Has anyone used the new Clement BOS? Looks like it could be a nice alternative to my beloved PDX. Any reviews?
I have a set that I’ll probably mount up on Wednesday. No ride experience yet.
I will say:
- I tend to run MXP tubeless on MTB wheels for training. The BOS will supplement that / be a set of training wheels for my “A” bike.
- I have PDX and MXP tubulars for racing
- PDX tends to be a little vague when slightly leaned over on loose-over hard conditions when compared to MXP
- PDX tends to have a touch less steep climbing traction when it’s loose / slick than MXP.
- PDX tends to shed sticky mud better than MXP, it also “penetrates” better into soft / wet ground.
- The new Tubeless casing has been great for. Airs up well, holds nicely, no burps.
I mounted the BOS immediately upon getting them (onto a wheel that had 142+ hubs {I cursed when I figured out why I couldn’t get it into the dropouts of my bike}). They mounted up pretty round in the tread. This may help them run a little faster, depending on pressure used.
They look like the grip is going to be great when they can penetrate the ground. I also think they will be a little less vague when partially leaned. I’d expect them to be best in loose over hard and very soft conditions where they can penetrate the ground / dig to a harder suface underneath.
PDX probably better in “moist”. Braking and climbing performance on BOS ought to be better than PDX. BOS will probably excel in “wet mud” vs. “Sticky mud”. Sand performance probably worse than PDX (will churn up more, larger side knobs to catch ruts).
Over all, I think they’ll be a great tire. Perhaps a bit slower rolling, but perhaps more confidence inspiring (which I often find out-weighs a rolling penalty).
Thanks for the rad analysis. I ordered a set, should get them this week, we’ll see if I have time to mount before racing this weekend or not. I’ve done the majority of my racing on PDXs for the past several years, but the BOS is looking like a good option.
As an aside, since you mentioned MTB wheels. I decided to experiment with racing on tubeless this year (always done tubular before). I got a nice set of 23mm internal width MTB wheels for racing. The tubeless PDXs measure a massive 37.2mm on them. I love it, the potential for a little extra width was the main driver of me trying tubeless this year. So far I’m really happy with it. I’m assuming that the BOSs are made on the same casing so I’m hoping they give extra width as well.
Rode them today.
Freshly mounted on a Stan Grail Rim, the casing was ~33mm. Knobs were closer to 36mm.
That means they’ll have pretty good leaned over corning, but will probably catch on sand ruts. (Also the tractor tread will cause them to dig-deep, not good in sand). So, I don’t think their Euro-style sand performance would be good, but for most US sand it’s probably not an issue.
Rolling resistance is higher than other offerings when riding pavement. I don’t think rolling resistance on dirt is too important.
What I think is more important is grip and confidence and I think the BOS has that in spades. They are less vague on loose-over hard than the PDX (but not as solid as the MXP).
The tire also seemed pretty round for being on a wider rim (ie it was tall in the center knobs and sloped off to the shoulders). Perhaps this will change as they stretch. Currently, IMO that shape is good for lower pressures and bumpy ground. However, it means there is a little less immediacy of side-knob bite.
I think the BOS is going to be a great all-around tire for locations that see moisture. In Colorado, I would still go with the MXP as a daily tire. Because I tend to race around the country, I have PDX tubulars that I’ll be taking to Seattle and Louisville because they’ll cover a good range of conditions.
I could see a BOS rear with a PDX front. I think the BOS will have great climbing traction and I’m good with small channels between center and side-knobs on rear tires in general and CX rear tires especially. (Here’s a mountain bike write up, I think that sideknob channels are more important in MTB because the bike is leaned over more. Often on a CX bike you’re kinda leaned over but often in the washy-area of a the sideknob channel http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/Knobby_choices_for_those_in_the_West_P6073592/?search_string=ardent%20race#p6073592).
Casing seems stout. They mounted on the Grails with a few easy pumps of the floor pump.
All in all, a worthwhile offering.
Thanks for the review. I got mine this week but have not ridden them. They certainly are aggressive, looking forward to trying them. I didn’t have a lot of luck mounting, though. Put one on my race wheel (Nox Skyline) and it just wouldn’t seat. Not even close, I tried every trick I know. Gave up and took it to the shop, they couldn’t do it either. Frustrating to say the least. I think that’s the fault of the rim, though, I also had shenanigans when putting the PDXs on a month ago (but this was much more). So I mounted the BOS to my B wheels (iron cross) and they went on perfectly with a floor pump. So strange. I put the PDX back on the race wheels. It’s been quite wet here (Seattle), so I’ll be racing those this weekend.
BOS looks like it won’t be sitting quite as wide as the pdx does, which is too bad. I agree, don’t really care much about rolling resistance on the cross bike, when you’re going 6mph through the mud that’s not usually the first thing on my mind.
Are you coming to the PNW to race this season?
Cheers,
-Colin
I’m coming into town for work in a couple weeks. Planning on doing Woodland park while I’m in town.
I’ll be the random guy in the Boulder Cycle Sport kit 
Raced them today. They were on my B-bike which I had to take halfway through.
Very dry and dusty course (all our races have been 75+ degrees and sunny… and windy! this year).
Rolling resistance not noticed.
Cornering was good. Slightly more drifty than my MXPs, but completely controllable. I did have a few extra PSI in them (maybe 27/29 @ 168lbs) (MXPs were 25/27psi).
I still think this is a tire that will be great on softer ground that it can penetrate, but it was solid on our dusty course today.
Sorry you had to switch to the B bike. We had perfect conditions, 60 degrees and sunny after a week of rain. Perfect mud for racing, great weather for spectators. Tomorrow looks the same.
This was one of my favorite courses, it had everything today. Deep loose gravel, wet mud, thick heavy muddy grass, peanut butter mud. The PDXs were good, although now that I’ve seen the BOS, I keep thinking the knob on the PDXs are tiny.
Afterwards I did half a lap on my B bike to try out the BOS. They felt really good in the gravel. Loose over hard is a weakness of mine, so I liked that. There was a steep grassy climb that was getting more torn up and less rideable as the day wore on, the BOSs handled it perfectly. However, it was not good in the peanut butter. The tires got packed up in a BIG way. Not great. There were enough puddles on this course that they probably would have been washed clean, but still not great.
You picked a good time for your trip, Woodland is the biggest bike party in the state, and a classic course. It will also be pretty mixed, some gravel, some grass but nothing deep, some dirt. The course is on the side of a hill, so it drains pretty well.
One more update on the BOS in case anyone comes searching for this in the future.
Raced at Woodland Park in Seattle this weekend. Quite a bit different from our Colorado Races! It rained off and on throughout the day. Mud was slick, but not not sticky.
I was on the fence about bringing Tubulars on a trip for work where I needed clinchers as well. Decided just to stick with one wheelset and only brought the BOS’s. I Ran them at 24.5f/ 25.5r PSI (I weight 170lbs).
I wasn’t sure what to expect and ended up lining up behind CCF. After a horrendously slow first lap moving up through the field (Lost 1 minute to the eventual leader), I was able to put the BOS through their paces.
First: “Go Traction” and “Stop Traction” are top-notch. The tractor tread really does it’s job and I felt like I was able to accelerate out of slow slick corners as hard I wanted to. I was also able to approach corners pretty fast and dump a lot of speed, which was perfect as this course had a lot of high-speed sections into slick corners.
IMO the best technique on slick courses is “Always keep pedaling”. Putting power down to the rear wheel will pull you out of dire situations. The great drive traction really helped keep everything moving in the right direction. I think they’re better than PDX and Supermuds in this regard.
Second: Turning traction was really really good. Sure, Rhino’s or Supermuds at 23 psi might have held a little better but if you don’t have extra tubular wheels or race in the mud constantly, I don’t think the difference is worth it. The course was fairly smooth; if the off-cambers had been bumpy / rough there may have been more of a case for the tubulars.
Over-all, I think the BOS is a great tire. As a clincher it is so close to tubulars in performance that in Sunny Colorado I’ll probably keep one set of tubular mud wheels and one set of these BOS clinchers.
I’ve been running the BOS as part of a tubeless setup on a bike I’m writing a review for, been on them for a couple of months.
They’re very, very good in very deep mud, and I think the tubular version would likely be my first choice tire for conditions like that.
Frankly, that’s just about all they’d be my choice in.
When you get these things up on edge in any conditions, they’re problematic. Don’t hold an edge as well as a Rhino style tread, aren’t as predictable as a Grifo style.
Granted, I’ve only been able to get the tubeless version of the tire to hold air/not burp down to about 22psi, and that’s pushing it; typically run more like 24 psi, and there’s a good chance that the BOS might edge better with lower pressure, but (shrugs.) For eg, I was doing warm up laps on the Seattle area race mentioned above on this tire, and then switched to a Rhino rear/PDX front setup. With 16 psi in the latter tires, the cornering traction wasn’t even in the same galaxy as the BOS at 22. I’m actually pretty sure that at 22 the Rhino setup still had a pretty significant edge - that’s the pressure I started course preview with - but I was letting air out before I had a chance to really form an opinion.
I’ve a/b-ed these a lot with Rhino/PDX tires and they’re not nearly as versatile. You can be confident that you won’t lose too much time on the courses that favor a Grifo style tread if you’re stuck running Rhinos, but if you’re lugging a set of these around, you’re going to feel it. There’s a lot of rubber there.
In short? This is a specialist tire for deep, tractor pull style mud. There are better choices for other conditions, and more versatile choices if you need something for varied conditions.
Nice job at Woodland Park, Robert! Local Cat 3 class is fast, and that was a big field. Strong podium performance.
M
Nothing to add except that woodland park cross races are awesome. Decaying bigleaf maple leaves make for such a mess let alone all the mud!
What work function were you up there for? Dont worry, you didn’t miss anything here. It was just 70 and sunny (again).