Will cutting my seat tube weaken my frame?

PB Forum :: Dirt Jumping & Street
Will cutting my seat tube weaken my frame?
Author Message
flag Blk-Mrkt
Posted: Dec 9, 2009 at 23:59 Quote
veet-88 wrote:
Ok be stuck up, what the hell is the point in making a thread if your not going to consider/see the point in other peoples point of view. I am sitting here giving some simple straight forward thought to you that can prevent a frame failure that will make a far greater differance. But what ever cut it if your frame cracks I will be sure to laugh my ass off if you post it on here.

Ryan

Dude I asked about my frame not my seat post and its offset and what not. I can slide it forward if i want and your not helping me at all. If you want your still welcome to input what you think about my frame,not my seat post. Thanks.
flag veet-88
O+
Posted: Dec 10, 2009 at 0:02 Quote
And I have, I would not cut it. Things are designe to be a certain way for a reason. All I did there was offer a safe alternative that will allow you to center or seat on the rails resulting in it being stronger and better pinch set up.

Ryan
flag Blk-Mrkt
Posted: Dec 10, 2009 at 0:03 Quote
veet-88 wrote:
And I have, I would not cut it. Things are designe to be a certain way for a reason.

Ryan

Ok thank you. I'll talk to a mate too who makes boats and works with all sorts of materials, Smile
flag nzbikerider
Posted: Dec 10, 2009 at 2:06 Quote
what sorta bike is it if it's resonably shit do it can't go to much wrong. oh and your saying thing under your avatar is freaking discusting a kid at school done it ages ago was pretty funny tho.
flag BSal
Posted: Dec 10, 2009 at 10:27 Quote
Your frame has a huge gusset connecting the top tube to the seat tube in the upper part of the seat tube, and it looks like your seat tube is about 2.5"(55MM) long. An inch would not hurt it, if you cut it right. As an intern at a Fab shop I learned a lot about metal. Thats why i felt safe cutting my seat tube. If BLK MRKt feels like he wants to cut it let him. He is taking a risk tho, sheet, we all take risks just riding!!
flag ezekiel
Posted: Dec 10, 2009 at 10:36 Quote
StevoFS wrote:
as long as you dont cut into the weld you'll be fine...its not gonna weaken your frame...I did it to my old old ironhorse i had back in the day.

I agree with this piece of advice.

Years ago I picked up a used BMX and someone had deformed the hell out of the top of the seat tube. It was so bad that it had to be cut right off and a new piece welding in. I rode that bike for over a year then sold it to a friend who rode it for another 2 and nothing happened to that joint. I've also done a basic trim on a seat tube and that bike never broke either.

Point being, if cutting out a piece of the seat tube and welding in a new one that was not the same length didn't cause any premature failure I would be extrememly skeptical that simply removing an inch of material is going to upset the balance to the point that it breaks.
flag joram-adams
Posted: Dec 10, 2009 at 11:12 Quote
After listning to all these guys ideas about cutting your seat tube I've been persuaded to the idea that it should be allright to cut. AS long as you don't cut into the weld it should be fine. Make sure you leave enough room for the seat collar and file it after. You should be fine.
flag Blk-Mrkt
Posted: Dec 10, 2009 at 11:36 Quote
joram-adams wrote:
After listning to all these guys ideas about cutting your seat tube I've been persuaded to the idea that it should be allright to cut. AS long as you don't cut into the weld it should be fine. Make sure you leave enough room for the seat collar and file it after. You should be fine.

Yeah I have too, but I just gotta persuade my dad because he reckons he'll weaken it but I'm gonna do it anyhow. He won't notice hahaSmile
flag Blk-Mrkt
Posted: Dec 10, 2009 at 11:41 Quote
nzbikerider wrote:
what sorta bike is it if it's resonably shit do it can't go to much wrong. oh and your saying thing under your avatar is freaking discusting a kid at school done it ages ago was pretty funny tho.

Hehehe yeah it is but funny as Smile
flag jaame
Posted: Apr 12, 2016 at 6:13 Quote
Is this thread still alive?

What about the slot at the back? It helps the tube deform slightly when you tighten the seat clamp.

Have you extended it?
flag veet-88
O+
Posted: Apr 12, 2016 at 6:18 Quote
I suggest checking post dates before replying last post was late 09 i think it long past died.
flag jaame
Posted: Apr 12, 2016 at 16:02 Quote
I did check the dates that's why I asked if it's still alive. I've been using pinkbike since 89!
flag Joffezcoffee
Posted: May 26, 2016 at 18:07 Quote
I'm curious to know also, let's track this guy down! I just got a Santa Cruz nomad and with the drop post its just an inch or so to high. I don't want to loose the drop post so I'm thinking of cutting the frame. I we will have to extend that slot Jaame. I'll post pics if I do it.
flag kwp2011
Posted: Feb 23, 2017 at 18:00 Quote
My Lbs said they use to do this all time. Im going to cut an inch off my rocky mnt blizzard. I'm tall with silly short legs. So I like the length of a large but need a medium or small seat tube. If anyone is still interested I will post a picture.
flag noisette
Posted: Mar 6, 2017 at 17:26 Quote
done both, trimmed the st, and extended the slot downwards, no problems at all (steel frame).
just use your brains...Wink

 


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