Rear dropout angles and frame geometry

[theery]

Hello there,
I'm designing my first frame by studying the geometry of my existing frames. My question is about seatstay-chainstay angles (and therefore also rear dropout angles).

In looking at dropouts, it appears there are few common angles, none of which match the angles of those on my current bikes. Can someone explain this? Without building their own dropouts, do builders generally need to design around the available dropout angles? Or are there adjustable ones?

Any help in clearing this up for me would be greatly appreciated.

[e-RICHIE]

All dropouts that have fixed angles are omni-directional enough so that they work outside of the as-cast shapes they are supplied in.

[David Tollefson]

Hooded dropouts are an option...

[Curt Goodrich]

Campagnolo 1010 drops came in one angle and still all frame sizes were a possibility.

[theery]

Thanks, guys. Would you mind elaborating a little bit? I'm still trying to wrap my head around it.

For example, it a dropout is 62 degrees, how would I make it work for a say, 66 degree seatstay-chainstay angle?

[e-RICHIE]

Thanks, guys. Would you mind elaborating a little bit? I'm still trying to wrap my head around it.

For example, it a dropout is 62 degrees, how would I make it work for a say, 66 degree seatstay-chainstay angle?

It depends. If it's a tab dropout, simply orient the two intercepts so that they mate with the pipes as you fixture them. If the part is a plug, you have to be more creative and resourceful; maybe file down the male parts so that they have some play, and let the stays find the sweet spot as you fixture the assembly. Conversely, it's the same with dropouts that have wells that hold the pipes.

[Eric Estlund]

For slotted drop outs you just come in at a different angle. Plugs and sockets have several degrees of wiggle. Beyond that you can grab another part, or do some physical manipulation.