New custom hard tail being built in Tustin

In my explorations, I think I've only seen one or two suppliers of 1.5" head tubes for custom builders - I've seen zero tapered head tubes, and considering what's involved in making a tapered head tube like that from steel is highly unlikely, not to mention the incredibly low demand there is currently for such an item. However, I could be wrong, so if you do find some, let me know!

 

1.5 head tube with a the 1 1/8 reduction cups on the top, and you can run a tapered steerer.

We are looking into options for a 1.5 steel steerer tube now.

Are you sure I am going to change seat angle more than 1/2 degree. I have not done the math, but here is the from the hip assumption:

I will sag the pike about 25% which is 30 mm. This should yield about a 1 degree change in head angle, and about a 1/2 degree change in seat angle.

We will be doing the real math to make sure.

 

Nice Tani!
DH hardtail is the way:bang:

 

Because the head tube is mechanically attached (fixed) to the seat tube (via the TT and DT), the ST angle will change exactly the same as the HT. I think you're thinking of axle-to-crown heights relative to BB heights.

Oh, and 25% sag of a 140 mm fork is 35 mm. Although if you're going to run it at 120 mm, 30 mm is 25% sag.

If you have some time, play around with this geometry calculator, and you'll see how much change you'll actually get with 25% sag. http://bikegeo.muha.cc/

Thanks for talking with Jeff.

 

I don't remember where I saw 1.5" head tubes, but if Denis can't find any, he can buy 2-1/2" 4130 chromoly tubing from Aircraft Spruce (http://www.aircraftspruce.com/catalog/mepages/4130tubing_un1.php) in 0.12" wall thickness, then turn the outside down a bit to reduce weight. You'll also need the appropriate reamer/facer. That's a lot of work just to get an oversized head tube.

 

Yeah, I priced the 1.5 facer/reamer today. It is a lot of $. It is something I have been meaning to bring in anyway. I will order it if I decide to go 1.5, or the first time we need it.

I may end up going 1 1/8. I know the down tube will work on the head tube, but I like the idea of 1.5 for strength. I think it is less likely to ovalize, and may provide a better weld surface for the down tube.

 

Hey Tani that bike that Duty had today, Is that the proto-type?

 

Thanks for sending Jeff my way.

That link is super cool. Thanks for that. I think you have posted it before, but this time I checked it out.

I was going from memory on what 25% of 140 mm is, and I can't believe I screwed that up in my post. I am even more surprised that you caught it. I already knew that you were like Rain Man.

Thanks for the clarification on head tube angle and seat tube angle having equal change. I wrongly intuited that the seat tube would steepen less because it moves less. I am still struggling to logically explain to myself why this is not true.

You are the man Lee.

 

I'm sure Denis knows all of this stuff, so I guess I'm only saying this for your peace of mind until you talk with him. If you're concerned with ovalizing the head tube, which I think could be tough with a 1.6 mm wall steel tube, he could also braze some reinforcing rings around the top and bottom of the head tube.

I'm looking forward to seeing this bike done - it should be hot!

 

No. That is another secret project.

 

Is there a thread with a collection of Duty's work? If not can someone start one? I've seen Aukmal's old ride. And wasn't that cute little 29er that Tink had a Duty bike?

 

Umm...Tink's cute little bike is a 26er...she's just that small that the bike looks big. :lol:

She'll probably get mad at me for posting a pic of her and her custom Duty, but...

 

My mistake! You've gotta admit... the proportions on that bike do kind of look like a 29er. :lol:

 

This thing sounds sick. The Ventani's already have my seal of approval. A custom Duty hardtail with some slack geo and low BB will be the hardtail "swiss-army knife" bike.

 

no, not mad at you for posting a pic of me & denis' awesome work, just mad at you for posting a pic of me in that jersey! doh!

 

Hey, you wouldn't take it off before taking the photo! :lol:

 

no, not mad at you for posting a pic of me & denis' awesome work, just mad at you for posting a pic of me in that jersey! doh!

here's a more recent pic of the duty beauty w/some upgrades.

 

that's a great idea! hey, tani! do you have room on your store site for a section of denis' work, since they've all been built up at your shop? just a thought...

 

"Ventani". That's hilarious.

So does Duty use that oversize shaped steel a lot? I don't think I've ever even seen a steel bike with anything other than round tubing...

 

He is very fond of big shaped down tubes. The down tube on my ss 29er Duty is I think coffin shaped.

I was embarassed the first time someone on the staff said it. Now I barely notice anymore.

It also gets called El Chingon, El Cavron etc.