Crease in seat tube

[Spasspecker]

Hi all,

I have a 2012 Trek 1.5 and after a ride on Sunday I gave the bike a quick wipe down and noticed a small crease or dent near the bottom of the seat tube, there is a flat area above it that stops at the clamp of the front mech.
I have had the bike since September last year and although from the shape of it it looks like it has been made that way I have never noticed it before.
Does anybody know if it is supposed to be there and if so what is it for?

Thanks for any help guys!

 

[Rob3rt]

Does the front mech hit the seat tube when it drops down?

 

[Spasspecker]

Hi Rob
I haven't moved the front mech since I got the bike if thats what you mean.

 

[accountantpete]

That is the result of a fairly hard contact with a sharp edge - either the front mech when the cable has been disconnected or by an object prior to being bought and assembled.

There is a crease in the alloy which will have weakened the tubing - but by how much is anyones guess.

 

[Rob3rt]

No, that is not what I mean, I mean when you shift into the small ring does it clang the seat tube? Especially if you put the chain onto the small chainring, then push the shifter to move the mech out, don't turn the pedals as you don't want the chain to climb up, then click to shift it back down (this will let the mech move more violently than normal as the chain won't be in the way), if it hits the seat tube, then that is what has done it. In which case you need to make some adjustments.

 

[T4tomo]

looks like the Front derailleur has been banged against the seat tube, is it on an arc for that if the FD is on the little chainring?
posibly whacked whislt in trasport box
on the upside its looks like its only cosmetic and not in place many will notice

 

[Spasspecker]

No, that is not what I mean, I mean when you shift into the small ring does it clang the seat tube? Especially if you put the chain onto the small chainring, then push the shifter to move the mech out, don't turn the pedals as you don't want the chain to climb up, then click to shift it back down (this will let the mech move more violently than normal as the chain won't be in the way), if it hits the seat tube, then that is what has done it. In which case you need to make some adjustments.

Oh I see what you mean. No the mech doesn't hit the seat tube at all as far as I can tell.

 

[Spasspecker]

This is the reply I have just got from the company I got the bike from, does anyone have the same bike to confirm either way:

The crease and flat you see under the front mech clamp has been designed and pressed into the frame during production. I have had two bikes with similar shaping to the seat tube. It is designed into the frame to take into consideration the throw on the front mech so that doesn't strike the front tube when on the inner chainring.

 

[mcshroom]

IS there any scratched paint on the tube where the indentation is? I'd expect a mech colliding with the tube would scrape across the tube as it hit it. I've not seen that sort of shape before, but then again it's possible it's deliberate. What model of bike is it?

 

[Spasspecker]

IS there any scratched paint on the tube where the indentation is? I'd expect a mech colliding with the tube would scrape across the tube as it hit it. I've not seen that sort of shape before, but then again it's possible it's deliberate. What model of bike is it?

Its a Trek 1.5c (2012).
The lack of paint damage is what I find strange as well

 

[T4tomo]

This is the reply I have just got from the company I got the bike from, does anyone have the same bike to confirm either way:

The crease and flat you see under the front mech clamp has been designed and pressed into the frame during production. I have had two bikes with similar shaping to the seat tube. It is designed into the frame to take into consideration the throw on the front mech so that doesn't strike the front tube when on the inner chainring.

Ah fair enough I gues it gives a bit of extra clearance very easily - when you look closely at photo there is no paint loss whatsoever in the crease.

 

[SpokeyDokey]

This is the reply I have just got from the company I got the bike from, does anyone have the same bike to confirm either way:

The crease and flat you see under the front mech clamp has been designed and pressed into the frame during production. I have had two bikes with similar shaping to the seat tube. It is designed into the frame to take into consideration the throw on the front mech so that doesn't strike the front tube when on the inner chainring.

As per above - it is supposed to be there although I understood the reason to be (from reading on one of the cycling forums way back) was that it straightend the flare of the seat tube to make sure the FD clamp gripped squarely if you see what I mean.

My Giant TCX has exactly the same thing.

 

[02GF74]

hmmm, seems to be there by design but why is it necessary on this frame and not on any others?
BTW I reckon the mech banging into the tube by the force of the spring alone would not be enough to dent it like that

 

[boydj]

I thnk you'll find there are plenty other frames with this 'feature'.

 

[biggs682]

I thnk you'll find there are plenty other frames with this 'feature'.

i have a Trek 1.1 with same feature