Check Your Carbon

So I just picked up a ControlTech Impel Mini clip-on aerobar to put onto Blackbirb, my XC mountain bike, in order to make it a bit more amenable to doing longer gravel-style rides.

You see, mountain bikes tend to be a bit miserable when riding for long distances over relatively flat terrain since the wide flat bars only really give you a single hand position to work with, and that position tends to catch a whole lot of wind. Attaching a mini aerobar gives you a second hand position to alternate with, and one which makes you a lot less of a human parachute.

But the trouble I ran into had nothing to do with the riding positions, but rather with this particular aerobar instead.

I opted for a carbon one to save weight, as I didn't want to A: have to lug even more weight up the hills, and B: make the steering feel heavy and awkward. But carbon, while it is a familiar material at this point, apparently still isn't a completely solved science.

I discovered this as I was using my torque wrench to tighten the clamping bolts to the recommended 5nm. On one side this went great, but on the other side I noticed that as I was tightening one of the bolts, the head was sinking down to Davy Jones' Locker. That's not good.

I removed the bolts to examine the situation and found the culprit pretty easily.

The bottom of the counterbore for one of the bolt holes was defective. It was full of dry carbon weave; the resin didn't properly penetrate and left a bunch of voids.

Needless to say, this is not ideal. I don't think this would have caused a complete catastrophic failure if the bolt somehow managed to pull all the way through the bar, as the clamp on the other side was plenty sturdy, but it's not really an experiment I want to be a guinea pig for.

Thankfully I bought it off Amazon, so the return policy is super easy, and I expect I'll see the replacement show up on my doorstep in a day or two. I wasn't planning on doing any rides immediately, as I also ordered a new carbon handlebar to take even more weight off the front end, and that's not going to be in until later this month thanks to the perpetual bike parts back orders that are happening these days.

Update:

Received a second unit from Amazon and both of the forward counterbores had voids in them this time, and collapsed when assembling to 5nm. Not good.

To their credit ControlTech offered to send a free replacement bar no-questions-asked when I emailed them, so hopefully they'll be able to cherry-pick a good unit to send out to me.