Bottom Bracket Shell Hole Angles
 

Before 1990 (8 speed) were the bottom bracket holes made to line up to a 120 or 126mm Outer Locknut Dimension?

There is enough slop in the chainstay sockets that the rear dropout spacing doesn't really affect the angle. Maybe you would have to bend the sockets a little to get out to 148mm, but I'm not even sure about that.

Pardon me if I'm wrong, but IIRC you are obsessed with lug angles to a degree that nobody else is. I suggest you draft things out to figure out questions like this for yourself. I am pretty sure that the chainstay view of rattlecad will answer this particular question fairly quickly. it also might help to buy a tube/lug set and play with it a little

The answer is yes, the chain stay sockets were made to line up with 120 and 126mm spreads.

The angular difference between a 120 and a 126 socket angle is about .4 degrees, over about 405mm of stay. It's generally considered that lugs and other sockets have about 1 degree plus/minus of working range from intended angle. Almost every BB stay socket that I've worked with (not a pro so only a few dozens) needed some form of blacksmithy to open up, close down gaps or even get that stay to slide in to begin with.

Eric is correct, IMO, about miss placed obsession Re: lug/socket angles. IIRC I've mentioned before that when you start working with this stuff for real you'll see why we question your questions. Andy

For what it's worth, the chain stay holes on most bottom bracket shells I've messed with (30x16 type) don't even come close to matching up with the stays themselves. I blame the stays more than the shell but regardless, a lot of stay manipulation is needed to get a decent fit. I made a couple of wood cradles that can be used to crush and squeeze the stays in order to get the proper shape for clean plug in. I also try to fatten up the cross section as much as possible to resist sideways bending. At the end of the day a small angle misalignment at the shell is the least of my worries.

I just went through that with a new bike, trying to get some s-bend stays in a shell and the stays were horrible. So I put them in the vise and reshaped them. I need to bend the sockets out a little. Maybe I should make some wood blocks. I think Columbus is trying to do better with most of their stays that are meant for lugged bb shells

Who would draft this out, since you would need to collect the specs to do it. That also goes for buying all the frame parts too.
Thanks for the answer.

Yes that will be hindsight i will never have.

could you tell us what your interest is? Rattlecad has some of these parts available in the software, you don't have to buy or measure real parts

Just trying to answer some questions that come to mind. I will never have I experience base that you folks have.

They were whatever the builder needed them to be:
https://farm5.staticflickr.com/4757/...298666d5_c.jpg
Untitled by Duane Draper, on Flickr

Do you have a similar tool for oval stays?

All things being equal ,
Longer the chainstay tubes, the further apart the ends will be..

Oval stays have a lot of slop in angle relative to the seat tube, and it's not very hard to bend the sockets sideways a little. Even for a fairly radical s-bend stay, it doesn't take much.

I have made them for common sized lugs/shells and the rear round sockets but haven't done any for the oval sockets. It shouldn't be too hard to take a 1-1/2 " bar and turn down one end to ~30mm diameter and then use belt sander/grinder to shape the sides.

The one in the picture was just scrap bar I had that happened to fit the 22mm sockets. It gave me the idea to make more. I bought 4 1ft long chunks of 1-1/2" round steel (1018 I think). I then chucked them in the lathe and turned about 2 inches on each end to sizes that fit most frame tubes - 25.4, 28.6, 31.8 & 35mm. Then I took a hole saw in the mill and carved out where ST/DT meet in the BB shell and when I get to it, i'll do the same for HT and ST/TT joints. It might require making more but i'll cross that one when I get there. It could probably also be done cheaper/more efficiently than I did.

The 1-1/2'' round bar I used for lug socket benders is a bit cumbersome/heavy but not too bad. The benefits of using big heavy steel with a slip fit is

• it maintains the round socket shape as you move the socket around,
• it provides more surface area for measuring angles with a protractor and
• it acts as an anvil inside the socket to close up gaps around the perimeter.

I don't know if you need to use solid bar - tubes with .250 walls might be just as supportive but maybe not much cheaper and then you're limited on the smaller sizes so. I think the solid bar is the way to go. I've seen sets for sale somewhere but, didn't jump on them - regretfully.

In the picture I was opening up the angle to the ST on track bikes. I agree, width isn't generally too difficult get a couple extra degrees and that can take you from 120 to 135 even. I do like having these bars as anvils inside the sockets to tighten everything back up before brazing. I use an aluminum bar with blunt end as a punch.

22.2mm is 7/8", so it's not unlikely to find a piece of bar that size in a big enough scrap pile. I have a 5 foot long piece that I don't remember acquiring. First time I used it, I ovalized the shell fairly badly.

I'll have to look to see if I can find something to make into an oval. Angle grinder should make fairly quick work of removing the bulk of the material.

Omar Kheil (Oasis Custom Cycles) made bending bars years ago. The shipping cost more then the steel did. You can see the concaved mitered ends that some have. Above them is a 7/8" bender, it's working end bonded to a narrower tube. This is my general bending section of tools with pry bars, pickle fork, crank arm bender, head tube jack and an early attempt at a stay crimper/channel locks. Not doing much with lugs lately these bending bars are mostly holding down the peg board. Andy