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Cheap ally hardtail frame. Seat tube could do with being an inch shorter to accomodate prefered dropper. Doing so would still leave enough tube to fit a collar without catching the nearest weld. Any reason not to chop it? Will I die?
If there's enough room to extend the slot and drill the stress reliever hole at the bottom of the slot you should be good, I recall Jeff from worldwide cyclery doing similar with a carbon frame on YouTube.
Shine a torch down the seat tube, see how long the machined diameter/fit is. Really want a minimum of 100mm after you've cut the excess off.
If its really cheap, it'll be straight gauge and machined for 150+ mm.
I did it on a Rose full suss, in this case just 5mm so didn't bother altering the slot. Its still going strong.
I even thought about cutting my old Hemlock frame below the tube that gusseted the seat tube to radically alter the height for my boy but Cy said that the way it was butted meant it wouldn't work, which was a shame.
Cheers Folks! Externally it looks like plain gauge tube and I'd be surprised if there's any butting going on but I hadn't given any though to the internal dia. so will have a look. I guess they are just reamered for fit.
When you tighten the collar, seat clamp, the seat tube can move enough to clamp onto the seat post.
The closer the clamp collar gets to the welds, of the seat tube to top tube and seat stays, the less the seat tube will flex or close to tighten onto the seat post.
Good point @paton I think I have plenty of clearance to allow for that.
Should be fine provided you have enough reamed hole as mentioned earlier. I now deliberately build as short as possible - the only seat tubes I've had crack are where there was too much tube sticking out above the TT. If you have a good seatpost fit then it doesn't need much flex to clamp.
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Nice brazing @mick_r the reaming may not be quite so critical in this case, I forgot to mention I'll be using an undersize post that will need a shim. Anyone know who makes nice long shims? Someone mentioned them on a recent post and I forgot to take note.
Not being funny but wouldn't replacing the incorrect diameter post that's too long be much easier then all the chopping and drilling you're considering? It's not like useable droppers are expensive these days and would prevent the potential to ruin the frame.
USE do long shims
Cheers @dc1988. @chestrockwell I want to use what I have and like buggering about to see whats possible. Fairly confident about it tbh. So much so I'm gonna drill it for internal routing also so doubly jeopardy LoL!
Thanks - a file can make most brazing look good.....
Just remember I slammed a second hand Ridgeback seat tube for one of the kids years ago.
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@chestrockwell I want to use what I have and like buggering about to see whats possible. Fairly confident about it tbh. So much so I’m gonna drill it for internal routing also so doubly jeopardy LoL!
Fair enough!
i think "undersize" isn't what you mean here.
It's just too small/the wrong size. So a 27.2=>30.9 mm shim is needed (or whatever).
Undersize (in my world) would be something that's marked 27.2 and fits in a 27.2 hole, but is still loose. So the shim is 3 layers of coke can, hammered into shape...
Whenever there's been opportunity to cut the seat tube, i always have.
Not 100% sure but I think Cane Creek make the longest shims due to USE shims having a taller lip thus losing some millimetres of frame insertion.