Hotspur and Oversize Titanium Tubing

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For the Hotspur frame, Bill Davidson decided that to use the Feather Tech oversize titanium tubing. The key feature is the custom milling that Feather Tech employs to create external butting on very large diameter (for titanium) tubing.

hotspur%2013.jpg It’s simple statics that dictates that doubling tube diameter increases stiffness by a factor of 16 if the wall thickness is kept constant. So, what you do is increase the diameter by say, 20%, and decrease wall thickness until the weight is less than a standard tube but still thick enough at the ends to survive the welding process. Then you end up with a tube that is both lighter and stiffer than before. Large diameter, butted tubing is not a new concept. Steel bikes have evolved along these guidelines for over a hundred years, hastened by newer, stronger micro-alloyed steels and better tube-drawing methods that allow thinner walls to be created.

However, titanium is NOT steel. It’s material properties are such that higher strength ti alloys are not very suitable for seamless tube drawing. And not everyone can make titanium tubing; most of it comes from industries catering to aerospace companies. So, in other words, these companies are not interested in creating bicycle tubing. Smaller companies can then buy the tubing and modify the tubing. Feather Tech is one such company.

Steel is generally butted using a method called rolling, which doesn’t actually involve material removal (loss). This creates an internal butting profile, ie the change of wall thickness is only detectable on the inside of the tube, thus invisible on the finished frame. For titanium, Feather Tech removes material from the outside of the tube; you can see how the ends are thicker.

The Hotspur’s top tube is 38mm (versus the typical 32-35mm) and the downtube is a massive 42mm (vs 35-38mm). The seat tube is 35mm with a machined cap to bring the inside diameter down to fit a 31.6mm seatpost. Bill could have easily chosen the next size smaller for each of the tubes to create a lighter bike, but Bikehugger specifically requested a stiffer, more responsive frame.

Next Bill opted for the Reynolds carbon seat stay. Light, stiff, and clean, the Reynolds piece provides a little vibration damping where it can do the most good. And Paragon makes a ti dropout that elegantly connects to the bottom of the Reynolds seat stay. Bill then used Dedacciai tapered chainstays to stiffen the power transfer to the rear wheel. Bill thinks that that a metal connection from the BB to the rear axle is the strongest, most durable structure.

In the same philosophy of leaving material where it’s needed and removing it where it’s not, Bill eccentrically machined the head tube stock to thin the tube on the front and leave material on the back to reduce warp from the welding of the top and down tubes. The frame accepts a standard 1-1/8 headset, because there is no good reason to incorporate an integrated headset into a steel or titanium frame. It would just unnecessarily add weight (for reasons beyond the scope of this article, integrated works pretty good for aluminium and great for carbon).

The resulting frame weighed 1280 gr before paint in a 56cm equivalent size, just about 80 grs heavier than the ‘07 Trek Madone frame that it will replace. When combined with paint and a Reynolds UL carbon fork, the whole thing is just about the same as the Madone and its respective fork (within 5gr or so). Quite competitive, especially keeping in mind that ultra-light wasn’t the design goal. Bill could have built a lighter bike, but that wasn’t what Bikehugger asked for. The Hotspur is a bike for the roads you actually ride, and how you want to ride them.

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Hed After Hours @ One On One

HED Cycling Products is un-tapping kegs, un-corking bottles and shedding parkas for a social this weekend at One on One Bicycle Studio.

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Details

Friday, February 15th
7pm-12am, Product preview, social

Saturday, February 16th¨
10am “ 7pm, Product demos, informational talks, 7pm “ 12am, Social
117 Washington Ave N. | Warehouse District ¨Minneapolis

More HED

  • The Hotspur debuted at the Handmade Bike Show with the new Ardennes
  • Trek blogged about working with Steve Hed in the wind tunnel
  • I’ll ride the Ardennes extensively in Maui next week and post all about them.


Builders at the Handmade Bike Show

In our 3rd video from the Handmade Bike Show, we stop at the Dean booth, check a Roark S&S frame, see the JK special, and the BME C-Thru. We also talk with Bike Friday about the Tikit, custom carbon frames from RR Velo, and wondered what the robots were all about at the SRAM booth.

Notes



Impressions of NAHMBS

wood

I took the family on a quick trip down I-5 to see the show. My little guy made it a little “interesting” as he was on a mission to turn every crank and wheel he could reach. At most bike shops, this is cute and fun. At the show…not so much.

Pictures here

A couple impressions:

  1. Lots of people complaining that it’s $18 to get in the show, and yet they are oogling at $10k bike frames. The detail on these bikes is certainly amazing, but it seems that this doesn’t make sense as a business model. The pricing on even the lower-end frames at this show are well over $1k, but it’s not the doctor/lawyer set clamoring for these things. I hope there’s enough folks out there to pay for these amazing rigs.

  2. Bike parking was a mess. I was rather surprised to see this in Portland where all the locals rode there. There was even a sign saying that if you locked your bike to a tree or a handrail, that it would be “towed”. Ridiculous. My wife did mention that “man there are a lot of Surly’s”.

  3. Paint these days is truly incredible. Vanilla Cycles has a new group called “Coat” with some amazing work.

  4. Racks are big - I was surprised to see how many clever options were shown by the various builders. There were even a couple guys just pitching racks.

  5. The trend is City bikes, and not necessarily commuter bikes. I take a pretty common route that’s ~20mi each way. There is a large group of folks who follow the same route, and I can’t say that many of the bikes there met the needs of the longer-run commuter set. I mostly wanted to see comfortable road bikes with fatter tires, disk brakes, etc. I only saw 2.

  6. Somebody needs to invite Robin Williams or some other loaded bike nut to this thing to buy up all the stock to keep these guys in business. The creativity in the room came up with some really innovative work and hopefully there is enough dollars to keep it rolling.



Custom Fizik Saddles

arione%20bianchi%20wcs.jpeg I’ll admit it: I’m obsessive about colours on bikes. I know that black saddles are practical, but they so soboring. I love seeing someone with a white saddle on a black bike. To me, a new white saddle says, I’ll get dirty but I look good now.

But how about white with gold, or maybe metallic red? Fizik’s US distributor, Highway2, is offering a custom saddle program through selected bike shops. Expect a wait and an upcharge.

I’ve got a Bianchi bike on order…maybe I’ll get celeste with world champ stripes down the middle. But how will that look? No worries, the Fizik website has a nice little interactive that allows you to see your saddle before you order. Go there and play with the colours. Some saddles offer more options than others.

(added for Byron’s sake at 11:49AM): shopImg_Customizer.aspx.jpeg



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