Install Thule roof rack tracks

[bencpeters]

I'm very interested in getting an I3, but need to be able to put a roof box on it for transporting skis in the winter. I was dismayed to learn that there are no roof rack options available "out of the box" for the car, but I was wondering if anyone knows whether aftermarket rails like these could be installed:

http://www.thule.com/en-us/us/products/carriers-and-racks/roof-racks/load-accessories/thule-top-tracks-42-tp42-_-6238999

The installation process involves drilling through the roof, is there anything about the carbon fiber body that makes that not feasible?

Thanks!

 

[jadnashuanh]

I would not drill any holes in the roof, or, for that matter, anywhere in the car! Cut a fiber in carbon fiber and you've changed the overall strength of it. Even a deep scratch can be problematic on CFRP. Metal's a bit different in that respect.

 

[brorob]

I wouldn't advise drilling any holes either. Even if you're able to drill clean holes without damaging the carbon fiber, you may damage the roof since it wasn't designed for those mounting feet.

I searched for any available roof rack option before leasing my i3 and couldn't find any. I was really disappointed about this and it almost broke the deal. I know the car was designed as a city commuter but it seems like a target market for an EV would be outdoor enthusiasts that would have a need for this. I would rather drive my EV to a trailhead than an SUV.

Maybe Thule or Yakima will come up with a foot pad design that will work with the i3. They make these for other vehicles so not sure why it's not possible for the i3. Wondering if it has anything to do with the load that the roof can accommodate. A few pair of skis or a bike would be fine but a carrier box full of gear might sag the roof if all 4 doors are open and the B pillars aren't supporting the roof.(?) Could just be there hasn't been a big enough demand yet.

I'm able to fit my 29er mountain bike in the back after taking the front wheel off but this isn't the most convenient option, especially since I put a tarp in first to protect the interior from dirt. If I want to drive to a bike trailhead with my wife or daughter, the i3 can't accommodate. I may check into rear mounted rack options for this as I've seen a few of these.

 

[jadnashuanh]

Two things come to mind...a metal roof doesn't have 'grain' and fibers, so drilling a hole isn't as radical as cutting CFRP; most of the exterior panels are plastic, so not perfectly rigid like metal, so the typical straps or clamps that hold the feet in place would take some considerable engineering, if it could be made to work at all. You might be able to epoxy some mounting feet in place - lots of the car is held together with adhesives, but those generally are not readily available to consumers that might be adequate. Keeping things neat looking and getting things exactly where you want and need them would be tricky as you'd only get one chance, and it would be permanent.

 

[Jeffj]

Other thing that would concern me about a "permanent" addition of a roof rack is the rather large negative impact they make on efficiency. I drove a Murano for years and noticed, over many months, that when I had a set of Yakima bars on the top, it would cut the mileage by 2+ mpg (on a car that struggled to get 20 mpg on my commute route). 10% hit is pretty huge for something that you don't use all that often.

I've seen a number of references to a rack system called SeaSucker (note, I don't have one, just seen references) that uses suction cups. Users of it seem really satisfied.

 

[jadnashuanh]

I wonder on the SeaSucker's vacuum cups, how often you need to repump them to maintain a good hold? MIght differ based on how hot or cold it was, and how clean the roof was at the time of installation. You wouldn't want to be moving down the interstate on a long haul and watch your bike crashing in the rear-view mirror! When pumped up, they certainly should have more than adequate hold, it's just how long will they stay that way.

 

[bencpeters]

I talked to a ME (mechanical engineer) friend of mine who specializes in carbon fiber about this - he said if there was a bidirectional weave, he'd have no issues at all drilling, it shouldn't matter. However, after looking at some articles about the manufacturing process for the i3, he said it sounds like the weave they use for the roof is unidirectional, and thus not a good idea to drill into.

FWIW - he suggested stripping paint away on the surface and using Hysol epoxy with as close to flush-mount/rail mounts as available, then repaint around (and use removable feet so racks can be removed). Apparently the peel strength # for hysol is higher than the base laminate of the CF itself... I haven't tried it yet, but it's an idea!

The SeaSuckers seem like a great solution if you only occasionally need racks. For me, I drive into the mountains almost every day with skis in the winter, and my car spends much of its winter covered in all sorts of road salt, so I'm not sure it'd work very well, and I need a daily solution, not an occasional thing.

 

[I33t]

FWIW - he suggested stripping paint away on the surface and using Hysol epoxy with as close to flush-mount/rail mounts as available, then repaint around (and use removable feet so racks can be removed). Apparently the peel strength # for hysol is higher than the base laminate of the CF itself... I haven't tried it yet, but it's an idea!

I'd get a second opinion on that suggestion.

We are not dealing with standard CF here that uses epoxy or similar resin. This is CFRP (Carbon Fibre Reinforced Plastic) I think you'd need to find a totalled i3 and get a roof section to test on for hysol peel strength and if it even adheres to CFRP.

 

[S3RDP]

This may be of interest. I believe you can attach various carriers

http://torkliftcentral.com/rving-and-towing/ecohitch/bmw/2014-bmw-i3-ecohitch-reg

There is also a YouTube video showing how to install

 

[imolazhp]

Subbing for a solution.

 

[ian4x4]

Carbon fiber laminates with different fiber alignments are then arranged into stacks made up of several layers and following various lines, before being cut to shape. These stacks form the base material for the production of CFRP parts and components at the BMW facilities in Landshut and Leipzig. Scrap CFRP is recycled in Wackersdorf and subsequently channelled back into use – in roof of the BMW i models, for example. Currently, around 10 percent of the carbon fibere used in the BMW i3 is recycled material

http://www.compositesworld.com/news/bmw-formally-launches-i3-manufacture-and-assembly

It seems to say that the roof is unstressed.

 

[imolazhp]

Carbon fiber laminates with different fiber alignments are then arranged into stacks made up of several layers and following various lines, before being cut to shape. These stacks form the base material for the production of CFRP parts and components at the BMW facilities in Landshut and Leipzig. Scrap CFRP is recycled in Wackersdorf and subsequently channelled back into use – in roof of the BMW i models, for example. Currently, around 10 percent of the carbon fibere used in the BMW i3 is recycled material

http://www.compositesworld.com/news/bmw-formally-launches-i3-manufacture-and-assembly

It seems to say that the roof is unstressed.

Drill baby drill!

If it's safe.

 

[jadnashuanh]

The scraps are from cutoffs before curing, and placed in positions that were engineered to be able to accept them...I think it's risky to drill into the roof of the i3. Plus, do you really want new holes in your roof?

 

[CARiD]

Looks likr the roof rack on the original link is universal and designed for regular cars with metal roof, so it's a bad idea to use it on a CF roof.
I am sure Thule roof racks will come up with a custom fit variant designed for i3, it's just the question of time.

 

[jadnashuanh]

Looks likr the roof rack on the original link is universal and designed for regular cars with metal roof, so it's a bad idea to use it on a CF roof.
I am sure Thule will come up with a custom fit variant designed for i3, it's just the question of time.

The fact that the coverings around the CFRP roof are flexible plastic means a clamp-on device is not likely to work very well, so I'm not sure that will happen!

 

[electrons]

I'm very interested in getting an I3, but need to be able to put a roof box on it for transporting skis in the winter. I was dismayed to learn that there are no roof rack options available "out of the box" for the car,

Ski trips in an i3? RWD, in snow/ice, up mountains, with 70 miles range. Backup power is 30 hp at the wheels, so not much for going up mountains. Plus, who wants to drill into a leased car's roof?

 

[psquare]

I'm closing in on a purchase of a Thule Raceway for our ICE car. I am wondering whether it could also be fitted on our i3. I checked the Thule Buyer's Guide and i3 is not amongst the BMW models in the dropdown, which could mean that the vehicle is not supported by the Raceway, probably due to the pressure on the glass tailback.

Anyway ... here is a link:
https://www.thule.com/en-us/us/products/carriers-and-racks/bike-carriers/rear-door-mounted-bike-carriers/thule-raceway-pro-9001pro-_-1685473

 

[bencpeters]

Ski trips in an i3? RWD, in snow/ice, up mountains, with 70 miles range. Backup power is 30 hp at the wheels, so not much for going up mountains. Plus, who wants to drill into a leased car's roof?

Not all of us live so far from mountains... Skiing for me is only 10-20 minutes of driving depending on which trail head I go to, and doesn't have to involve steep roads. Plus, I ski almost every day in the winter and only a relatively small fraction of days actually have appreciable snow (anything under 6" or so I find is very manageable with RWD and good snow tires if you know how to drive on snow).

I own my i3, so no worries about drilling into a leased car... just worried about safety/long term damage.

 

[user 3172]

I may have misunderstood but while discussing sunroof weight, I thought my iGenius mentioned the new model CF roof panel was being replaced with aluminium. Don't take that as gospel though.

 

[jadnashuanh]

Federal safety requirements in the USA require a vehicle with a sunroof to have metal reinforcements in the roof. Not sure how BMW solves that issue, but they could embed some aluminum in the CFRP...will have to wait to see.

Anyone in Europe with a sunroof? What does the roof look like? Can you see the fiber pattern in the roof?