Tuesday, 4 July 2017

Rub a Dud Hub......Shifting the Seized Sprocket








Well, despite herculean efforts, primal grunting and copious amounts of penetrant spray, the EAI Gold Medal Premium sprocket was right royally stuck.  Thankfully, John was around that morning, so I dashed down, inbred hub in hand. Locked within his vice, the usual, measured force was applied.
Extra long, custom brewed chain whips, hammer and punch shifted the lock-ring. Persuading the sprocket free ultimately lead to intelligently engineered force.
Having established the hub was at the end of its long and useful life, we donned ear defenders and he cuts the opposite flange square with his angle grinder. Flat flanges are easily gripped within the vice jaws, making lock-ring and sprocket extraction that bit easier...In theory. Practice proved a bit more involved...
The former required some blunt persistence, from his hammer and punch. A gentle tinkling as it bounced across the floor announced successful liberation.
Launching the final assault, John grabs his prodigious, home brewed chain whip and wraps it anaconda fashion around my prized, titanium oxide coated stainless steel sprocket. Starting gently, he steadily increases the pressure, working counter clockwise until it eases free-mission complete!
A reminder to strip, inspect and re-grease components regularly, especially those under a lot of force and in the firing line of dodgy water. John was trained by his father to strip his bikes on a monthly basis.
The argument is very persuasive. From a mechanic’s perspective, it enables easy evaluation of component health and any potential problems to be blitzed before bigger problems present.
Team mechanics will perform this at the end of each stage race, given the money and potential losses at stake.  Seasonal strips are arguably the best balance, especially on bikes seeing hard service. When testing really “stiff” greases etc, I may exceed this.
Given the amount of waxy frame preserve sloshing around inside my frames, bottom brackets and seatposts will usually relent with nominal effort-even after 12months or so. Fixed transmissions are low maintenance.
Beyond keeping an eye on tension and drizzling lube on the chain, sprockets are usually forgotten, until replacement, or some other remedial work needs doing.
White Lightning Crystal grease, as used on the Halo hub threads was my default. https://www.sevendaycyclist.com/white-lightning-crystal-grease 
However, I’d managed to misplace the tube in all this excitement. Hence, the new hub threads received a liberal basting of Park PPL1.
Galvanic corrosion (where metals of different parentage seize) is to be avoided, at all costs. Lessons have been re-enforced, so I vow to strip, inspect and replenish every three months. Watch this space... https://www.sevendaycyclist.com/wheel-building-part-one-theory-and-
Otherwise some rim tape and a 30mm tyre later, we are ready for road testing.  John reckons there might be some bedding in and spoke stretch during the formative miles. Frankly, this is to be expected and will necessitate another quick tweak on the jig but nothing out of the ordinary.  A bit like rot around Mk1 KA filler caps...