If you could choose only one bicycle tool to own, a multi-tool would be the way to go. Multi-tools are small, affordable and pack a big punch by combining a variety of implements into one easy-to-carry package.
There are many makes and models sold at a variety of prices, but most will have the tools you need to do basic adjustments at home or on the road. The most useful are the allen or hex keys. These are the six-sided wrenches that are used to adjust most bolts on modern bikes. A basic multi-tool (center, photo above) will come with a size range of 2mm to 8mm allen keys, plus phillips and flathead screwdrivers. Fancier multi-tools may add a chain tool, spoke wrenches, tire levers, torque wrenches, box wrenches and even a bottle opener. Since you are going to be carrying the tool around with you, more is not always better. Think about what tools you would actually use on the go, and buy accordingly. Here are four key uses for that handy multi-tool:
- Seat Adjustment- Your leg length doesn’t change, but your shoes do. Sometimes, depending on what shoes you are wearing, a seat height tweak is needed to make for a comfortable ride. Also, if a bike is shared by more than one rider, maybe a friend or a son or daughter, you will want to make height adjustments. Most seatposts adjust by using the 4, 5, or 6mm allen key to loosen the bolt on the collar where the seatpost enters the frame. A guideline for seat height is that your knee should have a slight bend when your pedal is in the 6 o’clock position.
- Brakes - Over time, your brake cables stretch out and your brake pads wear down. This causes loose brakes. Use one hand to hold the brake arms against the rim and then, using the appropriate allen key, loosen the bolt on your brake that pinches the cable. Then pull the cable hand tight and tighten the bolt back down. Squeeze your brake lever and check the adjustment. Too tight and your wheel won’t spin. Too loose and you have to pull the lever too far. Play around with the cable tension to find a proper adjustment.
- Handlebar and Stem - Say you have a little run-in with a curb, or you needed to throw your bike in the trunk of a cab and now your handlebars are misaligned. Grab your multi-tool and loosen the bolt(s) that hold your stem (the neck-like part that your handlebars are clamped into) in place. It will look like this on a threadless stem and this on a quill stem. Turn your bars so that they are aligned with the front wheel and re-tighten the bolts. Test tightness by giving the bars a good torque while holding the front wheel in place with your legs. The bars shouldn’t move at all under force.
- Racks, Fenders, and Other Accessories - If your bike sounds like it’s going to rattle apart over every bump and cobblestone, it’s time to take a minute and tighten up your accessories. Look at the places where your rack, fenders and water bottle cage attach to your frame. Find the appropriate size allen key or screwdriver and tighten those bolts. The bolts should be nice and snug, but take care not to over-tighen them as this may strip the threads in the frame.
Whether you use a multi-tool once in a blue moon for an emergency or often for all sort of simple adjustments, stay well-prepared: Toss in a multi-tool into your purse!