Thursday, June 19, 2014

29er tires: Mavic CrossRoc Roam 2.20

My Santa Cruz Tallboy Carbon came with the Maxxis CrossMark LUST tire, which is arguably one of the worst options for any kind of XC riding except on buff hardpack. My first clue came just a week after getting my new bike, when a random rider at Kingdom Trails derided their charms. Now, having ridden the damned things for a year, I agree that the side knobs are lame and vague when cornering, and the mainly continuous centre ridge, despite offering low rolling resistance and decent tracking under ideal (hardpack) trail conditions, is slippery as hell on anything damp and pretty much useless in mud. Rocky descents and tight rooty single track are doable but not confidence-inspiring. 

Then my rear tire got a gash and couldn’t be patched, so it was just the excuse I needed to try something new. Strong contenders were the Maxxis Ardent, Aspen, and Ikon, and the Kenda Slant 6. In fact the Slant 6 was my first choice until I saw just how minimal the tread is. Probably fine on slickrock, but not for my trails. Then the guys at Phat Moose pointed me to the all-new Mavic CrossRoc Roam

Here’s a tire that’s UST compatible, has a relatively low centre tread for speed, yet large side knobs for more cornering grip. It has a beefier appearance than a pure race-light XC tire, but isn't as ponderous as something like the Kenda Nevegal (which I used to ride and loved on my 26er). Although I didn't measure it, the 2.2 appears to be a full 2.2” wide (noticeably wider than my CrossMark 2.1) and features the most durable of three rubber compounds that Mavic offers. That should stand up to the many sharp-edged rocks in our neighbourhood. And at 780 grams and 66 tpi they are 55 grams lighter and likely stiffer than the CrossMark LUST (835g/120 tpi). Not bad for around $75 a hoop.

Found a sealant gremlin while changing out my old tires:


Rode them for the first time today. Trail mostly hardpack, some rocks and a little bit of mud that had dried into a wonderful play dough consistency. Couldn't really crank it because of a leg injury, but the tires felt good. Fast and quiet on pavement and packed dirt, and the wider footprint and side knobs gave way better control through the mud sections. Cornering felt more predictable without the sensation of a rolling drift that the CrossMarks gave. Decent traction on rocky ledges. The stronger side knobs gave more support when hitting obstacles on edge, as sometimes happens.

Both the front and rear tires had gone flat after sitting for two days since I mounted them, which I  expected because the sealant hadn't had a chance to slosh into the bead area. Pumped them up to 28 front/30 rear to allow for some leakage on my first ride. This is harder than I normally ride tubeless so they did bounce around a bit, but not as much as I expected. Didn't lose any air though. Must've gotten enough sealant into the bead to finally seal them up.

Overall I'm pretty happy with these tires and am looking forward to a longer test ride at full speed and power, probably a few pounds lower to reduce bounce.

Update 2 (Aug 1, 2014)

Have run them through soft mud, hardback, loose gravel. Recommended pressure stamped on tire is 29 psi, but I find they're too bouncy at that pressure and work better a little softer (maybe 25 psi - still experimenting). Good grip and control in the front, not sure they make the best back tire. In the rear, straight line grip is excellent, but when cornering, I find the back end will suddenly hop out a bit at a certain lean angle, probably on the transition to the edge knobs. Then the back end becomes a little vague. This could be my mediocre riding style (I'm not super technical, but can usually make up with speed and power what I lack in finesse).

Update 3 (Oct 5, 2014)

I've found that 25 pounds of air in rear with 24 lbs in front, with 180/80 lbs of air in rear shock/fork is the magic formula for my Tallboy to come alive. However, I've come to the conclusion that while the CrossRoc makes a decent front tire, it doesn't perform well on the rear. The side knobs tend to let you ride partially up an obstacle like an off-angle root, only to then to deform and pop off, throwing you sideways when you least expect it. A shorter knob would skip off earlier and not lead to that kind of surprise. This is mainly an issue in the kind of wet, rocky, rooty stuff I ride in the Ottawa area. Both tires work much better in the sandy/grippy dirt of Kingdom Trails in Vermont. Rode with some other guys today who find the Maxxis Ardent is the special sauce for our local trails, so I'm planning to give one of those a try on the rear. They have shorter side knobs and should therefore be more predictable.

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