Head tube protrusion, any good?

[Avispa]

Does a frame that has some amount of head tube protrusion would be better in terms of durability than a frame that does not have any? It is better to leave head tube protrusion, especially if the frame does not use integrated head sets, like Serottas, Kirks, Sachs and most Colnagos, for instance...

..A..

[swoop]

do you mean extension or the carbon bulbousness that's supposed to represent a stiffer head tube in some of the frames coming out of china?
a robust frame in any material that's also well made should be more durable than a less robust frame that isn't well made... no matter the shapes of the tubes.

[TACSTS]

I think the OP means, like a freuler (sp?) style extension above the point where the top tube meets the headtube. Is it better to do it like this (like a lot of Pegoretti's) or slide the toptube up so that there is little extension of the HT above the TT. Does the smaller front triangle of the freuler style lead to a stiffer, stronger front triangle?

Is that what you were meaning Avispa? I've wondered about this as well.

[Avispa]

do you mean extension or the carbon bulbousness that's supposed to represent a stiffer head tube in some of the frames coming out of china?

Swoop, you are quick when responding! ;) Thanks...

About your question... Well, not just those Chinese frames, I mean the amount of head tube that sticks past the top tube on many "robust frames". I mean, what is the purpose of leaving this extra amount of tubing there if there is no need for it (or is there)?

..A..

[RudAwkning]

Swoop, you are quick when responding! ;) Thanks...

About your question... Well, not just those Chinese frames, I mean the amount of head tube that sticks past the top tube on many "robust frames". I mean, what is the purpose of leaving this extra amount of tubing there if there is no need for it (or is there)?

..A..

If a rider needs more rise, but is using a carbon steerer where the maximum recommended spacer stack is say 30mm, then these will get the bars even higher.

Same theory applies to a threaded system when the rider is using a stem with a shortish quill length.

[David Kirk]

It's not a structural deal but a matter of fit. The whole treadless headset and stem thing changed the rules and the greater protrusion (amount of head tube above the top tube) reflects that. If you don't need the extra then it can be omitted from the design. If you need more then more can be built in.

Dave

[Kirk007]

primarily for the reason Dave states (makes sense as two of my bikes are Kirks). My old landshark, and all stock Pegorettis have a larger extension in the large size 62+ for me. It has been explained to me by a vendor for both Landsharks and Pegs that the theory also includes providing more support for a long steerer tube in the forks that necessarily go with such large frames (particularly if a carbon steerer) as well as the theory you set forth: stiffer, perhaps a tiny bit lighter. This vender, George at Il Vecchio in Seattle started carrying Pegs in the late 90s, early 2000s. When I talked to him around that time (and when threaded headsets and quill stems were still quite prevalent) about the headtube extension/dropped top tube idea he said that Dario started this when building Indurain's frames. Whether its true I'll let others decide, but if that's how Mr. Pegoretti chooses to design his large size frames that's good enough for me - It's by design not accident.

Greg

[David Kirk]

I'd like to see the term that is often used (head tube extension) go the way of the Edsel.

In my perfect world it would be called "head tube protrusion" just like the Rude-man stated. It's more accurate for sure. Protrusion is the amount of head tube that extends above the top of the top tube. Simple enough.

The term "head tube extension" is confusing. How can one tell how much something has been extended unless you know where you started from and since their is no standardized protrusion it could mean anything. Even if one says that a bike has a '10 mm extension" that doesn't mean squat unless you know the starting protrusion. Am I beating a dead horse here or did I make my point?





The other thing I'd be happy to see change is the use of head tube length numbers. Folks seem to think that you can take the head tube length and get an idea of how much bar drop you end up with. In a gross sense that is true but if you are concerned with accurate numbers the head tube length is a red herring. The head tube length is affected by all of the following -

head angle
fork rake
fork span
bottom bracket drop

So if you have two bike you are comparing that have the exact same spec's listed above and the only thing different is the headtube length then I think it's a real number. Otherwise it just is what it is.

I'm out.

Dave

[Badgers]

How would fork span affect HT length? I get all the others but not that one.

[Badgers]

Never mind. I stand self-corrected. I was thinking in the horizontal axis re: span.

[RudAwkning]

I'd like to see the term that is often used (head tube extension) go the way of the Edsel.

In my perfect world it would be called "head tube protrusion" just like the Rude-man stated. It's more accurate for sure. Protrusion is the amount of head tube that extends above the top of the top tube. Simple enough.

The term "head tube extension" is confusing. How can one tell how much something has been extended unless you know where you started from and since their is no standardized protrusion it could mean anything. Even if one says that a bike has a '10 mm extension" that doesn't mean squat unless you know the starting protrusion. Am I beating a dead horse here or did I make my point?





The other thing I'd be happy to see change is the use of head tube length numbers. Folks seem to think that you can take the head tube length and get an idea of how much bar drop you end up with. In a gross sense that is true but if you are concerned with accurate numbers the head tube length is a red herring. The head tube length is affected by all of the following -

head angle
fork rake
fork span
bottom bracket drop

So if you have two bike you are comparing that have the exact same spec's listed above and the only thing different is the headtube length then I think it's a real number. Otherwise it just is what it is.

I'm out.

Dave

Another measurement I'd like to see go the way of the Do-Do is "Standover".

"Wow, my balls don't touch the top tube with both feet on the ground! Perfect fit!".

The measuremeant people should really be looking at is the theoretical top tube length. How much reach do you need. With the advent of sloping TTs and/or varying bottom bracket heights, gauging size according to standover is stoopid. If you find the right reach, you don't have to compromise everything else about the fit using silly seatposts and stupid long/short stems.

There are other equations and measurements that play a part in fit, to be sure, but standover shouldn't be one of them.

BTW, I want to send my frame back to David Kirk as my balls do happen to touch. With a steel frame, it's especially irritating on cold days like today. If only I had a carbon frame. :p

[DarrenCT]

I'd like to see the term that is often used (head tube extension) go the way of the Edsel.

In my perfect world it would be called "head tube protrusion" just like the Rude-man stated. It's more accurate for sure. Protrusion is the amount of head tube that extends above the top of the top tube. Simple enough.

The term "head tube extension" is confusing. How can one tell how much something has been extended unless you know where you started from and since their is no standardized protrusion it could mean anything. Even if one says that a bike has a '10 mm extension" that doesn't mean squat unless you know the starting protrusion. Am I beating a dead horse here or did I make my point?

The other thing I'd be happy to see change is the use of head tube length numbers. Folks seem to think that you can take the head tube length and get an idea of how much bar drop you end up with. In a gross sense that is true but if you are concerned with accurate numbers the head tube length is a red herring. The head tube length is affected by all of the following -

head angle
fork rake
fork span
bottom bracket drop

So if you have two bike you are comparing that have the exact same spec's listed above and the only thing different is the headtube length then I think it's a real number. Otherwise it just is what it is.

I'm out.

Dave


how do u know all this?

are you a builder or sumfin?

[capybaras]

Totally! :banana:

[classic1]

Another measurement I'd like to see go the way of the Do-Do is "Standover".

"Wow, my balls don't touch the top tube with both feet on the ground! Perfect fit!".

(snip)


BTW, I want to send my frame back to David Kirk as my balls do happen to touch. With a steel frame, it's especially irritating on cold days like today. If only I had a carbon frame.



Yours only reach the toptube? I thought correct fit had them hanging either side?

[RudAwkning]

Yours only reach the toptube? I thought correct fit had them hanging either side?

Depends on whether I'm in my cleats or my walking shoes :D

Oh, and another thing that throws standover height out the window is tire size.

"My bike only fits when I ride 23s.....that's what my balls tell me anyway....."

[Fixed]

darn i thought this was a kinky thread



never mind imho
cheers :beer:

[RudAwkning]

darn i thought this was a kinky thread



never mind imho
cheers :beer:

I can make more references to my balls if you like :D