Velocite’s commits (to) a Syn with all-new aero road bike

Aesthetically not a problem. Cross winds . . . ?

I don’t have a geek-like knowledge of dynamics for all aero bikes out there, but this seems like a BS statement to me: “to date no bicycle design delivered optimal aerodynamic performance once water bottles are mounted.”

Surely companies with greater finances took into account pro peleton aspects like bidons when designing their bikes…

Hell, even Cervelo plastered a sticker saying “built for bottles” on their S5 frames from 2012.

“to date no bicycle design delivered optimal aerodynamic performance once water bottles are mounted.”

I’m just going to point out that the Giant Propel also claims to have been designed around having a bottle on the downtube….

and yeah the front wheel is either not dished properly of not in the frame straight… either way pretty poor.

@G – Re: Cervelo, yep! Congrats, you’ve built an S5 with disc brakes.

For all the talk, discussion, design and expense spent over the Aero design on road bikes it really becomes a moot point when you can *instantaneously* destroy ALL the Aero on the bike by riding in a bad (draggy) position.

IMHO, the truly *revolutionary* Aero road bike will be one that allows you to *comfortably* fit into a tuck/superman type position and still produce good power at the pedals. I have yet to see this bike.

All that aero and they put disc brakes on it. So stupid.

The cfd picture says everthing about real live…. No cockpit, No seatpost, No discs. Truely Marketing only.

I love the fact that this “aero” bike has a round seatpost. I tweeted them already, CFD model is essentially bike frame with wheels and not rideable. (deleted).

My original reply seems to have gone AWOL.

so let me thank you all for your interest, and start again 🙂

@Mike, the primary problem with cross winds is the torque on the front wheel. Also the Syn was tested for side pressure and torque and it should handle well.

@G yes they do, but not to the extent that we took it.

@Nate & jeb yes. I just grabbed this prototype and rushed outside when the public display embargo was lifted and took some photos in the local park. The wheel is missing an axle nut so it is loose in the fork, and the wheel was angled to brace the bike so it does not fall over while I am lining up the shots 🙂

@Ginsu & @sark. Completely agree, but the frame remains aero regardless of what the rider is doing.

@MICHAEL and @nightfiend we also have a rim brake version. Disc brakes are indeed not as aero, yet, or ever.

@Eaton. I replied to your tweets, thanks 🙂 The round seatpost is clearly not an accident and the CFD image presented is not the only CFD work that we performed. We spent about 6 months on it. The data is solid and more will come out as we prepare for the proper product launch.

Victor (the one from the story above)

All that aero and they put a human on it, that’s stupid too

Wow. Haters gonna hate. I think this bike is stunning.

The aesthetics of the down tube might not appeal to everyone, but people will be lining up to buy one if it wins a tunnel test.

And the stiffness… this bike will be rocket to ride unlike the Cervelo wet noodle.

@Victor–I think it looks fantastic and I am an old retro-grouch who prefers steel. Cheers!

GOOD catch Nate! That bar tape looks like it was done by a Walmart employee and the front wheel is nearly touching the side of the fork. Shame on Velocite for letting this bike even be photographed.

I’m pretty sure that the riders movements on the bike play a bigger role in aerodynamics than a water bottle…

@Sam: You are correct, Specialized: https://www.youtube.com/watch?v=HXQuSnKkS-I
…and VeloNews had pretty much the same conclusion: http://velonews.competitor.com/2014/12/bikes-and-tech/discs-drag-wind-tunnel-testing-disc-brake-road-bikes_355621

There is a detriment to running discs in a crosswind, depending on the angle… which on an aero frame shaped for forward motion – it’ll suck either way, just a little more.

The larger issue with discs now is weight. The lightest disc brake wheelset I’ve seen or heard of is in the 1350-1400 grams region 🙁

What dinger said, whether or not your body position sucks, you can still improve the other things and benefit. Hopefully, you sort the position first but it’s not like a bike doesn’t make a difference if you don’t…

In all, only the numbers can really tell the story if the design is effective for their goals but I wonder why the bottle recess goes so high on the down tube/head tube, it seems like they could have done something narrower behind the head tube and fork crown and then widen where the bottle actually sits. I also wonder if they played with a compromise idea, like a fairing built for aero bottles, that was still better for round bottles(say a 35-40mm wide recessed down tube).

@ Neilthemeal and @ Jez,

thank you for the technical questions.

Numbers. We will put the bike through wind tunnel testing, and will get the numbers. However wind tunnel testing is also not “the truth” but a set of numbers generated in a controlled environment under specific conditions. I do not want to post a link in here as it may nuke my comment, so please search for the following document: NASA-aiaa-2000-2201.pdf

It discussed some of the intricacies of wind tunnel testing

The profiles were very carefully shaped, but we did run into “packaging” issues – ie. how do we wrap a bike around the required profiles. There is only so much room to work with and we had to avoid sharp corners or sudden profile changes. Sharp corners due to material requirements (carbon fiber is not strong in corners, resin does not flow if corners are too sharp and I hate having to patch this up with putty), and sudden changes as we had to maintain a favourable pressure gradient so that we do not induce premature boundary layer separation.

Also consider that the bike travels through a fluid medium so the actual profiles interfacing with the fluid are projected along the z-plane and are normal to the fluid. The downtube integrates the water bottle perfectly, and it even works with longer water bottles.

We did consider the fairing and even deeper recess, but, and this will hopefully be more clear as we release more information and more messages, the Velocite Syn is not a traditional aero road bike. It is a superbike, even though I hate that moniker as it has been appropriated by some designs that are anything but. So, we had to make sure that we can deliver the stiffness and handling characteristics, as well as comfort that befits its “real life” superbike positioning. The Syn will work well in all conditions and situations. You do not need to choose between an aero bike or the road bike.

I cannot post images here, but I will make a blog post over the coming days that will discuss the design in some more detail, and will show some more airflow data. Basically the head tube works exceptionally well. On our Facebook page (search for Velocite) I showed one CFD image in the main comments thread that shows laminar flow at 10 m/s and 6 degrees AoA,

The screenshot in the Bikerumor post is mainly for visual effect. One thing you can notice is that the wheels are spinning, that pressure distribution on the downtube and the bottles is almost magically event and that there is little flow mixing between left and right side of the bike. This is a transient simulation screenshot, not a steady state averaged result, so the result that can be interpreted is actually truly impressive.

The vortices were already there owing to the spinning wheels, except at the head tube which displays the laminar flow that I mentioned. The main effect of the downtube profile is to not add additional energy to the vortices coming off the wheels, and to keep the flow separated so the vortices from left and right side of the bike do not combine into a much higher energy vortex stream. We performed simulations on a round tube frame which displays pressure hotspots, high energy vorticity and the mentioned vortex mixing. Basically with a normal frame the airflow from the right curves around the DT and the DT water bottle and mixes with the airflow from the left of the frame just behind the DT water bottle.

So in fact, as you rightly noted Jez, the design (Except for the head tube) is all about downstream flow conditioning and our simulation setup (transient LBM with LES turbulence modelling) is just about perfectly suited for downstream flow modelling.

One other thing that I can mention now is that we also considered pressure drag where the rotating wheels meet the fork and frame. We allowed ample space for the tires and rims to pass through, which as a side benefit also allows the use of very wide tires if one so desires.

@sss. We will show that data set too, but I can let you know the findings now.

Handlebars and stem do not materially influence the airflow around the frame, and the rider does not influence the airflow around the frame as much as expected since at the leg level the airflow around the frame is already turbulent thanks to the wheels and the downtube, and anything above the saddle (ie. torso and arms) are either in the turbulent wake of the rest of the front of the bike or presenting their own frontal area to the airflow independent of the rest of the bike.

The handlebar and stem (and all components or accessories attached to them) are however very important for overall bicycle aerodynamics, as is the rider and the rider’s position.

So from CFD simulation perspective when optimizing an entire bike, including the stem and handlebars is important, however including the rider isn’t for a simple reason that the rider is a largely uncontrollable variable. Conversely, only including the most significant parts in the simulation reduces the number of variables and statistically makes the simulation more meaningful and more appropriate during research and development stage. In fact, our r&d process started just with the head tube segment, then we tested the downtube segment and only after those two parts were developed to our satisfaction did we make the rest of the frame 3D model and start simulating the bike.

This also applies to wind tunnel testing. Adding a test dummy or a rider to the system reads well for the marketing story or magazine sales, but does not necessarily deliver meaningful results for the following reasons:

1. Static or movable dummy adds yet another very large setup variable and even small variations in setup can generate significant differences in drag numbers. Wind tunnel testing is actually all about reducing the number of variables to the bare minimum and asking very narrow and specific questions.

2. Tuning a bike design to a single dummy (or handlebars and stem) and testing against it is not really that meaningful unless the dummy or the 3D model is one of the eventual rider of the bike who will adopt the identical riding position regardless of the geometry or ability.

The best way to “use” a human on the bike is to place them both in a wind tunnel and tune the rider’s position and use that to set up the bike to achieve the optimal aerodynamics and rideability – ie. there is no point in achieving the optimal aero position if the rider cannot stay in it long enough, or if the power output in the most aero position is significantly lower.

Article is incorrect in its claims about water bottle.

Giant specifically designed their Propel around a water bottle and cage bolted to the mounts on the down tube.

Since the bike doesn’t appear to try to meet UCI regulations which require water in round bottles inside the frame diamond, I don’t understand the logic of optimising an expensive non-replaceable structural frame around a $5 plastic component.

There are some much smarter, cheaper and more elegant ways to go fast while being able to drink
1) put the water somewhere else like between the arms or behind the saddle (99% of tri bikes)
2) develop non-round bottles that mate with the frame (Falco, Cervelo P4)
3) put the water inside the frame (Shiv, Cheetah)
4) use the water to make an aero hump on the rider (Camelbak)
5) use widespread public drinking fountains (Switzerland)
6) pay someone to ride a moped and hand up drinks (Lance Armstrong)
7) use a fuel cell to provide onboard refreshment as well as electric power

Seems like someone didn’t really think this product through.