Roof Carriers vs. Towbar – economies and thoughts

Having just got a new family car (CMax 1.8 petrol) I am wondering about fuel economies etc and bike carriers. I currently have Thule 591 roof carriers and for £20 can get a new set of fixpoint feet. The car will do about 15000 miles per annum, with the bike carriers permanently on. Of these miles, perhaps 4000 will be with 1 or 2 bikes, and occasionally 3 up top. I reckon this might cause me to lose about 2 mpg on average ??, which means that it will cost me maybe £100 per annum. Alternatively I could get a towbar fitted and a Pendle rack, I’m guessing maybe £300- 4000 all in ???, which might pay for itself over a 3-4 yr period.

Any thoughts on the economy figs and pro’s and con’s of going to a towbar system – I guess the bikes get more road crud on them ?

I/m no expert but I think your estimate of MPG lost is too conservative. I have a roof box which I remove when not in use and the MPG dips a lot more than that.

I have the Thule towbar mounted carrier & on a run will lose about 10mpg with one bike on it. (Saab 9-5 diesel)

I have used both on the same the car. Used to have a Thule roof rack it’s ok carrying two bikes very hard to get a third on. The towbar on the otherhand is very easy to load very quick to install I have a Thule Tow bar rack with a single lever to install takes secones. If you are leaving the bars on all the time then it will be a little less faff.

I found that in the current conditions the salt get’s on the bike weather on the roof or attached to the back so there is no difference there.

My car is a diesel passat and putting bikes on the roof would knock 20mpg compared to not having them on, and on the back about 10 – 13mpg less than I’d get without. Bars on their own around 5mpg and the extra noise!!

For me I can’t see ever moving from the tow bar solution it just works and Mrs F can load her bike on it which would never have happened with a roof rack 🙂 I think the only better solution is VW Transporter 🙂

forge 197 – what Thule towbar rack are you using ?

I’ve got a thule roof bar set on the go with two bikes, and we get on average 50 miles less from a full tank than we did before we fitted them.

we’ve got a Pendle 4 bike on our passat and only lose about 8mpg on the motorway with 4 bikes on and a weeks worth of camping stuff in the boot

i dread to think what putting them on the roof would do

ianc got one of these Thule G5 908 2+1

Depends entirely on what speed you’ll be driving at, on average, and your vehicle (oddly). At low speeds <40 average your roof rack will make very little difference as the added drag is minimal. Spend lots of time on motorways at or near the limit and you’ll notice a couple of mpg gone roughly on an average sort of car. A family member owns a hilux surf and very little affects its mpg – it sits at 25-26 regardless of whether it is in 2wd or 4wd, whether it has roof racks on or not (with and without canoes – never tried bikes on it), whether it is fully laden internally or not – I can only conclude that the majority of its fuel use is in inherent drivetrain loses! I’m not sure what my 306 estate would get, but its unimportant as I put all my bikes inside it.

Got to say I always preferred my towbar mounted racks, less fuel use, bike hidden from direct blasting of cack into bearing areas at speed, all extents of vehicle visible in mirrors and not having to lug bikes onto the roof!

Focus TDCi, 2 Thule 591’s and 2 Thule 531’s on the roof, average 48mpg back and forth to work and general driving, as above with 4 bikes (2 adult, 2 child and camping gear for a weekend, average 48mpg, go figure that one (mpg calculated by dividing mileage done by fuel added, not using the onboard computer)

mmmm, food for though indeed. Thinking I will stick with the roof option for now, towbar is looking like £200 and much the same again fro a decent rack, so it will take a fair few miles to recoup £400 when I only need to spend £20 to fit my existing roof kit with new fixpoint feet

My estate TDCi will easily loose more than 15 MPG with roof mounted bikes on a fast motorway drive. 55 dropped down to 37 when I went to France in ’07. Exactly the same trip with a towbar mount in ’08 and I got 47.

Clean car, no bikes or roof rack fitted will average 55 on motorway trip, and 68 when driving everywhere very carefully. I have averaged up to 64 when being very gntle with it, even with the bikes on the towbar.

Towbar DIY should only come to £120 ish, pretty easy to do. Thule rack works well for three bikes and should be £60 or so.

Skoda Octavia 1.9Tdi estate here – we get 50-55 mpg without the bikes and carriers on the top but fully loaded, with two bikes we get maybe 47-52mpg.

Removing the bike racks and roof bars when not in use saves us about 2mpg.

With hindsight, I’d have got a towbar rack, principally as we cannot get two bikes and a roof box on the standard Skoda roof bars

I have roof mounted carreirs that I have stopped using when it is only my bike for a couple of reasons:

– bits of my bike started corroding that have never corroded before when i started putting it on the roof. It picks up a suprising amount of crap.
– fuel economy takes a right old whack – 55mpg quite easily become 45-47mpg or so with bike & rack on roof.

If girlfriends bike is coming along as well then they have to go on roof.
I always take racks and bars off though – only takes 5 mins and wouldn’t be able to tolerate extra noise & drop in fuel economy.

Friend of mine drove us to Plymouth last yr for 24/12 in his Subaru Forrester. He has got a Thule towbar mounted rack and noticed no change in mpg.

Inline on the roof is probably not that bad.
Stick my high level mount & bike on the back of my Rover 25 diesel & on a steady run it goes down from about 55mpg to 35mpg. It will go in the car next time, muddy or not.
Dont buy a high level rear carrier.

taking them off when not in use would be ideal, but I have fixpoints and the threads look a bit fragile for regular on off mounting -(

Recently gone from roof mounted to tow bar mounted. Has made no difference in fuel economy. In line on the roof, wouldn’t use an awful lot more fuel. Mounted transversely on the back, probably more drag, but out of the way. Swings and roundabouts

I use a towbar mounted one on my Honda CRV. Doesn’t seem to really hit the mpg. More my driving. Had 4 bikes & 4 blokes in it to the Lakes last Nov and averaged 37 mpg – given my driving I thought that was good.

Only downside is the weight of some of the rear racks that life up the front of the car.