Fasteners: How tight? Also, threadlocker a good idea?

[mrhawk166]

Greetings all,

This may be a dumb question, but here goes: How tight is tight enough when tightening fasteners on a bike? And, is using a threadlocker compound a bad idea?

I've never really been one of those guys who could take something apart, and put it back together perfectly. And, now, w/ my beloved bike, I worry about whether or not I am tightening things enough, or too much.

Say that I have some accessories (rear fenders, and a rear rack) that bolt onto some eyelets in the rear. The screws thread directly into the "aluminum" frame of my Trek 3500. How tight is tight enough?! I really don't want to risk stripping any threads, but at the same time, I don't want anything shaking lose and losing screws (It's happened to me).

Is there any sort of rule of thumb as for tightness, whether for something screws into threads on the frame, or for bolts passing through the frame to their own nut on the other side? And is threadlocker a bad idea? Any input would be greatly appreciated.

Thanks in advance,

Michael

 

[boudreaux]

Originally posted by mrhawk166


Is there any sort of rule of thumb as for tightness, whether for something screws into threads on the frame, or for bolts passing through the frame to their own nut on the other side? And is threadlocker a bad idea? Any input would be greatly appreciated.

Thanks in advance,

Michael

Yeah, tight enough but not too tight, and it varies with the material. aluminum strips easily. Bolts into steel nuts can be tighter and loctite is probably good on racks, but pretty pointless on most other stuff.Use the non permanent kind.

 

[el Ingles]

Just because a tool is such a length don´t mean you can use all the leverage available , use hand pressure ie the strength of your fingers not the leverage of your arm , and be carefull with aluminium it breaks suddenly with no warning if over tightened .
If in doubt buy a torque wrench , expensive but cheaper than the problem and will set your mind at rest when working on expensive components .

 

[Calvin Jones]

Tightness is important for all fasteners. See http://www.parktool.com/repair_help/thread.shtml

 

[daveornee]

Originally posted by Calvin Jones
Tightness is important for all fasteners. See http://www.parktool.com/repair_help/thread.shtml

Calvin suggest a great article at the Park Tool Site.
Thread preparations are also covered well in this article.
Don't miss the part of the article about the anti-sieze compounds. Some on this forum don't seem to value the difference between anti-sieze and grease.

I also suggest the another one there, that includes torque specifications for most bicycle fasteners at URL:
http://www.parktool.com/repair_help/torque.shtml

Park Tool's sockets/crowsfeet/bits, when matched with a two good torque wrenches, to cover the ranges used on bicycles is a good investment. Park Tool's Torque wrenches are fine for the application, but you might find others that are just as good for a lower price. Park Tools offer packages with wrenches and bits through it's dealers. These packages can make the total price easier to take.

 

[boudreaux]

Originally posted by daveornee

Don't miss the part of the article about the anti-sieze compounds. Some on this forum don't seem to value the difference between anti-sieze and grease.

It seems to reference use on threaded interfaces.

 

[mrhawk166]

Thank you all for your replies. That Park Tools site is an excellent reference, I've found. Hopefully these will help relieve my anxiety with fasteners. Thanks!

 

[labicci]

Grease, anti-seizing compound, and thread-locking compound. I will use one of them on the threads of my fasteners.

Grease is sometimes used because it happens to be around, but anti-seizing compound is supposed to work better for this specific purpose. Thread-locking compound is even better because it prevent loosening from vibrations, especially useful for delicate components where I dare not apply too much tightening torque.

 

[meehs]

I think that overtightening fasteners is one of the most common mistakes made by folks working on their own bikes. I do all of my own work and while I'm NOT a professional mechanic, I wind-up doing a lot of work on my friends bikes by default. They bring their bikes to me with rounded out allen bolts, fasteners with the heads twisted off and all manner of other freaky stuff resulting from overtightening!

It's actually pretty easy to wreck aluminum fasteners by overtightening them. And it's not too hard to wreck aluminum parts (i.e. stripping out threaded holes, etc.) either. In some cases I've had to drill-out and re-tap holes going to the next size up because they're completely stripped out! So I always tell my friends that it's probably better to undertighten something and have it come loose (you can always retighten it) than it is to reef on a fastener like a hairless gorilla! I'm not sure if this is the best advice or not but what the hell, nobody has died yet.

I use non-permanent (blue) Locktite only on non-wear items that don't need to be removed regularly (bottle cages, racks, etc.). On everything else I lightly grease the threads and check it periodically to ensure that it's not loosening up.

 

[laurenlex]

Keep tightening until something breaks. Then back off 1/4 turn!