Grams Light Bikes - Mountain Bike and Gear Reviews, and News: CDI Preset Torque Limiting T-Handle Review

During some winter downtime between snowstorms, I started to do some bike builds and upgrades, and I was doing lot's of part swapping, re-installs and tweaks. A great deal of this work involved using my home shop tools, and I was really enjoying using the CDI Preset Torque Limiting T-Handle. This clever little tool uses a built in cam-over torque limiting clutch, to prevent you from applying too much torque to fasteners, which reduces damage to components and frames, and allows tightening to exact manufacturer specifications. The T-Handle's are factory calibrated, and come in three color coded torque ranges, 4Nm (yellow), 5Nm (orange), and 6Nm (white), and retail for $30 each. They are made by CDI Torque Products, which is a sub-company of the Snap-on tool conglomerate.

When tightening a fastener to a component using the CDI T-Handle, it will click when it reaches the specific torque (4, 5 or 6Nm), and any further application of force does nothing other than cause more clicking noises, as the torque limiter prevents any additional torque application. When using a normal torque wrench the user needs to be careful with the acceleration and force being applied to the lever arm, as well not continuing once the specified torque is reached, all of which can cause over tightening issues. The CDI Preset Torque Limiting T-Handle takes the guess work out of applying too much or too little torque, and in low-torque applications, such as the assembly and adjustment of stems, handlebars, brakes, seatposts, etc., it allows precise and accurate tightening.

Torque 101
A torque wrench is a tool used for precise application of a specific torque to a fastener (bolt, nut, screw, etc.), to achieve the proper clamping force. It was invented by Conrad Bahr in 1918 while working for the New York City Water Department, to prevent over-tightening of bolts on water mains and steam pipes.

An interesting factoid is that only 10% of the torque applied to a fastener is for the clamping force, while the remaining portion is to overcome friction; 50% for friction underneath the fastener head and 40% for friction from the thread's engagement. Other factors that are involved, are lubricants on the threads, fastener material, thread finish, etc.

Torque is the twisting or wrenching effect, or moment, exerted by a force acting at a distance on a body, equal to the force multiplied by the perpendicular distance between the line of action of the force, and the center of rotation at which it is exerted. The symbol for torque is the Greek letter τ.

τ = r x F

r is the length of the moment or lever arm to the pivot point (aka the fastener)
F is the force vector applied to the lever arm
for example - 6Nm equates to a 6 Newton force applied to a 1 meter lever arm
units are expressed in
- in. ozs. = inch ounces
- ft. lbs. = foot pounds
- Nm = Newton meter
- cNm = Centi Newton meter

Impressions
I think that having some sort of torque wrench is a necessary tool for the home and shop mechanic, especially when dealing with lightweight and fragile frames and components, and materials such as carbon fiber and titanium. Tightening fasteners to components without a torque wrench relies on an innate 'feel' and wizardry that the correct torque has been applied, and it's more of a guesstimate than anything else. When using a normal torque wrench, whether it's beam or click type, it requires proper technique and usage, otherwise over-tightening can occur. If the user slowly applies the torque, and doesn't force things and stops immediately when the wrench clicks or reaches the needle mark, then the settings should be close to specs. Some of the ultra-expensive electronic wrenches, like CDI's Computorq3 (retail $720), use a solid-state electronic force transducer, which allows very precise torque application, since they remove acceleration and other factors out of the picture.

The CDI Preset Torque Limiting T-Handle effortlessly gives you the calibrated torque to the fastener you are tightening, and once it reaches that setting, you can't apply additional force. Call it making a tool idiot proof or dumbing down? You can click, click, click to your heart's content, and the torque limiting clutch prevents any more tightening. The tool has a life expectancy of around 5,000 clicks, and then it would need to be factory re-calibrated. For a home mechanic, it would last an extremely long time, while a shop would either send it back or replace it in perhaps a year's time? The tool is only meant for normal right hand or clockwise tightening, and isn't to be used to break loose fasteners. Neither of those constraints were an issue when I used the T-handles, as I always used them for final application and assembly scenarios.

The tool has a nice ergonomic feel in the hand, with a big and bulbous shape, and works the best by fitting it between your middle fingers, and cupped in your palm. The shank is magnetized, and the tip has a socket to hold generic hex bits, and each version comes with a 4mm as standard. I do wish it came with a set of hex bits, like 3, 4, 5 and 6mm, instead of the meager 4mm? I got used to the color coding, and usually knew which ones I needed for a particular task, although I wish, they had big bright numbers on them for my brain-dead days, or when I had tools strewn around everywhere. Since they only come in 4, 5 and 6Nm settings, you can't use them to tighten something to 4.5Nm, although I didn't find that issues since most parts generally have a small +/- range around their torque specifications. On the back of the packaging that the tool comes in, there's a calibration certificate for validation of their torque settings.

At $30 a pop for the CDI T-handles, they are more expensive than the other small wrenches, like Ritchey's Torque Key, but you get a better, more robust and ergonomic tool.

Bottom Line
The CDI Preset Torque Limiting T-Handle is an incredibly useful tool, allowing one to apply exact torque settings to fasteners during assembly and adjustment of frames and components. The tool is idiot-proof, and the clever torque limiter only allows the calibrated application of force, and no more. It clicks when that setting is reached, and will keep clicking without letting any further torque to be applied. The CDI T-handle is a well-made and robust tool that has a great ergonomic handle, and a useful magnetic shank for easy bit swap-outs, and is color coding for identification purposes.

It's not meant for breaking or removing fasteners and only works for normal clockwise tightening. I do wish it came with an assortment of hex bits, like a 3, 4, 5 and 6mm, and that it had big bright torque numbers on the handles for easier identification.

The CDI Preset Torque Limiting T-Handle is a convenient, tough, and accurate tool meant for low-torque applications and assembly of bike components and frames, especially with regards to precision carbon fiber and titanium parts.

Pros