Park Tool DT-3i.2 Professional Bicycle Wheel Truing Dial Indicator Kit - Precision Spoke Tension Gauge for Bike Repair & Maintenance - Perfect for Home Mechanics & Bike Shops

Most new bikes over $400 in the USA, unless they are road racing bikes have disc brakes. And the rotors on those wheels can slow you down and create drag if they are out of true by as much as 1/2 a millimeter (500 micrometers) in some calipers. Which is where this doo-dad dial comes into play, allowing you (as long as you have a rotor truing fork) to get your rotor completely true (or at least down to 1/100 of a millimeter (which is 10 micrometers)). You can jury rig this to fit most truing stands but it works best in conjunction with the Park Tool DT-3 rotor truing gauge and the Park Tool TS-2.2, TS-2 or TS-4 truing stands.This newer DT-3i.2 is improved over the older DT-3i dial by having an elongated end cap that will not get caught in some rotor's holes and by using a swivel washer set that allows you to better hold the end cap flat against the rotor. It has the same precision of the DT-3i and once you read the directions and mount it to your truing stand, you can easily precisely align your rotors. I perform a rotor check on my two mountain bikes about every month or if I hear rubbing and so far, the DT-3 and this DT-3i.2 have allowed me to run my rotors with no problems. Unlike the much higher priced TS-2Di dial set used in truing wheels (or making new wheels), which is really not that helpful, this DT-3i.2 rotor dial really is helpful and does get used often. I highly recommend to more advanced home mechanics and shop mechanics. Five stars in my book.