Be your own brand.

Back to front or front to back…

After Brant found me on Twitter (Hello, and thanks for the mention!). He reminded me of his experience with forward facing slots on extended seat tubes – ie, like the White Lines, ‘Don’t do it!’. I realised that I’d not mentioned it yet and thought it worthy of a few words…
Seat clamp on Ti-Bride - note plenty of clearance between the weld and the seat tube slot.

Seat clamp on Ti-Bride - note plenty of clearance between the weld and the seat tube slot.

He feels that titanium frames are particularly vulnerable to cracking around the extended seat tube area when running a forward facing slot. Designers normally specify extended seat tubes to make the frame triangles smaller which increases strength and stiffness while reducing weight – it also looks cool too 😉 Forward facing clamp slots became the norm as people felt that it meant less crud getting into the seat tube as you move your saddle up and down.

On the Ragley Ti, Lynskey keep the seat clamp area very conservative with a standard rear facing slot and very little extension of the seat tube over the top tube.

Porter cautioned me on this as well so it’s probably a tip worth passing on, his email was a bit garbled but I think he suggested a seat tube extension of around 25 – 35mm. Ti-Bride had an extension of 43.7mm which was made without comment the last time. On the original drawing of L.Y.L.T the dimension was 37.7mm. The slot depth is 33mm and I didn’t want the weld to get too close to the bottom of the slot so I specified an extension of 42mm.

The Genesis Altitude is typical amongst some and shows a generous extension beyond the top tube.

The Genesis Altitude is typical and shows a generous extension beyond the top tube.

Before making my choice I took a look at what other people are doing – the Charge Duster Ti, Cotic Soda and Genesis Altitude Ti all seem very comfortable with putting the seat tube out there and sticking the slot towards the front. Cotic even extend the seat tube a whopping 60mm above the top tube. Surely if it was that dodgy we’d have heard of frame failures  before now?

Brant commented that with the incoming CEN test certification we might see a number of manufacturers having to review their designs to make them compliant – let’s see what happens…

This Cotic drawing shows how close L.U.L.T. is to a medium Soda. If it's to scale it also shows that the seat tube extends a whopping 60mm above the top tube!

This Cotic drawing shows how close L.U.L.T. is to a medium Soda. If it's to scale it also shows that the seat tube extends a whopping 60mm above the top tube!

Personally I’m happy with it as it is, and I’ve ridden Ti-Bride for a year without incident. It’s probably worthwhile to note that I’m pretty light and have a 400mm seat post sitting well into the frame that’ll help distribute stress around that area. If you enjoy the odd pie or want to be on the safe side then it’s a point worth bearing in mind when you design your frame…