Upgrade your Trek Marlin to a Suntour Raidon front fork!

Here's the TL;DR for this post: I bought a 2019 Trek Marlin 5 and realized the fork sucks.  I used Suntour's upgrade program to buy a new Radion XC-LO-R fork for $200 and I'm thrilled with it.

I recently got into mountain biking after being out of the bike scene since about 2004, when I was a full-time bike mechanic for a few years.  I haven't ridden at all in about 15 years, and even back then I ended up selling my Cannondale F600 because there weren't any good trails to ride around here (Springfield, MO) and the road biking was so good.  A few years back I bought my son his first good bike, a 2015 Trek Marlin 5.  This last year we visited the Crystal Bridges Museum of American Art in Bentonville, Arkansas, and as we walked from downtown to the museum we saw the All-American mountain bike trail, and were blown away.  Have you seen it?  Insane.  It turns out Bentonville is packed with amazing trails, and more importantly it turns out that there's a really nice new mountain bike park near my town, the Two Rivers Bike Park.  I dug out an ancient Trek 800 with solid forks and cantilever brakes from the '90s my neighbor had given me and we went riding the next day.

It was pretty awesome, but my arms were so badly vibrated that I couldn't feel them for an hour afterward.  Still, I was worried that I wouldn't be into mountain biking enough that I would do it long-term, so I mostly rode that bike with my son for about a month, before breaking down and buying my own Trek Marlin 5.  I had ridden his on the beginner and intermediate downhill trails, and it was so sweet.  I could ride so much faster, more comfortably, and with better control on his, even though it was a bit too small.  When I took mine out on the trails it was a great improvement over the old Trek 800, but I was distinctly disappointed in its performance compared to my son's bike.

Mostly my experience consisted of my front shock (a Suntour XCE 28, which comes stock on the 2019 Marlin 5) klunking loudly as it topped out (which is like, always), and bouncing around like a pogo stick.  The ride was not plush in any way.  There is absolutely no dampening, and of course no rebound adjustment.  I was kicking myself because I hadn't even test-ridden the bike, as I assumed it would be like my son's.  His front forks were nothing to write home about (Suntour M3030, described on the Suntour website as a "metropolitan" fork), but at least they didn't make machine-gun klunking noises like mine did when riding over rough terrain.

I decided I would upgrade, but dang!  Good shocks easily cost more than my whole bike.  Good shocks seemed to require a tapered head tube, which I didn't have, or even know what that meant. Disappointment.  Despair.  I desperately considered adding some kind of dampening myself.  Then on a forum somebody mentioned the Suntour Upgrade Program.  You can upgrade your Suntour forks to a nicer fork, and on the forums it was told that Suntour offers an actually decent air-spring fork with adjustable rebound and a lockout with a 1-1/8" non-tapered steerer tube.  The Raidon!  I had to prove that I was the original purchaser of the crap fork, but my bike shop printed me a new receipt for that, and for $199.95 and free shipping I was the new owner of a non-crap fork.

When it came in the mail I cut it off at the same length as my old one, transferred over the lower bearing race, and installed it.   I turns out you can buy a fork pump to adjust the fork air pressure more easily than what I did, which was to over-inflate the fork and bleed off pressure until it feels good, but whateves.

Before I installed it, I noted how heavy the XCE 28 felt in comparison to the Raidon, so I pulled out the postal scale and weighed them.

6 pounds and 3.4 ounces!  Obscene!

Now for the Raidon:

That's more like it!  4 pounds and 6.6 ounces, a nearly two pound weight savings!  Sweet!

The whole point of this post is that I took it riding today, and it is like having a whole new bike.  I absolutely can not recommend this upgrade enough.  I was easily faster, jumped higher, landed softer, and had more control and comfort than ever.  I could be wrong, but as far as I can tell, the lowest end bike Trek sells with an actual air fork is the X-Caliber 8, for $1,200.  I feel like this makes the Marlin 5 at $540 plus $200 fork upgrade a really good deal.  I realize the X-Caliber has a lot else going for it, but still.

When I was a bike mechanic I got to talk to a lot of customers, and I would always focus on how much fun a bike/part/upgrade was.  Most of us are buying fun at the bike shop.  Can you ride a Wal-Mart bike on the trails?  Yep. Will it be a fun enough experience to make you want to go back the next day?  That's a lot less likely.  This fork easily passes my fun test.

While we're talking about the Trek Marlin 5, I want to offer a few of my other, non-fork related thoughts on the subject.  Firstly I wish I hadn't bought a bike with a freewheel cassette.  Most modern bikes have the ratcheting mechanism in the rear hub, not in the gear cluster like the Marlin 5 has.  I could have upgraded to the Marlin 6 to get the freehub, which has unlimited upgrade potential as far as rear gearing and derailleurs go, but I didn't pay enough attention at the time.  The thread-on freewheel gear cluster has no upgrade potential, and now I'm stuck with 7 gears in the rear until I upgrade my whole rear wheel.  Secondly, the rear Tourney derailleur is awful.  The main problem is that the spring in it is weak, the body of it is heavy, and so it klunks against the gear cluster when I hit bumps.  It's almost as annoying as the topping out of the crappy old forks.  Additionally, it often changes gears on its own when I come down from a drop or jump.  I upgraded to an Alivio rear derailleur, which is two or three steps up from a Tourney, and for just $36 that tells you how cheap the Tourney must have been.  The klunking and mis-shifting is gone.  It's a noticeable improvement.  Thirdly, I'm pretty happy with the wheels, especially for how cheap the bike was, but I really wanted to convert it to tubeless, which I did with the stock wheels and tires.  You can see the process here.  After that, I upgraded the tires to Maxxis 2.20 DHF and DHR tires, and they fit.   Fourthly, the brakes on the Trek Marlin 5 are awesome.  My son's 2015 Marlin 5 has disk brakes too, but they are cable-controlled mechanical jobs.  Mine are hydraulic and the difference is huge.  Back when I was a mechanic in the early 2000's I remember the early adopters of hydraulic disk brakes always bleeding them and endlessly tinkering, so I was hesitant, but apparently times have changed.  These aren't even near top of the line brakes, but I love them.  Fifthly, I'm seriously considering converting to a 1x10 drive system.  I would need a new rear wheel with a freehub, a new 10 speed cassette, a 10 speed shifter, a 10 speed chain, a narrow-wide front chainring, a crankset that would fit a new chainring (current crankset has riveted chainrings), and a bottom bracket that would fit a modern crankset.  That sounds like a lot, but I'm pretty sure it could be done for about $350.  I guess at that point I really am into the X-Caliber 8 price range, but as a former bike mechanic it's pretty appealing.  Edit 3/21/19: I've pretty much given up on converting to a 1x system on this bike, but rather I'm saving up for a different bike.  I'm currently deciding between a Roscoe 8, a Stache 7, or a Fuel EX 8.  Sixthly:  A good upgrade for the front derailleur is the Shimano FD-M313, which is no longer made, but are still available.  Don't get a low mount front derailleur, as they will interfere with larger tire choices, but rather the M313, which is a high mount and doesn't take up so much space behind the seat tube.  It's cheap and solved most of my chain suck issues.