Swan Neck

[Gromit C15]

Hi Folks

I have read the C15s had 'Swan neck' frames, what exactly does that mean?

Thank you in advance

[scifi]

I have never heard of that, but it could be something to do with the shape of the steering head lugs casting.

[DAVE BRADY]

Hi,

If you look at a bare C15, B40 and Tiger Cub frame you will see that the frame curves up quite dramatically from the top tube to the head stock resembling a Swans neck.
Considered a weak spot for competition so some bike modified with braces.  I believe the Tiger Cub tank serves as a brace for this weakness as it incorporates bracing in its construction to link the head stock to back of the engine frame loop.
Use Google for good photos.

Dave.

[V500]

The four-lug early T21/T100/etc frames were the same, and also used the tank as a stressed frame member. In about 1964/5 (from memory) they moved away and installed a frame top brace and non-stressed tank. A far better idea.