Lately, I've noticed that the threaded headsets on a couple of my bikes have loosened while I ride. Both nuts were tight at the start but began to work loose. How do you keep headsets tight?

Thanks

I find this happens on new installations when I don't lock the upper race and its locknut together tightly enough. When older installations start to show play, I try to tighten it but often just proceed to rebuilding the headset. It could be caused by wear.

Consider a fork on a bike ridden over irregular pavement. The front wheel is bouncing up and down, flexing the fork blades, the fork crown, and as the fork crown is torqued by the blades it transmits that motion to the steer tube. As the lower bearing thus twists, the upper bearing is pulled and twisted. All this may tend to loosen a bearing that is not secured enough.

I wrap a towel around the top tube to protect it.

I use a headset wrench for the race bearing, and a large socket for the top nut. I make sure all residual grease from the repacking is wiped off from the top headset threads, the top of the upper race nut, the washer, and that the locknut is free of grease, too. I want a good friction grip there.

Once I have the adjustment the way I want it, I try to turn the fork until I can put the headset wrench on, secure it along the top tube with duct tape wrapped around it and the top tube. Just so it's easier to deal with. Then, I overtighten the headset just a hair.

Then I put the socket down over the top and, while holding the headset wrench along the top tube, crank the lock nut down hard. Very hard, making sure any movement of the headset wrench is towards the handle of the socket wrench (counterclockwise). It often moves a bit while I do this, which "undoes" the overtightening I just did, giving me the play I want.

Seems elaborate, but takes just an extra couple of minutes, and less time than it would take to go back and do it again.

Bearings and races are "bedding down". Adjust again and it should be OK for a while. It might take a third slight adjustment before it stops loosening on you till normal wear starts after many miles.
This is pretty normal for most headsets to differing degrees.

Chombi

I adjust a headset with the stem installed and tightened; I find that the stem affects adjustment slightly; YMMV.

That never occurred to me.

Me neither, if initially done correctly. You can crank those things pretty tight.

BTW, I always use a wheel in the fork while adjusting the headset so I can hold the fork from turning. In, out, check, repeat; usually takes a little fiddling to get it right.

Thanks all. Good advice. Yes, these are new builds.

My steer tube was trimmed for a much taller stack headset than the Levin I'm currently running. As a result, I've got a 10mm aluminum spacer between the upper cup and the locknut.

No matter how well I locked it down, my rough-and-bumpy commute would work the headset loose after a couple of weeks. I put a bit of blue (hand-removable) Locktite on the locknut and it's stayed in place over a month now.

I suspect the alloy spacer was compressing easily during bumpy patches, and the resulting moments of looseness were letting the locknut back off a bit at a time.

Campagnolo states this in there instructions, (in the 80's and 90's at least, not earlier) With the mass and cables that usually go along with the stem, I use a empty stem and insert it the same amount of the same type and depth, wedge or conical expander. Adjust headset, remove and then insert the functional stem with bars. It is easier to tell if you have the headset assembled with the least meaningful amount of mass to "feel" the bearings.

I was looking at a Bianchi fork and frame for purchase once and while inspecting it found a "dent" on the front inside of one leg of the fork and one on the inside rear of the the other. Both were nearly undecernable. I suspect the damage occurred from tightening HS lock nut or trying to remove a stem. Becareful with how you "secure" loose parts. Yes it was Celeste in color.

Protocol?

If it's Japanese, in your case I would bow deeply, after removing your shoes, of course. Smile, but not too much, don't stare.

Procedure?

Park Tools has a web site.

Bob, you crack me up.

Handlebars in. Front wheel in. Bike on the ground, not in a repair stand. Front brake hooked up and working.

Front wheel between legs. One wrench on threaded race, another wrench on locknut.

Adjust race approximately. Hold locknut with wrench and wheel (and thus the fork) with your legs. Tighten locknut. Bounce the bike or rock it with the front brake engaged. If there is play, it's too loose, so release the locknut, tighten the race a bit, and tighten the locknut and test again.

Once you have it so there's no play, assume you've overtightened it. Overtightening is what causes the brinelling (aka indexing).

So do it all over again. Find the adjustment setting which causes a very tiny amount of play. Then tighten the adjustment very slightly, using the technique above.

The way I treat any "jam nuts" like a threaded headsets, cone-nuts, etc. is to NOT final tighten the top or "locking" nut against the inner nut. Instead just snug the locking nut against the inner nut with bearing preload just a hair tight, then back off the inner nut tight against the locking nut. When done right you can get perfect bearing preload and the nuts will be jammed together very tight. It takes some trial and error but it's much easier to get the bearing preload correct this way. As you only need to use one wrench on the inner nut and hold the tightened stem for leverage. This method works great on headsets, pedals, hubs, etc. You'll get more accurate bearing prelaod and will not have the nuts loosening.

noglider and Otis, excellent, erudite advice. Thank you.

what otis said.

In all seriousness, this is the tool you want, in addition to the thin wrench:



It will make your wrenching life easier, and removes the risk of damaging a tube/paint from a slipping wrench.

The aluminum is yielding, and will continue to do so. Either switch to steel (or stainless) or modify a top nut so that you can run it down to the upper cup.

Speaking of yielding, the headset should not loosen if you've done it right. If it embeds further, you didn't put it in right in the first place. The cups and crown race should be put on really hard. If you've ever done it wrong, bring it to a bike shop. Have them do it. If they're gracious, they'll teach you, too, so you know.

BBM, thanks for the tip on the tool. I'll put that on my wish list.

[QUOTE][Protocol?

If it's Japanese, in your case I would bow deeply, after removing your shoes, of course. Smile, but not too much, don't stare.
/QUOTE]

Too funny! I should pour a spot of tea before I approach an English bike I suppose?