SR Suntour ships its SF9 Epicon RLD and Axon RLD forks with 100mm of travel, however, both can be adjusted to 80mm, 120mm, or 140mm if you need more or less travel. For this How-To, I’m using my 2009 Epicon RLD, but the Axon’s travel is adjusted the same way. The only difference between the two is how much torque you use when tightening the lower bolts during re-assembly, so pay attention to that part.
First, you’re going to need a few things:
– 5mm and 8mm Allen wrenches (or 8mm & 10mm for the Axon)
– large adjustable wrench
– rubber mallet or dead-blow hammer
– fork air pump
– in-lb torque wrench with 5mm and 8mm bits (or 8mm & 10mm for the Axon)
– various shop towels
– pin driver
– bench vise or something similar
** Don’t even bother with this if you don’t have all the above tools already at hand, unless you want to end up with a (partially) disassembled fork, broken parts, and a bike that can’t be ridden until you have it put back together again.
As I mentioned, my Epicon came with 100mm of travel. It raised the front end of my bike about 1.5" over my rigid fork, slowing cornering response. I ended up lowering it to 80mm, and I’ve been riding it like that for the past few months. After my little flight over the handlebars last week, though, I thought I’d raise it again, giving me less of a forward-leaning stance, and perhaps lessening my chances of that happening again. Besides, I’m close to giving this fork a full review, and I figured it’d be better to try it at different travel lengths to see how it performs overall.
Instead of going back to 100mm, I decided to go to 120mm, which is the most amount of fork travel I’ve ever had (as a long-time XC rider, I spent about a decade at 80mm, or on a rigid fork). My frame came stock with a 100mm fork, so going to 120mm adds some stress, but not so much that the frame can’t take it. However, I think 140mm would be pushing it a bit much, and I don’t want to take a chance with snapping my head tube.
Here’s the fork before I took it apart, still set at 80mm of travel.
First thing first, clean the fork as well as possible. I also took it off my bike to make the process easier, and I’d suggest the same for you. Cleaning it will keep dirt from finding its way into the fork lowers, which could result in scratched stanchions later. Make it shine before you even touch it with a wrench! Pay extra attention to the seals around the stanchions, since a lot of dirt and grime collects in that area. Removing dirt will also make it easier for you to inspect every part, because it anything is excessively worn, now would be the time to order some new parts.
Next, we need to remove the air, so take off the top cap on the left side of the crown, and use a ball-end Allen wrench (or whatever you have) to depress the valve.
With the air chamber empty, the stanchions will slide into the lowers.
Flip the fork upside-down, and pull out the rebound adjustment knob. You can use a pair of needle-nosed pliers, or just grab it with your fingers and pull. It’s pressure-fit, so it should just pop out.
If you look into where you just pulled the adjustment knob out of, you’ll see a recess for an 8mm Allen wrench. You’ll need to back this bolt out just a few turns, but not all the way.
Next, grab your 5mm Allen wrench, and back the bolt on the other leg out about the same amount. Remember, the 5mm bolt has a washer on it, so don’t lose it!
Now, using a rubber mallet or soft dead-blow hammer, tap lightly but firmly, on both of the bolts you just loosened.
Tapping the bolts forces the internal seals to break loose, so you can now slide the stanchions out of the lowers. Set them on a surface where they won’t get scratched.
Next, grab your large adjustable wrench and loosen the aluminum nut on the bottom of the left stanchion. I’m making a point to tell you it’s aluminum so you don’t destroy it with your steel wrench. It’s pretty tight, so keep yourself stable and make sure the wrench is adjusted as tight around it as possible. Rounding the edges off would pretty much entirely suck, so use some common sense here.
This is what it looks like with the aluminum nut removed:
Keep in mind, this thing is full of grease (fortunately, not the drippy kind), and it’ll pretty much get all over you, even if you’re careful about handling it. Don’t wipe any of it off, and you won’t need to add any when you re-assemble it later.
Take the damper assembly out of the stanchion and lay it somewhere it won’t get damaged.
Like I said, I have it on the 80mm setting. The next photo shows you your travel options. I know, it seems counter intuitive that the further you get from the wide end, the shorter the travel is, but I guarantee this is right.
Okay, now the shitty part begins… and you thought this was all going to be a walk in the park. You’ll have to improvise in whatever manner you can, but I place the damper assembly in a bench vise, surrounded by a rubbery, non-marking jacket that won’t damage it. I’ve always accomplished this one-handed, but if you have someone around who will hold it while you hammer away at it, it’ll be a huge help.
Using your pin driver and a hammer, gently tap the pin all the way out. It’s tiny, so it’ll probably fall into the depths of hell under your workbench if you’re not careful, so keep an eye on it. Tap straight down, and don’t let the damper rotate on you. Having someone hold it steady will really help a lot at this point. That damper rod is aluminum, so if you whack it with your steel hammer, there’s a good chance you’ll dent or crack it.
Here’s the pin that you’re trying to knock out. It’s a split design, which compresses when you tap it into the hole in the damper rod. I’m sure there’s a name for it, but I have no idea what it is. All I know is, it’s a bitch to get out.
With the pin out, you can slide the spring holder to whichever position you like (I chose 120mm).
Make sure you line the spring holder up perfectly with the hole. Otherwise, when you go to hammer the pin back in place, you might be off a little, and dent the (soft aluminum) damper rod with the (harder) steel pin. This time, feel free to skip the vise, and just place the assembly on some soft wood, like a workbench top. Using a normal hammer, gently tap the pin until it’s flush with the edge of the spring holder, and then finish hitting it in deeper using your pin driver.
When you’re all done, slide the spring assembly up to meet the holder, and it’s ready to go back inside the stanchion.
Thread the aluminum nut back in by hand (lightly grease the threads first), then use your adjustable wrench to tighten it down. SR Suntour doesn’t give a torque spec for this, so just snug it down tight, but don’t go overboard.
If you haven’t already, then now is a good time to clean those bushings/seals off as much as possible. When you have them entirely clean, apply some grease to the insides. I just used Park Polylube 1000, but SR Suntour has some stuff called ConPanna that they recommend. However, the Polylube will work fine if you don’t have access to any ConPanna.
Now, just gently slide the stanchions back into the lowers, being very careful to get the threads on the bottom of the stanchions lined up with the bolt holes on the bottom of the lowers. If you don’t have them lined up well, you risk cross-threading the bolts and destroying the aluminum threads. Tighten down by hand, or use the long end of an Allen wrench, being very careful to keep the threads lined up.
***SR Suntour recommends adding a tiny bit of air to the left stanchion, and then pulling both damping rods out to full extension before inserting them back into the lowers. I tried this the first time around, and it just made it more difficult for me to line things up. This time around, I didn’t bother, and the threads lined up perfectly on the first try. Go figure .
Once the bolts are hand tight (and I mean, just barely), you need to finish them off with a torque wrench.
Torque specs – Epicon:
5mm bolt – 88 lb/in (10Nm +/- 1Nm)
8mm bolt – 53 lb/in (6Nm +/- 1Nm)
Torque specs – Axon:
10mm bolt – 35 lb/in (4Nm +/- 1Nm)
8mm bolt – 53 lb/in (6Nm +/- 1Nm)
Now all that’s left is putting the rebound adjuster knob back in, then adding your preferred amount of air pressure.
As is typical with air-sprung forks, you’ll have to add air in increments, occasionally stopping to pull the crown away from the lowers. This will cause the air pressure to drop, so you’ll have to pump some more to get it back to where you want. After a little trial and error, you’ll have the fork fully extended, and the air pressure will stay where you want it. SR Suntour recommends a MAX 180psi no matter what your body weight.
All finished, with 40mm more travel than before!
Time to mount it back on your bike, attach the remote lock-out, and go for a test ride.
As you can see, it’s really not that big of a job. Sure, it’s not as easy to adjust as a Rock Shox fork with U-Turn, but it’s probably the silkiest fork you’re going to get for the price.
I’ve already had a long ride on the fork in the 120mm travel setting and absolutely loved it. I’m more impressed with this fork than ever before, so expect a review in the coming days/weeks.