Lug/BB Reshaping (changing angles)

[mxboy349]

Question on lug/bb reshaping. BB shell I purchased is a 60° x 62° x 7.5° (“Richie-issimo Series”). My design with the fork I am using will require the 62° to be more like 66°. Can the CS sockets be “reshaped” for this much of a difference? Bend the CS slightly to make up the difference? Am I crazy and I shouldn’t even be close to 66° for an angle of the CS? Am I way off base on anything? For my design I am just copying and existing frame that I ride with a slightly less “standover”. Attached is a pick of my design.

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[Pi Guy]

Assuming this is a standardish road bike your BB drop seems a bit small to me. Please keep in mind that I am only speaking from my limited experience (10 frames).

[Eric Estlund]

No comment on the design (I haven't clicked on it yet), but changing angles in lugs and shells is par for the course. Stick a piece of bar in there, grind away, hammer, etc. Make the parts work for you. Of course, some parts might need less "encouragement"- that's why there are so many great BB shells on the market. But don't be afraid to lean into it a bit.

[Andrew R Stewart]

The chain stay sockets can be bent a bunch. Do as much as you can prior to attaching any tube, if you screw up it's easier to start over with only the shell the loss.

I will comment on the design. Why so tall a BB height? Are you running 185mm arms? Pedals from a exercycle (which have a lot below the axle)? Will this be a fixed gear bike?

[Andrew R Stewart]

As I look more at the design i have more questions. Axle to race is 365mm- Is this correct? Is the tire diameter 688? If so then the fork height is really tight. If you are running long arms or have big feet or run fenders the front center is a bit tight (espically with the 33mm tires).

One of the reasons to build your own frame is to try out stuff no one else is building. But there's a reason that the manufactured bikes fall into such a narrow range of geometries... Andy.

[mxboy349]

Andy-Fork is off the shelf and it is 365mm Axle to race, I have measured it twice.. Don't have the skills to build a fork yet. I have the tire diameter drawn at 668 (700x23 tires). BB height is a "result" of the fork. From what I can tell the "off the shelf" fork is painting me in a corner with the rest of the frame geometry. Seems like I may have to play with the DT socket on the BB and the DT/HT socket to get the geometry in the norm.

[Mtblucas]

The chain stay sockets can be bent a bunch.

I just finished a front triangle and am working on the chainstays. Even after working on the CS sockets with a rotary tool they are still off by a degree or two. I'm a little worried about hollowing them too much. I am trying to decide if I want to bend them and am wondering if the chainstays themselves are strong enough to do the work. I'd assume oval chainstays would be plenty strong enough to not kink under pressure but I didn't want to risk it without seeing what y'all think first. Thanks!



Matt Lucas

[Eric Estlund]

Singing tubes as a lever isn't a great idea. At least not the ones you intend to use.

[Cooper Cycles]

I like having BB cups threaded in when using brute force to manipulate the BB to prevent ovalizing...

Have Fun!
Travis

[mxboy349]

Made a "persuader" and it worked like a champ. All I had was a short piece of stock, but it was long enough to put a "cheater" bar on and get the job done. Thanks to all for the tips.

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