Park Tool TM1 Spoke Tension Gauge

If you get into building wheels and you're anything like me, you'll probably do the first couple in your bike frame with allen keys blu-tacked to the fork blades as primitive gauges. Form there it's a leap into the buying of a jig of some sort, and once you're at that point the next thing on your list should be a spoke tension gauge, like this one from Park.

The TM1 measures spoke tension by loading up the spoke between two static pins, with a third, sprung pin pressing down on the spoke and giving a readout. This is just a number from zero to 50; if you want to know the actual spoke tension there's a chart which maps that number to actual tension in different sorts of spoke. You get a circular measuring tool thrown in so you know what diameter of spoke you have.

Once you've had a look at your chart to see the acceptable range of numbers for a certain kind of spoke, you can set to work on your wheel. The TM1 is a valuable tool because it allows you to easily get the spoke tension even all the way round the wheel. Once the spokes are roughly tight and the rim central, it's a case of going round the wheel one spoke at a time and making sure that all the spokes on each side of the wheel have the same tension.

Obviously different dishing and spoke patterns can mean that the tension is quite different from one side to another, but if you can equalise spoke tension around the wheel then you'll invariably end up with a wheel that's more or less true, especially in the vertical plane where errors are more difficult to correct. Once you're happy with both the amount of tension and the fact that it's even, you can make the (normally minor) adjustments necessary to get the wheel perfectly in line.

Using the TM1 is simple: just clamp it on to the spoke and read the number. There's a couple of places to trap your fingers but you soon learn where they are, and to avoid them. If you fiddle around with the indicator when the gauge is in position it's possible to move it through quite a range, which made me worry a bit that it wasn't going to give repeatable results. But clamping a spoke and taking the first number the TM1 settles on does give a very consistent reading, plus or minus about 0.5 on the gauge. It's quick to use too, you can work round a wheel in no time and be confident that you haven't left any loose spokes.

It's not cheap at over £60, but it's less than the price of a new rim and spokes if your wheel falls apart, so if you're planning on building more than a few wheels it's a worthwhile addition to your workshop.

Verdict

Worthwhile companion to your truing jig if you like building your own hoops