The Air Tool Big Bore is Specialized's mini pump for those who ride high-volume mountain bike and – primarily – fat bike tyres. It delivers 90cc of air with every stroke and is designed to work well even in gloved hands, but the head is faffy and it's hard work to use.
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This stout mini pump has an aluminium inverted barrel, a plastic collar around the end of the main barrel and a plastic head. The course aluminium feels pretty solid and offers decent grip, plus it’s great to see a retractable hose. When you’re really charging on the pump, you know your valve is safe from any over-exaggerated movement.
Specialized has actually designed the pump for winter, so rather than digging at the usual awkward-to-pull lever in your gloves, all you have to do is push the head on. It locks itself onto the valve with an almost clawlike interface, and to remove it, you just push on the opposite end.
It's clever, but I found it quite tough to get it locked and unlocked. The mechanism is stiff, and needs a lot of force. It helps to use two hands to almost pull the head into the unlocked position rather than push the other end in... a syringe kind of grip would help a lot here.
As it is, the head is very exposed, and if dirt finds its way into the mechanism it could stop it from closing.
The hose, while a great addition, is difficult to pull out. This could be seen as a good thing as it’s nice and secure within the pump, but it's a pain to use. There’s not enough sticking out to easily grip, and my fingers constantly slipped off with the hose still buried inside the pump.
Specialized says the Air Tool Big Bore delivers 90cc per stroke, and while there's no gauge to judge that by, it really does put a lot of volume out and gets large tyres inflated to a decent pressure quickly.
The compact size doesn't help once you're actually pumping away. The stroke really stiffens near the end, so I found myself using my palm to push the pump from its end, which bruised my hand after a prolonged effort.
If you primarily ride fat bikes this pump is absolutely one to consider thanks to how hard it huffs, but for this money there are other options: no, they may not inflate tyres quite as quickly, but they’re a lot more pleasant to use.