Just wondering...changing tubes in a frame?

[slowandsteady]

A friend asked me this question yesterday and though I had thought about it had never really considered it as a viable option. I had some ideas but wondered about the actual possibility of doing something like this.
I'll use my own bike as an example (he has a similar "problem")

Ti Frame and the top tube is too long (58.5)
Can you have your builder (serotta) cut down (or replace?) the old TT with a shorter TT? I am looking to go to 55. I assume you would also have to replace or cut (and change the angle) of the Downtube at the same time? The frame would need re-painting though in my case I would strip the paint and leave bare Ti.

Can it be done?
What kind of cost are we looking at?
How would effect the bikes handling etc.

[William]

http://www.uncrate.com/men/images/stanley-fatmax-hacksaw.jpg

http://www.repairproducts.co.uk/userimages/jbweld_lrg.jpg


Ride report please. ;)





William

[David Kirk]

This is one of those things that can be done but it's debatable as to whether it's a good idea or not.

To replace the top tube with one of a different length the builder will also need to replace the head tube and in almost all cases the down tube. A 3 tube replacement is an expensive proposition even before you get into refinishing the frame.

I think the best thing to do in cases like this is to sell the current frame and buy one that is the proper size. It won't cost much more and it will be as it should be and not be a 'repaired' frame.

Dave

[slowandsteady]

That's kinda what I thought and coming from you Dave is pretty much the final word :-)

[Volant]

This is one of those things that can be done but it's debatable as to whether it's a good idea or not.

To replace the top tube with one of a different length the builder will also need to replace the head tube and in almost all cases the down tube. A 3 tube replacement is an expensive proposition even before you get into refinishing the frame.

I think the best thing to do in cases like this is to sell the current frame and buy one that is the proper size. It won't cost much more and it will be as it should be and not be a 'repaired' frame.

Dave

Dave,
Why couldn't you make a cut/re-miter just behind the head tube on both the top tube and down tube and weld-in a new head tube. The head tube will need to be longer now, but you can keep the angles the same. FC gets shortened, so gotta check toe-overlap. But, why would you need to replace the down tube as you described?

[Mike748]

The bottom of the new longer head tube will be lower (closer to the ground). Unless you could take a corresponding amount off the fork bridge, the front end will now sit too high.

[David Kirk]

Dave,
Why couldn't you make a cut/re-miter just behind the head tube on both the top tube and down tube and weld-in a new head tube. The head tube will need to be longer now, but you can keep the angles the same. FC gets shortened, so gotta check toe-overlap. But, why would you need to replace the down tube as you described?

As you shorten the top tube the angle that the DT meets both the head tube and BB/seat tube tightens. when you re-miter the front end of the DT you can take care of this but the other end will be off and you would need to flex the DT up but a degree or so. Not a great thing.

Can it be done with replacing the DT? Maybe. Should it be? I don't think so.

dave

[bobswire]

Very short stem.... :beer: