Frame Feature:
DROPOUTS of Death!

Sorry for the sarcastic title, but someone equated these dropouts to death which is retardedly funny to me. Okay, there has been a lot of interest, debate and speculation on the internet about the Sunday frame’s hollow dropouts. Why would somebody make a thicker dropout when everyone is going to thinner ones? This is simple because when you thin the dropout from a 1/4 inch to 3/16 inch, you end up reducing the strength by about 40%. That is a great reduction in strength for a simple 1/16 of an inch in weight savings. So what happens when you add a 1/16 of an inch to a 1/4 inch dropout, but make them hollow? You get a dropout that is twice the strength and the same weight as a normal dropout.

Outside and inside views. Please not the tapered “Sunday” stamped caps on the outside and the tapered seat and chain stays on the inside create a smooth transition to the dropout. Just super clean with smooth lines.

Peg side clearance and non-peg/axle clearance. Small and out of the way is what these dropouts are trying to achieve. I am pretty sure that this has been achieved.

So, now you are wondering how in the world is a hollow dropout constructed? I can’t fully divulge the process, but let me just stress that the dropout is made from forged parts to make a hollow structure that saves weight and is stronger than a basic “plate”. Nearly all non-hollow dropouts are simply cut from plates, there isn’t any forging or machining done just simple cutting out like a Christmas cookie. Naysayers out there should consider that lots of engineering structures use fabricated hollow parts. Some examples are airplane wings, car chassis members and suspension arms, motorcycle frames, super expensive mountain bike swing arms etc. These examples can be very strong for their weight provided the detail is engineered right… and these ARE engineered right.

To show the dropout width to scale.

Width 8mm roughly equal to 5/16 inch.
Material-Forged 41Thermal 4130 chromoly.
Size-Small enough for a 1.5 inch diameter peg to fit cleanly without any dropout hangover, so no cutting is needed to fit your dropout to the peg.(See above)
Internally-Walls surround all the outside edges with support across the dropout to prevent crushing.
Axle Slot-14mm

Next Feature Highlighted: Brake mounts
Just so you know the bike below weighed in at 25lbs using a home scale with a .5lb error range and that was with 3 pegs.