"Nothing stays as it was," is Schwalbe's tagline for the Procore dual-chamber system - their novel tire-within-a-tire anti-pinch-flat system that has created quite a stir among the DH and enduro community. What's the point of a dual-chamber system? For those who missed the introduction 18 months ago, Schwalbe's Procore system consists of a small-diameter tube and tire that is inserted inside of a conventional tubeless tire and pressurized to over 80psi. The insert acts as a secondary impact cushion that allows the user to ride with lower, or at least the optimal, tire pressures for a given course without being concerned with pinch flatting. The insert reportedly increases grip, reduces rolling resistance over rough terrain, protects the rim, and helps to prevent the tire from 'burping,' which is when the tire bead is pushed inboard of the edge of the rim and allows air to escape from a tubeless tire.
The success of Procore in professional competition has been questioned by the downhill community after some dramatic wheel failures were broadcast live to the world by Red Bull's World Cup videographers. Rumors quickly surfaced that the high-pressure inner chamber was causing carbon wheels to explode and that the Procore system was a nightmare to install and service.
• Intended use: More grip and less punctures
• Diameter: 26", 27.5" or 29"
• Minimum 23mm internal rim width
• Minimum 2.2" tire
• Weight: 440 grams (approx
• MSRP: $230 USD / €195 (parts available separately
• Contact: Schwalbe Procore
To help mute some of that cynicism, it should be pointed out that the exposed and highly visible blue-colored liners gave both the announcers and viewers much to talk about. Had Schwalbe opted to color Procore black, we suspect that the reactions to those few instances would have been on par with the significant number of non-Procore wheels that were destroyed at those same events. We put Procore to task to discover the truth behind the speculation.
Schwalbe's Procore kit (from top left) consists of a pair of tubes and inner tires, a roll of high-pressure rim tape, tubeless sealant, air sleeves, tire installation lubricant, dedicated tire levers, and decals to outfit two wheelsets.
Installation is fairly simple and in some ways, more so than with a standard tubeless system:
• First, the high-pressure rim tape is applied to the rims and then perforated at the valve hole.
• Next, a small clear patch is applied over the valve hole as an additional seal and also pierced using the valve stem.
• Mount one side of the blue Procore liner (basically, a small treadless tire) making sure that the silver stripe is lined up with the rim's valve hole.
• Then, slip the red AirGuide sleeve over the tube's valve stem and insert the tube into the Procore liner.
• Install the other bead of the liner just like any tire and it will fit loosely between the flanges of the rim, allowing room to mount up the tire.
• Finally, slather all of the beads with Schwalbe's Easy Fit lubricant and mount the tire over the Procore assembly as you would any other, (the Schwalbe tire levers, which clip on to the rim help hold everything in place). Add the tire sealant just before closing the final bead.
• Inflate the liner first between 60-80psi using the dual-position valve stem and it will automatically seat the tubeless tire’s beads with resounding "pops."
• Next, switch the dual-position valve stem to the "tire" position and inflate the tire to your race pressure (12 to 25 psi)..
• Screw the dual-position stem down to the locked position, close the Presta valve, and you are done.
High pressure rim tape is supplied to handle the 6-bar pressure (87psi) recommended for the Procore insert.
The first time I mounted the Schwalbe system, I watched the video
and everything went smoothly (except making the mistake of fitting the Procore bits to a wheel with the wrong free-hub driver). After remounting the system to a different wheel, I must have accidentally damaged the seal where the valve stem enters the rim. It took a while to realize where the air was escaping, but replacing the clear patch solved this (there are no spares included, so I used a normal glue-less inner tube patch in this instance
). A second time, I fitted a new tire without using the 'Easy Fit' fluid and had issues with the bead not seating correctly regardless of which chambers I inflated first. Lesson learned? "Follow the directions and you should have no issues."
So, how is it easier in some ways than a standard tubeless, you ask? Well, if you want to switch out a tire, just deflate both chambers and switch the tire. You can get pretty aggressive with tire levers if needs be, as there is no chance of damaging the tube when doing so. When you inflate the Procore, it locks the tire into place, so there is zero faff trying to get the tire seated and sealed.
The clear patch at the rim's valve hole is a security measure to ensure proper sealing. I successfully replaced mine with a glue-less patch;
The red AirGuide is key to allowing air to flow into the outer chamber, it must be lined-up with the silver line of the Procore liner.
Of course, the first thing I did when somebody told me that it would be virtually impossible to pinch-flat or burp a Procore protected tire, was to try to pinch-flat and burp it. The first test was to put 6bar/87psi into the Procore and 0.3bar/5psi in the outer chamber; pedal as fast as I could towards a 20cm tall curbstone, then sit down and hit it, full speed. I can report no punctures or dings to the rim, and not even the sound of a metal to concrete connection. Second, was to perform a few cutties and square off a few corners. (The previous curbstones worked out well as a berm.) I was pleasantly surprised by my parking lot trial. There was seemingly no way of getting the tire to lose any pressure. Even if you release all the pressure from the outer chamber and try to dislodge the bead with your hands - you can't, it's locked in there solid by the Procore liner. Later, on the trail, I never managed to puncture the tire during a normal ride.
Remember to screw the dual-position stem to the closed position before heading out as it will leak down eventually.
I confess to two flats that were directly related to my unwillingness to follow directions: I punctured the inner chamber once after snapping a spoke, which then pierced the rim tape and the tube, and resulted in complete air loss. In the Procore's defense, I did not use the supplied high-pressure rim tape which could have prevented that. Leaving the valve core unscrewed in the "tire" position after checking pressures will cause it to lose pressure. I did that more than once. I can attest that Schwalbe are correct in saying the minimum rim width is 23mm. I tried to fit the system to a Mavic Crossmax rim with a 19mm internal width, which was indeed nearly impossible and I managed to damage the Procore tube in the process. Lesson learned: "Follow the directions."
After seeing Procore liners wrapped around swingarms at World Cup DH races, rumors circulated that the pressure that the Procore liner exerted upon the rim could cause certain wheels to fail after a few hits. I asked Schwalbe's Michael Kull about that:
" In Lourdes, the wheel of Neko [Mulally] exploded where we saw Andrew's [Neethling] wheel exploding just a few minutes earlier, down to a gnarly rock in a gully. Taking the wrong line can still mean your whole wheel can fail. In Fort William, there was impact damage to Harry Heath's (Norco Factory Racing) rim, but it was missed, and it lasted through training. Once the team was at the start (for Harry’s finals run), they discovered that the tire had lost air and was leaking due to rim damage. They pumped it up again, but Harry was losing air on the track and hit a rock very hard just before the drop and another one after, so his rear wheel collapsed while having, basically a flat tire. We`re in close contact with Norco Factory Racing and their wheel sponsor. Since then, they have solved all issues. They have told us they would not race without Procore in the future."
Riding with Procore seemed to be a mix between, "this is the best MTB product ever!" and, "hmm, it seems OK." Generally, the benefits of running low pressure in the outer chamber were most noticeable as trails got rougher, more technical and slower. Super technical rock in Chamonix was incredible, the rolling speed and increased small bump compliance was huge. I felt invincible, pushing harder and faster, and gaining more and more confidence. Climbing with low pressures was also great - a massive improvement in traction, as it was when braking, especially in rough sections. You'll still need to run higher pressures for fast smooth, bike park riding. Running 13psi there left me with a feeling of instability and rolling tires. In the bike park, I started to wonder if I needed the Procore.
If you want to up reliability for racing or in general, the Procore could be for you. I don't understand why some Schwalbe supported racers haven't been using the system after suffering punctures during races. Talking to various teams, this is usually down to the weight disadvantage, but there's is nothing slower than getting a puncture. OK, it might not stop Aaron Gwin, but Josh Carlson was looking like a winner at the EWS in Whistler before he punctured at the top of the last stage. I was using the system at the French EWS and got a front cut in the tire near the beginning of the most downhill predominated stage, I lost all the pressure from the outer chamber, but the Procore kept the tire on and I managed to ride it out to the finish, somehow clocking my second fastest stage of the weekend.
And, the weight? Adding 200 grams to the outside of your wheel is going to make a big difference when it comes to accelerating, and for long days on the pedals. But, consider the benefits of greater gyroscopic stability and rollover through bumps. I generally prefer a heavier wheelset, as my riding is more biased towards downhills. Plus, the added rim protection and puncture resistance means I can get by using a lighter wheelset and tire casing. That said, I generally preferred the feel of the low-pressure tires with a heavier, slower-rebounding casing, as that combination molded better and more predictably to the terrain. I settled around 18psi for the front and 22psi for the rear tire to give a good compromise for most conditions, with 70psi in the Procore.
• Improved puncture resistance
• More grip, and better rolling speed over bumps
• Increased rim protection
• Increased rolling mass
• Another thing to worry about
|Procore's protection allows a rider to choose from a larger combination of tires and rims, and to optimize tire pressure for any track situation without regard for pinch flatting. If you want more reliability and grip and you don't mind the additional labor and expense, it's great. Pump them up for dry park laps one day and then find yourself riding low speed tech the next, at half your previous pressures while your mates are struggling for traction. - Paul Aston|