Took me 2 years to realize I was over-torquing headset bearings

I was rebuilding a customer's carbon fork last Wednesday and something felt off. The headset felt gritty even after I assembled everything by the book. I've been a mechanic for about 5 years now and I always just cranked the top cap until things felt snug. Well I grabbed my Park Tool torque wrench and looked up the spec for that particular headset and it called for 5 Nm. I had been doing like 8 or 9 Nm this whole time. Sure enough my own bike's headset had that same notchiness I thought was just normal wear. Now I'm wondering how many other little habits I've picked up that are actually messing stuff up. Anyone else have a moment where they realized some shop trick they learned was totally wrong?

2 comments

2 Comments

grant_ross2723d ago

Yeah do you use the palm method for checking preload? I had the same rude awakening a couple years back when I started actually measuring things. Now I just finger tighten the top cap with a hex key until I feel the play disappear, back it off a quarter turn, then do a quick test with the front brake on. Saved me from crushing a set of Cane Creek bearings last winter.

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charles_kim23d ago

...and that's exactly the problem with most things these days. People just go by feel and get lucky until they don't. I see it with headset preload, the "palm method" is like setting your fork air pressure by bouncing on it in the parking lot. You'll probably get close enough for a ride around the block, but you're not doing yourself any favors long term. The real pattern I noticed is how many things in life have a similar sweet spot between too tight and too loose. Bolts, relationships, even cooking eggs. Once you start measuring or timing things consistently, you realize how much time you wasted guessing. The quarter turn back off trick works because it accounts for the fact that the top cap isn't drawing any real load.