Shovelon's corner--Aluminum frame breaks

[Thunderchild]

Shovelon, this one is for you.  Not a Pro flex, but a Mongoose Canaan Elite broke at the seat tube(this topic is related to pro flex by frame material .  This is/was my buddy's bike.  He has been riding it for 2-3 months.  He weighs about 165 and does not ride hard downhill.  The crack started at the weld and migrated horizontally around both sides of the seat tube.  When I saw it, it had cracked about 3/4 around the tube.  So, was this a design flaw, material problem, bad weld or something else?  
Was real interesting riding my 1998 Pro Flex 5000 with thousands of miles on it and still working fine (albeit you fixed the water bottle cage braze on cracks) with his bike with fewer than 300 miles on it.  He is getting a frame replacement.  I have tried to convince him to use his frame credit to buy a different bike without much luck.    
Others have broken too.
http://www.mtbr.com/cat/bikes/xc-suspensio/mongoose/canaan-elite/PRD_414731_1526crx.aspx

Thunderchild

[shovelon]

Shovelon, this one is for you.  Not a Pro flex, but a Mongoose Canaan Elite broke at the seat tube(this topic is related to pro flex by frame material .  This is/was my buddy's bike.  He has been riding it for 2-3 months.  He weighs about 165 and does not ride hard downhill.  The crack started at the weld and migrated horizontally around both sides of the seat tube.  When I saw it, it had cracked about 3/4 around the tube.  So, was this a design flaw, material problem, bad weld or something else?  
Was real interesting riding my 1998 Pro Flex 5000 with thousands of miles on it and still working fine (albeit you fixed the water bottle cage braze on cracks) with his bike with fewer than 300 miles on it.  He is getting a frame replacement.  I have tried to convince him to use his frame credit to buy a different bike without much luck.    
Others have broken too.
http://www.mtbr.com/cat/bikes/xc-suspensio/mongoose/canaan-elite/PRD_414731_1526crx.aspx

Thunderchild

Could be the seat stay is reamed too large, enabling the post to wobble and eventually fatigue the area. Cant see how the weld would be at fault, as it did not break in the weld itself. Definately design flaw.

Whatever the case, I would go after another bike myself. The reviews look pretty bad. I see that the seatpost is 31.6mm. instead of a 31.8mm. Hmmm.

Terry