Cutting seat tube slot

Hello Chaps,

I have yet another Moser frame (Alu) that comes with an unslotted seat tube which is intended to take a quill type seat post.

My question is what is the feasability of getting a slot cut into the seat tube so that a conventional seat post and collar can be used?

i won't be doing this but would seek out a local frame builder to do the job.

If you look at the attachment the yellow one in the middle is the candidate for the operation. the dark red one to the left is a Cannondale which as you can see employs a pretty basic slot. the pink one to the right is a steel Moser leader with a factory original hole and slot, i reckon they did this because of the ultra thin walled tubing.

Would clamping and cinching the tube that didn't have that as a option originally cause any issues?

And yes i do have a quill stem to go with it but it's a pain to use.

Thanks.

1 Attachment

Quill for coolness

Presumed you'd be doing this as you didn't have original post.

Probably unlikely to result in catastrophic epic failure but irreversible and probably very harmful to any future value of the frame.

I do have a quill post for it, however as you most likely know they are quiet rare and very expensive and apart from the hassle of not being able to casually adjust the saddle height if it ever got stolen it would be game over.

If i can get a chap to do a good clean job on it then any re-sale value may well be enhanced because any regular post can be utilised.

take it to the frame builder and ask them what they think. i don't see why it would be a problem though. have you measured the tube ID and OD to make sure you can get a non-quill post and seat collar that will fit? clamping shouldn't be a problem, seat posts fit snug and the collar or pinch bolt doesn't really move the tube much (unless a pinch bolt is over tightened).

the keyhole is cut in the thin wall steel because it tends to tear or split. aluminium tends to be thicker walled so doesn't usually need the hole. but again, if you're going to have a frame builder do the mod, they should be able to advise.

^exactly this, a slot with a rounded bottom or intersecting a pilot hole. As long as the clamp and post are correct sizes so no crushing or shifting occurs in use, it should be fine. I'd do it if it sorts seat post issues and makes the bike rideable. I don't think it will negatively affect the cost of the frame as long as it's done well and obviously if it's not a hugely rare, sought after collectors frame then you will have trouble from the killed puppy police.

they may have to ream out the tube, which they may charge a lot for. i'd keep the quill for stylez

but if you do do it, the circle at the bottom is a good idea as it alleviates stress that you have if it is just a cut.