IRC Boken Gravel Tire Reviewed | SoCal Cyclist
When it comes to gravel riding, tire choice and tire pressure is a downright passion. There are number of different and growing choices when it comes to tires and the people at IRC have made a huge investement in the gravel cycling. IRC is based out of Japan and most of their tires are equipped on scooters and motorcycles. IRC is a brand that has a long history with tire and rubber compounds so looking into the gravel scene, they have resources to make a tire that works.
The Boken tire tested is a prototype and is currently not available for consumer use. The one's that will be available for use will have a reinforced sidewall with "X guard" technology that will help with punctures especially in some of the SoCal conditions. The IRC Boken's as of now come in 36 and 40mm width's and have been a popular choice in SoCal's biggest gravel event the Belgian Waffle Ride. The reason being is that the tire is a minimalist design both in tread and weight but offers the most amount of grip when it really counts. The file tread diamond pattern with knobs on the side is perfect for conditions ranging from loose sand to rocks as well as actual gravel.
The only conditions that were not tested was mud. I was tempted to hose down the backyard and ride around but my wife was not going to have me wreck her succulents for the sake of tire testing. These tires, run as a tubeless setup were lucky enough to be tested on two sets of wheels. The first set offered a wider internal rim width at 20mm while the second wheel set (Spinergy Z lite) have a narrower internal rim width at 17mm. That caused the tire when pumped to about 40-45psi to be a more rounded shape. When it comes to cornering, the tires held but in terms of the tire pressure, the lowest used was about 38psi. Some people swear by going lower and get those rim "burps" when really pushing the tire to it's limit.
The IRC Boken's really work. They were tested in a variety of loose conditions and held up every time.
As a self proclaimed roadie who raced mountain bikes for only four years, I'm not as technically good as some of my gravel groadie counterparts. I have a habit of standing rather than sitting in sections that I shouldn't be. There were a few times I felt the rear tire slip under me but it's safe to say that would have happened with the beefiest of treads underneath me. The Boken's kept me humble and honest and made me ride dirt the way it was meant to be. With as much grip and contact to the ground as possible.
The 36's were perfect for the conditions I was riding in. There was no need for anything wider unless I was looking for a more plush ride. For the mix of different types of terrains, it was a great all around width. More of a bike problem than a tire problem also is that the Cannondale SuperX I was on is asymmetric and the Spinergy was not dished so if there were excess mud or a wider tire, there might be a clearance issue. Thankfully the tires were only covered in light dust and there were no issues in clearance. When Cyclocross comes, that might be more of an issue.
Luckily there hasn't been a flat yet. These particular set of tires are light and there might be issues with the sidewall and some stray rocks. The tubeless set up was a breeze, using some Stan's No tubes sealant and a floor pump. Interestingly with the new set of Spinergy's used the tires tend to lose air a little faster compared with the old WTB KOM wheels being used. In terms of longevity, these have about 200 miles on them and the tread pattern is holding up great. The side knobs have plenty of life in them and the center pattern on the rear is nowhere near smooth to the touch. I imagine I'll stick with my method of taking a new tire to the front and moving the front tire to the rear and then recycling the worn out rear tire. Rotating them the traditional way may mess up some of the handling characteristics.
For faster racing conditions or conditions where there is a healthy amount of pavement I would go narrower with a 32mm tire. IRC also makes a version called the Serac that is just like the Boken but with no side knob pattern. That is more geared for cyclocross or smoother sections. In terms of tire pressure it's relative. Depending on your weight, the width of the tire and your confidence in your ability you can have a wide pressure range. My mechanic said not to go over 50psi on a tubeless ever. Some guys are swear by going under 30psi. I hover in between 35-40psi. It's actually interesting to note that on longer rides, the tires loses pressure over the course of a single 5 hour ride like a very delicate tubular tire.
In fact when riding next to the bike, people have often mistaken the rear tire for looking or going flat. There is still plenty of air in it and so far have never experienced the rim bottoming out. Once the consumer edition comes out, what the tire will no doubt gain in weight will also gain in durability and the ability to hold air for longer periods of time. The IRC Boken's are the best all around tire for almost year round riding and can be used as a bit of a multitool for training and racing applications.
Product Tested: IRC Boken Tubeless 36mm 390 Grams
• Incredible handling and grip
• Versatile in wide conditions
• Light and still puncture resistant.
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• Use in wetter conditions
• Tire pressure must be monitored closely