Bicycle Mechanics - FSA are some lying bastiges!!!

So, my crank is creaking when I climb. I pull the crank and BB, clean and lube everything, and put it all back together. It's still creaking so last night I pull the chainring bolts, clean and lube everything, and get ready to put it all together. I'm not sure how tight the bolts should be so I check the FSA website and see that they advise 120kgf/104in lbs/12nm. No sweat; I take out my trusty torque wrench and T30 bit and get to fastening. The first bolt torques but I've got a bad feeling about it so on the next I back the torque wrench off a bit. I'm tightening the second bolt and as soon as I feel it bottom out, snap, it cracks right below the head of the bolt. I pull the two parts out and can back the broken piece out so I know it wasn't crossthreaded or siezed up, the damn thing just snapped and well below the recommended torque.

So, I've just gotten back from the shop where I picked up a new set of bolts. Anybody want to tell me how tightly they put there on? I really don't want to snap off another one. There's too much nice stuff in my garage that might get broken when I start hurling tools around.

Thanks,
Mike

Sorry to hear of this annoying incident. I installed a Team Issue Mega Exo on my Spectrum Ti touring bike this winter. No issues following the torque specifications throughout.
Just to cover all possibilities, I would suggest you also repeatedly check the crank arm fixing bolts. My experience was that they needed to be retorqued after every ride for the first 6-8 rides.

Anybody want to tell me how tightly they put there on?
Just tight enough. No more, no less. And all equal.

Sorry, I know that's not very helpful, just 30 years of bike wrenching talkin'! :p

What might be helpful is that I had the same situation a few years ago and did the same routine you're doing. Turns out the PEDALS were the culprit!!

if the bolts are chrome that may have been the problem. that said i would never use a torque wrench on a bike.

I have found the aloy FSA chainring bolts to be on the delicate side(DuraAce too). They are fine when new but once they have some miles on them, esp. if they were ridden loose(even a little) if you remove and reinstall them they sometimes break before hitting torque.

Another problem might be greasing them. I always grease ring bolts, and usually torque specs are dry.

I would suggest you also repeatedly check the crank arm fixing bolts. My experience was that they needed to be retorqued after every ride for the first 6-8 rides.
This is a very effective way to break square taper crank arms. Bolts torqued to spec will automatically "loosen' with use but if torqued properly the first time, they will remain tight enough to do their job. Repeatedly retorquing them to full spec will "chase" the crank arms up the taper and result in eventual failure.

ISIS and Octalink cranks aren't prone to this type of failure because the mounting interface isn't tapered but the same rule applies; torque them to the right spec initially and leave them alone.

Well, I removed all the remaining chainring bolts and torqued them to find out where they break. Dry, with only the threadlock that was on from the factory the most I could torque them was 70in lbs. I had one crack the head off, another split up the outside, and the other two pulled the threads out. I installed the new chainrings bolts and torqued them to 65in lbs. I'll check them over the next few rides and see what they do. I'm also going to drop a note on FSA asking them what gives. The good news is that a quick spin around the block and up a few hills resulted in no noise from down there so I think I've fixed that annoying little problem.

When was your torque wrench last calibrated?

I wouldn't waste my time torquing chain ring bolts - they need to be "tight enough" which is to say pretty much a solid hand tightening.

Good Point --but this advice leads to yet another thread about loose crank arms on a Mega Exo installation which was my point. Anyhow, since OP has never indicated which BB they are running, we are all guessing . . . .

When was your torque wrench last calibrated?

Calibration??? We don't need no stinking calibration!

Seriously though, I haven't had it checked since I bought it but I doubt seriously that it's off that much. BTW...the BB is a Mega Exo.

Some bolts cannot be re-used, and all bolts weaken with re-torquing. I'll bet the FSA procedures say that you should replace the bolts after every use.

104 in-lb isn't much - only 9 ft-lb. What size torque wrench are you using? If it's a 1/2", then 9 ft-lb is way outside the accurate range - I wouldn't try anything less than 15 ft-lb. Not sure I'd even trust a 3/8" wrench with 100 in-lb.

How about alloy/steel bolts difference?

So, I'm the latest one to join the "FSA chainring bolts are crap" bandwagon. I decided to swap out the inner chainring on my FSA Carbon Pro crank. Four bolts were removed without problems, and one abruptly "snapped" loose. Of course, this was the first bolt to fail when I torqued it back on, and one of the other bolts failed too (both snapped right at the head).

Here's a question though: the bolts had a bit of teflon plumbing tape on the threads. Is that supposed to be there? Wouldn't grease be a much better option to protect the threads from galling?

How about alloy/steel bolts difference?There's a HUGE difference in strength between alloy vs. steel bolts. Due to being forced into the same dimansions, the alloy bolts can't be oversized for strength. Being the same size as a steel bolt means the alloy version has only 1/3rd the strength. Fatigue resistance is also much lower and removing and re-torquing an alloy bolt will often cause them to snap.

Also make sure that the nut on the back side is threaded all the way through. If the nut has a solid back side, make sure the length of teh bolt doesn't bottom itself out on the nut before it's got sufficient clamping pressure. This may be the case if there are some washers used and they were left off.

A lot of problems could be fixed if riders weren't such weight weenies. Good old grade 8 steel bolts would let you get more than enough torque applied. The weight penalty isn't really that much either. I doubt anyone could feel the difference, on the bike, between aluminum and steel chainring bolts.

Tim

Alloy bolts!!! That would definately be a one time use.

That "teflon tape" isn't there to seal the bolt as in plumbing. It is a factory installed thread locker. Nominally it is also a one time use, then clean it and apply your own thread locker.

Just tight enough. No more, no less. And all equal.

Sorry, I know that's not very helpful, just 30 years of bike wrenching talkin'! :p

What might be helpful is that I had the same situation a few years ago and did the same routine you're doing. Turns out the PEDALS were the culprit!!

I agree w/ the Doc. My brand new 3/8 torque wrench is on the shelf collecting dust as I hardly torque anything anymore, you just get a feel for how tight it should be. However, if you get ahold of FSA, ask them if the torque specifications are with the bolts dry or lubed, thread torque is affect by lubrication. BTW, what type of torque wrench do you own? Clicker, dial drive, beam? If it's a clicker, make sure to unwind it all the way down to it's lowest torque setting after each use. For all types, it may miscalibrated.

Ah, the torque wrench debate. Put me on the don't-own-one side.

Put me on the own-four side.