I recently tried my hand(s) at some maintenance work on my bicycle, an old Diamondback mountain bike. The rear brake pads were routinely wearing down quickly, in large part because the rear wheel knocked (wobbled side-to-side on its axle) significantly (several millimeters), which turned out to be related to a chipped cone and missing (!) bearings in the back wheel… And while we’re there, might the internals of the freewheel be scrambled, too? And the cassette cries for a cleaning…
With Park Tool’s “Big blue book of bicycle repair” [1,2] and YouTube (videos linked below) as my shop masters, I did the following:
- Replaced the bearings and realigned cones, lock nuts, etc. on rear axle [3,4]. A few remarks.
Cone adjustment. My rear wheel is a quick-release (QR), and getting the cones and lock nuts set just right took many, many adjustments. In particular, if the cones and lock nuts are set too tight on the axle prior to tightening the QR, the compression from the QR mechanism will tighten the cones into the wheel even more, causing the wheel to not spin freely . The rule of thumb for QR wheels from the Park Tool book is helpful: You want just a trace of knocking when the wheel is off the frame, and no knocking when the wheel is on the frame with the QR mechanism closed. At the end of the day, what I looked for was, when the wheel is on the frame with the QR closed, (i) there is no knocking and (ii) the wheel spins freely.
Dust caps. Be gentle when removing and replacing the dust caps! On my bike, these turned out to be fragile, and I bent one badly out of shape. Fortunately, the dust caps don’t seem to touch any parts of the wheel inners — they sit off the bearings, and are just to keep debris out of the wheel inners — so so far the bent-up dust cap hasn’t caused me any issues. Though if it’s so bent up it falls out, then the wheel inners get clogged up, that would be an issue… The dust caps on my wheel seem to have a rigid outer ring, but the rest of the cap is bendable metal. When putting the dust cap back in place, gently tap around the edges, ideally with something soft (e.g., plastic), until the dust cap sits snug.
Personal reference. On my bike, the rear axle shows 6 threads on either side, beyond the lock nuts.
- Deconstructed, cleaned, and rebuilt freewheel and cassette . Getting the freewheel off the wheel was the hardest thing I did. You need a special freewheel removal tool, you need a large wrench (go go Gadget torque!), and even then, you need upper body strength — the freewheel can be on there tight!
Personal reference. The Shimano MF-Z012 cassette on my bike has 30 bearings on the outside and 40 on the inside . All bearings appear to be the same size. One of the pawls seemed to be oriented backward.
- Replaced all brake pads and brake cables . Installing and adjusting the brakes went fast and smoothly for me.
Personal reference. The cantilever smooth post brake calipers on my bike were installed with a Shimano link unit, which comes in different sizes. The A link unit — with a 7.0 mm rigid arm — is the correct size for my bike.
- Retaped handlebars . Pay attention to the direction of taping. You want the tape to rotate the same way as the rider’s hands on the handlebars, so that the rider’s natural motion will tighten, not loosen, the tape. On the outside of the handlebars, wrists tend to rotate outward (away from the rider). On the uppers (inside) of the handlebars, wrists tend to rotate down (toward the rider). Tape correspondingly.
- Park Tool’s “Big blue book of bicycle repair” at Park Tool.
- Park Tool’s “Big blue book of bicycle repair” at Amazon.
- “Repairing a loose bike wheel — hub overhaul” by RJ The Bike Guy (YouTube, 2013-10-04).
- “Knock knock, loose hub : Tech Tuesday #117” by Park Tool (YouTube, 2018-10-16).
- “Very stiff rear wheel” (Bike Radar, 2011-07).
- “Bicycle freewheel disassembly/assembly” by RJ The Bike Guy (YouTube, 2014-04-03).
- How many balls in a MF-Z012 cassette : Post #11 (Bike Forums, 2011-07-02).
- “Brake caliper mounting & adjustment — cantilever smooth post” by Park Tool (YouTube, 2016-04-05).
- “How to wrap handlebars for road bikes” by Park Tool (YouTube, 2016-01-07).