How tight can I do Renthal stem bolts?

Fitted a new Apex stem the other evening (as well as finally cutting down my steerer), and nipped up the bolts to the Renthal specified 5Nm. Trouble is I’ve managed to shift the stem around on the steerer a couple of times now so clearly it isn’t tight enough. How tight have others got their bolts done up, I REALLY don’t want to strip them by over-doing it…
Cheers!

4.5Nm here according to my torque wrench and it hasn’t slipped. I’ve been told that particular stem is very likely to crack around the bolts if over tightened

I wouldn’t go any tighter than the recommended 5Nm. There will be built in tolerance but they recommend it for a reason. I would try cleaning the mating surfaces and apply some carbon assembly paste before over-tightening.

Your bar might be on the small end of tolerance. Also – did you grease the bolts?

Also – did you grease the bolts?

If you did you might as well throw away the torque wrench.

You’re also assuming the tool is accurate, could easily be 10% off from new. Then you’ve got stem and steerer tolerences to look at.

Best to clean everything up as best you can and try again. Then I’d gradually up the torque a bit until it holds.

legend – Member

If you did you might as well throw away the torque wrench.

Renthal recommended greasing bolts on their previous stems – don’t have the installation instructiosn for the Apex, but expect it’s probably the same

Cheers all, it’s slipping in the steerer tube, not the bars. I did apply a small bit of anti-slip to the bolts before fitting. The torque wrench is only the cheap/cheerful superstar one so it could be a bit out.

Greasing will increase the clamping force…. check the label and see if they recommend it

My Hope and Race FAce stem bolts require the threads greasing too

anti-slip

is that like the opposite of grease? if it is and the threads are supposed to be greased then the bolts might not be tight enough.

You don’t want anti slip on the bolts, needs to be on the steerer tube stem interface area.

Anti-slip such as Loctite or carbon assembly paste on the bolt threads will increase friction and mean each bolt isn’t as tight as it should be even if the torque wrench says its 5Nm.

If that’s the case, i’d clean them and start again. 5Nm should be more than enough to hold a stem tight on the steerer tube.

EDIT: You beat me to it Downhilldave 😉

Thanks, back to the workshop!