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PostPosted: Mon Apr 17, 2006 10:31 pm 
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Joined: Sun Jan 29, 2006 8:02 am
Posts: 147
I am getting it for time trials in stage races and will not be using it for any sort of triathalon. I was wondering...

1. Should I be using the forward seat position? From what research I have done on here and on cervelos site, it seems that is the better choice.

2. If so, what top tube length should I get? My road frame is a 57 cm top tube and has a 120mm stem. The size 58 with the forward position seems the right choice at 56... but if i do rear position it would be too long at 58.9. Is it supposed to be longer or shorter??

3. One last consideration is that it must comply with the UCI as far as the 5cm saddle setback rule.


Im lost with this...

Thanks!


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Posted: Mon Apr 17, 2006 10:31 pm 


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PostPosted: Mon Apr 17, 2006 10:40 pm 
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Joined: Thu Dec 08, 2005 6:09 pm
Posts: 115
Location: CO
BoulderBlunder wrote:
I am getting it for time trials in stage races and will not be using it for any sort of triathalon. I was wondering...

1. Should I be using the forward seat position? From what research I have done on here and on cervelos site, it seems that is the better choice.

2. If so, what top tube length should I get? My road frame is a 57 cm top tube and has a 120mm stem. The size 58 with the forward position seems the right choice at 56... but if i do rear position it would be too long at 58.9. Is it supposed to be longer or shorter??

3. One last consideration is that it must comply with the UCI as far as the 5cm saddle setback rule.


Im lost with this...

Thanks!


1. Using a more forward position allows you to open the hip angle when in a low TT type position. This typically allows most people to produce more power than when the hip angle is reall tight. You'll have to train with this some though as it will be quite different than your roadie position.

2. TT bikes should have shortet top tubes than road to ensure that you wont' be too stretched out as you want your weight on your elbows which is typically achieved by having your upper arms perpendicular ( or close to) the ground.

3. Well on this you should play around with what amount of power you can produce with the saddle far forward. Might be that you are better off back further than that 5. Maybe you are better way forward, if so some chop off a bit of the front of their saddle. IMO it's a stupid rule that is easily outsmarted.

What cat are you in Boulder?


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 Post subject:
PostPosted: Mon Apr 17, 2006 11:02 pm 
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Joined: Sun Jan 29, 2006 8:02 am
Posts: 147
So it sounds like the shorter frame is the way to go? That is kinda the feedback I have been getting. I can always run a longer stem anyways...


Im a 3 but should be upgrading in a couple of months.


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 Post subject:
PostPosted: Mon Apr 17, 2006 11:15 pm 
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Joined: Tue Mar 21, 2006 12:56 am
Posts: 4907
I think you can get in trouble with the 5 cm peak of saddle behind centre of BB rule if you use the forward position, but it's easy to try which position gets the saddle nose 5 cm behind the BB.
CSC use saddles with a cut off nose on their P3/P3C TT bikes to be able to move the saddle further foward. But remember there's also a UCI rule for the minimum and maximum lengt of the saddle (24 cm to 30 cm), so you can't cut too much off. The maximum allowed lenght used to be 27,5 cm, and many of Selle Italia's saddles are stil 27,5 cm. Fizik Arione is 30,0 cm and would not be legal under the old rule.


Here's a picture of Zabriskie (probaly the most aerodynamic TT position in the pro peloton), it looks like the saddle is in the front hole in the seatpost, but the nose of Zabriskie's saddle is also cut off to make the saddle only 24 cm. A lot of riders only sits on the nose of the saddle like this to get further forward without violating UCI's 5 cm rule.
Image




UCI CYCLING REGULATIONS
PART 1 GENERAL ORGANISATION OF CYCLING AS A SPORT
http://www.uci.ch/imgArchive/Rules/1gene-E.pdf
Quote:
1.3.013 The peak of the saddle shall be a minimum of 5 cm to the rear of a vertical plane passing through the bottom bracket spindle (1). This restriction shall not be applied to the bicycle ridden by a rider in a track sprint event, keirin, 500 metres or 1 kilometre time trials; however, in no circumstances shall the peak of the saddle extend in front of a vertical line passing through the bottom bracket spindle.

(1) The distances mentioned in footnote (1) to articles 1.3.013 and 1.3.016 above may be reduced where that is necessary for morphological reasons. By morphological reasons should be understood everything to do with the size and limb length of the rider.

Any rider who, for these reasons, considers that he needs to use a bicycle of lesser dimensions than those given shall inform the commissaires' panel to that effect when presenting his licence. In that case, the panel may conduct the following test. Using a plumb-line, they shall check to see whether, when pedalling, the point of the rider's knee when at its foremost position passes beyond a vertical line passing through the pedal spindle (see diagram «Measurements (2)»).


1.3.014 The saddle support shall be horizontal. The length of the saddle shall be 24 cm minimum and
30 cm maximum.
(text modified on 1.01.03).


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 Post subject:
PostPosted: Mon Apr 17, 2006 11:40 pm 
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Joined: Tue Mar 21, 2006 12:56 am
Posts: 4907
Btw. also try to ask your question at http://forum.slowtwitch.com/gforum.cgi?forum=1
There's a lot of triathletes and also a lot of Cervélo TT bike owners, and some professional TT bike fitters. And Cervélo co-founder Gerard Vroomen very often answers questions like these at Slowtwitch.
Recently Gerard has also started answering some questions here at WW, so he might give his advise in this topic. http://weightweenies.starbike.com/forum ... ile&u=3484


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PostPosted: Mon Apr 17, 2006 11:45 pm 
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Joined: Wed Dec 15, 2004 10:54 am
Posts: 1491
Location: Melbourne, Australia
BoulderBlunder wrote:
I am getting it for time trials in stage races and will not be using it for any sort of triathalon. I was wondering...

2. If so, what top tube length should I get? My road frame is a 57 cm top tube and has a 120mm stem. The size 58 with the forward position seems the right choice at 56... but if i do rear position it would be too long at 58.9. Is it supposed to be longer or shorter??


If where you are buying has good bike fitters, ask them for advice. I fit a 56 or 57cm road frame, but have just purchased a 52cm 700c non carbon P3 (for Triathlons - so no troubles with the seat / bottom bracket rule).

I was skeptical about that sizing, but a friend is my build and has that framesize P3. I borrowed his bike for a couple of hours and was immediately sold on the smaller frame for a TT bike!


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 Post subject:
PostPosted: Mon Apr 17, 2006 11:45 pm 
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Joined: Mon Dec 06, 2004 4:07 am
Posts: 178
Location: arizona
You should usually run a shorter top tube on the TT bike. I ride a 54cm top tube on my road bike but have a 51cm top tube on the road bike. I would size it for the forward position, but if you look at guys like Zabriskie and Landis they run forwards on the saddle. A saddle with a padded nose is an option in this case.

Remember USCF only requires UCI rules for races that pick riders for national teams. Even as a cat 2 this may not affect you, but if you are planning on moving up and trying for national team selection at some point it may be an issue.

It hasnt affected me for races with my P2, but the most I might try is masters nationals where the UCI rules dont apply. Local 1/2 non UCI races are not a problem.

_________________
www.santanracing.com

www.paragoncycling.com


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 Post subject:
PostPosted: Tue Apr 18, 2006 1:02 am 
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Joined: Fri Mar 17, 2006 4:59 am
Posts: 13
Location: Calgary, AB
On my P3SL and my dad's P2SL, the forward saddle position places the saddle too far forward for the 5cm rule. Not sure if the case is the same for the P2C though.


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 Post subject:
PostPosted: Tue Apr 18, 2006 4:43 am 
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Joined: Tue Feb 14, 2006 4:42 am
Posts: 973
Location: Calgary
Lots of good advice above about set-up.

I ride road bikes with 57 or 57.5 cm top tubes and 12 cm stems. I'm using a 56 cm P2SL with a 9 cm stem and think I'll swap that for an 8. I would probably use the 9 if I moved the saddle forward. With the rear postion, my saddle is right at 5 cm behind the BB. This sizing is consistent with my experience in my tri-geek days of the past when I rode a Quintana Roo with a 56 top tube and 8 cm stem (and lots of drop). In this case, the shop fitted me and I only checked the stem lenght later.

I'm a commissaire in Canada and our instructions are to tell riders they may be measured or weighed at any race, even though the only place I saw measurement last year was nationals and weighing was only at the provincial hillclimb championship.

You may want to get used to riding at the legal setback in case the rules are enforced at any time during your ownership of the bike. If you look at pictures of top triathletes, they use a forward position AND ride off the front of the saddle so we can do that on the road too. The rule is dumb but why flaunt it if there's a chance someone may protest against you?


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 Post subject: size DZ
PostPosted: Fri Aug 11, 2006 9:04 am 
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Joined: Mon Jun 05, 2006 3:19 pm
Posts: 169
Location: Greve, Denmark
Does anyone know what size Cervelo P3C David Zabriskie use?

_________________
Bring the mountains to Denmark!!


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 Post subject: Re: size DZ
PostPosted: Fri Aug 11, 2006 11:11 am 
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Joined: Tue Mar 21, 2006 12:56 am
Posts: 4907
tcramer wrote:
Does anyone know what size Cervelo P3C David Zabriskie use?

Yes, Zabriskie is on a 54 cm P3C. His height is 183 cm: http://team-csc.com/person_profiles.asp?p_id=73

Here's the answer from Gerard Vroomen from Cervélo:
http://forum.slowtwitch.com/gforum.cgi? ... 92;#518192
Gerard wrote:
bigred3 wrote:
Gerard,

Just curious what sizes in the P3C is the CSC team riding? I understand they all ride the bike in the rearward position, but it would be interesting to compare measurments and sizes with the pros..

Well, although the CSC riders are good example of how people can fit more than one size, I don't think they are necessarily the template to follow for most triathlete. If Zabriskie were a triathlete, I would probably put him on a 56cm frame. But as a time trialer, he is on a 54cm. Same goes for most CSC guys, they are on one size smaller than you would think based on their size. But of course they are in a situation where they are looking for specific handling characteristics (combined with the cycling experience that they have) that is a bit different from the average triathlete. It's easyto make jokes about Zabriskie in that regard, but of course he is still head and shoulders over anybody on this forum when it comes to bike handling.

Gerard
Cervélo Cycles


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 Post subject: Re: size DZ
Posted: Fri Aug 11, 2006 11:11 am 


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