Bicycle Mechanics - steerer tube mod.
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i've got a 1" threaded steer tube on my old schwinn. only problem is that the ID of the steer tube is 13/16" (not the standard 7/8"). as you may know, this seriously limits me in stem varieties(huffy). what i wanna do is get a 7/8" bit and drill out about 4" deep to allow for normal stem size. i would think that since the OD is standard 1" then the wall thickness would be brought down to 1/8" as normal, no harm no foul as long as i drill it straight. any thoughts on this opperation? am i crazy.. or cheap? thanks!
03-15-06, 06:14 AM
What you are wanting to do is ok with one exception, use a reamer instead of a drill bit.The end result will be a much better finish.
a reamer.. yes! thank you!!
03-15-06, 07:11 AM
Do you have good dental coverage?
I'm not so sure. All steels aren't created equal. Manufacturers frequently use thicker sections of weaker steels to get the strength they feel is required.
03-16-06, 07:51 PM
You only ream to the max depth of the quill.
04-20-10, 08:30 AM
Hello, and sorry to drag up an old thread as a first post. Has anyone done this and survived? I'm in the middle of doing this to a mountain bike steerer that I want to fit a road stem into, and I'm not sure about the risks involved. The late great Sheldon Brown says, here (http://www.bikeforums.net/archive/index.php/t-380151.html), that it should be okay, but it would be nice to know if it has been done successfully. Any input much appreciated.
04-20-10, 09:16 AM
I would shave the quill stem down as there is more material to work with than on the head tube itself....
04-20-10, 09:39 AM
That would be the sensible thing to do, but I'm using a nice expensive quill and a cheap bike, so the bike gives. Hopefully not literally. I'm hoping someone will say " i've done it without problems." We'll see.
04-20-10, 10:11 AM
Wet and dry on the quill stem, and a barrelload of patience? If necessary get a cheaper stem with the same dimensions, there are gazillions of them around. Best of luck!
04-20-10, 10:34 AM
Thats true, but they're all BMX shaped as far as I can gather. Its a crazy idea but I want to make a towpath tourer from a steel-framed 1989 Raleigh mtb, which came with a 21.4mm internal diameter steerer, external being normal 1" size. planning to use a Nitto stem/bar combo. The tubing looks thick enough to take the metal out, but it may be weaker and breakier and end up being painful. I'm not hoping for anyone's endorsement, just whether its been done successfully, or otherwise.... Maybe anyone who's tried it has gone quiet?
04-20-10, 10:54 AM
Maybe anyone who's tried it has gone quiet?
Or has lost the use of their typing fingers.
I would rather find a stem that works.
The other option is to use a threadless stem adapter.
04-21-10, 03:51 AM
Or has lost the use of their typing fingers.Or they're dead...
04-21-10, 04:08 AM
Or they're dead...
Ever notice how zombies are all stiff armed and legged? Probably affects words-per-minute.
05-04-10, 05:19 AM
Despite reservations all round, (and many thanks for the help and suggestions), i've gone and done it anyway. I am not recommending anyone else do this. The steerer tube got reamed first with a 22mm reamer, then a 22.2mm to accept the road quill. It was messy, hard work, and I'm going to be cautious with the result. The nitto stem has a ramp type expander which will put the interference pressure over a bigger area than the round expander type, so it may last. Steerer tubes are definately not all the same. A 'proprer' steerer tube rings when you flick it with your finger nail. This one 'plunks,' both before and after reaming.
In my experience, which has been 15 years of motorcycle service and repair, a mechanical mishap is rarely something that happens out of the blue. The first sign that this bodge is going wrong will be a loosening of the stem. That will be time not to re-torque the bolt but to start saddle-pushing to the nearest lamp-post. I measured the external expansion of the tube when a stem was tightened up in it, and it was the same 0.1mm that a genuine 22.2mm tube gave given the same treatment.
I should have been more patient/less tight-fisted, and bought a new 1" steerer fork for a 700c rim and had the canti posts moved. That is what will happen if this breaks (when I brake.) I'm well happy with the result so far though.
I have done one thing I'm not happy about. I'm confident that I will spot the impending disaster if there is going to be one. But if I sell this, with these forks, I may have created a problem for someone else who wouldn't recognise the danger signs. If you see it on ebay, come for a 'viewing' and bring a stick to beat me.
05-04-10, 03:47 PM
In my experience, which has been 15 years of motorcycle service and repair, a mechanical mishap is rarely something that happens out of the blue. The first sign that this bodge is going wrong will be a loosening of the stem. That will be time not to re-torque the bolt but to start saddle-pushing to the nearest lamp-post. I measured the external expansion of the tube when a stem was tightened up in it, and it was the same 0.1mm that a genuine 22.2mm tube gave given the same treatment. Well, I have to commend you on the effort, good job! The expansion is about correct as the Young's modulus doesn't change for steels of different fatigue and ultimate strengths. A stronger steel will just last longer. Depending upon where the seam is on the steerer, it may last quite a while. Have fun!
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