we could squeeze some better performance from the fork, and give it another shot on the Anthem X 29″er test sled.

Inside the air spring of this fork, resides a molded plastic ‘compensator’ that basically takes up space and regulates how progressive the air spring is. At Mike’s (Dunn) suggestion, we removed the compensator and added a small amount of suspension fluid (in this case, I used Fox Green 10wt). It was fairly simple to accomplish. Removing the air valve cap on the top of the left fork leg, (after bleeding all the air out of the fork), unscrew the cap from the top of the compensator. We found the best way we could remove the compensator was to take an appropriately sized wood screw and thread it down into the small hole in the top of the compensator, and grab the top of the screw with pliers and pull the compensator up and out. This only took a few minutes and the fork was back together and ready to go.

The compensator with the wood screw we used to 'grab' the little plastic devil and pull it out of the stanchion tube.

I ended up with about 95-100psi being about the right pressure for me (I weigh about 265lbs). My first ‘up and down the street’ to check out the ride had me pleased with the travel and air spring rate, yet still concerned about the rebound speed. I could have slowed the rebound on the rear shock to better match that of the fork in my first round with this fork, but didn’t want it packing up. A quick check of the rebound knob found it still had two clicks left and once I opened it all the way up, things got noticeably better and I was anxious to get it out on the trail.

On the trail, I was pleased to find the performance of the First Air was MUCH better than my previous experience. I have the sag set at a little over 30% (right where I typically prefer it) and I’m getting close to full travel. As for the rebound speed, I would still prefer to have it just a bit faster, and in a perfect world, my ideal setting would be somewhere close to the middle of the range of adjustment rather than all the way at the end of it. That said, it is acceptable as I have it set. I wasn’t getting the back end kicking up when boosting off the kickers on the local trails like I did the first time I tried this fork.

I’m not in love with the dropouts on this fork as it can still be a little clumsy to get the wheel into the fork and the axle inserted at the trailhead. It’s just not quite as easily accomplished as it is with the 15mm Fox or Marzocchi forks I have tried and could possibly be improved.

I said in my initial review of the First Air that I felt it had more potential than it had shown at that time, and I feel like we were able to realize a good amount of it by removing the compensator from the air spring. For me, it moved the First Air well into the decent/acceptable category for me. I would put the performance on the trail in roughly the same category as the Marzocchi 44 TST2. Considering the price point, if you’re willing to tinker with it and don’t need a rebound setting that is faster than average, I can now comfortably recommend it for budget minded trail riders.


Note: RST has sent these forks for test/review at no charge to Twenty Nine Inches. We are not being bribed nor paid for these reviews and we will strive to give you our honest thoughts and opinions throughout.