suburbanreuben
Old School Grand Master
Sunn are well made, highly respected bikes. Maybe the welder just had a longer lunch than usual... 
Seat tube crack - advice wanted
- Thread starter renaldo
- Start date
It would be interesting to know how you get on with Roberts. I didn't know they did welding. Most brazers think welding is the work of the devil and when you look at that failure they may have a point.
Having said that, it sounds as though your post has been the source of the stresses that have made the tube fail. If it's so small that it has to be mega-clamped, it means its only solid contact is at the very top of the tube and lower down it can move laterally against a fulcrum only just below the area of the tube damaged by the welding. The result is what we see. If the post had been filling the seat tube to minimise lateral play and the fulcrum was 5cm further down, that break may not have happened.
I'd be surprised if you get away without a new seat tube myself, but best of luck anyway.
Having said that, it sounds as though your post has been the source of the stresses that have made the tube fail. If it's so small that it has to be mega-clamped, it means its only solid contact is at the very top of the tube and lower down it can move laterally against a fulcrum only just below the area of the tube damaged by the welding. The result is what we see. If the post had been filling the seat tube to minimise lateral play and the fulcrum was 5cm further down, that break may not have happened.
I'd be surprised if you get away without a new seat tube myself, but best of luck anyway.
OK so I have my frame fixed and back from Roberts. I didn't get to speak to the guy who did it but I think they have brazed some brass into the crack and may have run the welder through it first too. Pics below. They seemed happy it was good to ride as normal which is the main thing, just needs a lick of paint.
Only problem now is that the sticker on the top tube has shrivelled from the heat. I'm going to call the distributer to see if they have replacements but I'll be amazed if they have any. Was thinking about getting a graphics / signing place to make a new one but I don't think I'll be able to get an exact copy as it has the raised oval shapes on it. The other alternative I can think of is to just cut off the shrivelled bit and leave it short. Any ideas?
Only problem now is that the sticker on the top tube has shrivelled from the heat. I'm going to call the distributer to see if they have replacements but I'll be amazed if they have any. Was thinking about getting a graphics / signing place to make a new one but I don't think I'll be able to get an exact copy as it has the raised oval shapes on it. The other alternative I can think of is to just cut off the shrivelled bit and leave it short. Any ideas?
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suburbanreuben
Old School Grand Master
Blimey, that was quick. :shock: 3 weeks turnaround must be some sort of record.
Beauitiful repair, innit?
Beauitiful repair, innit?
Looks a decent job they have done.
Before you refit the seat post is it good fit in the seat tube ?
I've had bikes from new with the wrong size post fitted and it stresses the top weld just about where yours has broken.
I don't like seat posts that drop into the frame when you undo the clamp, I find they usually have play in them when extended to riding position.
Before you refit the seat post is it good fit in the seat tube ?
I've had bikes from new with the wrong size post fitted and it stresses the top weld just about where yours has broken.
I don't like seat posts that drop into the frame when you undo the clamp, I find they usually have play in them when extended to riding position.
Agreed on the job, looks great! You must be the first owner of a brazed/welded sunn frame I'm sure it will inspire a few others on here with similar problems.
It may be worth sending a PM to the Gil_m on here who is the resident decal guru on here, although in my option I would lose the yellow graphic and try to keep the sunn decal on the top tube if possible, then it would look understated and cool...
I'm sure it will inspire a few others on here with similar problems.It may be worth sending a PM to the Gil_m on here who is the resident decal guru on here, although in my option I would lose the yellow graphic and try to keep the sunn decal on the top tube if possible, then it would look understated and cool...
suburbanreuben
Old School Grand Master
Would you expect anything less from Croydon's finest?
