Crankbrothers Gem Hand Pump

This little pump has some great features, especially the ability to change from high pressure to high volume for larger mtb tires.The mistake I made was strapping it to my bicycle frame. While mounted to the top tube, this pump occasionally came into contact with my knees. I finally decided to move it to the down tube, but discovered that water and sand had worked its way into the piston after a couple of light creek crossings. My pump was ruined and had to be returned. Also, be careful not to let it come into contact with the frame, as vibrations can scratch the paint.I would recommend this pump for people who plan to store it in a hydration or hip pack and away from the elements. I did keep the exchanged item, as mounting it on the frame wasn't a deal breaker.

The pump is compact and has two settings for high and low volume. Perfect for a small backpack or hip pack and anything crankbrothers is of quality.

I use this pump when mountain biking. It works just okay in a pinch, but I always prefer to use my full size pump. If I get a flat, I'll try the Co2 pump next time.

I had a lot of difficulty with this product at first. The instructions where not very clear as to how you where supposed to change the head to fit a presta value. This was made doubly confusing by the fact that you had to rip through the instructions in order to get the product out.Beyond this issue though, this is a great tool that is perfect for throwing in a biking bag so you can touch up where needed. If you get this product I recommend sitting down for several minutes and figuring out how to switch the heads back and forth before you try and use this.

Would like to have a dust plug on the valve.

This product is very good for the value, but it does not fit well onto the valve stems. Both Schrader and Presta valves fit very tightly into their respective configurations. I have to push the pump head petty harshly to get the stem far enough into the pump to actually work. This isn't terrible for Schrader valve stems, but I am afraid I will damage the Presta stems. However, when the pump is fully on, it works very well and with ease.I am sure with repeated use, the rubber opening will wear down enough to make this easier, but this is an emergency pump on my bike and won't be getting use (hopefully) very often.

This pump works way better than you'd expect such a tiny thing to work. Very little effort to pump a tire up to 40 PSI. While there is no gauge, there is a distinct change in the pump sound when you hit ~40PSI, so you have some indication of when you'd need to swap to the high pressure mode. As I keep my tires around 40, I don't really need the high pressure mode, but it surely works.Read the instructions. I found it a little confusing to switch from the default Schrader mode to the Presta mode, and ended up lodging a piece in backwards. Watched a video right after and fixed it. Don't be me :)My main complaint is with the mounting bracket -- it's sturdy, but I simply wish the mount had the pump flush with the tube, rather than sticking out to one side. I have enough clearance on my Grizl to have the pump hanging off to the side, thankfully, but your bike may not be as friendly to that. I won't take off points for it, since it worked out for me, but do keep this in mind.

I used it twice for a road bike where the pressure is 70-80 psi and it did not reach the desired pressure. but for my mountain bike it is ok, you know the pressure is much less than the road bike.

Buen producto pequeña y practica

Ligera y efectiva. Funciona para MTB Y ruta

Excellente taille et grand flow d'air !

Enfin une pompe qui tient bien sur la valve du pneu et qui n'a pas besoin de 100 coups pour gonfler à 60 lbs. Essentiel pour dépannage lors d'une crevaison.

Pratica, robusta, affidabile. Ne ho acquistata una seconda perché veramente ottima!