Aero bikes and the Pro peloton...

Discuss light weight issues concerning road bikes & parts.
Marin
Posts: 3518
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

diegogarcia wrote:
Sat Dec 01, 2018 7:34 pm
Never weighed a bike in my life.
You're on the wrong forum then! :D

diegogarcia
Posts: 557
Joined: Sat Apr 24, 2010 7:31 pm

by diegogarcia

Marin wrote:
Tue Dec 04, 2018 9:29 am
diegogarcia wrote:
Sat Dec 01, 2018 7:34 pm
Never weighed a bike in my life.
You're on the wrong forum then! :D
That may be so, but always interesting chat and sometimes though the aforementioned interesting I read things with fright when people try and save 7 gms with an unsafe third party steering bung which renders them in harms way :mrgreen:

by Weenie


packetloss
Posts: 28
Joined: Fri Dec 11, 2015 2:29 pm

by packetloss

I have a Venge Vias and a Tarmac SL5. From a ride quality perspective, the Tarmac is a little more comfortable, however, I wouldn't say the Venge was too harsh or it's ride quality was enough of a difference to deter me from riding it on 80+ mile rides. On the flats, when riding alone or on the front I was definitely faster on the Venge at the same wattage. On a slightly hilly ride (no long hills, but several short 12-15% climbs) the Tarmac was significantly better. It was enough of a difference that I got dropped while on the Venge with my usual group that I never have a problem staying with on the Tarmac. What I can't say is if it is truly a weight issue (My Venge is 3/4 of a lb heavier than my Tarmac) or just the general ride quality difference of an Aero is everything frame vs the Tarmac. I can say the Tarmac is profoundly snapier on climbs and the Venge felt rather slugish and dead on climbs. I suspect it's more than just weight as my older titanium frame which is heavier than my Venge doesn't feel slugish on climbs.

So, having both types of bikes, I try to avoid taking out the Venge if I know there is any climbing. Sometimes I just don't know how a ride will be and will always opt for the Tarmac on such rides. If I were a pro I would only ride the Venge on flat days (but would ride it), or switch to it after the climbs were done. If I had to ride the Venge on climbs, I wouldn't be around long enough for the aero advantage to matter.

AJS914
Posts: 3463
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I have a feeling that what explains this is "planing". It would be great if there were more scientific testing in this area. With carbon frames, the industry went the 'stiffer is better' route. They have no choice with aero frames requireing the tubes they require. Does anyone even try and make a frame that feels springy and lively these days?

https://janheine.wordpress.com/2014/12/ ... f-planing/

https://janheine.wordpress.com/2018/01/ ... re-faster/

If I were a grand tour contender and a flexier bike could make me 12% faster up climbs I'd be testing one for sure.

mattr
Posts: 4673
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

It's quite well understood and utilised in many other fields. Making a chassis too stiff is counter productive.

AJS914
Posts: 3463
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

It doesn't seem to be talked about much in cycling though especially with regards to producing power.

TobinHatesYou
Posts: 4161
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Planing is another one of Jan’s crackpot ideas. Uncontrolled frame flex is more undesirable than desirable and results in power loss through hysteresis. Road bikes already have more than enough flex/springiness through their forks, rear triangles, stems, seatpost, saddles and tires. The bottom bracket is not an area I want to flex much.

packetloss
Posts: 28
Joined: Fri Dec 11, 2015 2:29 pm

by packetloss

I don't think anyone is talking about uncontrolled flex. I hadn't read any of this before, but the 2nd paragraph describe the difference in how the Tarmac and the Venge felt to me while climbing. I wouldn't describe the Tarmac as "flexy" at all. But it just felt a lot easier to climb on than the Venge. I really felt like I was fighting the bike when on the Venge. Both have almost identical geomotries. Only difference would be the compliance of the tubes I guess.

Along came another Bicycle Quarterly test bike (above). This one performed better than expected. It wasn’t particularly lightweight, and our initial expectations weren’t all that high. And yet, whether it was me or Mark (our second tester) riding it, this bike climbed faster than our other bikes. It turned out that it was made from very thinwall, and thus flexible, tubing.

So we had tested one bike that was stiffer than our own, and it didn’t perform as well. A second one was more flexible, yet it performed better. Even more startling was the difference in feel. On the flexible bike, pedaling faster didn’t seem as hard. We were out of breath, but our legs didn’t hurt. Once we got in sync with the frame, its response to our pedal strokes felt like a boat rising out of the water, going faster with only a little extra energy input. “You mean, it ‘planes’,” said Matthew Grimm of Kogswell, when I described the phenomenon to him. Deciding that the phenomenon needed a name, we used the term ‘planing’ to describe it.

AJS914
Posts: 3463
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I don't know if the idea has merit and I'm sure their testing isn't double blind or rigorous enough for a scientific journal but I know I've had bikes that just feel fast and bikes that don't. I never measured any of my bikes to actually be faster than one or the other (not talking about aero here). I do know that the bikes that felt a bit springy or lively were the bikes I've always enjoyed riding the most.

CAAD8FRED
Posts: 209
Joined: Mon Jun 18, 2018 10:52 pm

by CAAD8FRED

Having ridden an Evo and now a Foil, the Evo is substantially more comfortable and has a certain jump to it. If 'Dale is being truthful in saying that ride characteristics of the Evo and SysSix are similar, then it may be an aero bike that could be made lighter without sacrificing ride due to tube shaping.

asiantrick
Posts: 240
Joined: Fri Dec 04, 2015 11:18 pm
Location: the OC, CA

by asiantrick

Think of it as the Mario Kart game. Acceleration vs Top Speed (Luigi vs Bowser)

Climbing bikes always response better and accelerate faster than aero bike. It just doesn't have the top speed and can hold speed as an aero bike. I always choose fast, responsiveness, agile over aero and top speed. In a group, aero is meaning less especially for a wheel sucker like me

dastott
Posts: 178
Joined: Wed Jun 17, 2015 12:35 pm

by dastott

I have an SS Evo with shallow rims (6.5kgs with clinchers) and a Merida Reacto with 60mm rims (around 8.5kgs). The Reacto is an underrated aero bike and I picked mine up new for around $1500 with 105 groupset. The Reacto feels faster on that flat, although I have it set up more agressively. The Evo really shines on steeper (6% and over) and longer climbs. On twisty sections there is little to choose between them, with the Evo having a slight edge perhaps. It's great to have both.

User avatar
Lelandjt
Posts: 525
Joined: Tue Jan 19, 2016 7:10 am

by Lelandjt

Isn't the Tarmac laterally and torsionally stiffer than the Venge?

mattr
Posts: 4673
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

TobinHatesYou wrote:
Wed Dec 05, 2018 10:26 pm
Planing is another one of Jan’s crackpot ideas. Uncontrolled frame flex is more undesirable than desirable and results in power loss through hysteresis. Road bikes already have more than enough flex/springiness through their forks, rear triangles, stems, seatpost, saddles and tires. The bottom bracket is not an area I want to flex much.
"More than enough".
Maybe they have exactly the right amount?
Make it stiffer, you have a problem. Make it more flexible, another problem.

It's not a simple equation.

In RC car racing (another of my hobbies), most high end cars have multiple chassis plates to choose from, and multiple build options to tweak stiffness. In mine, in the stiffest setting, it's a full on effort to get visible twist between the front and rear bulkheads. In the most flexible setting you can get around 5 degrees flex along the axis of the chassis with essentially finger pressure. Completely different cars, but given two different different courses, both perfectly driveable. Get it wrong and you'll be off at the first corner.

There was a big article about GP motorbikes and how they were having issues with too stiff frames a few years ago.

by Weenie


User avatar
kgt
Posts: 7818
Joined: Sun Jun 18, 2006 10:29 am
Location: Athens, Greece

by kgt

I believe that the Tarmac is a much better climbing frame (that's why the pros prefer it) but I doubt that it is because of its lower or higher stiffness. There are many parameters that affect this feeling, it's not always easy to isolate one.

Post Reply
  • Similar Topics
    Replies
    Views
    Last post