London47

I too had problems with my right mirror being blown back due to air pressure at speed. This is because of the design: each mirror is rigidly attached to its mount on the handlebars by a bolt that is securely held in place by thread-locking compound and a retaining nut (17 spanner), and the mirror stalk is meant to move backwards and forwards freely without touching this bolt or its retaining nut. Instead, it is supposed to be held in place by friction in the sleeve of the mirror stem. Unfortunately, it sometimes appears to be set too loose, or perhaps works loose due to vibration, to frequent adjustment, or to people constantly knocking it out of position when the bike is parked. It seems that the friction is controlled by a tensioning device inside the mirror stem. The fixing bolt, which is under a plastic cap on the mirror stem, can be used to tighten this tension within the stem (10 socket), but the sleeve of the stem fits too closely to allow a normal socket to be fitted over the bolt top. I see that various solutions have been suggested, including locking the stem in position with a pin fitted through a hole drilled through it, and someone has even ground down a socket to fit. But all this is not necessary. Remove the mirror assembly entirely: there should be enough friction in the stem to use the mirror stalk as leverage to remove the bolt from its housing on the handlebars, as it is actually quite loose in its thread once the locking nut has been untightened. Turn it upside down, and you should find that a slot has been cut in the end of the bolt. A large screwdriver can then be used to increase the tension by turning the bolt from the other end. Be careful not to overdo it, though, as the alloy used for the bolt is quite soft! I put the stem in a vice and tightened the tension as much as possible, then refitted the bolt on the handlebars in the position I wanted using thread-locking compound and the retaining nut, leaving the stem sleeve alone, hopefully to “bed down” in one position. So far, so good: I have ridden at, er, high speed for a sustained period without the mirrors moving. If this doesn’t work, the only other thing I can think of is squirting something into the sleeve of the stem to increase the friction: you can get access to the inside of the sleeve by removing the mirror stalks. Superglue should do it, but that is a bit drastic and irreversible!