GS Astuto carbon/DA first impressions

j-sworks

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Feb 5, 2012
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#1
Hey fellow TCC peep's,

Tim recently put together an orgasmic wheel set for me, the set up is DA hubs laced with Sipam Lazer spokes (I believe) to carbon 38/50mm front/rear rims respectively.

Firstly, I have to say that they look so hot, and I thought I had a problem with checking out my bike when I walked by her before :rolleyes:, secondly, the ride is plush, smooth, and only a slight swooshing sound to remind me that I'm on these bad boys oh and they spin super nice, thirdly and most noticeable is the ease of spin-up, rolling resistance, and cornering.

The cornering is superb, I am taking corners with greater speed and confidence (it's like driving a prius and then hopping in a 911). Flat land speeds are easier to hold constant with what feels like reduced effort, and the spin-up is fast which is really nice as I don't have to work as hard to get to a good cadence.

All this great stuff topped of with Tim's beyond reproach service and I've got a winner on my hands, highly recommended to anyone else.

And now for some bike porn:
 
Dec 17, 2011
267
8
38
kanazawa
#4
First of all, congrats on the new wheels, wish I could afford a pair of them!

This is mostly intended towards G.S.Astuto but I have a question: why is the front wheel laced radially?

I got my 105 hubs and they came with a big, fat warning that shimano hubs (including 7900 series) shouldn't be laced radially. I did go with the "cross 3" pattern, and since I was reusing my old spokes I laced it the same way. However a quick search showed that there shouldn't be any problems, at least for front wheels laced radially..

Any input/insight on this? Any realistic assessment of radially laced front wheels' structural integrity? Cheers!
 

j-sworks

Maximum Pace
Feb 5, 2012
1,199
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Tokyo
#6
First of all, congrats on the new wheels, wish I could afford a pair of them!

This is mostly intended towards G.S.Astuto but I have a question: why is the front wheel laced radially?

I got my 105 hubs and they came with a big, fat warning that shimano hubs (including 7900 series) shouldn't be laced radially. I did go with the "cross 3" pattern, and since I was reusing my old spokes I laced it the same way. However a quick search showed that there shouldn't be any problems, at least for front wheels laced radially..

Any input/insight on this? Any realistic assessment of radially laced front wheels' structural integrity? Cheers!
Thanks
 

GSAstuto

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Oct 11, 2009
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www.roadfixie.com
#8
1) Radial spoking looks better IMO. And builds a slightly stiffer (laterally) wheel. Other than that - no difference from a 2x or 3x wheel - including aerodynamics - almost exactly the same.

2) On carbon rim the tension is lower than alloy - there is no issue with radial spoke especially on the 24h. Now for 28 or higher I would always lace cross. This is due mainly to the chance of cracks in the flange cause material becomes narrow, btw, unless the flange is constructed to support the radial spoking specifically.

3) You should always use new spokes and nipples, btw, if you've changed the hubs. Because the 'J' hook will bed-in to the flange and work harden to fit perfect. By using old spokes on a new flange you will risk breaking spokes.


Josh's wheelset is a very conservative, team build. You'll see this same type wheel on dozens if not more bikes across many teams and quite a few years. Using the off the shelf DA hubs and CX-Ray spoke is the approach most Conti team mechanics prefer (unless of course they have Shimano sponsorship - which few do) and the 24 /24 build is super strong enough for sprinters and light enough to work under any road condition.




First of all, congrats on the new wheels, wish I could afford a pair of them!

This is mostly intended towards G.S.Astuto but I have a question: why is the front wheel laced radially?

I got my 105 hubs and they came with a big, fat warning that shimano hubs (including 7900 series) shouldn't be laced radially. I did go with the "cross 3" pattern, and since I was reusing my old spokes I laced it the same way. However a quick search showed that there shouldn't be any problems, at least for front wheels laced radially..

Any input/insight on this? Any realistic assessment of radially laced front wheels' structural integrity? Cheers!
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
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103
tokyo
www.roadfixie.com
#9
One thing that doesn't show clearly in Josh's picture is that the rear wheel is a 50mm and the front is a 38mm. Personally I really like this combo. A little less tweaky up front in the cross winds (and lighter) with the rear a little more aerodynamic and laterally stiffer due the increased spoke angle.
 

joewein

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Oct 25, 2011
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Setagaya, Tokyo
joewein.net
#12
First of all, they look like great wheels!
it's like driving a prius and then hopping in a 911
Hey, hey there -- the Prius is a great, sensible car! :)
thirdly and most noticeable is the ease of spin-up, (...)
One thing that always puzzles me when people talk about wheels is how quickly or easily they spin up. The physics of that statement confuses me, because, assuming we're talking rubber side down, the only way to make the wheels spin faster is to accelerate the whole bike with cyclist on it (whose body mass provides as much as 90% of the inertia) by that same factor.

If I were to compare two bikes, one in which the wheels make up 5% of the bike+rider combination mass and one with wheels 20% lighter (i.e. the bike+rider combination is 1% lighter), will the second bike not accelerate only about 1% quicker? From an acceleration point of view, is a 1 kg saving on the wheels any different from a 1 kg saving on the frame? I wouldn't have thought so.
 

FarEast

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May 25, 2009
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#13
Joe - its one of the things that make a lot of veterans laugh as well. Basically we can blame the magazines for it as they need something to talk about when writing the reviews :D
 

Aron B

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Mar 24, 2012
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Nerima-ku, Tokyo
abeekman.nl
#14
One thing that always puzzles me when people talk about wheels is how quickly or easily they spin up.
I'm not sure this is what you mean, but just in case: there is a lot of energy in the rotation of the wheels (angular momentum). The amount of energy is proportial to the "moment of inertia" which is basically the distribution of the mass within the wheel. Lighter wheels have lower moment of inertia, and therefore you don't need to put as much energy into the rotation of the wheels. As a result, you will feel that you pick speed much quicker than on heavier wheels.

There is no difference when moving at constant speed, except that the angular momentum is for a large part responsible for the stability of a bike.
 

j-sworks

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Feb 5, 2012
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#15
I'm not physics type of guy so I will reiterate in more plain terms what I said earlier, as said by Aron B, they require less effort to get up to a 'good cadence' than did my aluminum wheels hence they feel as though they 'spin-up faster'

I guess the operative word in that statement is "feel"

I believe that anyone can tell the difference between the two wheel materials, irregardless of being new or a "veteran"
 

j-sworks

Maximum Pace
Feb 5, 2012
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#16
@Joe

I actually like the Prius, and in addition I like the fact that it is easy on the greenery and the pocket book (I mean the gas cost)
 
Dec 17, 2011
267
8
38
kanazawa
#17
1) Radial spoking looks better IMO. And builds a slightly stiffer (laterally) wheel. Other than that - no difference from a 2x or 3x wheel - including aerodynamics - almost exactly the same.

2) On carbon rim the tension is lower than alloy - there is no issue with radial spoke especially on the 24h. Now for 28 or higher I would always lace cross. This is due mainly to the chance of cracks in the flange cause material becomes narrow, btw, unless the flange is constructed to support the radial spoking specifically.

3) You should always use new spokes and nipples, btw, if you've changed the hubs. Because the 'J' hook will bed-in to the flange and work harden to fit perfect. By using old spokes on a new flange you will risk breaking spokes.


Josh's wheelset is a very conservative, team build. You'll see this same type wheel on dozens if not more bikes across many teams and quite a few years. Using the off the shelf DA hubs and CX-Ray spoke is the approach most Conti team mechanics prefer (unless of course they have Shimano sponsorship - which few do) and the 24 /24 build is super strong enough for sprinters and light enough to work under any road condition.
So, lower spoke count (24) makes it ok to build it radial, I see.

I'm rebuilding the old wheels for fun, I've used them for 4-5 months before this. I'm taking the risk of using the old spokes just because it's super convenient and they do seem to be in a good shape. Hope I don't really get to regret this!
 

GSAstuto

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Oct 11, 2009
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#18
Thanks Aron, perfect explanation. Physics works. Joe - you are accelerating not only the total mass of the bike and rider but also 'spinning up' the wheels (and other moving parts) as well. Energy is required for all of these. Reduce the energy losses throughout the system and you increase the power available to accelerate the bike. Moment of Inertia scales by the square of the radius from the center of rotation - so, getting the weight down at the edge of the circle is a tangible concern.

The other aspect is aerodynamics. It's just very hard, if not impossible, to make large rim depth wheels from alloy. Extrusions do not like that curve without crimping - so you are limited to roughly 40mm skirt by using most mfg extrusions. Carbon has no limit this way, so you are free to make any rim depth with only marginal increase in weight. Since the wheel is a prestressed object and the skirt is a structual part held in tension. And carbon fiber is very very strong used in this way (tension), you can make a very strong structure with minimal material.

Now, as for wheels feeling 'soft' or 'comfortable' or other stuff. 99% is just marketing hype. The wheel IS a prestressed object and to maintain its shape, it MUST be stressed to do that. EVERY WHEEL EVER MADE will only deflect or depress less than a fraction of an inch!! Regardless the spokes are radial, 2x, 3x twisted or whatever. ALL THE SAME. If the spokes somehow became 'soft' , they would break immediately upon the wheel rotating as the additive force of re-stressing at the top would surely snap them! And this is what happens ALL THE TIME. When you break a spoke it ALWAYS breaks at the top of the wheel rotation!

Laterally its a little more tricky - thanks to the increasing dish of 10 and 11sp cassettes. Getting enough bracing angle with proper tension is critical to keeping the wheel from becoming a $1000 taco. So, a stiffer wheel is generally what you'd feel that has more lateral stability. But even then, we're talking less than 1-2mm of 'flex'. But hey, it's stored energy and you CAN feel it.

Anyway - I can go on for hours about this. But at the end of the day , it's 99% marketing and 100 yrs of riding that makes a wheel work. No big secrets. Just build them accurately and they will work perfectly fine.

The most important aspects are consistent spoke tension and building a uniform, pre-stressed structure (in this case, round). ANY variation will introduce stress points that may lead to failure. You can build a round wheel with variable spoke tension and it will fail, and you can build a perfectly tensioned wheel that isn't round and it will fail too. So the closer you come to a round, perfectly tensioned structure, the better.