Learning lessons can be expensive.
Hobbes is the first bike I’ve owned with any carbon fiber (CF) parts. CF parts must be installed with appropriate care, always paying attention to the appropriate torque values to avoid damaging anything. I have a set of torque wrenches I use to ensure I am not over tightening anything on my bikes, remaining within the specified torque values.
So when I purchased a new stem for Hobbes, I checked the torque settings on the stem – 7 Nm. I installed the stem and set off to ride, including my most recent bikepacking trip.
Yesterday when cleaning Hobbes, I saw what looked like a scratch or possibly a crack on the CF steerer tube underneath where the stem clamps onto the steerer. Oh… 💩!
I took the stem off, removed the fork from the bike and ran it down to my local bike shop. The shop confirmed that the steerer is cracked and should no longer be considered safe to ride. I tightened the stem to 7Nm, but the fork specs recommend tightening to 6Nm, and the shop suggests 5 Nm is sufficient for mounting a stem on a CF fork.
The shop has ordered a replacement fork which should arrive by the end of the week. I’m out over $650 for the new fork. Yet, I’m thankful that I saw the crack before it failed catastrophically, sending me over the bars in a dangerous crash. Maintaining my bikes means keeping an eye out for anything that might need to be fixed and fixing it before it becomes a problem.
As a standards nerd who knows the value of identifying and following standards, I should have known to double check the torque specs for every CF part on my bike (both of them – the fork and the seat post!). This is a lesson I won’t soon forget.
Bikepacking for Nerds 