Whenever I hit a biggish bump on my road bike, the bars will rotate a wee bit downwards with my weight. Its a Ritchey stem, Cube Aero bars.

Tightened the **** out of the stem bolts already.

Any tips for keeping them locked?

Less weight on the bars?

If you’ve already tightened up the stem bolts massively, I’d take it apart and check everything out. Is it new stuff? Maybe the bars are a bit thin, or the stem is a bit big?

Sounds like you haven’t done the bolts up evenly. Make sure the bars are centred in the clamp and that you have the same amount of thread visible on each bolt. Tighten them alternately.

Could be RM. I’d swapped the stem from my Cube to the Boardman, and its the Boardman thats demonstrating the issue. Might be one is 25.4, one is 26. Will check.

Carbon assembly paste

It’s like grease but with bits in it sort of like swarfega orange
Stops seat posts bars and the like moving with out crushing the hell of of them

If bars are alloy then I’d not recommend this fix as you prob have other issues

Gee- will check that out too.

Check that there is not a high spot inside the stem. I once put a wee bit of wet n dry round the bars. It worked and I didn’t die 🙂

A bit of olde-worlde Roadie wisdom, although with the advent of modern technology and manufacturing processes this is, perhaps, a mite olde hatte by now:

Fit handlebars and stem made by the same manufacturer as small differences in tolerance and manufacturing techniques may present themselves in the form of creaks, or in extreme cases, movement.

But as has already been said…I would reckon bolts aren’t evenly tensioned.

Don’t over-tighten tho. Tight’s tight, stripped’s knackered.

All good advice- cheers.

Try some fiber grip

Take off, clean off any white residue with soapy water and dry. Tighten up evenly and slowly.
Make sure the bolts have their washers so they don’t run out of thread.

Of course the ‘old roadie in me’ see’s the word Cube and instantly blames that POS brand.
(POS IMO all rights reserved)

Edit. Ask for a mini torque wrench this Christmas.

what Vinnyc said, fiber grip will sort it, tried everything with a post and the=is stuff worked first time 😀