Rear Hitch/Bike Rack, Drop in MPG?

I have the Coastaltech 2" Hitch receiver + Yakima KingPin4 hitch bike rack and it's stable! I've seen a drop of about 4-5mpg when traveling @ 75mph.

On the other hand, i've seen people with roof racks (which are more secured imo) sacrifice about 10 mpg!!

 

One reason I bought the Prius is the hatchback allows me to lay the bike inside, with the wheels attached. My Impreza needs a trunk rack that works OK, but I prefer the inside, locked up Prius for my bike. Inside the car, there is NO MPG loss. I have popped two bike tires from proximity to the exhaust on my Impreza and also my wife's Outback which can share the same rack. I now remove the bike wheel on the exhaust side when using the trunk rack. I haven't tried the rack (Rhode Gear Shuttle) on the Prius, but would rather lock the bike inside. It takes literally 2 seconds to throw the bike in back and to retreive it. I saw a nice mtn bike laying on the freeway one morning. No rack is fool-proof.

 

<div class='quotetop'>QUOTE(eyeguy13 @ May 15 2006, 10:14 PM) [snapback]256050[/snapback]</div>

i didn't think a bike would fit inside. hmm. but obviously you've proven that it does. next time i'll really try to fit it inside.

 

My bike does also fit inside, but after mtn biking it's not something that i would like to put inside.

I forgot to mention that i use this bar extension that allows me to lower the bike on the rack so it "sits" lower. IMO, this helps minimize the loss of mpg because the bike is not sticking UP and out in the air as much.

I'll try to post pictures later.

 

http://priuschat.com/index.php?showtopic=19883&hl=

Here's my setup. Way at the end of the thread. Works great.

Cheers,

Curt.

 

Nice work on the mods. Any test drives to see any differences at speed? I love the idea of making my Prius my own by tweaking it and its accessories to suit me.

This car rocks!

Cheers,
Curt.

 

<div class='quotetop'>QUOTE(eyeguy13 @ May 7 2006, 03:37 PM) [snapback]251169[/snapback]</div>

Hey eyeguy (and others),

Would you mind pointing me to where you read about which kind of receiver hitch (2" or 1 1/4"). I'm trying to figure this out myself and haven't had any luck finding anything about it other than make sure you get the right size for whatever you are connecting. The racks I'm looking at come in both 2" and 1 1/4" and I was wondering if there were any other considerations like one is sturdier, more stable, or more things are made for that receiver hitch size. I'm currently resisting the urge to start a new thread. Thanks!

 

I got the 2" after looking for 1 1/4" racks. There seems to be more 2" accessories and as an engineer, I'm always 'overbuilding it' as it were. Seemed to me a larger receiver would have a more solid base in which to mount stuff. I didn't want to load 4 bikes and see it bend or twist. I'm sure that wouldn't be the case, but...

Coastaletech.com has both. Adaptors are also available to make either size rack work in either size receiver.

cheers,
Curt.

 

Thanks Curt. I was figuring the 2" would be more stable (also an engineer, so I'm had a similar train of thought ), but I couldn't find anything that supported 2" hitch accessories/equipment being more prevalent than the 1 1/4". I guess the adapter makes that a moot point and the larger/sturdier piece wins.

You actually have the setup I'm interested in. How is the visibility with a rear hitch bike/snowboard rack? I rarely cart my bike around, so it hasn't been an issue so far and I don't even own a bike rack, but I can see a roof bike rack being a pain compared to a rear bike rack. I chose the roof rack b/c it doesn't affect visibility and the Prius is a low car and easy to load snowboards and skis on top. Also, the roof rack will fit into my garage, while a rear rack would not. But the drag and resulting mileage hit is horrible! I get maybe 25-30 MPG driving from LA to Mammoth. The combination of uphill, cold, roof rack drag, and loaded down car just kills mileage and going the final stretch uphill at freeway speeds with that much drag is a bit too much (battery drains and I end up driving on ICE alone). It seems like a rear rack would fix some of the drag issue, be easier to load/unload, at the cost of not fitting in my garage and reducing rear visibility.

Anyhow, I would appreciate an engineer's perspective of the rear rack.

 

Well, from the pic I posted (see above link, way above), the bikes sit a little too high. I like what eyeguy13 did in cutting and shortening his rack, getting the bike to sit lower and centered behind the Prius.

That being said, when winter hits and I load up by board and friends' skis (yes we can all get along with this very versatile rack from Aspen!), I'm glad the rack is as high as it is...longer items run about 8" off the ground when loaded. I use cinching straps that came with the rack and a few bungees for stability. Got 41 MPG on one cold trip to our hill here in S. Dakota. 4 adults and all associated gear. About 20 degrees F, and I'd say 1500 ft. elevation climb and subsequent trip back. "Better than my Subaroo's 19 MPG" was a friend's comment on that trip! "And more room". This car rocks.

Bottomline, the roof rack seems to be more of a MPG killer (actually the cold is, too), than the rear rack. Plus nothing ever contacts my precious when loading or unloading or hauling using a rear rack.

I've never hauled my board in the summer to see the actual effect, nor the bikes in winter, to verify that the cold is a major MPG factor and not the stuff on the rack...well...my significant other would really ridicule me then. I've come to loathe winter for MPG, yet love the fact my Prius is so versatile in hauling gear in any season.

Cheers,

Curt.

PS Almost forgot the visibility thing...it's semi-blocked, but not so much that makes it unsafe. It doesn't improve it, let me say that! But really, it's fine by me, I can be careful and look twice and adjust for my limited hindsight. I find rear passenger's heads more intrusive than stuff hanging out the back end...

 

Thanks for the info guys. If I go the rear hitch route, I'll be looking at a 2" hitch. The no contact with the Prius is a nice plus too. I always be sure to clean both the pads and the roof contact area to try to ensure I won't scratch my Prius when I use the roof rack.

One more question. I was concerned about the rear hitch eating into the Prius's rather low weight limit (pretty easily hit it with 4 adults plus luggage). Any idea how much the rear hitch weighs? I'm guessing that the roof rack and rear hitch rack are comparable in terms of weight. TIA.

 

<div class='quotetop'>QUOTE(ryogajyc @ May 30 2006, 09:01 PM) [snapback]263145[/snapback]</div>

My guess is that the hitch alone weighs as much as the entire roof rack. So adding the receiver-rack would definitely put it in the heavier category. The hitch is permanent too, a minor source endless drag.

I enjoyed mine on my Classic, but no where near as much as the convenience of the hatchback from the HSD. Sorry.

As for the MPG drop, it really depends on the direction of the wind... and in my situation, time of year since I once coated the bike with ice on a drive home from an early spring biking trip. I generally tell people to expect a 3 to 5 MPG drop.

 

<div class='quotetop'>QUOTE(eyeguy13 @ May 30 2006, 11:28 PM) [snapback]263204[/snapback]</div>

do you have to drive to ride your bike? if you ride that much maybe you should find a route that starts from your house.