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PostPosted: Sat Aug 10, 2013 11:05 am 
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Joined: Tue Jul 30, 2013 7:06 pm
Posts: 55
This Light-Bicycle is frustrating cause they have too many nice designs. So Carolin emails me and says I can switch to the 50mm profile that berg posted and its a brand new rim.

I think I am going to keep that 45mm profile. The shape seems to flare a touch more and that will be good to create more of an airfoil effect and I like the idea of the ultimate all-purpose wheel. That is what I wanted. Ultra-light, aero, and good in all riding situations including climbing. Honestly its so close I don't think I would ever notice a difference between the 2.

What do you guys think?

@54x11
I will be your crash test dummy. Now you have another profile to choose from too in that 50mm lol. I am having Light-Bicycle build them with the Bitex/Ed hubs. Super light but might not be as durable as some of the other choices.

@November Dave.....were the wheels in your trip to the wind tunnel spinning at speed?


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Posted: Sat Aug 10, 2013 11:05 am 


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PostPosted: Sat Aug 10, 2013 11:46 am 
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Posts: 55
@velo1990
That should be a nice wheelset! Think about it your getting a wheelset that is at worse 3 or 4 watts more drag than Zipp, Hed, Enve, Bontrager, for $500.

Its almost training wheel price

Sweet!


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PostPosted: Sat Aug 10, 2013 8:09 pm 
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Joined: Mon May 06, 2013 5:29 am
Posts: 18
So, how close to 303 Firecrest are these 45mm Light-Bicycle rims? What about the 50mm ones, are they the same shape (aside from the extra 5mm depth)?


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PostPosted: Sun Aug 11, 2013 3:40 pm 
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Joined: Tue Jun 30, 2009 9:04 pm
Posts: 95
Location: Denmark
Here u go :)

I have put together a picture with the Light-Bicycle 45 and 50mm U-shape rims superimposed on Zipp FC profiles. Also Bontrager 5 D3 rim is shown. I tried tried to match scale based on rim height.
Someone with Photoshop can probably make a better illustration, but hope my crude attempt can be of some use in the meantime..

Image

All drawings are from the respective websites, except the Zipp 303 FC profile, which I found on a link someone has posted earlier in thie thread.

Note how the Light-Bicycle 50mm U-shape fits the bottom part of Zipp 404 almost perfectly. To me it looks like a marriage between 303 and 404. Interesting they would choose to make both a 45 and a 50mm though, I mean they are quite similar. Wonder why they didn't go up to 56mm and match the Zipp 404?

Light-Bicycle 45mm U-shape looks almost identical to Zipp 303. Perhaps the Zipp is a little wider in the top half, but that difference could just be the poor quality drawings I had to work with.

EDIT> Just had a look at the 303 dimensions at Zipp site, and they actually support what the drawings seems to show: That the 303 is wider in the top half than Light-Bicycle U 45mm:
Light-Bicycle brake track: 24.50mm
Zipp 303 FC brake track: 26.40mm
Light-Bicycle max width: 27.22mm (based on the 50mm rim drawing, which is more precise)
Zipp 303 FC max width: 28.50mm

- So perhaps my illustration is more precise than I thought :wink:


Last edited by Berg on Sun Aug 11, 2013 7:32 pm, edited 1 time in total.

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PostPosted: Sun Aug 11, 2013 4:26 pm 
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Joined: Tue Jul 30, 2013 7:06 pm
Posts: 55
Awesome work Berg!!!

I too was wondering why they came out with the 50mm. Its probably cause people are asking for 50mm rims instead of 45mm and don't understand that the Firecrest design 45mm is more aero than most 80mm V shape rims. The extra length is not that important when its a virtual airfoil anyway! The key is to get the air moving smoothly and quickly back to center without creating a pressure center behind the tire. Thats why the 303 FC has a wide bulge, so it gets the air moving back to center quickly and smoothly. It acts almost like if there was a solid trailing edge of 30 mm behind the tire itself.


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PostPosted: Sun Aug 11, 2013 7:18 pm 
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Joined: Tue Jun 30, 2009 9:04 pm
Posts: 95
Location: Denmark
I'm no expert on aerodynamics, but based on page 15 in Bontragers very interesting whitepaper (http://media.bontrager.com/images/features/201108_aeolus/bontrager_aeolus_d3_wheels.pdf), there is clearly a difference between Zipp 303 and 404, albeit not huge: Up to yaw around 5, the difference is very small, but from around 7 to 14 degrees yaw, which is a typical range for the "medium fast" rider, there looks to about 40g difference. But again, since 10g at 40 km/t equals 0,75w power, this only translates to around 3w difference - at 40 km/t (25 mph).

These 3w probably comes out to a few valuable seconds for a pro (or semi-pro) TT rider, but for me personally it really doesn't matter :)

Edit> But of course your point about the 303FC vs a "classic" narrow V rim is correct (based on both Tour magazine and Bontrager wind tunnel testing). Many people probably don't realize this - OR maybe they just like the look of the deeper rims..

Edit2> Zipp 303 is actually 2mm narrower at the brake track than Light-Bicycle U shape (see my edit in above post with picture). For me this is a good thing, as I don't think the really fat rims are very elegant on the bike, and they are also incompatible with many brakes and forks. But it likely makes a (negative) measureable difference in the aerodynamics..


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PostPosted: Mon Aug 12, 2013 1:05 am 
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Joined: Tue Jul 30, 2013 7:06 pm
Posts: 55
They are testing the previous generation 303...not the 303 Firecrest.

As far as comparing the different wheels......I think all of em are good.

Good solid designs and a big improvement over the V shape which I honestly always questioned as it was the opposite shape you want and not aero at all on the rear part of each wheel.

This is the shape you want front half and rear half of the wheel....but that isn't possible cause of the tire being a big bulging hunk of rubber that keeps us upright. Its an NACA airfoil profile and perfect drag coefficient.

Image

I will try to explain how the 303 FC works and I wish i had your illustration skills. Draw a 23 mm tire flush with the outer diameter of the aft half of the airfoil. Like 2/3rd of the way to the right and cut off everything behind that.....aka cutting off the tail. Now what happens is the air comes off the tire and flows very similarly to the manner in which it would if the airfoil was actually still there. This is why the 303 FC is more aero than 80mm V shape wheels..its cause the air thinks its an 80mm wheel.

Now compare this shape to the 303 FC and that is basically what you have. Draw the tire in there and the cut off the tail. The air still flows in this general manner as if the tail was still there. And if you make the nose slightly more blunt you get a virtual airfoil going in both directions. Front half and rear half of the wheel.


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PostPosted: Mon Aug 12, 2013 7:13 am 
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Joined: Tue Jun 30, 2009 9:04 pm
Posts: 95
Location: Denmark
Ahh, hadn't noticed the 303 was older shape, and only the 404 was Firecrest (in Bontrager tests).. :oops:
But I guess that shows even the old shape was pretty good, since the difference in real life to Bontrager 5 D3 and 404FC is small.

I think I get your airfoil explanation :)


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PostPosted: Mon Aug 12, 2013 9:41 am 
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Joined: Thu Jan 08, 2009 1:41 pm
Posts: 221
Location: Shetland, Scotland
Image
This kind of idea, for virtual aero sections for leading and trailing edge sections.


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PostPosted: Mon Aug 12, 2013 10:48 am 
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Joined: Mon May 06, 2013 5:29 am
Posts: 18
Berg wrote:
Here u go :)

I have put together a picture with the Light-Bicycle 45 and 50mm U-shape rims superimposed on Zipp FC profiles. Also Bontrager 5 D3 rim is shown. I tried tried to match scale based on rim height.
Someone with Photoshop can probably make a better illustration, but hope my crude attempt can be of some use in the meantime..

Image

All drawings are from the respective websites, except the Zipp 303 FC profile, which I found on a link someone has posted earlier in thie thread.

Note how the Light-Bicycle 50mm U-shape fits the bottom part of Zipp 404 almost perfectly. To me it looks like a marriage between 303 and 404. Interesting they would choose to make both a 45 and a 50mm though, I mean they are quite similar. Wonder why they didn't go up to 56mm and match the Zipp 404?

Light-Bicycle 45mm U-shape looks almost identical to Zipp 303. Perhaps the Zipp is a little wider in the top half, but that difference could just be the poor quality drawings I had to work with.

EDIT> Just had a look at the 303 dimensions at Zipp site, and they actually support what the drawings seems to show: That the 303 is wider in the top half than Light-Bicycle U 45mm:
Light-Bicycle brake track: 24.50mm
Zipp 303 FC brake track: 26.40mm
Light-Bicycle max width: 27.22mm (based on the 50mm rim drawing, which is more precise)
Zipp 303 FC max width: 28.50mm

- So perhaps my illustration is more precise than I thought :wink:


So, not sure I follow. Is the 50mm Light-Bicycle rim the same shape as the 45mm, just stretched 5mm more? Is there any advantage/disadvantage of 50mm over 45mm for this? I assume the extra 5mm will make it "more aero"?

To sum up the Light-Bicycle 45mm (LB45) vs. 303 Firecrest (303FC) comparison, the LB45 is ~1.9mm narrower at the brake track and ~1.3mm narrower at the max width, but almost identical in shape to the 303FC?


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PostPosted: Mon Aug 12, 2013 1:55 pm 
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Joined: Tue Jul 30, 2013 7:06 pm
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@FPSDavid
Your guess is as good as mine on the LB45 vs LB50 competition. They are slightly different with the LB45 being a little more aggressive of an airfoil.

I say go with the one you think is sexy


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PostPosted: Mon Aug 12, 2013 4:36 pm 
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Joined: Mon Jan 24, 2011 8:09 pm
Posts: 719
Anybody have links to the LB50s they have recently released? 45mm on their site, would like to see the 50mm though.

Thx


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PostPosted: Mon Aug 12, 2013 8:18 pm 
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Joined: Thu Jun 03, 2010 6:20 am
Posts: 347
Carolin sent this to me when I asked about future sizes for the aero wheels. She said that they have this one in the line up already, although not on their website ::

Image


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PostPosted: Tue Aug 13, 2013 4:24 pm 
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Joined: Fri Nov 04, 2011 11:44 am
Posts: 2
So has anyone here purchased these from light-bicycle.com?
Maybe i missed read what people are riding earlier in the tread.

I'm very keen to buy these in the next month or so. So keen to hear peoples experiences.

And whats the thoughts of tubeless on road bikes? i'm a fan on my MTB but judging by the gapping wholes and slices from glass and other shiz in my GP4000's i can't help thinking one real puncture and the tyre needs placing.


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PostPosted: Tue Aug 13, 2013 8:29 pm 
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Joined: Mon May 06, 2013 5:29 am
Posts: 18
steviemidnight wrote:
So has anyone here purchased these from light-bicycle.com?
Maybe i missed read what people are riding earlier in the tread.

I'm very keen to buy these in the next month or so. So keen to hear peoples experiences.

And whats the thoughts of tubeless on road bikes? i'm a fan on my MTB but judging by the gapping wholes and slices from glass and other shiz in my GP4000's i can't help thinking one real puncture and the tyre needs placing.


I'm probably going to buy them (undecided between 45mm and 50mm) in 1-2 months, unless reason surfaces not to.


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Posted: Tue Aug 13, 2013 8:29 pm 


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