Sunday, November 6, 2011

CX0 Tubless Update - Riverside State Park

Yesterday I had the good fortune of riding with about 15 riders through Riverside State Park trails between 9 Mile Dam and 7 Mile Bridge.  This was THE off-road test of which I was dreaming when I installed the Bontrager CX0 Cyclocross Tires on the Gary Fisher Superfly back in October.  The setup for the day was tubeless with about 40 psi front and rear on in the 700x38 tires.

This ride was a good test for several reasons:

  1. The course included a lot of climbing and descents with some varied trail surfaces and technical challenges.
  2. There were 14 other fat-tire mountain bikes available for comparative purposes
  3. It was a blast!

I WAS able to climb anything the fat-tire bikes could climb though technique became more important.  The narrower tires meant that I had to keep my fanny planted in the saddle to maintain traction on the steeper sections.  I missed being able to maintain traction while standing to generate more power to get to the top of a climb as I can with full-on 29" fat tires.  This also meant that I had to be more deliberate in line and gear selection well prior to the base of the climb.

I WAS able to descend with reasonable control on the steep loose stuff dropping in to the Deep Creek area.  Again, this involved being a bit more cerebral at the top of descent and maintaining control since I could not depend on a big footprint rolling beneath me to save my bacon if I had to come to a complete stop quickly.

No surprises with either of these scenarios based on my test runs across the HD Bluff Trails the last few weeks.  

The tires absolutely rocked on the hard pack sections and paved road compared to the fat tires.  I observed that I was rolling faster at a lower energy expenditure than my cohorts.   One place I found myself wanting for big-volume fatties was anytime we encountered exposed baby head rocks.  The low-volume tires did not yield and wrap themselves over the rocks like I took for granted with a 29x2.2 at 30 psi.  This meant again that I was forced into picking better lines, and using more body English any time I encountered these smooth beasts.  I also felt more of the bumps through the hard tail with this setup.

Where they did not rock is when we hit some very deep and loose sand at the end of the ride.  I became the only casualty of the day in the battle to remain vertical when I sunk in the deep sand and fell over with an unceremonious thud.  The following riders showed incredible compassion riding around me while hurling various insults.

In addition to sand, I expect the tires would be miserable and ineffective in deep, slick mud as you often get down in the sections close to the river.  

Bottom Line:  

The set-up performed well for 99% of the conditions encountered and are a great set-up if you like commuting or road riding on your 29er with some off-road or gravel road jaunts.  the climbing ability was acceptable and the bike was lighter and faster as a result of the cross tire installation.  

Because they are not hardened against glass, running tubeless with sealant is a must for the streets of Spokane.  Remember, these are not high mileage tires so you can expect to replace the rear somewhere around 500 - 600 miles of road riding (your mileage may vary).


  1. Are you planning to throw on some studded 700s for the winter? I'm watching for the first sign of black ice in the mornings, and that's my cue to mount up the studs. Might be soon...

  2. I try to get my front studded tire mounted right BEFORE I first see ice, then the back one a couple weeks later.
    - Ventura