Seat Stay Question

[Thomas Norton]

On my Surly LHT touring bike the SS are brazed/welded to the backside of the ST. In my class,with Doug Fattic, I brazed them along side od the ST cluster.
Is one "stronger " than the other? Kinda thinking sheer strength.
Thanks!

[Andrew R Stewart]

I suppose the fast back stay style, if attached to a butted tube portion or lug, would test out at being stronger in a destruction test. However, in real life when both styles are well brazed neither proves to be too weak or less than the other. When my assumptions stop is when the fastback stays are attached to the thin non butted tube location. The stays can (and I've seen this happen) start to "punch a hole" in the seat tube back side and/or more readily crack at that weld/braze.

What is a difference that maters is the tire clearance around the tire at the seat stays. If the stays are straight and they come together behind the seat tube that clearance is far less than with side of lug attached stays. Andy

[Paul Jacobs]

I think that frame is TIG welded. It would be more difficult to make a neat looking join by TIG welding the seat stays on to the side of the ST/TT junction compared with brazing them in that position, I think. Also, with brazing, a large area of contact for the filler is advantageous whereas the welded joint occurs just on the edge of where the tubes contact each other. As Andy says, the thickness of the tube the stays are butted on to is important, as are the diameter and thickness of the stays themselves. Other TIG welded frames use a similar configuration to the Surly LHT.

https://www.wkndr.cc/

[Thomas Norton]

Thanks for your replies!
The project I have in mind is a frame with the same geometry as my LHT but it be with a sloping TT. Almost like a mixte. So I want to braze the SS along side. Initial idea is to braze a sleeve atthe top of the ST to do double duty. Add thickness and create a seatpost clamp.