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PostPosted: Tue Jan 12, 2010 8:50 am 
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Joined: Tue Sep 22, 2009 10:14 pm
Posts: 49
Location: Copenhagen, Denmark
Hey weenies,

I'm looking to build a set of tubuluar racing wheels for 2010. I'm steering clear of carbon rims and I was looking at the Ambrosio Crono 28 hole on a set of Zipp hubs (total weight 1270 grams).

I weigh 68 kilos - any input as to wether the Crono is too weak/has flaws? I'll be using the wheels for racing in Denmark (long crits on windy, rainy, semi-rough roads).

Thanks

/t

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PostPosted: Tue Jan 12, 2010 8:55 am 
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Joined: Mon Jan 23, 2006 3:03 pm
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Location: Denmark
Hi

If get a good builder to build they will be fine in 32 hole. I am just under 70 kg and was adviced to take 32 hole over 28. And with 2,0-1,8 spokes in the rearwheel. With this combo they are just fine and hold up just perfect. They are build by leloby here from WW. If you want to go 28 hole you might consider heavier rims...

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PostPosted: Tue Jan 12, 2010 9:40 am 
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Joined: Tue Jan 23, 2007 11:22 am
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Location: Leg hurty
The crono is easily strong enough at your weight.
Obviously it also depends on spoke choice but with comps and laced on a hub with a reasonable flange width you'll be fine.
I wouldn't go 28h with revs or cx rays.
I ride cronos in 32h drillings with comps and have been as heavy as 86kg and used them for everything including training on terrible roads.
I'd stay away from 28/28h though, as I just don't see the point of having the same spoke count front and rear, you don't need as many spokes in the front and will end up with either an overly stiff front wheel or an overly weak rear wheel.
IMO you'd be far better off getting rid of the Zipp hubs (they aren't that great) and building on some decent group hubs instead, and going 28/32h built with light spokes like revs or cx rays.
You may have real problems getting straight pull spokes in the very long sizes (about 305mm) you'll need to build F20s with.

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PostPosted: Tue Jan 12, 2010 10:03 am 
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Joined: Tue Sep 22, 2009 10:14 pm
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Location: Copenhagen, Denmark
I just happened to have a sat of unused Zipp 28 hole high flange hubs (for traditional j-bend spokes) lying around next to a bunch of Sapim X ray spokes, soooo ...

/t

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PostPosted: Tue Jan 12, 2010 10:25 am 
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Location: durp durp durp
I've got a set of the f20's on records 32h. They feel fine built up with rev spokes, but the rim isn't particularly re-assuring when your have it in your hands, as its such a small low profile rim. The braking track is quite narrow as well, so generally speaking there isn't a lot to them - personally I wouldn't use them as an all rounder wheelset, more of a event specific wheel - seems like a relic from time before carbon rims.

The rims I got also had a stinking joint on the brake track, so you might want to check & look at them before handing over the money as it takes some time to wear down those brake joint bumps.

Any reason why you want to stick with alu?

Possible alternatives I would consider are either the kinlin tub rim http://fairwheelbikes.com/kinlin-tb25-tubular-rim-p-1212.html which has more weight, but not so much & better profile...

or some generic brand x carbon rims in either low or medium profile - which will generally cost about £150. Weight on those things will be closer to 300gr ea, so you'd be getting the weight down by another 200gr over the f20's too.


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PostPosted: Tue Jan 12, 2010 10:45 am 
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Location: Leg hurty
Hotfeetdk, well if you already have the hubs and the are for elbowed spokes I agree, you may as well use them I suppose. :wink:
I've had a pair of TB 25 kinlins but didn't overly rate them TBH, I didn't like the tubular bevel shape (too narrow and shallow) and much prefer the F20 for both it's aesthetics and also it's performance.

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PostPosted: Tue Jan 12, 2010 10:55 am 
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Joined: Tue Sep 22, 2009 10:14 pm
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Location: Copenhagen, Denmark
Hey,

Reasons I'm sticking with a low profile alu rim:

Better breaking in the stop-go conditions we've got for most of our races (crit-like).
Less affected by wind (Zipp reps might disagree - but we ride in serious wind conditions here).
Cheaper when they brake in one of all the pot holes we got.
Better braking in the rain.

/t

Btw: Have no fear, I got a set of Zipp 303s handy for the occasional sunny no wind-race :thumbup: .

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PostPosted: Tue Jan 12, 2010 11:57 am 
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First of all, the claimed weights are a lie. They are not 340g ea. The last pairs I saw on scales were 750 and 760 per pair, so you should figure that in your equation.

Second, how heavy are you and what kind of riding are you wanting to do on them?

Third is my reccomendation of velocity escapes. They are only 30g/pair heavier and I have been riding a pair for much of this year. They are tough (even good enough for 'cross). At 65-69kg I have had not broken a spoke in a year, the wheels are 3-4 years old (virtually no brake track left), built radially on the front, 28h front and rear, are plenty stiff and come in lots of pretty colours, if that is as important a motivation for you as it is me. :D They also have a brake track, which is a nice thing.

If you want the lightest set of alloy tubs, you could try to hunt down a set of araya adx-1s. which are deeper than either of the above, a legit 335-345g, and stiff enough for me on a track bike. Damn near impossible to get outside of Japan though, it seems.

The ambrosios seem like a very nice rim. I have not built any up, but from all accounts they are very well made and somehow 'nicer' than anything else on the market. That said, they are not what you would call tough.


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PostPosted: Tue Jan 12, 2010 1:07 pm 
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Location: Denmark
But there nothing like a classic set of Ambrosio tubulars 8)

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PostPosted: Tue Jan 12, 2010 2:04 pm 
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Joined: Fri Apr 10, 2009 1:30 am
Posts: 118
Location: Shakopee, MN
I built a set of Crono F20's a few months ago and have been really happy with them. I weigh 69 kg and went 28 2x front/32 3x rear with DT Rev's on DT240 hubs. They feel great and don't seem flexy at all. The rims did come in at 370/375 grams each and if I'm not mistaken the set finished up at 1320 grams. I use these for rain days or when the wind is over 20 mph steady and I don't feel like dealing with my Edge 1.68's.


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PostPosted: Tue Jan 12, 2010 3:15 pm 
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Joined: Tue Mar 21, 2006 12:56 am
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Tokyo Drifter wrote:
Second, how heavy are you and what kind of riding are you wanting to do on them?

Read the first post...


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PostPosted: Tue Jan 12, 2010 3:41 pm 
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Joined: Wed Aug 26, 2009 11:24 am
Posts: 95
I’ve recently had a pair built by a respected wheel builder. He seemed to say that the rims were flimsier than he remembered from the last time he built Crono F20’s, and said it was a bit of a struggle to build them, and it wasn’t a job he’d want to do again. I haven’t ridden them yet, so can’t comment on ride or longevity, but I’ll be riding long audaxes in all conditions, and on varying types of road surfaces. I’ve been using older Mavic GP4’s and some older Campag rims until now. I’m 69Kg and not had many wheel problems on those rims – one broken spoke in front wheel at 2am! The Crono F20’s weren’t built with CX-Rays – it would have been some model of Sapim or DT spoke, though. To give an idea of weights for 32rear/28front wheels they’re 950g and 680g respectively (total 1630g). My front hub is 100g, and the rear is 328g.


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PostPosted: Tue Jan 12, 2010 5:30 pm 
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Joined: Tue Feb 14, 2006 4:42 am
Posts: 896
Location: Calgary
We've used the Crono/F20s for years on the track and found them fine there. My son had enough power to be competitive as a junior sprinter so that's a pretty good test of their ability to stand up to strong power forces. We just used 32/32 with butted Wheelsmith spokes. His weight would have been about 75 kg, my weight is 80-85.

However, when we went to build a set of road racing alloy wheels, we went with Velocity Escapes 24/28 on White hubs. These feel a little sturdier for daily use, are still inexpensive to rebuild when you crash them and have a better braking track. They have tires mounted now so it's tough to weigh them reliably but I show them as 1944 for the set with glue and Vittoria CXs. The front is identical to our Zipp 404 with the same tire, the rear about 90 grams heavier.


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PostPosted: Tue Jan 12, 2010 8:21 pm 
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Joined: Sat Feb 10, 2007 2:00 pm
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Location: Stockholm, Sweden
If you prefer a classic set of Ambrosio tubulars and are worried about the rims being too weak the answer is simple: Go for Ambrosio Nemesis instead.


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PostPosted: Tue Jan 12, 2010 9:23 pm 
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Location: US
I built myself a set of the 32 hole crono's last year 14/15 spokes and record hubs for use in some races I was doing with some rough roads and gravel sections. They have held up well to that and I found them as easy to build up as any rim I've worked with.

The brake track is narrow and IMHO does affect the braking performance of the rim. I don't like to use my set for anything with serious descents in it but other than that I've been very happy with them. I've recently built a set of the Kinlin tubulars and have been happy with them through the build and mounting tires. I haven't had a chance to test them out on the road yet as the weather has been heinous here lately.


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Posted: Tue Jan 12, 2010 9:23 pm 


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