Anthony Taylor wrote:
> Eric,
>
> "Stop drilling" as it is known is a widely accepted method for stopping
> crack propogation. It is even commonly used in the aviation industry.
> The only thing you need to be careful of is that you really catch the
> end of the crack (they often extend beyond the point where they are
> visble to the naked eye). The best way to determine this is to have a
> "liquid penetrant test" performed. Chech your local phone book under
> "test labs". Weld repair is the best permanent repair. A good local body
> shop can do this for you.
>
> Hope this helps.
>
> Tony Taylor
> Manchester NH
>
> Matthew,
>
> The easiest way is to drill the bottom of the crack, an 1/8" hole should
> be fine.
>
> Take the seatpost, insert it to the depth of the slot and gently pry the
> top of the seat tube 'till the slot sides are parallel and the ears are
> straight.
>
> If you have access to reamers, use them to clean up the inside of the
> seat tube, if not at least use a round file to clean up the slot and
> around the top so it won't mark up your new seatpost.
>
> Find a long, MB type seatpost in the proper size, probably 27.2mm. The
> long seatpost will extend way past the crack and will eliminate any
> further stress on that area.
>
> You should be able to ride it for years that way, but do glance at it
> from time to time <g>
>
> The proper repair would be to have the seat tube replaced, but that is a
> bit more involved and and pretty expensive too.
>
> Have fun,
>
> Rick Burns
> Streator, IL usa
> _______________________________________________
Tony,
NO, you didn't help me a bit: Matthew is the one with the problem.
Of course he would have a bigger problem if he welded it as you recommend.
If that crack was welded, you would never get a full-sized seatpost back in without reaming. Try reaming that and you will find out how expensive reamers really are <g> Plus the weld and the brass running out of the seat lug won't help the paint at all and I don't think that Matthew was looking for a 300.00 paint job for a rider.
The key here isn't drilling the crack, but removing the stress that caused it. This is done by opening up the seat tube to accept as close to a full sized seatpost as possible and by using a longer seatpost to transfer the load to well below the damaged area.
Remember the ears, binder, whatever is only to keep the post from falling down inside the tube, it isn't designed to prevent lateral play from an undersized seatpost.
Best wishes,
Rick Burns
Streator, IL usa