[anden]

Just trying to understand the headset thing:

I assume that one reason why we don't see 40 mm high headtubes, is that the contact area between the head tube and the combined ends of the top tube and the down tube would be so small that the frame would be too flexy and too weak. Another reason probably is that the bearings need to be an enough distance apart so that they don't take too high forces and get worn out too fast. Internal headsets should allow for the top tube and down tube to be welded further apart due to the longer headtube. Thus, as long as the bearings are strong enough, aren't internal headsets giving niners a welcomed possibility to a lower front?

Below is an illustration of my point, and pics of three niner headtubes with internal headset and one with a classic. Wouldn't for example the total height of the headtube plus headset on the white Fisher be impossible with a classic headset?

 

[Cloxxki]

Thanks for those great explanations and graphics!
It seems like many old skool designers (like Walt and Fisher) don't like internal headsets, especially after their poor track record the first years.
Chris King only liked the idea when he made his own, slightly wider headtube standard, so he could use his rear hub bearings in a headset. Not many followed his standard.
Mainstream brands simply started using internals headsets, as it sells bikes much easier. It's the latest new thing to cycling, very attractive to use a selling/purchase argument.

Nishiki uses internal headsets for their 29" Bigfoot range, but kept the headtubes the same length as on their 26" bikes, so it helps nothing towards lower possible bar heights.
I hope internal headsets are now durable enough to be spec'd on Fisher niners, I'd help them even more to promote the new 29" standard, as bikes will be fitting more riders better.

Just trying to understand the headset thing:

I assume that one reason why we don't see 40 mm high headtubes, is that the contact area between the head tube and the combined ends of the top tube and the down tube would be so small that the frame would be too flexy and too weak. Another reason probably is that the bearings need to be an enough distance apart so that they don't take too high forces and get worn out too fast. Internal headsets should allow for the top tube and down tube to be welded further apart due to the longer headtube. Thus, as long as the bearings are strong enough, aren't internal headsets giving niners a welcomed possibility to a lower front?

Below is an illustration of my point, and pics of three niner headtubes with internal headset and one with a classic. Wouldn't for example the total height of the headtube plus headset on the white Fisher be impossible with a classic headset?

 

[D.F.L.]

IN THEORY, internal headsets allow for wider spaced bearings and the same stack height.

While this is true for the upper bearing, there can be issues with the lower one. Suspension forks have wide crowns which usually come very close to hitting the downtube when the bars turn beyond 90 degrees. This tendency is exaggerated on a 29er, due to the higher head tube. (greater angle between the HT and DT) Even though you could weld the downtube closer to the lower edge of the head tube with the internal system, the fork crown would hit the downtube. So, the internal lower bearing isn't much of an advantage, packaging-wise.

UNLESS you use a formed gusset, ala Giant, to fill the space between the Downtube and the lower edge of the head tube, then the internal bearing is an advantage...

...if you ignore all of the possible disadvantages of the internal system. I really like King's Perdido, but have not built with it, yet.

 

[ncj01]

Suspension forks have wide crowns which usually come very close to hitting the downtube when the bars turn beyond 90 degrees. This tendency is exaggerated on a 29er, due to the higher head tube. (greater angle between the HT and DT)

Agreed, my fork leg is very close (but doesn't touch) on the new steed, see image:

you know who's: only 2nd time:

 

[Walt]

Cloxxi, you know me too well!

I guess I hardly need to throw in my $.02 here, since everyone already knows I'm a grouchy traditionalist. But I will say this: If you can't fit on a 29er because the bars are too high, there is almost NO chance that an integrated headset will help enough to matter. At MOST, you're talking about 10mm lower, which isn't that much. You could go with a stem with less (or negative) rise and solve the problem pretty quickly, assuming you're willing to accept the odd look (well, not that odd - Cannondales with Headshocks always had negative rise stems back in the day).

Secondly, there are a lot more serious problems for small people who want 29ers - we can already build them for people down in the low 5 foot range, so toe overlap is pretty much going to kill the 29er idea for most people smaller than that, no matter how low you get the bars.

There's not really a weight advantage, the lower bar advantage is offset by the problem of fork crowns hitting the downtube on a 29er, and the parts are harder to find and have not been show to be as reliable. So why bother?

-Walt

 

[Speedub.Nate]

It's important to not confuse King's rant against against INTEGRATED headsets with Zero Stack systems, sometimes referred to at SEMI-INTEGRATED or INTERNAL.

King points out in their article that Zero Stack, as shown on the Fisher in last week's post and in anden's drawings, is superior to cupless integrated designs in which the bearing race is machined directly into the head tube. The removeable cups of the Zero Stack system essentially duplicate the reliability of a conventional threadless headset while providing the designer a greater weld area to join the downtube.

The lack of precision that King laments in Zero Stack headsets -- and tries to answer with their Perdido standard -- is nothing more than a Zero Stack headset with press-fit bearings and higher tolerances at the head tube. This is really no different than a conventional threadless King headset with precision press fit bearings versus a conventional threadless headset from another brand, i.e. FSA or Cane Creek, with drop-in bearings.

In any case, I've had FSA Zero Stack headsets on two bikes now over the past three years, and they've been as troublefree as any conventional headset I've ever run. I'm surprised these haven't been adopted in greater numbers by the 29"er manufacturers, although as pointed out, the fork crown/downtube problem is real and would need to be addressed through formed downtubes or other creative techniques.

 

[cursivearmy]

just run....

a custum built frame, with a rigid fork that is not sussy corrected. the axle to crown height of about 425 to 430mm in length. then your HT is purdy standard, using a regular King headset. the crown of a rigid fork won't hit the downtube, and dang, besides the big volumious 29"er tires are suspension in their own right. i got no need for the suspension forks, and yes, even in terrain that is to be found out west in the likes of Colorado high country and all.

just my thoughts. the suspension isn't that great, just adjust, and learn to ride more with your body. it's fun.

over and out
nate

 

[ssmike]

For what it's worth, I've seen a huge decrease in ovalization of head tubes on frames with internal cup type headsets - Zero Stack type. Basically, I don't see any warranty related issues with Zero Stack headsets where I saw a few with standard headsets. The bigger diameter head tubes coupled with placing the cup and bearing inside, just seems a smart way to eliminate ovalization on jump type frames - not something that's very common with 29" wheel bikes.

But the traditionalist, retro grouch in me just likes the shape of a nice King headset pressed into a minimalist head tube.

The major obstacle, like Walt pointed out is making sure there is clearance between preload knobs and the down tube when using zero stack headsets. Solution for this problem - rigid forks!

 

[cursivearmy]

Yup!

what Mike said.

word.

over and out
nate