We’ve all been there. You go to shift, and the chain pops off the ring straight to the frame. If you’re lucky, you can simply pull over, stop, and put the chain back on with your hands with only a bit of chain lube on your gloves or fingers as evidence. If you’re unlucky, the chain can cause damage to the paint, or worse yet get jammed in the frame digging into the actual frame material. Sometimes no matter how perfectly your front derailleur is adjusted, if you hit that bump just right in conjunction with shifting it can cause your chain to derail from the front rings.
Not surprisingly, chain spotters (or chain catchers/keepers) have become fairly popular. Current designs are light, work well, and are unobtrusive. However, most designs for braze-on derailleurs require you to adjust the derailleur and the chain spotter at the same time, all while tightening down the bolt. Sram has taken the design a step further and not only separated the adjustment of the derailleur from the adjustment of the chain spotter, but also managed to make the actual chain spotter adjustment easier as well.
Better yet, as of June 1, it will be available a la carte, meaning you don’t have to purchase an entire Red group just to get one.
More on the Sram Chain Spotter after the break.
The secret to the Sram chain spotter’s dual adjustment is a special 4mm braze-on Allen bolt that is threaded both externally and internally. This means you install the derailleur as you normally would, using a regular Allen key to torque the braze-on bolt. Once the derailleur is installed, then you can install the chain spotter which has a recess on the back that fits perfectly over the head of the bolt. Place the chain spotter on the bolt, then install the 2.5mm Allen chain spotter screw which threads into the braze-on bolt. Simple right?
To make things even easier, Sram has included a 2.5mm Allen horizontal adjustment screw located below the mounting bolt. Presumably just before the mounting bolt is fully torqued, a simple twist of an Allen key will move the chain spotter closer to or farther away from the inner chain ring. Set your precise adjustment, then torque the mounting bolt and you’re done. Keep in mind that if you ever have to make small adjustments of the chain spotter, you can still do so at any time without effecting your derailleur alignment.
To keep the weight conscious happy, adding the chain spotter to a braze-on system will only add a scant 12g to the total weight, which is a small price to pay for chain security and peace of mind. Sram states that their chain spotter is compatible with Red 2012, Red, Force, Rival, and Apex, which makes it sound like it’s compatible with pretty much any Sram road derailleur. MSRP on the Sram chain spotter will be $36 dollars for the braze-on model. If your frame uses a band clamp braze-on adapter, you will have to add in a separate Sram chain spotter compatible braze-on adapter, which will set you back another $32, for a total of $68 if you need the band clamp and the chain spotter.
Expect to see it on Sram’s website in the near future.