Bike Forums - Dropouts not parallel

Bike Forums (https://www.bikeforums.net/forum.php)

- Bicycle Mechanics (https://www.bikeforums.net/bicycle-mechanics/)

- - Dropouts not parallel (https://www.bikeforums.net/bicycle-mechanics/1141586-dropouts-not-parallel.html)

Thanks Andy!

Your contributions have been invaluable reflections of the real world.

John

Quote:

Originally Posted by Andrew R Stewart (Post 20295459)

Real life does things to theory, speculations or hope. When I read people saying that a jig insures alignment and I see frequently enough misaligned carbon/bonded frames I have to side on what I see. I've seen many minor wheel sitting "offnesses" on many brands and types of bikes (mostly road as they comprise most of the carbon built bikes I've worked with), both forks and rear ends. The tight clearances of TT bikes have been especially prone to power induced tire rubs when this off center wheel stuff happens. I have shifted the dish of a few wheels to compensate, not the best solution but sometimes you do what you need to. I have filed quite a few drop outs, mostly on forks, to allow the wheel to center at the brake/crown/stays.

This is rather interesting to me as a many year "gentleman builder" and also as a front line shop wrench. What I do in a LBS isn't always what I am happy with at home in my own shop. For years I have wondered about carbon frame alignment, seeing what I see and knowing what I do about steel frames. I've never bothered to pursue carbon frame tolerances in a setting where real numbers are found. But this thread has me rethinking my lack of motivation to measure carbon frames on my flat surface and use the same methods of testing I apply to my own (and other's) steel frames. (Why take time when I had no interest in trying to make one and also knowing that any corrections are limited?) So I have a new project that I'll follow up on in my own sweet time. At some point, likely this fall, I'll do some checking on whatever carbon frames I can come across (and take home for a while) and post back. Andy

I agree with all of the above. However, the jig does "insure alignment" - the bike will come out exactly as straight or crooked as it is clamped into the fixture. Unlike the warping that can happen with aluminum frames during heat treatment, CF doesn't want to warp during curing.

So when we see CF frames that aren't straight, it is because they weren't clamped in the jig correctly or the jig was not aligned. Or with CF forks, the dropouts were inserted after the rest of the fork was molded without the proper use of a fixture.

It would be dispiriting to check an expensive production carbon frame on an alignment table since there is so little you could do about it.

Quote:

Originally Posted by Kontact (Post 20295343)

I don't think every thread starter is obliged to jump through hoops for any poster that demands a picture or wants their opinion acknowledged. Especially posters that largely ignore the information already posted in the thread. THe OP sounds VERY thorough in his inspection of his frame and in trying multiple wheels.

If you believe there is some avenue left unexplored, you should point to what it could be rather than imply that withholding a photo from you is some sort of cover up.

If this was a metal frame or hadn't been closely inspected already there would be more to check or other solutions to consider. But the fact that this bike consists of small pieces of aluminum glued decades ago into unbendable carbon tubing limits what can be done without causing damage. Minorly truing up the dropouts with a file accomplishes what the OP needs without extra inspections that won't yield solutions - it doesn't matter if the whole frame is crooked if you can't fix a crooked CF frame or the dropouts can't be bent without straining the bonds.

It's not cool for the OP or someone else working with em to take something private -and expect US to take their word for it - on a thread that was PUBLIC and OPEN to start with.

Intended or not, it DOES carry the odor of "something to hide." Keywords = "intended or not"

Actually, it's kinda rude...and it is certainly NOT unreasonable to request pics / images for a further look.

It's par for the course almost here in the Bicycle Mechanics forum.

=8-P

Quote:

Originally Posted by mrrabbit (Post 20295556)

The OP isn't hiding anything, and it is ridiculous to assert he is just because I chose to reveal part of my conversation with him. As you can clearly read in the thread itself, the OP both said and was advised multiple times before you came along not to base his measure on one wheel.

He doesn't need to prove anything to you just because you assume people are knuckleheads. The purpose of this subforum is to solve people's mechanical problems, not to satisfy subsequent posters' desires for vindication. The OP asked the right questions, checked the right things and got useful answers which he successfully executed. It's a win all around.

Quote:

Originally Posted by mrrabbit (Post 20295556)

It's not cool for the OP or someone else working with em to take something private -and expect US to take their word for it - on a thread that was PUBLIC and OPEN to start with.

Intended or not, it DOES carry the odor of "something to hide." Keywords = "intended or not"
Actually, it's kinda rude...and it is certainly NOT unreasonable to request pics / images for a further look.
It's par for the course almost here in the Bicycle Mechanics forum.
=8-P

Let me try to shine a little light on your comments and the thread in general.

I have actually PM'd 2 participants in this thread. Neither of those 2 PM's were regarding the repair or soliciting additional advice. Everything I had to say about the repair has been presented in this thread. The basis of these PM's were to introduce myself to these members while thanking and agreeing with their comments and input throughout this thread. Nothing more, nothing less.

The reason I dropped out of the conversation was that I thought I had been clear that the problem had been fixed to my satisfaction. At that point, I did not revisit the thread that often. If others want to continue this conversation regarding dropout alignment or who thinks they have the best answer... then go for it. I came and asked a question, I got some good advice, I applied what I thought was the best solution and confirmed that solution worked.

Your frame is bent. The rear triangle is pushed over. Use the string test to measure the rear triangle Frame Alignment.

If you don't know what the string test is look it up it's really easy and it works.

Quote:

Originally Posted by San Rensho (Post 20298498)

Explain how a carbon fiber frame gets bent.

If you don't know that a CF frame can't bent it's easy to look up.

Quote:

Originally Posted by San Rensho (Post 20298498)

How do you know this (set aside the "bent"/"pushed over" reference) that the frame's rear end is off center? A wheel can sit off center at it's rim/stays location and have the hub on center very easily. Andy