K2 / Proflex Riders Group

General => Tech Forum => Topic started by: Carbon_Angus on March 18, 2017, 09:00:46 am

Title: Crack seat tube on BB weld
Post by: Carbon_Angus on March 18, 2017, 09:00:46 am
Hi guys...not a proflex but a 2004 stumpjumper. I still have one Pro~flex  :)in my stable though. LOL And I trust the opinion and kind responses on this board as always

I'm thinking this is toast because of location. The area would seem to take a lot of stress. I noticed it when I was hammering the pedals up a hill. the whole BB area flexed and at first I thought it was a loose BB or BB cup problem. It had what I though was a minute albeit deep scratch when I built the bike up a month ago.

Looks like it will be recycled into some pie tins or coke cans. But looking for a quick opinion 'cuz I know a few of you guys from way, way, way back.

PS I've cleaned it up with a toothbrush and it's still there.
Title: Re: Crack seat tube on BB weld
Post by: kiwi on March 19, 2017, 02:31:58 pm
someone here knows a lot about weding and alloys,cant remember who it is though!!!Hopefully he will be along soon!
Title: Re: Crack seat tube on BB weld
Post by: Carbon_Angus on March 20, 2017, 11:06:11 am
I had one by the house who was familiar with welding aluminum and said..let  me see what I can do. Granted he is good.

The LBS I've been seeing for years was a drive from where I live but he took one look at it and said...nope, not there.

If any of you still have an opinion, share if you like.

The frame has been cut and recycled. After lamenting I realized I had a similar era frame of same size in my shed so all is not lost except for a sezxy raw aluminum frame. Maybe next winter I'll have a frame stripped so I have something to do.
Title: Re: Crack seat tube on BB weld
Post by: Tel on March 20, 2017, 12:19:56 pm
Not seen him on here in an age but Shovelon is the man, if Terry doesn't know its not known.
Title: Re: Crack seat tube on BB weld
Post by: kiwi on March 22, 2017, 01:48:24 am
Not seen him on here in an age but Shovelon is the man, if Terry doesn't know its not known.


according to the power of id riders he was last active here March 17, 2017, 09:21:38 am,message him Carbon!
Title: Re: Crack seat tube on BB weld
Post by: shovelon on March 28, 2017, 06:20:59 pm
I pop in on occasion. I really need to ride more.

Anyway the key is what alum alloy the frame is. If it is 6061 then it is probably toast because it will loose it's temper.  If it is 7005 it can be weld repaired with 5356 or 5183 filler and not need retempering if "cold welded". It is a time thing. 6061 de-tempers in minutes as opposed to 7005 de-tempering in hours.
Title: Re: Crack seat tube on BB weld
Post by: Carbon_Angus on April 01, 2017, 11:50:56 am
Thanks for the info. I may have been too hasty with trashing the frame without finding out exactly what grade of aluminum was used.

All the parts (mostly from an Oz frame )except the seat post and obviously the hanger went onto a Giant Boulder SE frame.