Headtube length

[rpettet]

Are headtube lengths on bikes designed for threaded forks typically shorter than threadless systems?

[Louis]

Makes sense to me.

[John H.]

Threaded forks were also in the flat toptube days.
Headtube length was usually whatever it ended up with based on the seattube length- go straight out- it ends up where it ends up.
They figured that you could adjust front end height by adding a spacer in between bearing cover and top nut and/or raise or lower the quill stem.

It was threadless that threw a wrench in the works- then people had to decide how long the headtube on a frame needed to be for fit reasons.
Many companies still don't have it right (for most). They go on making bikes with super short headtubes. Great for riders with an aggressive position. Not so good for most of the population.

[Peter P.]

John H. gets it.

Most frames with threaded forks are older and were designed around level top tubes. So, headtube length wound up being whatever it was once the top tube length was determined.

In my opinion, only in the last few years have manufacturers more commonly made their frames, particularly carbon frames, with taller head tubes to make up for the loss of height vs. older style level top tube frames with threaded headsets.

I recently took delivery of a new frame with a threadless headset. I took into account my old frame, with its level top tube and threaded headset, and spec'd the headtube of the new frame to make up the difference. Fortunately, you can do this with sloping top tube frames and in most cases it won't look out of place.

[lhuerta]

...stack and reach is what really matters, regardless of head tube length (threaded or threadless, integrated or not).
Lou

[Ken Robb]

John H. gets it.

Fortunately, you can do this with sloping top tube frames and in most cases it won't look out of place.

Everything with sloping top tubes looks out of place---said the curmudgeon. :)

[soulspinner]

Fork span matters too, steel forks usually are longer than say an Enve......................which makes the stack higher....

[tv_vt]

On the bikes that I've owned over the last 20 years or so, the threaded fork frames definitely had shorter headtubes that threadless fork frames, by about 20-25mm, at least, up to about 40mm (170 to 210mm for 60cm frames).

[wallymann]

the move to sloping top-tubes and integrated headsets.

Are headtube lengths on bikes designed for threaded forks typically shorter than threadless systems?

[ean10775]

Everything with sloping top tubes looks out of place---said the curmudgeon. :)

Unless it's a large frame...I'd love a level top tube, but in my size they all tend to look goofy unless the wheelbase is really long.


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[FlashUNC]

the moved to sloping top-tubes and integrated headsets.

Yeah, I think you're looking at this backwards. As Wallymann points out, HT lengths increased as frame designs went to compact geometries. You can easily build a quill headset/stem into a sloping frame. The style of headset has nothing to do with the length of the HT.

The shift was more due to the industry's push to a different frame design that allowed them to, ahem, make fewer sizes.

[carpediemracing]

Are headtube lengths on bikes designed for threaded forks typically shorter than threadless systems?

I didn't read as much into your question.

Threaded fork frames need headsets that have threads, and I don't know of any threaded headsets that are integrated. Since integrated headsets sit inside the head tube the head tube will be that much longer for a given "lower bearing to upper bearing" height. The extra height envelopes the bearings.

It's sort of like having BB86 vs an English threaded Shimano BB (I think I have the right integrated bearing BB). The bearings are in the same spot relative to each other and to the cranks. The BB86 simply puts the bearings in the frame, the English threaded frame keeps the bearings in the bearing cups. The BB86 is wider but functionally the bearings are in the same spot.

I have regular headsets in my frames. If I could have used an integrated headset head tube I'd have a 2 cm longer head tube to put the bearings in the same spots (stack height 21mm or so for my headsets).

[Coluber42]

Another change since the days of level top tube is that at the same time, handlers were higher compared to the saddle, but riders spent more time in the drops, and the levers and handlebars were designed for that riding position. Modern levers have gotten bigger and are designed for a more ergonomic hand position on the hoods. The result is that with the arms and torso in a similar position, the hands would be on the hoods now and would have been in the drops before. So that would indicate a longer head tube to arrive at that position, except that you might well have had a longer quill, too, so maybe not. But at the same time, you'd also have a lot less exposed seat post and not a lot of stand over clearance, putting the top tube, and therefore the top of the head tube, relatively high, so maybe so.

I think the simple answer to the original question is that there are so many other confounding factors, mechanical, stylistic, and historical, that it would be a useless generalization to say whether the head tube is longer one way or the other.

[rpettet]

I purchased a frame with a threaded fork. TT measures 56.5 but the headtube is 14. Not sure if this is going to work since I am used to 16 or so headtubes on my threadless bikes. Trying to decide whether to keep it or send it back. Didn't want to invest alot for headset and stem until I knew. Thanks for all the good info.

[EricEstlund]

Head tube height in isolation tells you very little about the bike. Fork length, BB drop, top tube angle, headset type and height above TT all play in to changing the relative length of the HT on a bike of the "same size".

[eddief]

make up for the shorter headtube by using a longer or upjutting quill stem. One of these from VO and Bob's your uncle:

http://store.velo-orange.com/index.php/components/stems/quill-stems/vo-quill-stem.html

I purchased a frame with a threaded fork. TT measures 56.5 but the headtube is 14. Not sure if this is going to work since I am used to 16 or so headtubes on my threadless bikes. Trying to decide whether to keep it or send it back. Didn't want to invest alot for headset and stem until I knew. Thanks for all the good info.

[oliver1850]

Set the frameset up with wheels and tires that you plan to use, or as close to the same diameter as possible.

Set saddle height and setback to the same as the bike you're riding, measured from BB centerline.

Put whatever quill stem you have available (but preferably one with a level extension) in at the min insertion (max height) mark.

Measure from floor to top of bar hole in stem and compare it to the height from floor to top of bar on your old bike.

Adjust for any difference in BB height between new frame and old bike. If the BB is higher on the new frame, you will have to add that amount to the floor to bar top dimension from your old bike.

See how far off the two bar top heights are. Then you can look at what's available in quill stems to put the bar where you need it. If it's high enough and you used a level extension for the mock-up, all you will need is to adjust extension for reach. If it needs to be higher, you can look for a stem with a longer quill, or one that's angled up.

[lhuerta]

I purchased a frame with a threaded fork. TT measures 56.5 but the headtube is 14. Not sure if this is going to work since I am used to 16 or so headtubes on my threadless bikes. Trying to decide whether to keep it or send it back. Didn't want to invest alot for headset and stem until I knew. Thanks for all the good info.

as EricEstlund indicates above...headtube length in isolation tells you nothing about potential fit without other important indicators....the easiest way to figure out fit differences between two frames is to calculate the stack and reach.

Here is some required reading:


http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=29177&start=0

http://velonews.competitor.com/2012/05/bikes-and-tech/technical-faq/technical-faq-setting-your-bikes-up-identically_216035

http://www.cervelo.com/en/engineering/thinking-and-processes/geometry-and-fit.html

Lou