juvela

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it may be perspective or a photographic effect but the non-drive side blade in this image appears to exhibit a shallow lateral bow in about the middle of the chromed area

deformations of this sort can reduce the blade's effective blade length

could be checked by laying a straightedge down lateral face of blade




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RandolphCarter

Porkchop BMX has 5mm clear housing for 1.5mm cables - you can get a inner cable, ferrule, and housing kit or
bulk cable housing by the foot.

I'm guessing that would work for most vintage rear derailleurs.

And to the original poster - great job on the bikes so far!

IdahoBrett 

Went for a pedal to test the 3rd and hopefully final front derailleur. I’m starting to tire of Delrin.

But what has been repeatedly perplexing me is the seat post tension bolt. I’m cranking it down to about two white knuckles (25 ft lbs / 34 Nm). But it’s still dropping on my rides. I’m 190 lbs (86 kg) so I don’t think that’s the issue.

A self gratifying picture just because I’m amazed the darn thing works more or less considering I’m a rookie:

daverup 

Seatpost that slips could be a size too small

IdahoBrett 

Hmmm. Will have to measure….

Thanks.

daverup 

When it's too small the slot in the top of the post is often narrower at the top from being over tightened.
Good luck

markk900

Do you have the collar that goes in the seat tube - steel and looks like a top hat sleeve with a slot in it? The OEM seat post is smaller than usual and the collar makes up the difference. If you remove the collar you can use a more standard post.

Also beware that the OEM post sometimes has no shoulder for the seat clamp. You can (and some have) had the seat slip down the post itself, with disastrous consequences to your nether regions if it happens hard enough…. DAMHIK.

Edit: take a photo of the seat post clamp area especially from the back so we can see the slot and the ears of the lug….

Edit 2: both our AO-8s have the collar removed and both have seat posts that measure 25.4mm

IdahoBrett 

The collar is present markk900 . Will take a photo later...

juvela

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in comparing the blades on the Mr. machine to those on the Mrs. machine it is clear that the Mrs. blades have "relaxed"

a common cause for expression of this symptom is when a juvenile male has gotten hold of the cycle and employed it for jumps, riding off curbs and down steps

they can noticeably deform a fork in just a few moments with such actions


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IdahoBrett 

pics: Bike is in the repair stand. Blue painters tape on the front of the tube is so I can see if it’s sliding while hanging. Especially if it’s there for a day or two. The bike falling to the floor would be too close for comfort for the Mustang that occupies the space next to my bike work.

daverup 

The top of that seat tube looks a bit mangled.
Does the collar/insert have more than one slot?
If you straighten the top of the seat tube you'll have to watch out that you don't create sharp burrs that will damage something else.
Many of us use brake hones on a drill to smooth out seat tubes.

markk900

Yeah, I agree with daverup : looks like the collar was stuck at one point and someone used some force to get it out.

Good news is that the slot in the seat tube is not closed up or even looking all that unusual.

My suggestion is first check the inside of the seat tube to make sure it is as round and burr free as possible (maybe even that brake hone idea or the bare seat post with some light sandpaper); then align the collar so that the seat tube slot and the cuts in the collar do not line up; and finally that the collar is fully seated. Retighten. It should be quite firm but not white knuckle firm.

If that doesn’t work try a seat post without the collar…..

daverup 

A very old thread on this issue,
https://www.bikeforums.net/classic-v...post-size.html

IdahoBrett 

Seat post measures 22mm as expected. OD of seat tube is 28mm.

I am suspecting that the gap in the shim should be aligned with the gap in the seat tube. A quick turn test with channel lock pliers with a moderate don’t gouge anything force was used, to which it was revealed that the shim likes to stay where it’s at. I’ll have to break out the Kroil and let it do its thing for a bit.

juvela

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many are the ADGA 28A saddles seen in the field with a distinctive circular marking in the centre of the top measuring approximately 22mm



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daverup 

I think if the Collar/Insert is not free to expand or contract with the seat tube clamp, then that could be part of the problem. Good luck freeing it up. If the Kroil doesn't do it, maybe one of the other stuck seat post remedy fluids would help.

markk900

I also note that it appears the post is itself straight - ie no shoulder for the seat clamp. Are you sure it’s the post that is moving in the seat tube and not the seat moving down the post (see juvela ’s comment).

The collar should not be stuck so is indeed likely the problem - still it and the seat tube are steel so it’ll just be rust and not galvanic corrosion.

edit: to protect the mustang I would not worry too much about bike damage and place the top tube in the clamp. It’s not like the UO series is made with delicate tubing and you don’t need to tighten the clamp too much anyway.

As well, I don’t recall ever worrying about lining the slot in the collar with the one on the tube. I think daverup is correct and if you free the collar and clean it and the tube you should be good.

IdahoBrett 

Yes the seat post is sinking down into the seat tube. Normal extension for my leg length is about 3 inches.

When I first bought the repair stand I was tinkering with Cannondale’s, so I got in the habit of clamping the seat post. I realized my months of dumbness this morning and clamped the A08 by the top tube.

Just returned from the eye doc and a side trip to the LBS. The clock starts in about 5 minutes on the penetrating oil soak….

Cheers

IdahoBrett 

Seat post fixed. Pulled the collar, cleaned and polished it and the seat tube with mineral spirits, 600 grit and blue scotchbrite (still plenty of blue paint inside tube). Reinstalled collar, aligning the gaps. Seat post stayed put for a short and bumpy ride.

Rerouted brake cables on the proper side of the bars while I was fixin’ stuff. Front brake pads are still howling. Still looking for the sweet spot on pad position.

Now for Mrs. Idaho’s fork tweak. Tomorrow. Maybe….

juvela

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wrt anti-howl adjustment for MAFAC Racers -

it a good thing the MAFAC Dural formula permits a good amount of tweaking

try that on a Fratelli Pietra caliper and you have a broken caliper


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markk900

I can no longer find it but I had a supposed “mafac factory” adjustment guide and it said use a crescent wrench to set toe in…. I have had good luck getting rid of the howl with just a touch of toe-in.

Congrats on fixing the post issue!