Touring - Stripped Rack Braze-ons
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02-22-08, 08:40 PM
I have an older Bianchi mountain bike frame that I am turning into a tourer. The frame didn't have anything covering the holes where the water cages and racks are installed, so I decided to place some screws in there to keep out water until I get the cages and racks. When I got to the braze-ons in the seat stays, the screw on the right side slid all the way in and on the left side, I was able to screw it in, but it seemed very loose to me.
Is there a different size screw that these take or are they stripped? I am assuming they are stripped, since the screws went into the braze-ons on the dropouts correctly. If they are stripped, is there a way to fix this? I guess someone could tap them again to a slightly larger size, but I am unsure if the tool could get there. But, if it is possible, what size should I get these tapped? If tapping is not possible, I guess the only other option would be p-clamps? I know p-clamps are not the best option, but since it has braze-ons on the dropouts would there be much if any difference in strength. I am assuming the strength comes from the dropout clamping and the seat stay braze-ons are mostly for stability.
02-22-08, 08:42 PM
I have stripped many braze ons through sheer stupidity, and I have found the best way to remedy this is use a longer bolt with a nut on the end.
02-22-08, 08:46 PM
Huh? How would that work?
Another option is to retap them for a larger size. There are some long distance world touring types who do this just to avoid the stripping in the first place. Metric stuff is designed so that the size smaller drill is the prep size for the tap. So a stripped 5 mm hole for a rack, would ideally get a 5mm drill run through it, then a 6mm tap. Bingo you have a place to put a 6mm screw after enlarging the rack hole to 6mm. This only works if the parts are large enough to allow the 1 mm diameter increase, but it must work often enough that people recomend it.
"Huh? How would that work? "
You get a longer bolt and a nut, run it all the way through the BO and nut it on the other side. This works with the little barrel jaspers since a longer bolt will poke out and accept a nut. It won't work if the original BO only has one end showing.
02-22-08, 09:18 PM
Oh, I know what you mean. If the braze-ons were the type that sit above the stays. No, these are the kind that are like water cage braze-ons where they sit inside the stay tubes.
I think retapping is the best way, but I don't see how a drill could be used, not enough room. Unless it was drilled at an angle.
02-23-08, 09:48 AM
Good news. Now that is lighter and I can see a bit better, the braze-ons are not stripped! They use a bigger screw. I had some screws with wingnuts from some bike laying around. I thought I would try them and they went in nice and tight. Now I just have to figure what size they are so I can get some new ones. These are flat head screws and I would rather have hex key type.
One thing I do know is that they are bigger than the water bottle cage size, (M5?) but smaller than the size for cantilever brakes.
02-23-08, 09:58 AM
Take the one that fits to the hardware store with you...;) probably an M7 Good news they aren't stripped tho.
02-23-08, 01:00 PM
Yup, just got back from the LBS. There is one about 5 blocks away that I use for small parts. Took the screw and bike of course. Got it all set up now.
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