Bicycle Mechanics - lever pivot-rod sliding out of Tektro aero levers

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TallRider
01-29-07, 07:37 AM
I've got the Tektro aero levers on my newly-built-up Centurion Comp TA (http://www.unc.edu/~cupery/pics/bikes/Centurion_Comp_TA_repainted/IMG_7854--Centurion_no_bar-tape.jpg), and I'd previously used the levers on my Raleigh aluminum racing bike (http://www.unc.edu/~cupery/pics/bikes/Raleigh_aluminum/IMG_7705--whole_bike_side.jpg). The road on which the brake lever pivots is press-fit into the plastic of the brake hood body, but it's not press-fit very tightly and over time the rod can migrate sideways. It doesn't happen quickly, and it's not much of a problem because every so often I press it back into place centered in the brake hood body.
But I'm wondering, how many people have this problem with this lever, and are there any easy fixes?
The levers used to squeak when I would clamp down on them during hard braking - I applied a drop of Phil Tenacious Oil to the pivot contact between the lever and the rod, and it took care of the squeaking but some of the oil seeped into the contact between the rod and the brake hood body and now the rod slides over a little more readily than it did before - still not a big problem.
On the whole, the Shimano aero brake levers seem a fair bit better-made, just more positive hinge action and less side-to-side play of the lever. But then, they cost more too, and I don't expect the Tektro levers to fail on me or anything.
Here's a picture and the arrow is pointing to the rod that I'm talking about:
http://www.unc.edu/~cupery/pics/bike_parts/Tektro_lever.jpg
HillRider
01-29-07, 08:01 AM
If you can support the ends of the rod so you don't impact the plastic lever body, you could use a punch to flair the rod ends and sort-of rivet it in place. I don't think Loc-Tite will work on the plastic body so that is probably not an option.
One more possibility just occured to me; replace the rod with a suitable size bolt and use a Nylock nut on the other end. Not too fashionable but it will never come off or slip.
I've only seen Shimano and old Diacompe so this may not apply, but those levers have a set screw in the body that fits into a groove machined into the pivot rod to retain the rod.
TallRider
01-29-07, 11:33 AM
No set screw in this pivot rode. Using a punch to bulge both of the ends is probably the best solution, although the bolt+nylock nut would work as well. I'm just going to leave it for now because it's not really a problem, more of an annoyance that I know it's there and it's imperfect than it is a real problem.
A dab of supergule or epoxy would be my first pick. The rod most likely isn't rotating in the body, so anything that will prevent side to side motion would be sufficent. I have two pairs of these levers and haven't noticed either of mine having this problem.
TallRider
01-29-07, 11:47 AM
A dab of supergule or epoxy would be my first pick. The rod most likely isn't rotating in the body, so anything that will prevent side to side motion would be sufficent. I have two pairs of these levers and haven't noticed either of mine having this problem.
Ah, very good recommendation. That'll be my first option. Thanks.
I do like the shape of the levers for all-day comfort, although I don't feel as positive gripping them while out of the saddle as I do with the Shimano hoods that I'd initially installed (http://www.unc.edu/~cupery/pics/bikes/Centurion_Comp_TA_repainted/IMG_7721--Centurion_no_bar-tape.jpg) on the bike but found to be less comfortable with the flat-"ramp" Nitto Noodle handlebar. I'm running the Shimano aero levers on my fixed-gear bike now.
edit: btw, tried the super glue and it worked well. The rod is rock-solid; before I could feel it moving (if I stuck my thumb against it) when I depressed the lever.
HillRider
01-29-07, 05:46 PM
btw, tried the super glue and it worked well. The rod is rock-solid; before I could feel it moving (if I stuck my thumb against it) when I depressed the lever.
I wasn't sure if glue would hold on the plastic body, or might even damage it, which is why I dismissed the Lock-Tite idea. Glad it works.
TallRider
01-29-07, 07:53 PM
Is loc-tite the same thing as glue? My impression (and that's all it is) has loctite in a different category than super-glue at least...
Anyway, super-glue is good at bonding with plastics and seems to do well on the anodized or otherwise coated metal rod. Even if it only bonds with the plastic, it results in a tighter fit around the metal rod so there's not the possibility of play anymore.
loc tite only cures in the abscence of air. would not work in your application. sounds like you picked the right adhesive.
Glad to hear it worked. Sometimes the obvious answer is the easiest one over looked. :)
cascade168
01-30-07, 01:06 AM
Sometimes the obvious answer is the easiest one over looked. :)
Which is pretty much the theory known as Occam's Razor ;-)
TallRider
01-30-07, 06:04 AM
Which is pretty much the theory known as Occam's Razor ;-)
Not really - the principle of parsimony says nothing about whether the correct answer is likely to have been overlooked. It also doesn't actually say that the simplest answer is more likely to be true. Rather, the simplest explanation or model is more likely to be useful.
Tim (who is teaching a class at UNC on religion and science, focused mainly on history and philosophy, this semester)
HillRider
01-30-07, 06:29 AM
Interesting philosophical digression.
Anyway, no Loctite isn't a glue in the normal sense but it can serve the same purpose. It is an "anaerobic" setting resin, i.e., it hardens in the absence of air, so if it wicked between the pivot rod and lever body, it would set up in the annular space. There are grades of Loctite made specifically for this type of application and used tor fasten bearings and collars to shafts.
I was concerned it, or super glue, could attack the plastic lever body since I'm not sure what the lever body's composition is.
TallRider
01-30-07, 07:57 AM
I was concerned it, or super glue, could attack the plastic lever body since I'm not sure what the lever body's composition is.
Good point, and a potential worry. I've seen super glue attack rubber before, but not hard black plastic. It looks like it worked, but probably something I should have tested on the backside of the hood body first.
bravozulu
01-30-07, 08:51 AM
Loctite is funny that way.
I was recently reminded how it reacts with some types of plastics when I put a drop of "blue" on the threads of a a pair of momentary switches for an announce microphone.
I didn't want to overtighten them but didn't want to have to fix them again. The locktite softened the switch body at the threads and it popped them both apart like they were cut by the nut.
I am still a Loctite addict and use it by the quart (thanks to Harley-Davidson).
cascade168
01-30-07, 09:37 AM
Not really - the principle of parsimony says nothing about whether the correct answer is likely to have been overlooked. It also doesn't actually say that the simplest answer is more likely to be true. Rather, the simplest explanation or model is more likely to be useful.
Tim (who is teaching a class at UNC on religion and science, focused mainly on history and philosophy, this semester)
My understanding of Occam's Razor is that "All things being equal, the simplest solution tends to be the best one.". And in practice (most specifically in troubleshooting computer systems), the simplist solution to most problems are the solutions that are most often overlooked. The principal of Occam's Razor is constantly referenced in troubleshooting when problems seem to be getting defined as more and more complex. Usually (but not always), the problems lend themselves to simple solutions. When people start looking for complex solutions to complex problems, then it's time to step back and look for simple solutions. Hence, my reference. Please pardon me for trying to offer a practical application of this truth. It's the context in which Occam's Razor is commonly used.
FWIW, there IS no definitive quote of Occam's Razor. While this phase is attributed to William of Ockham, it has never actually been found in his writings. So, the point is, your argument about what it says, or does not say, holds no merit.
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