Seat Tube Confusion
 

I'm embarking on designing my first frame and ordering the tubes and such and I'm having a hard time understanding when/if a seat tube collar is needed. I'm trying to find the right seat tube to buy and just a bit confused. I'm building a SS Mtb and the BikeCad model I'm going off of has a bent ST which has been hard to find. I found one on frame builder supply but it's external butted which I don't know if I need a seat tube collar with it. I'm diving straight in but need to learn a lot!

More specific info needed. Steel or other material? Is SS mtB a single speed or a Stainless Steel reference? How about the found ST dimensional specs? Andy

Thanks Andy! Steel single speed mtb. The ST length is 450mm

If it's external butted you can just TIG weld right onto that. That's basically why they do that. Obviously make sure you cut any extra tube you don't need off the bottom so you're keeping the fat bit that you need :)

Then you can just leave a bit of ST sticking up above the TT and stays so you can cut a slot and either just buy a collar to clamp the seat-post or weld on some kind of a pinch-bolt. I leave 48mm of extension which works well but you probably don't need that much.

This is great. Thank you!