As a result of an endo caused by a wasp sting to the face right as I should have been bunny hopping a ditch I’ve ended up with a new gravel frame and fork. After the first ride my back hurt and the saddle kept going nose up. My bike fitter recommended I move the saddle forward by 1 cm. Perfect! Very simple operation that I have all the tools for, I’ll loosen the tightening bolt, move the saddle forward a smidge and then tighten it back up. This time I decided to use a torque wrench to tighten it back up to spec. Seemed like a reasonable thing to do.
(I’m not sure if this is related but that bolt was replaced with the better bolt part 2 years ago after a particularly nasty race that meant a lot of other things needed to be replaced, so why not add some bling?)
I set my torque wrench to just under 12 Nm and went about tightening it after putting some grease on the threads. As I was tightening, well before I hit 12 Nm, I met some resistance and heard a kind of metal creaking noise. While thinking to myself “Well shit, thats not good, I should stop.” the bit, a silca S2 Steel torx bit, snapped before I could stop.
That sucks but at least I still had the saddle in the position I wanted to test. So I hopped on my trainer to do a test ride. During the ride it was clear I needed to raise the saddle. So I undid the collar bolt raised the saddle and grab a trusty hex key to snug it back up, that torque wrench wouldn’t get me this time! I snapped the damn bolt for the seatpost collar.
The torque wrench is a craftsmen 3/8” micro click torque wrench so it’s not like I foolishly missed the reading on a beam. I even confirmed that I had indeed set it to just below 12Nm when the bit broke.
Am I using the incorrect tools? The correct tools incorrectly? Just incredibly unlucky?
What’s the best way to go about that? Just snug something up to a reference value with a known good wrench, set my wrench to that same value and then see if mine clicks as well?
It probably doesn’t matter, but I can’t follow which bolt broke, and if it was the same bolt that the bit broke on. You start by talking about what I think is the clamp that holds the saddle to the seatpost, because you mention the saddle tipping and also moving it forward; and then about raising the saddle height and the bolt that holds the seatpost in the frame.
As I recall, titanium bolts aren’t as strong as steel, so maybe that’s one factor. For snapping a torx bit, how surprising that is depends on the size (smaller obviously more likely to fail).
Sorry that was a bit rambling. To summarize, broke steel bit on titanium bolt when using torque wrench. Broke bolt when not using torque wrench. The torx bit was T25.
All sounds very odd to me. Breaking a bit and/or a bolt both seem pretty unlikely to be the result of getting the torque slightly wrong. Any pre-existing damage? (Not clear if the broken bolt was also installed on the crash damaged bike, although this wouldn’t explain the bit). My best guess is you’ve just been really unlucky and had two unrelated defective part failures.
No. I was hand tightening the seat post collar and shooting for 5 - 6 Nm. Granted w/o a torque wrench there’s really no way to know what I was actually doing.
Can you see from the remains of the bolt if it was properly lubed/greased/antisiezed, and not just the threads but under the head of the bolt as well? Also, if a seat post is slightly undersized and/or the seat tube slightly oversized, and depending on the collar, the bolt can bend which is no bueno
Good call on checking the for grease. There was indeed some grease in there. The bike is an Enve MOG and the collar is the one that came with it. I’ve had issues with those bolts bending in the past on other OEM collars. I guess I’ll just need to replace this one much sooner than I have in the past with something from Thompson or King.
Can’t argue with anything Chris King. I’m also a fan of, and use, Wolftooth seatpost collars. In any case, I recommend using a design in which the bolt screws in to a steel barrel nut on the other side, i.e., steel threads for both male and female. I’ve stripped a collar with aluminum threads, and an older style seatpost binder bolt where the fixing side was aluminum.
Having the bolt go into a barrel nut is also a hedge against the bolt getting bent.
Silca tools are known to break. Always aim to buy tools from tool manufacturers, not companies that add tools to their line ups down the line.
Also, sometimes torque wrench’s don’t click when they should, especially if it’s the first time you use them that day. Dave Rome recommends warm up clicks to help improve accuracy but it can also be great to help get the clicker working well.