On Friday, March 31, 2017 at 10:43:07 AM UTC-7, Tim McNamara wrote:
On Fri, 31 Mar 2017 07:51:25 -0700, Joerg
wrote:
On 2017-03-30 23:37, John B. wrote:
On Thu, 30 Mar 2017 16:37:06 -0700, Joerg
wrote:

On 2017-03-30 07:31, wrote:
Ok my Habby shows up and beautiful Ti. I got the model with the
curved stays as opposed to straight. I was surprised by the large
curves ...


Until here I thought ... ahem ... about something similar to what
Andrew thought :-)


in chain and seat stays. Looks great have not had a chance to ride
it but any wizards out there give me the dope on curved vs straight
stays in a Titanium frame. Or any other for that matter.


I looked at Bertrand's link and began to wonder why they are so much
more expensive than the Ti cyclocrossers from BikesDirect. Those are
between about $1500 and $2000 depending on how they are equipped.

One reason might be that Titanium, isn't just one material. There are
a myriad of different alloys and grades. In addition some alloys and
grades are difficult to manufacture which might preclude the use as
thin wall tubes.. As an example, one supplier lists 11 different
grades of Ti tubes that are commonly used for aerospace and sports.

One might procure the cheapest alloy or the most expensive and label
each of them, honestly, as Titanium.


Certainly true but my MTB buddy has a Titanium HT from BikesDirect
that he beat the snot out of. That thing is indestructible. So their
Titanium seems to be among the good stuff. Which doesn't surprise me
because cheating there would very quickly destroy a reputation and
then the business.

The chief issue is whether the welding process is done correctly. If the
weld is contaminated, it is more likely to fail. And like other
materials, stress risers in the design must be avoided. My friend Doug
has been riding a Teledyne Titan for more than 20 years. It finally
cracked last summer where the downtube was swaged down to allow for the
use of a derailleur lever clamp designs for non-OS steel frames. Darn
shame, it was his favorite bike. The Teledyne was, IIRC, made from
commercially pure titanium so that may be a factor- perhaps less
fracture resistance than some of the other Ti alloys in use?

Gads, he must have bought it used because they went out of production in '76. The thing is at least 40 years old. Not bad service.

You know, that indent for a clamp-on BB cable guide is so stupid because they could have routed the cable under the BB with a little snap-in or screw on guide. I assume it's O.K. to drill a 2-3mm hole in the BB. I would have specially manufactured a super-light clamp-on DT lever boss. Forming the tubes to accommodate standard clamps seems like an odd solution for a super high-tec bike. Plus chrome cable guides look stupid against that matte finish. Pffff. The sure didn't know fashion back then.


-- Jay Beattie.