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Hello,
I've got a Bringheli Jig with standard sized headtube cones. I'm looking to build a frame with a 44mm headtube, and am going to contract someone to build the correct sized cones for me.
I've reached out to several people I know looking for the shaft dimensions and have had no luck. I do not have the proper tools to measure it, so I was hoping someone knew!
Cheers and thanks much
Ben Duncan
Gosh, the first thought is to measure the shaft. HT cone fit on a jig rod only needs to be a few thousandths of fit. Remember jigs are for speeding up tube fit up and maintaining geometry, not tracking alignment. If you are not able to measure the jig rod to this degree then maybe you need to step up your game.
IIRC Andrew Walker did a few Bringheli jig up grades including a fresh HT fixture. He might have some insight. Or Joe B for that matter. When it comes to the cones I would talk to Alex Meade. Andy
Your daily metrology tip: when I'm measuring something like this I just take a tape measure and assume it's the closest standard diameter. If it comes out to a weird fraction in inches, I check to make sure there isn't a close diameter in metric. Or you could call Joe, I'm sure he would be happy to talk to you. In fact, I'm sure he would make you bigger cones as well -- he's a machinist. If you email him your phone number, he will call you back.
I hope you have a string, a ruler and a sharpie. Wrap the string one time around the shaft. Where the 2 ends meet, mark the intersection point with the sharpie on both ends. Unwrap the string from the shaft and measure the distance between the 2 sharpie marks to get the Circumference. Dividing the circumference by pi (3.142) will give a decent approximation of the diameter.
There are diameter measuring tapes that will do the math for you, but if you are going that far, you might as well get some cheap Vernier calipers.
I wouldn't get a cheap vernier caliper. Cheap dial caliper or one of the iGauging digital calipers will keep you from making mistakes. It takes a lot of practice to read a vernier and I still screw up unless I take a lot longer to do a measurement than I want. The no-name digital calipers are fine, but they flake out when the battery is low.
Really, if you are at all serious about framebuilding, a set of mitutoyo digital calipers is a pretty good investment. You can get them for around $100.
Thanks to all who have replied. Personally, I would have taken my calipers to it, as that's something I am comfortable with. However, per the person manufacturing the headtube cones, it was requested I use a more precision instrument to measure it: Alex Meade.
Simply looking to see if anyone knew the exact measurement, not looking for advice on how to measure something, though it is appreciated.
Cheers
Ben Duncan
I just measured mine and it's a 3/4 inch shaft. Bringheli goes back and forth between metric and standard on things.