Handmade stainless and carbon roof rack concept looking for feedback…
Ben from Sheffield has been in touch with details of his concept for a car rack that attempts to address some of the disadvantages of current roof-mounted options. Most notably, the design would reduce the liklihood of hitting low overhangs and garages by lying the bike on its side. Once in the low position, aerodynamics should be improved and, as a result, fuel consumption and wind noise should be reduced.
“I’m trying to build a cool Sheffield based company which will provide an alternative to some of the big brands in years to come”
A gas strut eases the bike over and helps with its return to upright. Initial builds will be in stainless steel, with carbon fibre models to follow. Ben has partially completed prototypes in his own workshop- but would like our thoughts before going further. Beyond being restricted to one bike and the potential challenges with bendy road bike handlebars, it seems like an interesting concept.
At this point, the as-yet-unnamed company isn’t seeking funding or sales- only feedback. What say you all?
Nice idea. With the bars turned mounting position you could quite easily stack two bikes close to each other, could you not? I’m assuming front wheels go in the car?
Good luck with it Ben.
I’ve had a bike come off a newish roof-mounted cycle carrier, made by the market leader, due to a foot part shearing. Subsequently I rarely put a bike on the roof. However this does look interesting but obviously the downside is it only accommodating one bike with one wheel.
It could be useful for taller cars/mpv’s as well as appealing to those of a shorter stature.
er, wrt to aero dynamics, unfortunately, unless you can get the bike and rack into the “boundary layer” of the std car, it isn’t going to change the total drag load by very much. In fact, moving the bulk of the bike closer to the car, where air velocities are higher and flow is more turbulent could actually increase drag……..
I think it needs to hold at least two bikes, but then I have a family and am probably not the target demographic. Holding two bikes could be an advantage because with the rack in the upright position the second bike would be lifted on whilst the rack overhung the edge of the roof. This is easier than the up and over lift on existing roof mounted racks.
Makes you wonder about a large flat roof-box with bike-mounts inside. Like a hard bike-case, but aero. Or maybe even just a simple front spoiler to deflect air-flow over the flat bike?
Also, it needs to compete in price with a removable tow-ball and a good tow-bar rack.
Good to see an alternative idea though, good luck Ben.
Maybe some sort of deflector on the front of the rack to push the air over the bike?
Or if there were a top and bottom cover (ie like a roof box) that went over the bike so it stayed clean and dry, wasn’t visible, was more secure and more aerodynamic)?
[edit] what ir_bandito said [/edit]
Smart thinking, I hope he can get it into production!
Certainly helps the “driving under a barrier” issue
Wobbling bikes on roof racks always look as if something is waiting to break, and this reduces all the wobble so nice work. But yes would need to take two, as the weight is more stable can it be designed to hold the bikes further back along the car? so the windscreen overhang is reduced? just thinking it would seem better for aerodynamics to remove that, and yes a small fairing might be great too if it was tested and performed properly.
I’m not a fluid dynamicist, so could Maxtorque or someone explain why moving an object through more turbulent air might *increase* drag?
I always assumed that turbulence would decrease it – or at least keep it the same for a given volume…
As someone who looks at upright cars on roofracks wobbling about and repeats to himself how he would NEVER EVER DO THAT, I might actually consider this.
but I’d still have to take the golf clubs out of the boot of the Audi to fit the 29″ wheel in….
I like the idea and have a couple of thoughts prompted by previous comments. Overhanging in some way isn’t always a bad thing as it provides reassurance that the bike is still there! (May sound silly but whenever I’ve driven with a roof mounted bike rack it is a constant thought in my mind.) I agree with the comments about 2 bikes as this would be more versatile. Loading on nearside of road and then slide and fold onto roof? Not sure a cover or flap would make much difference to security or aerodynamics but I’m no expert in the latter.
Good to see fresh ideas Ben so good luck with it. I live in Sheffield and ride pretty regularly so if you ever need a tester for a prototype…
Pure drag wise i won’t bother hypothesising – could go either way. But I could see an aero and stability advantage from the reduction of nose up pitching moment as a result of reducing the moment arm of the drag.
Obviously better for preventing hitting the bike and something i have often thought about doing but just by strapping the bike on to the roof racks. Also puts your bike less on display as it’s harder to see the brand name and components.
Problem is getting 2 bikes up there, maybe one rack each side with one lifted up or two racks on one side at 90 deg to each other so you mount one and lay it flat which rotates the next rack to horizontal and then that has a separate and higher hinge so it can then lay flat over the first bike. May have to have one pointing back and one forward to avoid pedal clashes. Should still be at least half the height of an upright bike.
would work well with Thules sliding bars or if it had a sliding function
I think the idea has merit – mostly for the barrier height thing. good luck!
Good idea, the ability to carry 2 bike as a minimum would be needed for me and the spolier/deflector to help ‘lift’ the air over the bike sounds a good idea.
My bike is worth more than my car, so it only ever travels inside the car. Is there an issue with oil in shocks laid on their sides?
RE: drag. Aerodynamics is complex, extremely complex and due to the compressable nature of air, the exact conditions and subtleties of each and every situation will be different. However, in general, and muchly simplified:
If you want NO drag, the entire bike must be withing the layer of air that is already being “pulled along” by the unadorned car. Unfortunately, for a modern car this is tiny by design, and often less than 1cm thick, so you won’t get a bike into it (except maybe on the rear of a car with a steep rear profile)
Air a long distance from the car is moving at a constant speed (the speed of the car) but air near (say ~1m) the car starts to be affected by the car, and the fact the car must “push” air out of the way to travel through it. As such, locak increases in density and velocity above the mean are created, and turbulence on a major and macro scale created. This turbulence (pressure difference / velocity) with a non zero vector velocity that is not in the direct direction of travel, changes the thickness of the boundary layer and hence the total form drag of the car/bike combo.
So in summary, will this rack have a lower drag than a conventional upright rack, er, possibly, but it could also be higher depending on lots of factors. Unfortunately, although CFD is now relatively affordable,modeling and simulating a bike, where the drag comes from a huge number of tiny “drag artifacts” added up, rather than from one of two bulk shapes is complex and time consuming