Day 8- Shock rebuild, materials and metal cutting!

A full day of discussion and hands on. We had a long discussion on the many different brands and types of front shocks and how they have evolved over the years. Compression and damping materials and approaches are different and lots of options are available today. We then did a disassembly and fluid change (for dampening) on a shock. The parts look pretty simple, but adding 200cc of oil can be messy. Having the bike in a repair stand to rotate it helps because the shock must be inverted to drain and then put back upright to fill. The parts on the bench-

Our next topic was about the various materials used in bikes. Especially the properties which are important for performance characteristics and how they are applied for specific uses. The table shows the basis for our discussion. Bottom line? Titanium is the strongest, lightest, and yes---also the most expensive because of production and machining costs.

Now that we have established that titanium is out of the reach for most, we got to play with steel and CUTTING TOOLS!! YEAH!! Oil, chips, large massive levers and all the good stuff, but I digress. The learning was that the bottom bracket faces and head tube faces must be parallel so the respective bearing sets work correctly. So we had a chance to face the head tubes, and chase the threads in bottom brackets and reface the BB surfaces. This is incredibly important for external bearing BBs. Facing does not come into play for cartridge, but concentric threads drive side to non-drive side is important. Good stuff and hands on....the facing tool below and then in the bottom bracket shell ready to make chips!

And the same facing application with a similar tool inserted in the head tube and ready to face the tube.

The bottom bracket thread chasing tool set up and ready to go.

notice the pilot shaft which keeps both sides aligned and concentric during the operation. Cool!