Fixing a Victorian

[Mickeyspinn]

A collet so slim that it has to fit within the couple of mm available between the internal diameter of a seat tube and the external diameter of a seat post? I reckon you could install that from the top opening of the seat tube, you wouldn't have to do it from the bb. It may not even be 'captive'. If the slots were wide enough to squeeze together to get it in, then it could be got out the same way.


Maybe the outer 'female' conical part of the collet is integral to the seat lug?

I'd so like to get my hands on this for a good look and measure up! Intriguing isn't it!? Understated discreet yet brilliant...all steel 22lb bike..no aluminium...130 years old ....it just goes round and round in my head!
I worry that we are slowing up nabeaquam's progress on getting this bike going with all our interest

 

[torqueless]

He's swanning around in a Porsche when he should be shining a light down his seat tube for us and showing us the business end of his locknut.. bloody typical!

If that's a 1 1/8" diameter seat tube, then I'm guessing the seatpost is no more than 7/8", leaving 1/8" to fit all that gubbins in?

 

[Woz]

Definitely think it's the lug that is threaded. You can just make out slightly different wall thicknesses on the lug rim.

I did a similar scenario with the taper in the lug going that way (narrow end at the top), but rejected it because I couldn't quite see how the collet would remain in place and not fall down the seat tube, especially with some added force when you insert the seatpost.

If though, the taper in the lug runs the other way (ie. wide end at the top), the collet could be a dead simple cone shape. The locknut wouldn't need a taper either, it just drives the collet vertically down. However I couldn't quite figure out how it could be kept captive as it appears at the moment.

 

[Mickeyspinn]

He's swanning around in a Porsche when he should be shining a light down his seat tube for us and showing us the business end of his locknut.. bloody typical!

If that's a 1 1/8" diameter seat tube, then I'm guessing the seatpost is no more than 7/8", leaving 1/8" to fit all that gubbins in?

Yes I think it's time we got down to all the nitty gritty of tube sizes etc the whole bike, everything!

 

[Woz]

This is it. My last offering. I call it "The upside down hollow Champagne cork collet."

 

[Mickeyspinn]

When nabeaquam gets back logs in and sees all this it's gonna feel like coming home to find all the big news networks camped in his garden!
We just want the story mister nabeaquam do you have anything to say!

 

[torqueless]

Yes, it’s the collet. It’s got slot like things that act like a wedge and move upward to reduce the diameter. More overkill.

I'm going on this from p16, Woz. Your version seems to move the insert downwards to reduce diameter?
If I've got anywhere near the way this actually functions, then the top of the conical bore of the seatlug forms a 'shoulder' on which, (until the locknut is tightened) the threaded part of the 'insert' rests.
It cannot fall down the tube.
No part of the locknut is tapered in this scenario.

'Exploded' diagram:

 

[Nabeaquam]

I’m getting ready to take the ferry to Mackinac Island, they run every 15 minutes. I’m in the hotel on Lake Huron. This is looking off our deck at the Island.
I have another old bicycle, 1936 as that is the only year they did a collet seat post binder. It’s not real easy to move the seat up and down. I should write down the bike brands on my bikes because I promptly forget them, so I don’t remember who made it.

 

[Woz]

I'm going on this from p16, Woz. Your version seems to move the insert downwards to reduce diameter?
If I've got anywhere near the way this actually finctions, then the top of the conical bore of the seatlug forms a 'shoulder' on which, (until the locknut is tightened) the threaded part of the 'insert' rests.
It cannot fall down the tube.

Interesting what he say's on page 16. I must of skipped over that. It's the complete opposite I got looking closely at the photographs.

OK, I get that now - the threads cut from a slightly larger outer diameter at the top of the collet. Splayed out at the bottom keeping it all captive.

If you are right, this way solves the requirement to get the collet out. Simply tighten the locknut without a seatpost and pull the locknut up.

I'm not entirely happy with the scenarios I did with the lip arrangement to keep collet captive; it would require driving it down and out through the bottom bracket if removal was necessary. ( or a specialist tool of some sort? )

 

[Woz]

Just realised I messed up in my drawing. The collet should extend up in a cylindrical manner into the internal diameter of the lock-nut, the height being a bit over the lug rim like in the pictures.

Well that's my draftsman career gone to hell. My only excuse is I'm sober.