Crack at top of sear stay : repair or bin?

I've always believed that if there is a structural failure, the prudent thing to do is to scrap it. In the end, even a repair may wind up costing you a fortune. I think the first thing to consider is the frame itself...is it worth fixing? Is this frame a vintage collectible or just a scrap bike. An old aluminum frame may not be worth saving at this point.

5 years from an alloy road frame is good value, time for a new bike. 😉

jackchoo said:

hi...got a crack at the top of the seat stay where the seat tube goes in (see attached pic, thanks). Should i repair or bin it? I contacted a guy who says he can weld a plate a round the cracked area (prob don't look good cosmetically) while some shops tell me to bin it.....the cost of repair over here is about 100USD for the welding and painting for that cracked area.

If I go for the 'repair' route, I wonder how reliable it will be. Appreciate your ideas/advice or experience on this point.

Its a GT ZR 2.0 7000 series aluminium road bike (about 5 yrs old). Its a pretty light frame.

I don't know if 5 years is good value for ANY bike, but ...

Just how short was the portion of the seatpost which was inserted into the frame?

Just as a rule-of-thumb, I think that the seatpost should probably be inserted so that the BOTTOM extends BELOW the lower junction of the of top tube with the seat tube (except on an old, steel, GIRL's frame) ...

So, if your current seatpost in the GT frame isn't as long as I suggested that I think it should be, then make sure your next seatpost does in your next frame.

OR, if you do have the frame repaired (i.e., TIG welded, then filed smooth, then reenforcing collar TIG welded over the existing break with a gusset extensions ON the collar that go down-to-and/or-below the top tube junction), just rattle-can the paint the repair (it's a "TRUE BLUE"😉 AND get a longer seatpost.

Do they heat treat 7005 aluminum for bike frames? If so, then the repair will never be as sound as new. Even the reinforcements have to be welded to something.

That $100 would go far toward the purchase of a new frame.

Also, you're playing with your life here.

Nashbar or Performance will sell you a frame for $200-250 on sale.

It is getting pretty unanimous here. I recommend you start looking for a new frame, or a new bike if you want all the latest bits and goodies:p.

Hi guys, thanks for all your replies, they have been really helpful. Looks like its high time I begin hunting a new/used one!

Hi Jacko,

It doesn't sound like much of a debate so I'm going to
stand up for the other option (and disagree with the cognoscenti).

I would remove the cracked section and the present seatpin
and replace it with an external seat post clamp (collar).

I'm not sure I would rely on an alloy frame section to
provide enough strength for the seatpin anyway,
I'm guessing that's why everyone uses collars now.
so I'm not surprised that it cracked.

Do you think you may have over tightened the seatpin a while back?

regards, Matt.

MattAussie66 said:

Hi Jacko,

It doesn't sound like much of a debate so I'm going to
stand up for the other option (and disagree with the cognoscenti).

I would remove the cracked section and the present seatpin
and replace it with an external seat post clamp (collar).

I'm not sure I would rely on an alloy frame section to
provide enough strength for the seatpin anyway,
I'm guessing that's why everyone uses collars now.
so I'm not surprised that it cracked.

Do you think you may have over tightened the seatpin a while back?

regards, Matt.

Looks to me like there is not enough material left to slip on an external seat post collar once he cuts off the cracked section. Actually external seat post clamps really did not become common until aluminum frames became more common. Up until then, most steel and alloy bikes worked quite well with an integrated seatpost clamp. Actually if you check CF Bikes, many of them do not use an external seatpost clamp.

Well, I just got myself a used italian steel frame (circa mid 80s, I think) and getting it spray painted now. I will transfer all the uiltegra parts from the GT frame (which cracked) to this bike. Thats on-going now, ETA around 2-3 weeks I guess (still painting the wheels etc)

Back to the GT cracked frame.....I went to someone quite renown in the local bike circle and he mentioned that he can fix it (welding the crack AND welding a reinforcement place around the area) .

Well after my steel bike is ready, I might go this route and convert it into a cruiser (with flat bar) and old skool Shimano Sante parts (from the current steel bike I'm restoring).

Regarding the tightening of the seatstay nut, yes I think i screwed up and tighten it too much, but the problem was that the seat kept sliding into the tube previously.....can I opt for those special type of seat post whereby you tighten at the post itself rather than on the frame. These are neat! I think they are campys....

Good on you for REPAIRING it🙂
I've had alloy frames repaired with success.

jackchoo said:

Well, I just got myself a used italian steel frame (circa mid 80s, I think) and getting it spray painted now. I will transfer all the uiltegra parts from the GT frame (which cracked) to this bike. Thats on-going now, ETA around 2-3 weeks I guess (still painting the wheels etc)

Back to the GT cracked frame.....I went to someone quite renown in the local bike circle and he mentioned that he can fix it (welding the crack AND welding a reinforcement place around the area) .

Well after my steel bike is ready, I might go this route and convert it into a cruiser (with flat bar) and old skool Shimano Sante parts (from the current steel bike I'm restoring).

Regarding the tightening of the seatstay nut, yes I think i screwed up and tighten it too much, but the problem was that the seat kept sliding into the tube previously.....can I opt for those special type of seat post whereby you tighten at the post itself rather than on the frame. These are neat! I think they are campys....

No way. Frames / bikes (even aluminium) can easily last much longer than 5 years.
Sadly its usually 'fashion' that dictates changing one's bike:o .
I've had my steel framed singlespeed training bike I train on most of the time since new 13 years ago and its still going great🙂

I come from a family that (usually) keeps stuff for years - last year I inherited my dad's 1967 VW Beetle he'd had as (basically) his only car for the last 37 years !! Its still very good too.

gclark8 said:

5 years from an alloy road frame is good value, time for a new bike. 😉