BMC TMR01 vs. Giant Propel

Discuss light weight issues concerning road bikes & parts.
Post Reply
NGMN
Posts: 1536
Joined: Mon May 30, 2005 7:13 am

by NGMN

so is it your argument that all of the testing revealing reduced drag is irrelevant because riders are in some sort of vacuum? law of physics need not apply, this is bike racing.

by Weenie


quinner
Posts: 34
Joined: Thu May 03, 2012 12:58 am

by quinner

I can vouch for the ride quality of the BMC, superior to other 'aero' bikes I have ridden. The foil was too harsh IMO.

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

NGNM

Of. Ourse they apply. I presume you are au fait with them

Could you please tell me what the 8 watt saving into a 7km headwind @ 45kph becomes when sheltering fifth wheel travelling at 35 kph?

NGMN
Posts: 1536
Joined: Mon May 30, 2005 7:13 am

by NGMN

Lots of your post doesn't make sense.

Like is it 45kph, or 35kph? Either way, Specialized is doing this type of testing. And, you aren't always in a pack in bike racing, sometimes you descend stretched out, sometimes you break off the front, sometimes you are off the back, sometimes you are at the front of a pack, sometimes you are in the middle, sometimes you are on the side of a pack with wind from that direction. Take all of those sometimes and pretty soon you have a lot of times that you're saving 5-15 watts, and a bunch of other situations where you aren't necessarily losing anything.

Anyways, the whole stiffness/ride comfort thing that you raised is neither here nor there. People find non-aero and aero racing bikes to be too _______(stiff, harsh, soft) all the time. More common with aero bikes? yes, but certainly not the only way to make aero bikes, and this seems to be an area of focus and improvement.

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

Certainly an area of focus for manufacturers Hoping for an improve Kent in their end of year figures.

You don't have an answer for. me? I thought it was a simple enough question.

What does Specialized say about savings at any speed when sitting fifth wheel?

I'll try to clarify. If ou sit on the front or attack for say 5% of a 100km road race, you will save in theory up to 10w for that period. If you are only saving say 1w for the rest of the race then you are, in reality potentially saving a whopping 1.45 watts ( in theory).. and this assumes you can go on a solo break for 5km at the end of a race and maintain 45kph

For many, the savings are around 0.5% or considerably less than drive train loss. So I ask for perspective.

User avatar
53x12
Posts: 3762
Joined: Fri Sep 15, 2006 6:02 am
Location: On the bike

by 53x12

Anyone watch ITV4 coverage of the TdF this year? There were some good video excerpts with Chris Boardman and windtunnel data they have been doing on these very exact questions. Very interesting stuff. I haven't seen them posted to youtube yet and not sure they ever will be.
"Marginal gains are the only gains when all that's left to gain is in the margins."

spud
Posts: 611
Joined: Sat Feb 07, 2009 5:52 am

by spud

Airwise,

maybe you are trolling, but let's look at a plausible scenario - you get into a 4 man break for 40 minutes, and everyone shares the load equally, therefore you are doing 10 minutes on the front. Everyone is on a standard road bike, you are on an aero bike, so while they come through at 400 watts, you can come through at 390 conservatively, probably closer to 375. Do you think that would make a difference at the end? I've trained with power, and I know what adding 20-30 watts can do to your power decay during an interval set.

Furthermore if you get to the end to sprint it out, and everyone can go at 1200 watts, presumably due to aero advantage you only need about 1080 watts to hit the same peak speed. between that savings, and the fact that you come to the line fresher, you don't see a big advantage there?

I've done it on standard and aero road bikes, and I've won in field sprints and small group sprints. Aero won't make up for bad fitness, or lousy tactical knowledge, but I'll take an aero advantage any time.

sawyer
Posts: 4460
Joined: Fri Dec 15, 2006 7:45 pm
Location: Natovi Landing

by sawyer

airwise wrote:Ignoring the rather predictable and hopelessly inaccurate snipe, simply put, because there is NO evidence of ANY net marginal gain under normal racing circumstances.


How could one prove this?

There's similarly no such evidence for carbon frames, for aero wheels, for high threadcount tyres etc. etc.

Very hard, impossible even, to generate data showing power savings during a race given the unrepeatable nature of the activity. That's what labs are for ...
----------------------------------------
Stiff, Light, Aero - Pick Three!! :thumbup:

Ahillock
Posts: 466
Joined: Fri Jul 16, 2010 6:30 am

by Ahillock

What about wearing lyrca vs bag jean shorts and city of shirt? Any evidence saying that is slower or faster?

r_mutt
Posts: 331
Joined: Sat Feb 23, 2008 6:33 pm

by r_mutt

what about baggy jean shorts riding in the bunch for 87% or the race?

:twisted:

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

Spud

Sorry but your maths don't seem to work.

So bei g generous and saying a 10 w saving, that's only for a quarter or the time in the break so in reality 2.5w. Now it may be that you'll save 3-4w whilst sitting first wheel but over the course of the break your savings will be tiny - certainly no more than adding a narrower bar or wearing overshoes.

If such designs, and I have ridden with them and a power meter, we're really worth 25w, I think we'd all want them and all pros would insist on them.

FWIW, having ridden a couple of aero bikes, give me my Colnago anyday. I'll more than make up for any aero losses by cornering more confidently and sitting down more over the course of an event. Of purse there is no way of my proving that,just as the manufacturers can't prove real savings in bike races. That is the genius of this proposition from the marketers POV.

sawyer
Posts: 4460
Joined: Fri Dec 15, 2006 7:45 pm
Location: Natovi Landing

by sawyer

@airwise - manufacturers can't prove any of their products give a performance advantage in a race due to the non-repeatability of life outside the lab ...

You have a good point in that the way a bike feels and handles can make a bigger difference than a few watts ...

But the other part of your argument is to deny the relevance of laboratory conditions to experience in the world outside ...
----------------------------------------
Stiff, Light, Aero - Pick Three!! :thumbup:

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

Sawyer I would not deny any empirical data if someone can produce some with pedalling mannequin, in and out of drafting positions, at speeds more likely to be encountered by the target market, and also backed up by handling data and performance in gusting side winds etc.

Sadly, no such empirical evidence exists. Only selective data produced to sell the concept truly exists, or limited protocols like those employed by Tour which give some indication of the small benefits that might be incurred under certain circumstances.

I read Tour and think " hey the pros are tiny when you delve into it". Others read white papers and swear the future is complex frame design. If someone comes up with incontrovertible evidence I will happily accept it.


by Weenie


User avatar
Leviathan
Posts: 1010
Joined: Sat Mar 17, 2007 10:49 am
Location: Mallorca, Spain
Contact:

by Leviathan

Actually its more like
http://en.wikipedia.org/wiki/Occam%27s_razor
"the hypothesis with the simplest theory has primacy":

In this case "no aero benefits in a group unless you can prove otherwise"

Post Reply
  • Similar Topics
    Replies
    Views
    Last post