Please let me know what you think of my design?
Discussion
Mods – I’m not sure if posting this contravenes the forum rule 4. I don’t think it does, but if I’m wrong please remove
Hi all,
I’m posting here because I need to get some feedback on a design I’ve come up with from people like me who love both bikes and cars. PP seems like an ideal place!
In my spare time over the past year or so I've been designing a bike rack for my car. I’m an aerospace engineer by trade and feel that I can do a better job making bike carriers than what we’re offered currently. For example, roof mounted carriers are often wobbly and damage your bike (especially if it’s carbon), boot racks are plain dangerous, and tow bar racks need a tow bar.
For my first design I have concentrated on the needs of someone like myself (selfish, I know). I’m 30 and travel alone all over the country with my bike most weekends. Therefore I’ve developed a carrier for one bike designed for use on roof bars. I’m trying to incorporate some new design features which will solve some of the issues with existing solutions, the most obvious of which is the fact that the bike will lay flat to the roof of the vehicle. This will lower chances of damage to the bike and vehicle, lower wind resistance and improve access to low garages etc. To load/unload the bike pivots on a 4-bar linkage, powered by a gas spring. Below are a couple of computer renders showing how the thing would look.
And before you say it - I know, that’s a Z4 convertible with a roof rack….it was the best model I could find on GrabCAD...
Anyway, I’ve got as far as building a prototype which is in its final stages, but before I press on and invest more money I need to get some feedback from independent people. I’ve got a workshop, CNC machine, tools and equipment available and ready to go, but there is still plenty of development to do before I’d be happy to sell anything.
So, what do you think? If I take this to production it’ll be hand built in Sheffield in 316 stainless steel and anodised aluminium, with all components supplied in Yorkshire. I could also branch into composite racks at a later date if there was a market there?
It'd be great to get your feedback,
Cheers,
Ben
Hi all,
I’m posting here because I need to get some feedback on a design I’ve come up with from people like me who love both bikes and cars. PP seems like an ideal place!
In my spare time over the past year or so I've been designing a bike rack for my car. I’m an aerospace engineer by trade and feel that I can do a better job making bike carriers than what we’re offered currently. For example, roof mounted carriers are often wobbly and damage your bike (especially if it’s carbon), boot racks are plain dangerous, and tow bar racks need a tow bar.
For my first design I have concentrated on the needs of someone like myself (selfish, I know). I’m 30 and travel alone all over the country with my bike most weekends. Therefore I’ve developed a carrier for one bike designed for use on roof bars. I’m trying to incorporate some new design features which will solve some of the issues with existing solutions, the most obvious of which is the fact that the bike will lay flat to the roof of the vehicle. This will lower chances of damage to the bike and vehicle, lower wind resistance and improve access to low garages etc. To load/unload the bike pivots on a 4-bar linkage, powered by a gas spring. Below are a couple of computer renders showing how the thing would look.
And before you say it - I know, that’s a Z4 convertible with a roof rack….it was the best model I could find on GrabCAD...
Anyway, I’ve got as far as building a prototype which is in its final stages, but before I press on and invest more money I need to get some feedback from independent people. I’ve got a workshop, CNC machine, tools and equipment available and ready to go, but there is still plenty of development to do before I’d be happy to sell anything.
So, what do you think? If I take this to production it’ll be hand built in Sheffield in 316 stainless steel and anodised aluminium, with all components supplied in Yorkshire. I could also branch into composite racks at a later date if there was a market there?
It'd be great to get your feedback,
Cheers,
Ben
it looks great, but a bit complex. Why would you need a gas spring to lift the weight of a single bike? If you need leverage, a handle 18 inches long that would lie flat and rotate 90 degrees to vertical would surely be enough.
Could you add another one on top from the other side to get two bikes on?
Could you add another one on top from the other side to get two bikes on?
Cheers for the quick replys chaps.
S2sol; good thinking on the handle idea, that could really simplify things. The locking mechanism would be far simpler too, I'm going to look into it. I had also considered stacking another bike on but I want to get the first product perfect, so keeping it as simple as possible at the moment.
As for front wheels - at the moment I'd intended to provide a wheel bag. Even an MX5 boot would fit a wheel, but do you think combining a wheel mount would be preferable? I imagined it could be prone to theft?
S2sol; good thinking on the handle idea, that could really simplify things. The locking mechanism would be far simpler too, I'm going to look into it. I had also considered stacking another bike on but I want to get the first product perfect, so keeping it as simple as possible at the moment.
As for front wheels - at the moment I'd intended to provide a wheel bag. Even an MX5 boot would fit a wheel, but do you think combining a wheel mount would be preferable? I imagined it could be prone to theft?
Great idea and love the engineering, but to my ignorant mind, it looks a bit over engineered , I would keep it simple , i'm not convinced on the bike pivoting down
DO you know how much it would cost to produce and how much you would want to retail it for, or are you just making it for yourself?
DO you know how much it would cost to produce and how much you would want to retail it for, or are you just making it for yourself?
Will you need to remove the pedal, or is there enough space between pedal and roof.
Would want to think about weight (can one person lift it onto roof).
Know that you have only used the Z4 as an example, but my SLK (with factory roof rack) has a weight limit of 50kg which can be supported (before adding the rack and bikes).
Shaking a horizontal bike, is there a fear that the chain will fall off (a vertical bike, gravity keeps it in place)? (don't know just a thought)
Would want to think about weight (can one person lift it onto roof).
Know that you have only used the Z4 as an example, but my SLK (with factory roof rack) has a weight limit of 50kg which can be supported (before adding the rack and bikes).
Shaking a horizontal bike, is there a fear that the chain will fall off (a vertical bike, gravity keeps it in place)? (don't know just a thought)
Edited by nike 5 on Tuesday 30th September 17:40
Twistingmymelon, it is over engineered I suspect! I'm trying to keep it as a nice product, a bit special, but not too over the top. I think without a bike on theree it looks quite subtle?
As for costs, I'm still working on them. It wouldn't be cheap, but as with everything with enough volume the price could come down massively. I've had quotes for batches of some parts (like the stainless for example) which have price breaks of 100's of percent when moving from one-offs to batches of 20+. Big difference in affordability....how much would you consider reasonable out of interest?
Nike; the pedal would stay in place. The Z4 model clashes, but that's because the curve from b pillar to the peak in the roof is HUGE compared to cars with normal roofs. I have a decent Audi A5 model on its way which will help me get it right.
Great point about the chain though, that's precisely the kind of feedback I need and can only get from lots more eyes looking at it. I honestly can't say until I've tested it!
As for costs, I'm still working on them. It wouldn't be cheap, but as with everything with enough volume the price could come down massively. I've had quotes for batches of some parts (like the stainless for example) which have price breaks of 100's of percent when moving from one-offs to batches of 20+. Big difference in affordability....how much would you consider reasonable out of interest?
Nike; the pedal would stay in place. The Z4 model clashes, but that's because the curve from b pillar to the peak in the roof is HUGE compared to cars with normal roofs. I have a decent Audi A5 model on its way which will help me get it right.
Great point about the chain though, that's precisely the kind of feedback I need and can only get from lots more eyes looking at it. I honestly can't say until I've tested it!
I've used the thule 591 for (carbon) mountain bikes for years,
but was advised by bike shop to use the thule 561 for (carbon) road bike,
and when you read their website, thule suggest this too.
Don't know why?
http://www.thule.com/en/gb/products/carriers-and-r...
but was advised by bike shop to use the thule 561 for (carbon) road bike,
and when you read their website, thule suggest this too.
Don't know why?
http://www.thule.com/en/gb/products/carriers-and-r...
everGreddy said:
Cheers for the quick replys chaps.
S2sol; good thinking on the handle idea, that could really simplify things. The locking mechanism would be far simpler too, I'm going to look into it. I had also considered stacking another bike on but I want to get the first product perfect, so keeping it as simple as possible at the moment.
As for front wheels - at the moment I'd intended to provide a wheel bag. Even an MX5 boot would fit a wheel, but do you think combining a wheel mount would be preferable? I imagined it could be prone to theft?
I'm afraid my mx5 boot won't fit a wheel in. They're just too big. S2sol; good thinking on the handle idea, that could really simplify things. The locking mechanism would be far simpler too, I'm going to look into it. I had also considered stacking another bike on but I want to get the first product perfect, so keeping it as simple as possible at the moment.
As for front wheels - at the moment I'd intended to provide a wheel bag. Even an MX5 boot would fit a wheel, but do you think combining a wheel mount would be preferable? I imagined it could be prone to theft?
Also have used a Saris bones rack on my mx5 for a road bike and the girlfriends Ibiza with two mountain bikes on. Not dangerous at all if you make sure it's strapped down correctly and no lights are obscured. The major downside is the time setting everything up.
How is the weight of the bike being carried? The bike is best carrying load vertically down through the fork and wheels where they are strongest but the images suggest the bike is either hanging horizontally from the wheel and fork or it is sitting on something where it will rub as it moves?.
Edited by Oscar the Grouch on Wednesday 1st October 08:37
Wouldn't worry about aerodynamics, but it could avoid the rather more common bike to roof of carpark interface issues 
Also have no issues with the thule or saris bones options, having used both extensively. Can see there being a (small) market for something like this tho, mostly for the MAMIL who has to have the 'best' everything to put on top of his AMG
Also have no issues with the thule or saris bones options, having used both extensively. Can see there being a (small) market for something like this tho, mostly for the MAMIL who has to have the 'best' everything to put on top of his AMG
Question - what happens if your sports car has a soft top?
Also why limit it to bikes? It seems to me with very small design tweaks you could fix skis or a surfboard to it the unique selling point is the folding mechanism making it much easier to use than centre mounted options.
You certainly have a good idea.
Also why limit it to bikes? It seems to me with very small design tweaks you could fix skis or a surfboard to it the unique selling point is the folding mechanism making it much easier to use than centre mounted options.
You certainly have a good idea.
Thanks for the replies again chaps – challenging stuff but keep it coming 
Shortshift you’re quite right, the 591 downtube clamp is the problem I’m looking to avoid. I spoke to a carbon repair chap earlier this year who told me he gets up to 5 carbon bikes a week in with holes in various places caused by bike carriers, mainly crunched downtubes. I described what I was making to him and he was very supportive about the idea. My brother has also driven to within a few meters of a low bridge with his Stork Fenominalist on the roof – could have been a very expensive crunch!
I’m also not a fan of using the clicky ratchet wheel straps on carbon rims. Mine are the Cosmics with a carbon fairing (rather than structural carbon) which feels like it could be crushed too easily.
Oscar, the weight is carried on the vertical tube in the 2nd pic – rubbing might be an issue but I’ve spec’d a thick closed cell polyurethane which should protect the bike. Rubbing also infers the bike is somewhat loose….something I hope will be eradicated! This again can only be verified through testing, so I’d better get my finger out and finish the prototype
Jayfish/shogun/somegrump – Personal experience tells me strap-ons are dangerous. I narrowly avoided an accident on the A61 last year when a specialized hardrock freed itself from a boot mounted carrier and cartwheeled over the central reservation of the A61 into my path. I cleared the bike from the carriageway and moved off before having a chance to interview the owner about his choice of straps, but if safety isn’t built in to the product (i.e. there is a large opportunity for user error) then I class that as dangerous? I'm sure it's rare for that to happen, but not everyone is as conscientious as you I suspect.
As for aerodynamics – as yet unproven, it’s a hunch. You’ve got the bike mainly sat in otherwise turbulent air caused by the roof bars which are there anyway. When the bike is upright it’ll be in largely laminar air. I’ve got two options to prove this, CFD or strain gauging the roof bars. Which do you think would be the most convincing? There is also an option for a fairing, as I’ve got access to CFRP equipment and materials, or I could Vacuum form using a polythene or similar for cheapness.
In general when comparing to Thule/Mont Blanc/ Yakima roof carriers, I hope that I’m being realistic in that I don’t see this as a replacement, but rather as an alternative which works for a very small niche. In fact, I’d expect the particular set of attributes of this design to appeal to <1% of the overall market, for whom the existing products are more appropriate. I guess I've designed it for myself - I'm a single 30 year old who, like this I will this weekend, often travels 400+ miles alone to a race or event. I'd like something more individual, different, higher quality etc. Basically I'm a tart
Again cheers for taking the time to comment, all your observations raise or reinforce issues that I need to develop. Regardless of whether I think it works or not, I need to work on the issues above to show they've been addressed.
Shortshift you’re quite right, the 591 downtube clamp is the problem I’m looking to avoid. I spoke to a carbon repair chap earlier this year who told me he gets up to 5 carbon bikes a week in with holes in various places caused by bike carriers, mainly crunched downtubes. I described what I was making to him and he was very supportive about the idea. My brother has also driven to within a few meters of a low bridge with his Stork Fenominalist on the roof – could have been a very expensive crunch!
I’m also not a fan of using the clicky ratchet wheel straps on carbon rims. Mine are the Cosmics with a carbon fairing (rather than structural carbon) which feels like it could be crushed too easily.
Oscar, the weight is carried on the vertical tube in the 2nd pic – rubbing might be an issue but I’ve spec’d a thick closed cell polyurethane which should protect the bike. Rubbing also infers the bike is somewhat loose….something I hope will be eradicated! This again can only be verified through testing, so I’d better get my finger out and finish the prototype
Jayfish/shogun/somegrump – Personal experience tells me strap-ons are dangerous. I narrowly avoided an accident on the A61 last year when a specialized hardrock freed itself from a boot mounted carrier and cartwheeled over the central reservation of the A61 into my path. I cleared the bike from the carriageway and moved off before having a chance to interview the owner about his choice of straps, but if safety isn’t built in to the product (i.e. there is a large opportunity for user error) then I class that as dangerous? I'm sure it's rare for that to happen, but not everyone is as conscientious as you I suspect.
As for aerodynamics – as yet unproven, it’s a hunch. You’ve got the bike mainly sat in otherwise turbulent air caused by the roof bars which are there anyway. When the bike is upright it’ll be in largely laminar air. I’ve got two options to prove this, CFD or strain gauging the roof bars. Which do you think would be the most convincing? There is also an option for a fairing, as I’ve got access to CFRP equipment and materials, or I could Vacuum form using a polythene or similar for cheapness.
In general when comparing to Thule/Mont Blanc/ Yakima roof carriers, I hope that I’m being realistic in that I don’t see this as a replacement, but rather as an alternative which works for a very small niche. In fact, I’d expect the particular set of attributes of this design to appeal to <1% of the overall market, for whom the existing products are more appropriate. I guess I've designed it for myself - I'm a single 30 year old who, like this I will this weekend, often travels 400+ miles alone to a race or event. I'd like something more individual, different, higher quality etc. Basically I'm a tart
Again cheers for taking the time to comment, all your observations raise or reinforce issues that I need to develop. Regardless of whether I think it works or not, I need to work on the issues above to show they've been addressed.
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