We are in the middle of Plus tire madness in this grand thing we call mountain biking. And along with this is comes a need to run very low tire pressures at very accurate levels. Where in the old days, we would have just pushed on the tire with our thumb and called it “good enough”, because 30psi more or less a few psi was just fine. But tire pressure levels have been dropping over time as tires got larger and we began using them without tubes. Wider rims exacerbated that to where 21psi would be what I would run on a 29er 2.3 tire running tubeless. Get that too far wrong and you might begin to feel some difference on the trail.
But really fat tires take that need for accuracy to the nth degree. On a Fat Bike you need to know the difference between 4.5 and 5 psi. Between 5 and 6 psi the tire feels like a completely different animal. Plus is almost as picky where 1 psi is significant and 1/2 psi is nuanced, but noticeable. It’s a whole new ball game.
And most bike pumps fail miserably at these low pressures, mostly because the gauge faces are not intended to be that ‘finely’ marked. You typically see 2 to 5 psi jumps from the zero mark to the top of the gauge’s limit which might be 150psi. It is just not possible to see the difference by the gauge between 15 and 16 psi as things are just too compressed…not enough real estate on the gauge face.
What I have come to use is a wonderful little deal called an Airchecker made by SKS. It allows me to know with a pretty high degree of accuracy, say to 1/2 psi, just what I have in there. So when I saw the Blackburn Chamber HV floor pump, retailing for $79.99 MSRP, with that huuuuge gauge and big, high volume barrel, I was elated! It tops out at 50 psi and begins at 5 psi with ONE PSI jumps per increment! OH JOY! Could this be the ultimate Plus bike (and Fat Bike) floor pump! Read on.
Unboxing the Blackburn Chamber HV floor pump revealed a very ‘metal’ built pump. It looks rugged and very cool, what with the knurled aluminum handle, big camo painted barrel, and huge orange gauge face. Oh yeah….the handle is attached with what looks like a 4 bolt stem clamp and there is a built in bottle opener too. For pure looks, this is the most bad ass pump I have ever seen. It is what the Terminator would use to inflate his Humvee once the inflate system fails. In the Apocalypse, this is the pump to have.
For pure function though, it falls way short of ‘bad ass’.
Why is that? Three words. Accuracy. Accuracy. Accuracy. That big old orange gauge that I had so much hope for is a liar, or is at least very optimistic. I began by adding what the gauge showed as 17psi into the tire of the Specialized 6 Fattie 27Plus. The tire felt a bit firm to the touch and using the Airchecker device showed 21psi! Oh dear. Back and forth a few times to see if I messed up….nope. Pretty much 4 psi off to the low side, at least at this low pressure. Would it be better at the typically higher pressures of a normal 29er?
In order to find out, and to see how well the HV (as in High Volume) pushed air into a tire, I took a few pumps I had around the garage and compared the number of strokes it took to get a 2.35 29er tire to 30 psi and then I used the Airchecker guage as the calibrated ‘last word’. Yes, I know that I have no real reason to believe it is perfectly accurate, but I am going with it as my ‘yardstick’.
Blackburn Chamber HV – 19 full strokes to an indicated 30psi. Airchecker read 31.
Topeak Joe Blow Ace – In the highest volume setting of the selectable twin chamber pump, 21 full strokes to 30psi. Airchecker read 23.5.
Lezyne Steel Floor Drive – 21 full strokes to 30psi. Airchecker read 28 (although the nature of the stupid thread on-off ‘chuck’ made that into a frantic move to not lose air pressure).
SKS Airminius – 42 full strokes to 30psi (it’s a high pressure road pump). Airchecker read 30 exactly. Kudos to German accuracy.
So when we look at that, the Blackburn Chamber HV is not so bad when compared to the others and was only 1 pound off at 30psi. Inconsequential, really. But grabbing it and taking over to the Fatbike with a fully deflated 3.8 tire, it took 20 full strokes to get to an indicated 5psi, but just by grabbing the tire, there was no way that was 5psi. The Airchecker said 10psi. Five pounds off at 5 psi indicated and about 4 pounds off at an indicated 16psi. What I have been doing is adding air to the Plus bike till it reads 12 to 12.5 and then going with that to get to 16-ish but I still like to check it with that nifty digital SKS gauge of German truth and justice.
Its tough looking and feels rugged as well. The flip-chuck is smooth but takes a good amount of force to seat it onto the presta valve. Once there, it does not leak air and releases easily. The bleed button is so slow to let out air that it is kind of silly.
The big alu knurled handle is most excellent, allowing you to really bear down on the downstroke and that is a good thing as that big barrel means lots of air per stroke and that means a higher than normal amount of effort to get the pump through the downstroke. Like a lot more. Enough to where my wife could not really do it without using body weight, actually to the point where it was over the top hard to do.
Another thing about that big barrel and lots of air per stroke: I had assumed that would be the holy grail for big, fat tires and it sort of is, seeing as how it got that 3.8 Fat Bike tire up to 5psi in what I would assume was 10 strokes (cutting the 20 strokes to get to 10psi in half). But what also happens is you get so much air per stroke that it is hard to creep up to a 1/2 psi change, meaning you will almost certainly overfill, then bleed down. Ok. I can handle that.
But the inaccuracy at the lower pressures is a buzz kill and I have to wonder if anyone checked it for that range before the Go Button was pressed for production? I have read two other reviews of this pump and both of them mentioned the same issue.
Bummer. Fix that and it would be truly good. Is it time for digital gauges on bike floor pumps? Would that be more accurate? That can’t be all that costly and likely is cheaper in materials than that big gauge. Maybe an iPhone app. Dunno.
Final thought: Your pump should not lie to you.
Note: The products shown here were provided at no cost to Twenty Nine Inches for test and review. We are not being paid, nor bribed for these reviews and we will strive to give our honest thoughts and opinions throughout.