BikeTechReview.com

  • Increase font size
  • Default font size
  • Decrease font size
Home Forum
Welcome, Guest
Username Password: Remember me

Interbike 2009
(1 viewing) (1) Guest
  • Page:
  • 1

TOPIC: Interbike 2009

Interbike 2009 8 years, 2 months ago #25408

  • kraig
  • OFFLINE
  • Administrator
  • Posts: 3285
  • Karma: 4
I made a strategic strike on interbike this year. It seems like only a few years ago that I was stoked to spend 2 days walking the floor and whatnot.

This year, it was on a plane at 8AM and back home for dinner... Nice! )

Here's what I noticed missing:

1) Trek
2) Cervelo
3) Felt
4) Panache!

Usually, when I walk the floor, I randomly run into lots of folks and have a nice chat - y'know, relivin' the good 'ol days! That didn't seem to happen with the same frequency this year... I did run into Frank Overton, who I met initially when one of his athletes tested at the wind tunnel here in San Diego, a few years back! So, yeah that counts as a random encounter - glad to shake hands with him again...

Didn't run into any other power groupies there of note, but I'm sure the gizmo crew was well represented...heck, they even had their own booth it seems ) :



Anyway, not much big at "the show" from my perspective...The whole power meter deal thing seems to be pickin' up a bit, though! I might just have to update the first unpaid link at this sucker, now that there are some new players out there:

http://www.google.com/search?hl=en&sour ... 2g-ms1g-m6

I shook hands with Jim at Quarq (hey, Jim, I forgot to ask you, when will you have something that is compatible with a campy square taper? -> y'know, this caveman is a slow mover! ) -> he showed me a cool data logger that they had developed to work with ant+ systems.



Pretty cool to see that off that memory stick you can run golden cheetah. Golden cheetah ( http://wwww.goldencheetah.org ) is a cool deal - love to see the independent guys givin' it a go!

Garmin had a new ant+ receiver deal as well -> this one is called the 500:



SRM has its new square form factor PC7:



and, the powertap folks have their joule 2.0:



so, I was able to pick up the Joule and play around with it (didn't do the same with the SRM nor the Garmin)...my impression was that the joule was "cheap" -> the display was cluttered and small, and low resolution - especially compared to the srm and the garmin 500. Really, though, it just "felt" cheap - flimsy, low quality, not solid, if you know what I mean. But hey, if it is under $200, I might consider it for an upgrade.

The new guys on the block are metrigear and their Vector product:



and



cool idea, and a really difficult way to execute the power measurement deal. but it might just be the most insightful way to git 'r dun, so to speak.

they apparently use a bunch of piezo sensors to measure force, and multi-axis accels to determine where in the pedal stroke one is.

My experience with piezo based sensors are that they are great at high frequency response, highly dynamic situations. Pretty tough to verify through static calibration, as they have a tendency to drift. Hell, though, like I tell most folks who will listen -> I'm from missouri... y'know, the "show me" state? If the sucker works, that'd be a pretty sweet deal - gotta offer more than just speedplay compatibility (and I say that as a devout former speedplay user).

Yeah, so that's the power deal...I thought these bikes looked really cool and simple - y'know somethin' my caveman sensibilities can grasp onto



What was your interbike experience like?
-kraig

Re: Interbike 2009 8 years, 2 months ago #25411

  • djconnel
  • OFFLINE
  • Gold Boarder
  • Posts: 203
  • Karma: 2
I wasn't at Interbike (I suppose I could get a pass, being the promoter of Low-Key Hillclimb Series. Maybe? I just wish it was somewhere other than Vegas...). But I think the new Reynolds/Lew clincher rim is super-cool. It took me several minutes to figure out how it holds the tire, then I realized tires are round.

http://www.velonews.com/article/98568/i ... -the-catch

I never was very good at 3-dimensional problems....

Re: Interbike 2009 8 years, 2 months ago #25412

  • SteveP
  • OFFLINE
  • Expert Boarder
  • Posts: 87
  • Karma: 0
djconnel wrote:
I wasn't at Interbike (I suppose I could get a pass, being the promoter of Low-Key Hillclimb Series. Maybe? I just wish it was somewhere other than Vegas...). But I think the new Reynolds/Lew clincher rim is super-cool. It took me several minutes to figure out how it holds the tire, then I realized tires are round.

http://www.velonews.com/article/98568/i ... -the-catch

I never was very good at 3-dimensional problems....

Did you see it mounted up with a tire? http://www.velonews.com/photo/98523
Ugh. Not looking good to me for $6000. Maybe the pic did not do it justice?

Re: Interbike 2009 8 years, 2 months ago #25413

  • JV
  • OFFLINE
  • Platinum Boarder
  • Posts: 1101
  • Karma: 0
SteveP wrote:
djconnel wrote:
I wasn't at Interbike (I suppose I could get a pass, being the promoter of Low-Key Hillclimb Series. Maybe? I just wish it was somewhere other than Vegas...). But I think the new Reynolds/Lew clincher rim is super-cool. It took me several minutes to figure out how it holds the tire, then I realized tires are round.

http://www.velonews.com/article/98568/i ... -the-catch

I never was very good at 3-dimensional problems....

Did you see it mounted up with a tire? http://www.velonews.com/photo/98523
Ugh. Not looking good to me for $6000. Maybe the pic did not do it justice?


I also thought it was a neat idea...but I'm trying to figure out what performance improvements it's going to enable. Can we make the wheel lighter? More aero? Stronger? Cheaper? Some combination of those?

Re: Interbike 2009 8 years, 2 months ago #25415

  • djconnel
  • OFFLINE
  • Gold Boarder
  • Posts: 203
  • Karma: 2
Well, I think advantages are:
  • More aero. Kraig's done work on tire-rim combinations for aerodynamics. Here's there's virtually no retrograde slope going from the tire to the rim. There is that bit of a lip.
  • Stronger. This is the big one. Carbon fiber simply is not the best material for the clincher rim shape. And stronger can be traded off for lighter.

My question is rolling resistance. In the hook-bead model, the bead is held in place relatively uniformly along its entire length. In this model, were the tire infinite radius , it would obviously come out. The restraining force need no longer be uniform along the perimeter, it seems. The bead might slide along the rim proximate to the contact area. Motion with force = work. Will this increase rolling resistance? Maybe not. It's not like there isn't friction resisting deformation in a conventional rim as well. Maybe rolling resistance will be even less. But Lew got his idea from avionics. In avionics, rolling resistance is hardly a big concern.

Re: Interbike 2009 8 years, 2 months ago #25416

  • SteveP
  • OFFLINE
  • Expert Boarder
  • Posts: 87
  • Karma: 0
djconnel wrote:
There is that bit of a lip.

This is what I was referring to. It just doesn't look like a good aero tire/rim match at all. I have a suspicion that the unique mounting mechanism may result in adverse aerodymanics of the tire/rim interface for pretty much any existing clincher. Again, the caveat is that the pic may have not done justice to this relationship.

Re: Interbike 2009 8 years, 2 months ago #25426

  • anthros
  • OFFLINE
  • Junior Boarder
  • Posts: 24
  • Karma: 0
djconnel wrote:
But I think the new Reynolds/Lew clincher rim is super-cool. It took me several minutes to figure out how it holds the tire, then I realized tires are round.

http://www.velonews.com/article/98568/i ... -the-catch

I never was very good at 3-dimensional problems....


Hey, don't feel bad. It took me a while too--but primarily because Lennard Zinn's account of the rim (which I read first) made zero sense. To wit:

"Standard hook-bead clinchers pumped up high have enormous pressure pushing outward on the rim walls [...] On Lew’s design, the mounting force is instead directed downward into the rim."

I have no idea what Lennard thinks is going on--mounting force? downward?--but the Ben Delaney article you linked to describes the retention mechanism better.

Dan, you wonder whether rolling resistance will be affected by slip between the rim and the tire. I'm not worried about that. If we treat a tire as an infinitely long cylindrical pressure vessel with a diameter of 22mm, and we pump it up to 115 PSIG, we end up with a hoop-direction force of roughly 1.43 KGF per mm of tire bead* (or 80 pounds per linear inch). That force is acting tangentially to the tire casing where the casing touches the rim.

The dynamics of how a tire would slip relative to the rim are complex enough that hand calculations are more trouble than they're worth. (Tire stiffness is highly anisotropic). But suffice it to say that the forces involved in retaining the tire generally dominate any other forces at the tire/rim interface.

Cheers,

Jason





* Lets assume our tire is a true 700x22 tire. That gives it a radius of 11mm.
115 PSI = 793 KPa or 793,000 Pascals

Hoop stress for a cylindrical pressure vessel is:
sigma_h=pr/t where p is pressure, r is hoop radius and t is wall thickness.

Lets assume our tire is a true 700x22 tire. That gives it a radius of 11mm, or 0.011m.

We can convert stress to force (actually, pressure) by leaving out the wall (casing) thickness term:

force_h = pr = 793,000*0.11 = 8723 Pascals

700C tires have a bead diameter of 622 mm and our "force" term includes area (it's really a pressure, as mentioned above).
If we consider that a Pascal can be defined as one Newton per square meter, we can divide our hoop "pressure" by the bead seat diameter to get the force per unit length of bead:

8723Pa/0.622m = 14024 N/M per meter, or roughly 14 Newtons of force acting on each millimeter of tire bead.

That's about 1.43 kilograms of force acting on each linear millimeter of bead, or roughly 80 lbf acting on each linear inch of tire bead.

Re: Interbike 2009 8 years, 2 months ago #25428

  • kraig
  • OFFLINE
  • Administrator
  • Posts: 3285
  • Karma: 4
FWIW, the original HED patent depicts a substantial lip between the tire and rim (see figure 5):

[attachment=0:22235t3w]<!-- ia0 Bicycle_rim_and_wheel.pdf<!-- ia0 [/attachment:22235t3w]

The geometry in the HED patent is a bit different than the Reynolds rim, but it is a substantial lip nonetheless.
-kraig

Re: Interbike 2009 8 years, 2 months ago #25430

  • whodesigns
  • OFFLINE
  • Junior Boarder
  • Posts: 20
  • Karma: 0
That patent expires in a few weeks!!
Specialist Sports Technology

<a class="postlink" href="www.luescherteknik.com.au">www.luescherteknik.com.au

Re: Interbike 2009 8 years, 2 months ago #25433

  • kraig
  • OFFLINE
  • Administrator
  • Posts: 3285
  • Karma: 4
whodesigns wrote:
That patent expires in a few weeks!!


I'm not a patent guy, but, dang - that'd be cool if the whole "peak rim width is >1.05 of the 'intended tire width' " deal is off the books.

I always thought that claim was pretty weak from an enforcement perspective...if what you say is true, I can't wait to see what the "fast follower" business model guys are emboldened to come up with.

Competition is a good thing!
-kraig

  • Page:
  • 1
Time to create page: 0.85 seconds

Poll

Which type of tire is more aerodynamic?