Homemade Sport Utility Bike (SUB)





Introduction: Homemade Sport Utility Bike (SUB)

I was faced with two options for my bike cargo needs - build and hitch a trailer or find another less cumbersome solution. Enter the Xtracycle.

From the Xtracycle website:
With a bike trailer, you'll leave it at home because you prefer the way your bike rides without it, then later wish you had brought it along.

Great, I'm sold! Except... College... Money.... Oh yeah, lackofcash-itus :( Here's my $10 solution for a great idea!

Sorry Xtracycle guys - At the moment, I just can't afford to pay for the engineering :(

Step 1: Materials

Donor Bike with rear suspension (note the type of swing arm used)
Conversion Bike
Steel Tube
Grade 8 Bolt

Step 2: Disassemble and Test Fit

First, make sure your current rear wheel will fit in the dropouts on the donor bike's swing arm. If it fits, disassemble the donor bike's swing arm assembly leaving the axle bearing intact.

Step 3: Attach Swing Arm to Bike Frame

Using the threaded rod coming out of the swing arm bearing, attach the swing arm on the drop outs of your conversion bike.

To align the swing arm, attach the wheel and fold over as shown - the wheel should be in line with the seat tube. Once aligned, tighten the swing arm.

Step 4: Frame Support

We need to prevent the swing arm from flopping over and make the bike ridable. I bought a 3 foot section of steel tubing and made a support bar that links between the swing arm (where the spring/damper normally would connect) and the kick stand mount.

I drilled the holes.... With a Dremel. Even that angled hole. Terrible, I know, but I made due with what I had.

This support bar is held at the kickstand mount with a half inch grade 8 smooth shank bolt. I had a grade 5 full threaded bolt at one time - it failed (bent). It was my fault, I didn't take the time to do the engineering (which I was capable of) and I would have easily seen that it was not sufficient.

Step 5: Brakes, Chain and Derailleur

You'll need long cables for your rear brakes and rear derailleur. If the cables you're finding just aren't long enough - ask for tandem bike cables ;)

For my chain, I combined my donor's chain and my conversion bike's chain to make a suitable length. This is quite easy with a chain tool which you can buy for a few dollars at any bike shop. I keep the chain tool in my tool pouch in case I need to convert back while on the road.

You may be wondering - why didn't I attach the support tube at the top of the seat tube? My goal was to make this 100% removable and not require any welding. The sacrifice is higher stress loads through my support tube which has not been a problem after over five hundred miles of use ;)

Now you've got plenty of room to mount an extra big rack to carry all your groceries, large items or even a passenger!



    • Paper Contest 2018

      Paper Contest 2018
    • Science of Cooking

      Science of Cooking
    • Pro Tips Challenge

      Pro Tips Challenge

    We have a be nice policy.
    Please be positive and constructive.




    Have you made a rack for this?

    It's on the todo list :P Since the date of the picture.... I have added pannier rack that attaches to the seat tube (very low weight restriction). And I can hang grocery bags off it without hitting my rear wheel :D I can do something similar with my laptop bag - as long as it's not raining :P

    OK, I'm a bit puzzled here...

    The whole point of the Xtracycle and similar longbikes is to provide support for a larger stronger cargo rack. Without such a rack, what's the point? You've added weight and complexity to the bike, reduced its handling and weakened the bike, all without any meaningful gain in cargo-hauling capacity.

    A seat tube rack could be fitted without any further modification of the bike, and such racks aren't really strong enough to be worth the trouble in the first place. Fabbing a heavy-duty version of a common frame-mounted cargo rack would allow at least as much cargo capacity, as well as eliminating the groceries-in-the-wheel issue, and wouldn't require any mods to the bike. Something like the heavy-duty built-on rack of the Peter White Cycles "Silk Road" bike maybe? http://www.peterwhitecycles.com/tout-terrain.asp

    Also, why the rod from the top of the donor rear triangle to the bottom bracket shell on the bike, as opposed to running it to the top of the seat tube?

    Here's the setup I use in Iraq. Originally I was going to build a trike, but trebuchet03's design saved me loads of time i don't have. I assembled this off-duty, with minimal sleep loss, within a week. I bent the rack out of discarded tubes (black: white board stand, white: part of a twisted metal bed) and the cage is what holds sandbags in place (they're stacked around our CHU's as protection from incoming fire). The whole bike, with the exception of the brake lines was completely free, as our FOB has lots of broken bikes laying around. Nobody seems to find the time to fix them, though most are fubar anyways (unless you're willing to go the extra mile and mod). I fashioned the mount out of a broken aluminum guard-rail. I realize, that bolting it through the frame is not the best option, but beggars can't be choosers. Though heavy, the result is stable, handles well, and can carry me, my weapon, and a full combat load. Thanks allot trebuchet03!!


    How many sandbags could you carry?

    That upper left image, the one with the SAW, is awesome. Makes me think of zombies.

    The charging handle kept digging into my back -that or the 30-round magazine well. So I made a mount out of a broken aluminum cot & a front fork of another bike. Had to cap the barrel with a plastic cap to keep the dust out. Initially it was screwed on, but I replaced the wingnuts with two hook&loop straps. I had a red/IR signal light dangling on my weapon as a tail-light :D

    It was too bulky to take when we left, but I heard some lucky soldier "inherited" it and improved the design by replacing some of the extra deraileurs with pvc-hoses.


    My tax dollars at work :) You deserve a raise and a promotion ... awesome!

    Also, why the rod from the top of the donor rear triangle to the bottom bracket shell on the bike, as opposed to running it to the top of the seat tube?

    Going to the top of the seat tube would have required welding or some goofy fasteners. Going down just behind the BB - there happens to be a mounting point to bolt to :) In this configuration, I can convert back to a normal road bike, on the side of the road (as long as I carry a chain tool with me).

    ...all without any meaningful gain in cargo-hauling capacity.

    As seen in the photos, perhaps - but I will disagree solely based on experience. As seen in the photos, I can sling my laptop over the seat and have it rest directly behind the seat tube - without interference with the rear wheel. The same goes for grocery bags and my cooler :)

    I've used a seat tube rack that I found on a derelict bike. It works much better when it's over nothing compared to over a wheel (bags of groceries don't get entangled). I have, rather precariously due to the small size, towed people on that bar too.

    More recently, I've been working on a rear triangle add on rack - as posted by TimAnderson - and not too dissimilar than what's in that link you posted (thanks, there's some nice stuff in there). When it's done, to my satisfaction, that will be posted - but it isn't a priority given school work and such.

    I have also discovered that riding in wet conditions, without fenders, is much better :) Water and grit doesn't fling up on my backside :) Especially nice when caught by a storm without wearing any foul weather gear.

    Things have changed in the 8+ months since I've posted this ;) And always keep in mind that, in situations like this, all or nothing perspective typically results in the latter ;)

    And again, there's no contest with the Xtracycle - it wasn't meant to ;)

    Keeping the shock would be a bad move. Due to the geometry of the bike pedal bob would be extreme. Well designed single pivot suspensions usually place the pivot in front of the bottom bracket. That means that when the rear suspension is compressed it makes the chainline slightly longer and that inherently cancels out most of the pedal bob.

    If the rear shock were hooked up with this design it would have the opposite effect and every time you pushed down on the pedals not only would your weight compress the shock, but the tension on the chain would try to do the same, just like you were pulling the string on a bow. In short, it would be an extremely bouncy bike.