S5 as a TT bike - first cut (Page 5): Triathlon Forum: Slowtwitch Forums

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S5 as a TT bike - first cut

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docfuel

Mar 18, 12 19:24

Post #101 of 129 (4538 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

How does that frameset compare aerodynamically with the P4? P5?
_________________
Dick

Take everything I say with a grain of salt. I know nothing.

jackmott

Mar 18, 12 19:26

Post #102 of 129 (4536 views)

Re: S5 as a TT bike - first cut [docfuel] [In reply to]	Quote \| Reply

docfuel wrote:

How does that frameset compare aerodynamically with the P4? P5?

its about the same as the p4 supposedly.

Boardman Bikes now in the USA
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

docfuel

Mar 18, 12 19:29

Post #103 of 129 (4533 views)

Re: S5 as a TT bike - first cut [jackmott] [In reply to]	Quote \| Reply

For the price, that's pretty remarkable.
_________________
Dick

Take everything I say with a grain of salt. I know nothing.

Tom A.

Mar 18, 12 19:32

Post #104 of 129 (4526 views)

Re: S5 as a TT bike - first cut [jackmott] [In reply to]	Quote \| Reply

jackmott wrote:

docfuel wrote:

How does that frameset compare aerodynamically with the P4? P5?

its about the same as the p4 supposedly.

That Lava test talked about above tends to confirm that assertion, no? :-)

http://bikeblather.blogspot.com/

jackmott

Mar 18, 12 19:37

Post #105 of 129 (4516 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

it sure does!

also the fact that the s5 looks a lot like a p4 and p5

Boardman Bikes now in the USA
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

Francois

Mar 18, 12 19:50

Post #106 of 129 (4496 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Which is strange since for years, we've been hearing that sloping geometry 'ain't aero' because the top tube gets in the way.
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http://www.fmcoaching.com

http://www.elpasotricoaching.wordpress.com

jackmott

Mar 18, 12 19:53

Post #107 of 129 (4487 views)

Re: S5 as a TT bike - first cut [Francois] [In reply to]	Quote \| Reply

I believe Damon Rinard has spoked on that subject and said that the difference on the s5 is very small.

Francois wrote:

Which is strange since for years, we've been hearing that sloping geometry 'ain't aero' because the top tube gets in the way.

Boardman Bikes now in the USA
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

damon_rinard

Mar 19, 12 5:46

Post #108 of 129 (4383 views)

Re: S5 as a TT bike - first cut [jackmott] [In reply to]	Quote \| Reply

I believe jackmott is right again. http://forum.slowtwitch.com/...post=3410358#3410358

"Conveniently, we tested level and sloping top tubes in the wind tunnel. (Phil insists on data for nearly every level of design decision.)
Result: With the tube shapes we use, we could find no significant difference.

Why? A level top tube can have less drag *on the top tube*. But a sloping top tube "moves" the seat cluster down, eliminating some seat tube below and substituting an equivalent length of (slimmer) seat post above. Sloping the top tube changes drag on other parts of the bike.

There is less difference with a sloping top tube now, than we used to think back then.

So with aero a wash, we went with sloping for all the practical reasons most road bikes have sloping top tubes these days."
===========
Damon Rinard, Senior Advanced R&D Engineer
Vroomen.White.Design
http://www.cervelo.com
http://www.bbright.net

jackmott

Mar 19, 12 5:48

Post #109 of 129 (4381 views)

Re: S5 as a TT bike - first cut [damon_rinard] [In reply to]	Quote \| Reply

now here is a question for - if it is a wash, why not slope it on the TT bikes too?

just because the market expects it to be flat?

Boardman Bikes now in the USA
The newest tri shop in Austin - ATC 360
Freelance sports & outdoors writer Kathryn Hunter

damon_rinard

Mar 19, 12 5:53

Post #110 of 129 (4374 views)

Re: S5 as a TT bike - first cut [jackmott] [In reply to]	Quote \| Reply

Good question. Sloping the top tube on a TT bike means there's no place to put the seat post on the small sizes.
===========
Damon Rinard, Senior Advanced R&D Engineer
Vroomen.White.Design
http://www.cervelo.com
http://www.bbright.net

Fastyellow

Mar 30, 12 9:30

Post #111 of 129 (4118 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Results are up on Tren's Facebook

Are you racing this weekend? Piru or Buellton? I'm doing the Crit at Buellton and maybe the 20K TT on Sunday.

-------------------------------
I'm faster in Kilometers!
Wattie Ink Triathlon Team
Powered by Accelerate 3

Tom A.

Mar 30, 12 10:12

Post #112 of 129 (4074 views)

Re: S5 as a TT bike - first cut [Fastyellow] [In reply to]	Quote \| Reply

Fastyellow wrote:

Results are up on Tren's Facebook

Are you racing this weekend? Piru or Buellton? I'm doing the Crit at Buellton and maybe the 20K TT on Sunday.

That's my plan as well...although the latest weather report hints at possible rain tomorrow in Buellton. If it rains, I won't do the crit...just one of my "rules" ;-)

http://bikeblather.blogspot.com/

Tom A.

Mar 30, 12 10:15

Post #113 of 129 (4067 views)

Re: S5 as a TT bike - first cut [Fastyellow] [In reply to]	Quote \| Reply

Fastyellow wrote:

Results are up on Tren's Facebook

Are you racing this weekend? Piru or Buellton? I'm doing the Crit at Buellton and maybe the 20K TT on Sunday.

Oh yeah, speaking of those results...anyone who thinks that "mere seconds don't matter" when it comes to equipment selection should look at how much I beat 2nd place in the Cat 3s by...and the total spread between 1st and 3rd. 'nuff said :-)

http://bikeblather.blogspot.com/

Fastyellow

Mar 30, 12 10:19

Post #114 of 129 (4057 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Yeah, I thought about that...although, if it rains, I may just start the race and ride around to get the finish.

Hopefully I'll see you out there....

-------------------------------
I'm faster in Kilometers!
Wattie Ink Triathlon Team
Powered by Accelerate 3

btmoney

Mar 30, 12 11:15

Post #115 of 129 (3994 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

damnnnnn close one
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redtdi

Apr 7, 12 5:43

Post #116 of 129 (3777 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Is the Quarq on your road setup a GXP model? If so which BB adapter are you using to get it to work in the BBright of the S5? I bought an S5 a couple of days ago not really thinking how to get my power meter over to it...

Thanks,
Ken

"the trick is to keep losing weight until your friends and family ask you if you've been sick. then you know you're within 10 pounds. if they start whispering to each other, wondering if you've got cancer or aids, you're within 5. when they actually do an intervention, you're at race weight." - Slowman

Tom A.

Apr 7, 12 7:08

Post #117 of 129 (3724 views)

Re: S5 as a TT bike - first cut [redtdi] [In reply to]	Quote \| Reply

redtdi wrote:

In the pic above, yes, it's a GXP. I ordered the Enduro adapters (reducing spacers) through Cervelo when I bought the frameset.

http://bikeblather.blogspot.com/

RRWJ

Apr 7, 12 18:27

Post #118 of 129 (3600 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Hey Tom. Sent you pm. Had a cople of questions.

drgwood

May 6, 12 8:44

Post #119 of 129 (3336 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Tom
finally got my S5 and used it as a TT bike yesterday. first time doing that particular event and do not have comparative data. It certainly felt fast and I had pretty good result.
anyway I used a Specialized bottle on bike during race and to fill the space a la P4. I never drink during straight forward TT. In your experience with this bike and bottle set up do you think you get aero benefit with bottle there or
would it be "better" without any bottle at all since I am not using it for fluids?
thanks
Rob

Tom A.

May 6, 12 19:01

Post #120 of 129 (3166 views)

Re: S5 as a TT bike - first cut [drgwood] [In reply to]	Quote \| Reply

drgwood wrote:

Well...for most of the races I've done so far with the setup, I basically wanted at least a little bit of fluid on board. If not for the race itself, then for either warmup on the road or cool down times. So, I've used the Virtue bottle on there. That thing fits SOOO well in the lower part of the triangle and up against the trailing edge of the downtube, my gut feeling is that it's actually faster that way.

But, I haven't tested it out to know for sure. My guesstimated CdA from some of my recent races though implies that having it on the bike definitely isn't slowing me down, at least ;-)

BTW, if you don't use it for fluids, then think about using it for a tube and CO2.

http://bikeblather.blogspot.com/

jcaf

Jun 5, 12 16:23

Post #121 of 129 (2795 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

Tom A. wrote:

rufio wrote:

looks pretty good for a "first cut". what upgrades do you have in mind for future iterations?

Well...I spent a lot of time trying to "repurpose" that open hole behind the stem and the 2 derailleur cable holes as the rear brake cable entry. It's actually intended for the Di2 cable harness entry point, but one of the things that bugs me about the S5 is the rear brake cable entry into the top tube. With it on the bottom portion of the tube, the cable is invariably routed out and forward and looped around (with lots of housing "hanging in the breeze"). Even with it going up through the middle of the Look Ergostem like I have it there, it still "pops out" to the side more than I'd like. I had made a couple of "cable guides" that plug into that hole and then turn the cable rearward towards the rear brake cable exit, but the material I made them out of wasn't up for the task :-/ So...I still intend on making that modification at some point.

Also, I think I will eventually replace the Ergostem with a -45d, 120mm stem. That's what I had calculated I needed, and it turns out it's exactly correct, but for the first cut I wanted to just use the Ergostem to get the bar into the right pad stack and reach spot and then measure what the stem needed to be to confirm.

Oh...and I'll probably figure out something different for the Garmin 500 mount.

Other than that...oh, maybe I'll try some alternate wheels ;-)

Hey Tom just wondering of you figured anything out for using di2 hole for rear brake I thought of running a full cable housing tru to back brake but there must be something available to use as cable stop

Also not sure if you managed to field test vs "old" tt bike , my own Testin should hopefully be done Sunday weather permitting Now that I have tt bars setup

EvenOlder

Jun 5, 12 16:43

Post #122 of 129 (2768 views)

Re: S5 as a TT bike - first cut [jcaf] [In reply to]	Quote \| Reply

I'm awaiting your results/impressions. What kind of stem length are you using?

Tom A.

Jun 6, 12 11:35

Post #123 of 129 (2605 views)

Re: S5 as a TT bike - first cut [jcaf] [In reply to]	Quote \| Reply

jcaf wrote:

No, I haven't. I tried running the full cable housing through the top tube but there apparently isn't a large enough gap somewhere inside the tube to allow that...I couldn't get it all the way through. I'm saving this for the "round 2 mods" I'll probably do this winter.

jcaf wrote:

Also not sure if you managed to field test vs "old" tt bike , my own Testin should hopefully be done Sunday weather permitting Now that I have tt bars setup

I haven't done ANY formal field testing this year...just too busy with other stuff. That said, my derived CdA from events is consistently much lower than it was on the Transition :-)

http://bikeblather.blogspot.com/

redtdi

Jun 8, 12 4:36

Post #124 of 129 (2438 views)

Re: S5 as a TT bike - first cut [Tom A.] [In reply to]	Quote \| Reply

What am I missing here Tom, I thought the lines were meant to overlap?

How do you calculate rolling resistance? I used an r4 aero front and tangent clincher rear with Michelin latex at 110psi for a race on good but not great roads.

Thanks,
Ken

"the trick is to keep losing weight until your friends and family ask you if you've been sick. then you know you're within 10 pounds. if they start whispering to each other, wondering if you've got cancer or aids, you're within 5. when they actually do an intervention, you're at race weight." - Slowman

Tom A.

Jun 8, 12 6:45

Post #125 of 129 (2358 views)

Re: S5 as a TT bike - first cut [redtdi] [In reply to]	Quote \| Reply

redtdi wrote:

What am I missing here Tom, I thought the lines were meant to overlap?

Only if there is no wind...in this case there was. However, since it's an out and back and the wind conditions didn't change dramatically, then a decent estimate can be had by lining up the end points (adjusting for the "jump" in VE at the turnaround due to braking, of course).

redtdi wrote:

How do you calculate rolling resistance? I used an r4 aero front and tangent clincher rear with Michelin latex at 110psi for a race on good but not great roads.

I've done enough roller and on-road Crr testing that I've got a pretty good factor that I apply to the roller testing to estimate it as an input for the Crr value.

http://bikeblather.blogspot.com/

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