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For Science!….. (DNM Burner coil shock experiment)

3191 Views 1 Reply 1 Participant Last post by  weasel1
I run about 310lbs kitted up and ready to ride. My main steed has been my trusty 2012 Surly Ogre, which I've put through several iterations and is now in full trail mode (29" front, 27" rear, RS XC32 front fork, Level T brakes, 1x9). I ride almost exclusively on single track now that my kids are old enough to ride with me. This summer, I thought I'd give a full squish bike a try, and picked up a barely (and gently) used 2008 KHS XCT555 for VERY cheap locally. Everything was in great shape and it's been fun, but at my tonnage, I have to run the RS Monarch 2.1 at max PSI. It's harsh there, at best, and I'm still at 30+% sag. Plus, I've been worried about reliability running it at that pressure all the time.

Sure enough, given it's age, the Monarch gave up the ghost last week - the dreaded stuck down - and needs a full rebuild. The IFP and damper seals have failed, and SRAM doesn't have any rebuild kits. So, I've taken this as a sign that I should give a coil shock a try.

After fruitlessly searching a while for a suitable used 7.5x2 coiler that didn't cost more than I paid for the bike, I bit the bullet and ordered a DNM Burner RCP-2S coil shock in my size, $119 shipped on eBay from CyclingdealUSA, which is the US distributor for these. It came with a package of trim-to-fit bushings and spacers. The ID of the bushings, fortunately, matched my frame bolts, so I just had to cut and grind the supplied bushing and spacers to the right lengths. Here it is installed:

The supplied spring is 550lb. The FOX calculator says I would need a 7-900lb spring to stay in the 25-30% sag zone on the KHS. As these are hard to come by, I ordered an 800lb spring direct from FOX (the DNM is compatible with FOX springs). DNM makes a 750lb spring that they sell for $15, but they want $70 in shipping from Taiwan. Also, 800lb seemed a better fit.

I fitted up the shock last night and rode around a bit (had to bed in a new rear rotor, also). Without adding any preload, that 550lb spring had much less sag than I expected, and given how others have called it stiff, I wonder if it's actually a heavier rate spring than they claim. The shock is rebound and compression damping adjustable. I fiddled with both and they seemed to have the expected effect on shock feel. Everything works nicely and smoothly, and I'm curious how this will hold up.

We are embarking on a 3.5-week family trip with lots of trail riding planned. As we are bringing a bonus kiddo, the KHS will get ridden by someone else, so the stock spring will stay on for now. I'll report back after the trip as to how it's holding up, and then swap to the heavier spring and put some time on it to see how it handles a rider of more substance. We'll see if this is a viable budget Clyde option long term.

Onward….for science!!
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An update: during our trip, my daughter rode the KHS with the DNM and its stock spring. She’s about 135lbs, and a novice rider. We rode at Copper Harbor, MI, Jackson Hole (a bit of lift served riding) and Phil’s World in CO. Our riding ranged from gravel, to XC blue trails (Trust Loop in Phil’s), to blue flow trails at Jackson Hole. She felt confident and comfortable on the KHS, and was more aggressive than she’s been comfortable being in the past. She noted that the shock felt “smooth” and that she had more traction than she was used to from her hard tail (same tires on both - Nevegals). Hard to say what the shock contributed to her experience, but clearly it didn’t detract.

When we got back, I fitted a Fox 800lb spring to the DNM. This seems to be about right for my tonnage, based on my eyeballing of the approximate sag. I bumped up the compression damping, and slowed the rebound some, until it felt responsive but not bouncy. I get a tiny bit of pedal pogo, but very, very minor. I took the bike up to the Saxon Hill trails in Essex, VT, and rode some intermediate flow trails. I chose the slightly more technical (still blue) climbs, to see how it did with rocks and roots. The trails were a mix of sand, dirt, wet rock and damp roots.

First - the climb. I won’t mince words here : the bike climbed way better than it had with the Monarch shock at 275psi. WAY better. Traction was much improved, pedaling was more efficient and the front wheel was more controlled. With the Monarch, my assessment of the bike’s climbing prowess was roughly “it kinda sucks”. Now, it’s totally fine. Not enough worse than my hard tail to even really mention. Wow. It’s not a climbing machine (at 35lbs+ and circa 2008 AM geometry, that’s no surprise), but it really doesn’t suck at all. I’ll be totally fine with using this all mountain and down-ier XC. I’ve gone ahead and put my commuter street wheels on the hard tail for the fall, as I don’t see when I won’t be just fine grabbing the KHS for any trail duty. And I’m a lazy climber, so that should say something.

As for the down: yeah, same story. WAY better. More stable, more controlled over chunder, smooooooooothness for days, and great grip. Never felt close to bottoming out. I can’t wait to get this thing on some gravity runs that let me push my (pretty limited) skills. I have no idea if this shock will hold up, but for this high-tonnage intermediate Clyde, it’s a clear win so far. Oh, and total cost was under $150 with the 800lb spring sourced direct from Fox. I can’t find a used shock for that. For now, I’m quite happy.

Sent from my iPhone using Tapatalk
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