K-Edge Chain Catcher
In this glorious era of bike componentry, the average rider has amazing access to pro gear. Just about everything we see on pro bikes can be had either at a bike shop or in a few clicks on the web. It brings joy to our heart that if we want it, and have the cheddar, we can wear it or have it on our bike.
One of the few places this doesn't happen is the lowly front derailleur overshift widget. It's a low-tech thingamabob that reduces the chances of you downshifting over your small chain ring and allowing the chain to derail onto the frame.
There are people who believe that a well-adjusted front derailleur and the proper cable tension in the Double-Tap/Ergo/STI lever should prevent all over-shifts. "Should" is a pretty big condition. Cables stretch, and that snappy feeling of downshifting is more than just a feeling; it helps speed shifting.
The problem, as any annoying British time trial sensation can tell you (see Millar, David and Wiggins, Bradley), is that when races count most, a chain falling off the chain rings will not only cost the most, but is most likely to happen. For them, an ounce of prevention would have yielded pounds. We hope both learned this lesson, and it's one the rest of us could heed.
The problem has been finding this ounce of prevention. Does a Third Eye Chain-Watcher, for all its utilitarian brilliance, end up on Pro bikes? As much as we love the thought of mating of a molded plastic part with a hose clamp, a simple design that allows it to fit almost all seat tube diameters and shapes, we shudder at the thought of mounting it to any of our bikes. It's ghetto without the je ne sais quoi that can make junkyard inventions poetic, or even aesthetically work on a bike.
We've run the Third Eye Chain Watcher on our road bikes for races where the likelihood of unshipping the chain seemed vaguely possible. We've mounted it on our cyclocross bikes. But we cringe whenever we spy it out of the corner of our eye. Ouch. The Deda Dog Fang should work on our bike, but the tube shaping is such that we need to customize it in order to get it on.
Still, we've seen spy photos of the custom chain guides that are fabricated for pro teams. They have that elusive beauty we prefer for our bike parts. They have even greater simplicity than the Third-Eye. And, we're guessing, that they're lighter as well.
Kristin Armstrong's mechanic was presented with a problem at the 2008 Beijing Olympics. The hilly course necessitated plenty of big-ring/small-ring shifting and called for a little extra security to make sure the chain wasn't dropped. But Armstrong's Cervélo time trial frame could not accommodate any chain guide on the market.
So he came up with a little CNC-machined piece of aluminum that hung off the front derailleur braze-on mount. Simple, light, small. Brilliant. Smarter still was to offer that same widget to the public. It's called a K-Edge Chain Catcher, and to put it to the ultimate test we installed one on our cyclocross bike. Even though our bike doesn't have a front derailleur mount, we've been using a braze-on front derailleur with an adapter. We went with the gold to celebrate Kristin Armstrong's success. It's also a nice harvest color. We first weighed the setup. The doo-hickey came in at 10g on our scale. The bolt and washer we used -- didn't need the "Hard to Fit" kit that comes with it -- weigh a total of 4g. The bolt that came off our front derailleur also weighed 4g.
Setup is simple. You want to get the chain catcher as close to the inner ring and spider as possible without touching. Generally speaking, the closer it is to parallel with the inner ring, the better. Sometimes, the back of the chain ring bolts can interfere with the K-Edge when it's really, really close.
Remember to first loosen the cable pinch bolt on the front derailleur before removing the bolt. We have a Campagnolo front derailleur, so all we needed was the 20mm long bolt and serrated washer included in the basic kit. Back out the old bolt, install the new. The serrated washer is easy to flatten with too much torque, so having a torque wrench set at 7Nm will prevent you from over tightening. If you don't have a torque wrench, you should probably stop tightening when you notice your starting to flatten the washer.
A good chain-watcher watches the chain for you so you don't have to think about over-shifting. We didn't have to think about the overshifting, so we didn't. And we never dropped the chain. Admittedly, Ergo shifting, with it's little clicks, is harder to shift past the small ring compared to SRAM and Shimano. And the 8-tooth difference between our big ring and small also minimizes overshifting risks. Still, with the force we're applying to the pedals and the often lumpy ground of 'cross racers, we have had occasion to push the chain past the small ring. But we didn't miss a shift once in a month of riding and several cyclocross races in widely varying conditions.
The K-Edge stays on the bike. We'll probably get one for our road bike, too. 10g of prevention is definitely worth the weight.