Preco

I have had some shifting problems as I ride down shifting becomes a problem. Have had bike in shop several times by the way bike is 2/12 months old Cannondale Synapse 5 105 to be checked out they have changed cables,shifters, adjusted rear derailleur still I have problems. I have adjusted rear derailleur myself when I ride down shifting becomes erratic when down shifting. So I placed a dot on barrel adjuster and one on RD as I ride the barrel adjuster loosens. So I tapped on cable housing barrel adjuster move the more I tap the more it moved. What do you think?

FBinNY 

"self adjusting" cable adjusters are a common problem. That's why most have some kind of retention system such as a locknut, click, or spring. Even so, many will self adjust anyway.

The best thing you can do is improvise a way to gum up the threads so the barrel is harder to turn. You want it to be fairly easy to move, but sticky enough to stay put. There's a product made for the job called "vibra-tite" sold for automotive and industrial markets where they (like us) want adjusting screws to be movable, but stay put until then. It's fairly expensive, so you might want to improvise using rubber cement or whatever.

Down the road when you replace the cable, buy a stainless steel nut, and put a locknut on the adjusting barrel.

joejack951

I've ran into "self adjusting" barrels due to corrosion between the housing ferrule and the barrel. If the ferrule can't turn within the barrel when you make the adjustment, the result is that the cable housing gets twisted and becomes a sort of torsion spring. The spring wants to unwind and will eventually do so assuming that there aren't strong detents holding the adjustment in place. I had it happen to me on the front derailler of a bike and I found myself tweaking it every other ride or so. I finally figured it out when I sold the bike because I re-cabled it for the new owner, something I clearly should have done for myself (but the bike had always shifted fine otherwise).

acrowder

In my professional opinion, your bike is haunted by unquiet spirits. They may be trying to hurt you. Try burning some sage inside of your frame.

tomacropod

Blue loctite or simple grease should work fine.

- Joel

joejack951

Typically those two items are used for very different purposes. How do you propose that either could fix the issue at hand?

FBinNY 

Why in god's name would anyone Loctite an adjusting barrel. A thick very sticky grease might work, but odds don't favor it.

rydabent

+1 on blue loctite. Blue loctite is NOT a glue. It will only create enough bind that the adjuster shouldnt move.

FBinNY 

Uh, I hate to say this, but T-242 (blue) Loctite, is one of a category of anerobic adhesives, which by definition makes it a glue.

If properly applied it'll bind parts together with low enough strength that they can be removed with hand tools, but the hold is enough that it'll be hard to adjust with your fingers. Once parts are moved, the bond is broken and it would need to be replaced. This is hardly suited for a part one expects to adjust routinely.

Moreover, many adjusters today have plastic parts in the assembly, and the solvent in Loctite products is harmful to many plastics.

No if applied to an oily part, the hold will be compromised, and it might work as you describe, but it's an expensive way to misuse a product for something which isn't what's intended for.

Painting the threads with 2 coats of five and dime rubber cement will give movable traction for a fraction of the cost.

Preco

Took bike LBS They found it had bad adjuster nob bad teeth on it replaced fixed thanks for the imfo.

fietsbob

Another online guessing game , resolved by actually having a 1st person LBS mechanic fix things.


as far as the thread thing..
This may be where the GP solution may be of benefit .. beeswax

since anaerobic threadlock is not suitable for adjustability, just a lock and assumes a bolt to be left as is .

joejack951

Rydabent may be confusing actual blue Loctite with the pre-applied blue (or yellow, white, etc.)-colored thread locker compounds frequently found on critical bicycle fasteners (anything to do with brakes especially). That stuff can be nylon, epoxy, or encapsulated "glue".

I agree though that actual blue Loctite on a barrel adjuster would make it virtually worthless as an adjustment. I'm fairly certain there's no way any normal human being could break the lock of blue Loctite using only the small knurled/lobed barrel, definitely not while riding along.

tomacropod

It's all about moderation. Grease will reduce the tendency of a fastener to vibrate loose because it fills the gaps in the threads and means less vibration is transmitted. More on a bicycle scale of vibration than a truck scale.

If you coat the bolt in blue loctite it will be hard to turn by hand. If you apply a small stripe it will be fine. The effect does not miraculously disappear as soon as you move the bolt, just as the product in the threads doesn't disappear.

Source: I fix bikes for a living and use fixes like this all the time. Most common place for loosening barrel adjusters - cheap v-brake levers. As for expensive, my loctite bill in the shop is about $40 per year, it's a commonly used industrial product and in bicycle quantities, very cheap.

You people need to chill out and remember there is no one "right way" to do anything, but many effective ways.

- Joel

rydabent

As in an old hair oil product ad----------"a little dab will do ya. I didnt mean he should slather the whole set of threads with blue locktite. One little spot would work quite well.