Park Tool TM-1 - Spoke Tension Meter Tool

For 20+ years, I have built wheels that needed to be re-tensioned/trued occasionally. I didn't realize that a spoke tensioning tool can make a huge difference in wheel builds until I got this Park spoke tension tool.Now, I am building some of the best wheels ever, and properly tensioned wheels need less maintenance and truing.

Let's hit the first question off the bat; Do you need this doo-dad to properly build a wheel or keep your wheels in good working order?The answer is it depends upon how close you wish to be to the bleeding edge.Mechanics have been building bike wheels for about 200 hundred years now (dating back to before the early velocipede designs), usually without the benefit of a spoke tension gauge. And for decades, racing wheels used in everything from the Tour de France to serious downhill competitions have been built without spoke tension meters as well. That is because mechanics overbuilt their wheels for the riding style and course, and their fatigue limit was sufficiently far from their elastic limit. (spokes that are tensioned too high are too close to their elastic limit, or that of the rim) Likewise, if you wish to build your own wheels and follow some basic safety factor limits when building a wheel, then a tension gauge is not important. That said, in today's world, there is always that rider out there who is 200 lbs (90.7 kg) and who wants a 24 spoke radially laced front wheel on a 330 gram rim. If bleeding edge riding is your style or you are trying to save 150 grams on your carbon fiber road or mountain bike or you want to push it right to the physical limits, then a spoke tension gauge becomes essential.This Park Tools TM-1 gauge works by using a spoke diameter gauge to measure the middle (or butted part, if your spokes are such) part of a spoke (or you could use precision calipers) and then applying the the tool so that the spoke runs between the two fixed posts and the moveable post. The arrow at the top will point to a number on the graduated scale and you then refer to the separate conversion table to see what kilograms of force (kgf) measurement this corresponds to. For most wheels, you want somewhere between 80 and 130 kgf. Although, this value can vary depending upon the exact riding application.I am not a professional or shop mechanic, but I do build wheels for myself and others that join our off road riding group. I have used this gauge for about twenty wheel builds over the last five years or so. I find it to work fairly well. My older mountain biking wheels (rim brake) are often set up with Mavic 32 hole X517 rims and are typically radially laced in the front and three cross drive/radial lace non-drive in the back. While my newer rims are often 32 hole DT Swiss, Mavic X317 disc or Stans racing rims. I can usually tune by hand and by sound my wheels so that no spoke is 20% above or below the spoke average of the entire wheel (this is a standard reference limit for bike wheels), but the TM-1 really helps me to keep my older wheels at right around 100 kgf and my newer disc rims at about 110 kgf. And these values are right in the happy middle between allowing for a long fatigue life while maintaining ample tension so that if one spoke breaks, the wheel does not taco and I can ride back to the trail head. Those tension levels also prevent fatigue at the rim eyelets and ensure long rim life.Are than any negatives about the TM-1? Not really, but I do find the spoke diameter gauge to be cheaply made. I much prefer to use my Neiko digital caliper when measuring spokes. I also wish that Park Tool would include a standard guide for major manufacturers in their conversion table. The values for a 1.5 mm butted generic spoke from China and one from DT or Sapim are not the same. (Although, you can find these exact values online) And because the gauge is a calibrated spring, I suggest any owner send it back to Park Tool every 25 wheel builds or so, so that exact calibration is maintained. However, those are relatively small quibbles.Thanks to the TM-1, I have never had a wheel taco so far or a spoke break. While this gauge is not essential to wheel building for most riders who are not bleeding edge weight weenies, it does allow the home builder to have some quantitative idea of how their wheels are doing. And for me, that means longer wheel life and no problems on the trail. Five stars in my book.

Great tool.

This is absolutely necessary for a correct and long lasting wheel build. It works on all size bike wheels.

A while back I decided to build my own wheels, I bought Park Professional wheel truing stand, TS-2, a copy of The Bicycle Wheel 3rd Edition, and a set of Bike Tool - Park Tool - Park 4 Sided Spoke Wrench wrenches. Thus armed with new rims, hubs and spokes from my local bike shop I successfully built two wheels. I used the "by ear" method of plucking the spokes and listening for pitch to know whether the spoke tension was even or not. Apparently my ear was good enough because the wheels outlasted the rims without any readjustment. (The repeated breaking with winter riding grit in the pads wore the rims to the point of concavity and thus were replaced.) The replacement wheels were built using the same original spokes and hub, with a new identical rim, I transferred the old rim out by loosening all the spokes, then moving them over one at a time. Then a session on the jig tensioning the new rim. It didn't stay true as long, maybe I hit more potholes who knows. I figure I rushed the job a bit, and I didn't listen as well and thus some spokes were uneven tension. Re-truing produced less of a big wobble and a lot of little ones. So I bought this meter, loosened all the spokes, then using the meter, set them all nearly the same, then tensioned them up to the middle of the manufacturer's suggested range. The wheel is now back true again and I'm happy.Using a tension meter like this is a bit tricky as you need to place it in nearly the same spot on every spoke. You can mark the spokes by spinning the wheel and putting tape at the same "centered" spot, or you can do what I did, and use the spoke wrench as a bottom of the meter guide. Note, you can't tension the spoke with the meter in place and get an accurate reading, you have to remove the meter, re-tension and re-measure.So now being an amateur wheel builder, I recommend this meter as making the process that much easier. Yes you can get by without it, but it like the professional jig makes the job easier. It did take a bit longer as I spent a bunch of time after the first bit of tension was on the spokes, getting them all nearly the same before cranking up the tension to full on. But I think it was time well spent, as I had very little to do with the final adjustments.Note: Keep the box to use for storage. It's just a spring, so you don't want anything resting against it for a long time as it would eventually cause it to bend. Fortunately Park offers a re-calibration service. I haven't used it as I just bought the meter, but in the event that I drop it or whatever I am sure that I'll eventually send it back for adjusting.