Is it a good idea to chop this seat tube?

My girl's work is running the ride to work scheme through Evans, and the only singlespeed that even comes close to fitting her is this interesting merckx. Problem is even the 50cm is too big because of the crazy extended seat tube.

Would a frame builder be able to saw it down to half an inch above where it meets the top tube?

Is that a good idea? Any one on here I should get in touch with to do it?

Cheers

http://i.imgur.com/Biz9MLk.jpg

I guess you could chop it and just use a regular seat clamp? should be fine

Is that Evans Wandsworth by any chance?

how tall is she? a 650c bike might be a better bet. I wouldn't chop a brand new bike as you'd void your warranty straight away

yup, well spotted Turkish.

She's 5'4". She tried another 50cm bike and it was just fine. Only the Merckx comes up massive.

Anyone know frame builders who own a hacksaw and the will do this?

you would lose only warranty on the frame and it's not like the frame was worse 10k so you could probably do that with an good hacksaw guide and hacksaw (24t blade).

Then you use a seat clamp like that (note the shoulder at the end, it would hide the cut):

Otherwise, a frame builder even the more basic can cut it and weld/braze back the original seat clamp but then you need a quick respray.

Nice one Santino, think we'll do that.

Cheers

Surely that wont work unless you cut a slot in the back too?

The seat post clamp wont work on a solid tube will it.

Have to cut a slot and then drill a hole at the bottom? Might get messy!!!!

^ yeah i thought this too. but i dont think it would be too hard, will just take a fair amount of time to get it nice.

I would look at getting a different bike tbh!

Personally I think this is a bad idea.

The high seat tube seems designed to compensate for the low rear stays, creating a kind of cantilever effect when the saddle/seatpost is putting load on the seat tube and the lugs/joins.

Shortening the seat tube to where it meets the top tube will negate this and put more stress on the top tube lug area, and possibly the stay welds as well.

I don't know if the difference in force would be enough to cause a problem and it could be compensated for by something as simple as a really long seatpost that descends lower than the stays to ensure the force is spread over a greater area, but it's something that personally I'd not want to do to a brand new bike when if I just shopped around i'd find something that fits straight off the bat.

^this.

5'4" is not a difficult size to find a fit for.

I don't think that the frame will snap i half just because you trim some seat post off..

Hacksaw, a file to tidy things up and a dremel with a cutting blade to cut the slot.. Just take it slow and easy..

if you feel confident doing it then go for it.
had to do this in the shop i'm in, we sell stunt scooters aswell as bikes queue the boo's, anyway, had to shorten bars on scooters before, same method, drill a hole and cut a slit. drill the hole first though, trying to drill a hole at the end of the slit without the bit jamming is pretty hard.

Personally I think this is a bad idea.

The high seat tube seems designed to compensate for the low rear stays, creating a kind of cantilever effect when the saddle/seatpost is putting load on the seat tube and the lugs/joins.

Shortening the seat tube to where it meets the top tube will negate this and put more stress on the top tube lug area, and possibly the stay welds as well.

I don't know if the difference in force would be enough to cause a problem and it could be compensated for by something as simple as a really long seatpost that descends lower than the stays to ensure the force is spread over a greater area, but it's something that personally I'd not want to do to a brand new bike when if I just shopped around i'd find something that fits straight off the bat.

Mate, this is steel frame so over sized by definition. The basic frame builder at the corner of the street love steel because they don't need to do any stress simulation, add the tube together and you are done. If you think in term of pure force apply to the frame and its direction from the saddle, it is a vertical force equal to the weight of the rider (i simplify). Then the weak point is probably at the connection with the top tube. But the force apply at that connection will depend of the leverage which depend of the distance between the saddle and the top tube plus its angle. If you reduce the distance....less leverage so less force and no extra force applied somewhere else.

So i can't see how it can be a problem, a good learning video to understand the weak points and how to stress a frame:

http://www.youtube.com/watch?v=MWtLIzgxqBQ

good thinking markxrat, you need to do a cut to be able to tighten the clamp. A 2 mins job to cut the tube 1.5cm and it should do the trick. You just need to make sure you leave at least 2cm tube to do that so you avoid cutting too low on the frame.

why not a small or extra small version of this?

Cheers for the thoughts guys, think we're gonna give it a go. She has her heart set on it.

If she manages to break the frame I'll buy her a new one out of respect for riding hard.

Take pics and post them so we can see your process and progress. I'd be really interested to see how it works out (well i hope)

Worth the gamble if she will love it and ride it lots :)

good luck.