Squeak and Rattles

Wednesday I rode the bike the usual 15-mile route to the gym, which took the battery down to its last, or last-but-one, segment. (The last segment of the eight is a little wedge, not a full bar. It and the next segment were on.) During the afternoon and evening, every 2 or 3 hours, the bike would emit a funny noise: a quiet little electronic squeak or chirp. It took a while to find the source of the noise, since it happened so seldom, but it was pretty certainly the bike. There was nothing else in that room that could have chirped, or squeaked.

There's nothing in the BionX manual about an audible alarm when the battery is low, but I charged it up and the noise did not recur.

The distance for that charge was 62.4 miles.

Friday I took the bike around the Arastradero loop, like before but this time I took the somewhat more demanding route past Arastradero Preserve which has a steep hill. I was panting and working hard even with assist level 3. Coming down the back side it was steep enough that I could set generate (negative assist) level 1 and the bike held its speed.

During this ride, as in the prior two, I was annoyed by a sharp rattle from the back, around the battery. On rough pavement it is quite loud. Also new to this ride was a higher-frequency, chattery rattle from somewhere up front. So today (Saturday) I put the bike up on the stand and went after these two rattles. The new rattle took a while to find. Banged on the frame with my fist and listened for several minutes before I noticed—Doh!—that the TerraCycle chain idler had disappeared! The rattle was from the remaining bracket which was slightly loose. The noise was hard to find because the fairing acts like a sound mirror and makes any noise from the center forward seem to come from the front.

Now, I first learned about vibration on bicycles when I was like, 12 years old, and I always assemble threaded parts with blue threadlock. Just the same, the bearing bolt for the idler had apparently unthreaded itself and fallen off. And the bracket bolt, which is fixed with a self-locking nut, had backed off a couple of turns. This latter makes me suspect that I might not have finished installing it in the first place. A self-locking nut just doesn't loosen itself.

I've ordered another idler ($60, ouch). In the meantime as long as I don't go down to the smallest chainring the chain should be alright.

As for the other rattle, the one in the back, I already knew what it was. The BionX battery case has a couple of metal brackets that mate with a track in the rack.

The rearmost of these had gotten loose; it has barely a millimeter of play vertically and horizontally but that is enough to let the tail of the battery box rattle. I'd already verified that if I stuffed some paper under it, it would shut up. So now I made a more permanent shim for it.