Introduction: Homemade Sport Utility Bike (SUB)

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!


Visitor (author)2007-03-31

Have you made a rack for this?

trebuchet03 (author)Visitor2007-03-31

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

Cosantoir (author)trebuchet032007-11-11

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?

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?

GroundingStick (author)Cosantoir2008-04-09

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?

dark8587 (author)GroundingStick2011-09-29

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

GroundingStick (author)dark85872012-09-10

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.

homba (author)GroundingStick2008-06-04

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

trebuchet03 (author)Cosantoir2007-11-12

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 ;)

Bob Gray (author)2014-01-12

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.

rmartinez27 (author)2011-11-21

check this out, sans support bar, via oldtimer hal, the man the myth the legend at Highland Park, Los Angeles, California's Bike Oven!!!

kennyraceboy (author)2008-10-08

hay thats pretty good!! I just had to make one!! Ya like?

trebuchet03 (author)kennyraceboy2008-10-08

Looks Awesome! Can you post more pictures (do you have a website - or flickr account or similar)?

kennyraceboy (author)trebuchet032008-10-08

thanks mate. : ) nah i don't have a website or anything of the sort. but here are some more pics

That gave me an idea... Is $2 USD a mile a good fare? We don't have taxi's around here, so I wouldn't have much competition, either. Then again, almost everyone has a car or truck.

actually you want $3.50 standard fare

I see... 25 cents a block, 14 blocks is a mile(here anyway), 14x.25 is $3.50.

Yep, pretty much.

Extremegta fan: While I think that the 'Taxi' bike is extremely cool, I wouldn't recommend using this specific bike as a pedicab (bicycle taxi). I think kennyraceboy would probably only carry groceries or a friend on the back, not paying passengers.

I think the front end of this bike would be okay for a pedicab, but on the back end I would put TWO wheels and make it a tricycle instead. I would also make the back end wide enough to carry two people, and consider that you will be carrying the weight of at least two people and their luggage. (i.e. 500 lbs.) when you buy wheels. Get some heavy duty wheels.

Brakes are also extremely important. You have to be able to stop that bicycle while it is going downhill, carrying paying passengers and possibly their luggage, in the rain or snow, in heavy traffic with cars cutting in front of you.

Lights are important too of course, front and rear. Consider getting brake lights.

Remember, one accident on the bike...or even a passenger that fakes an injury, could result in you being SUED, for millions of dollars. You might even become parapeligic, or make someone else parapeligic for life if you decide to cut corners.

Cars can be a problem too.

When I used to drive a bicycle taxi in Toronto, Ontario...I would charge as high as $3.00 per person, per city block. Yes, that is extremely expensive, but people would pay it.

Strangely, the owners of the pedicab companies would make more money from -ADVERTISING- than they would from their drivers leasing pedicabs from them (usually at the cost of $20 a day), or even their fares (which could be $200- $500 a day, or could be zero.)

Yep, you can place a billboard on the back too, and make money that way. About $500- $1000 a month, depending on your sponsor.

Depending on where you live, a fare of $5 anywhere, or a $20 flat rate might be more reasonable. So long as the rides are only a few blocks (i.e. downtown), most people would be willing to pay $5 even if just for the novelty. Anything past five blocks would be $20, or you could just give a half hour tour for $20 an hour.

A lot of it depends on where you live of course. Toronto, Ontario is the biggest city in Canada, and it's about the size of Chicago. Tourist-y areas tend to already HAVE pedicab companies, such as New York, San Francisco, etc.

kennyraceboy (author)trebuchet032008-10-08

hay i just created a flickr account, so you can view the pics in a higher resolution.

I made it outta an old huffy, full suspension bike and an old speed bike.
The tanks on the side are old petrol cans for a boat, with the tops cut off

Wasagi (author)2011-05-08

Beautiful! I have a P.O.S. Bike with rear suspension I got for free and fixed up, and I may just do this with it. Thank you!

The nerdling (author)2011-05-04

every one you need to put suspension onn them

the big smile (author)2011-02-26

Great idea, this plan for a wheelbase extension.
I added one more stay, to reduce the stress on the chainstays on the frontframe. And than I mounted two regular racks.

adamlorenz (author)2007-05-18

any way to see more detail pictures of the tubing and how you connected them to the two sections... i'm at the point of doing this and i'm in need of some visuals before i start at it... thanks!

trebuchet03 (author)adamlorenz2007-05-22

Right now... the bike is 3000 miles away from me :p But.... If you look at a rear suspension mountain bike of this design..... The support tube goes where the shock- clevis joint is fastened with a threaded rod. The bottom portion is attached with a grade 8 bolt through the kickstand mount (there's also a nut down there). The tube had a hole cut on a bias to fit that bolt ;) Mind you, I only have rather simple hand tools -- that was cut with a hacksaw and cheapo power drril :p

trebuchet03 (author)trebuchet032007-05-22

Errr... not power drill.... Dremel --with the milling bit :p

ctsp415 (author)trebuchet032008-11-20

Nice idea, have you figured out a rack system similar to the xtracycle for carrying loads. Otherwise it's just a very cool extra long bike.

joshfromga (author)ctsp4152011-01-11

i just finished a longbike of my own. my rack is an old wire-frame dvd rack. pics are here.

camp6ell (author)trebuchet032007-08-20

i too would like to see a pic of where the support rod bolts to the main frame, when you do get back to your bike. thanks.

da winksta (author)2011-01-10

you should attach the support tube at least to the middle of the seat post.

taiden (author)2010-07-09

I guess I don't understand the point of this. It looks like you extended the wheelbase. How does that make it a 'sport utility bicycle'?

turbonut48 (author)2010-05-21

Using the chain until it breaks is false economy. The chain stretches and then wears out the sprocket teeth because the chain pitch lengthens. 
Change the chain on a regular basis and your sprockets will last forever.

trebuchet03 (author)turbonut482010-05-21

 Or... when the sprocket teeth wear out, replace it with another one - free from a derelict bike (or from a $1 bike from the police auction).

junkmailca (author)2009-10-06

Hi All, I was inspired by the design, and found myself in a similar cash situation (grad school so you can do the math). Here are a few photos of my attempt (with some modifications) and it is AWESOME! I put about $50 into the metal and welding, and $50 into the army surplus bag panniers (also homemade). So all things being equal it worked out pretty well (especially when compared to the cost of a real xtracycle).

junkmailca (author)junkmailca2009-10-06

Here are the pics

Hycro (author)2009-09-21

I wonder if there were a way to attach to the seat post bolt...I can think of a way, but it requires a piece of flat bar (Or is it called flat stock??) welded into the end of the tube that will attach to the seat post bolt, that is also cut in such a way that the bar rests against the seat tube, and the bolt just keeps it from moving around, but most of the pressure is on the frame...I don't know if what I suggested would even work, if there were welds, let alone if you just used all bolts...but if it did work, it could have the potential to be stronger than attaching to the kickstand mounting bracket...since on some cheaper model bikes, the kickstand mounting bracket welds are VERY cheap...

budgieeye (author)2009-06-24

Hello here are the German version of a SUB. Details will follow. Greetings!

dmorrill22 (author)2009-03-28

I might try this sometime... Why didn't you take the spring/shock from the swing arm and use it as well... It would have added nice suspension to the new bike...

macrumpton (author)2008-07-01

I don't really understand the Xtracycle concept. You can buy a new cheap tandem bike for about $250 and that includes a second set of pedals for occasional passenger use. These cheap tandems must be pretty strong too since they are made to hold another person, which weighs more than any load I am likely to carry. A folding/removable rack/panniers and you are all set.

trebuchet03 (author)macrumpton2008-07-01

It's a different tool for a different job ;) A tandem just doesn't have the loading capabilities a load bike (such as the xtracycle add on). Load capabilities isn't just how many pounds ;) Big bulky boxes aren't an issue for the freeradical... Last week, I moved my apartment with such a bike :p But yes, you can buy a new cheap tandem for ~$250... But it's going to have crappy components - just like every other cheap bike out there. I personally like my DeoreXT components (on the bike I use all the time) and silent freewheel hub, they're buttery smooth and will last many more years. That's just not going to happen with crappy equipment for more than a few months... But don't get me wrong, do what works for you - I'm not trying to sell it to ya :p But, if you have the opportunity to ride one - go for it... It will probably make a lot more sense then ;)

frogmeetcog (author)trebuchet032008-12-23

random thought: where does one aquire a "silent freewheel hub" like the ones that police bikes have? I vaguely recall hearing that the manufacturer(s)have an exclusive contracts with various police departments...

Yerboogieman (author)2008-11-02

looks like your chain is in need of some care

trebuchet03 (author)Yerboogieman2008-11-02

Nah - it's fine as is... This bike has been in service for more than two years now... Those chains much longer than that.... It's arguably not optimal, but also not worth investing additional time or money. It's got a light coat of grease - I'll fix it when it breaks (the way things look, that probably won't be for many more years) :)

Yerboogieman (author)trebuchet032008-11-03

yeah, just dont use wd-40

visitor 5000 (author)2007-04-16

I agree this project is useful and ingenious in it's simplicity. I have one question though. In regards to the metal support rod being too short. If it was too short wouldn't that lower the back end of the frame? If so, that would increase your 'trail angle' or 'rake' on the front wheel. Which should have the same effect as a Chopper type front end, which can be ridden with no hands very easily.

I don't see how the chopper type can be ridden at all, as it seems that when you turn, the tire just lays over. A bike with good trail angle has straight front forks. If a bicycle has a good center of balance, combined with a good trail angle, even the worst bike rider could probably ride no handed. For example, saying the back of the bike was facing the right of the screen, forks like so- / would have fairly bad trail angle, and forks like these- | would be great, but not so easy to turn. Somewhere in between would be perfect.

There seems to be confusion as to what trail, rake and head angle is....

Trail is not an angle, it's a distance. If you draw an imaginary down the steering axis and another imaginary line perpendicular to the ground and through the axle - the distance between these two lines where they intersect the ground is called the trail.

Trail can be changed by making the head angle angle (steering axis) more acute with respect to the ground. But, this can make the steering "floppy" - the wheel wants to turn rather than a tendency to point straight.

The bike in this project has some offset. Which is where I disagree with your statement:
A bike with good trail angle has straight front forks.
No, a bike with offset forks just has less trail compared to a straight fork with the same head angle ;) Generally speaking, less trail results in a more responsive ride. That bike started service as a road bike ;)

Furthermore, when talking about bicycles, the term "Rake" is not used. Rake is the counter clockwise measurement from the vertical used for motorcycles. The "head angle" is the clockwise measurement from the horizontal used on bicycles. While this may be a nit picky point - the language and definitions have been set such that everyone can communicate effectively. If you paid attention in geometry, you'll notice that none of this corresponds with "standard" angle measurements counterclockwise from the horizontal :p

For example, saying the back of the bike was facing the right of the screen, forks like so- / would have fairly bad trail angle, and forks like these- | would be great, but not so easy to turn.

No, the fork that looks like this | would have absolutely no trail whatsoever. The fork that looks like / would have trail. Weather or not it is "bad" depends on the situation. Bike steering geometry is a very complex system, how much trail, head angle, offset, fork length etc. depends on a lot of other variables such as wheel diameter, center of mass, etc.

Being able to ride without hands doesn't mean "good" steering. On my bikes, I'd call that a pretty crappy setup. I prefer a more "jet fighter" responsive feel while riding compared to a more lethargic "bus" like feel. Except when riding my beach cruiser :D

Image for your viewing pleasure

Thanks for clearing that up.

galenorama (author)2008-10-06

Just add another seat to the old seat post, voila, passenger seat.

extremegtafan (author)galenorama2008-10-22

Nope. There's no seatpost there, that's just the rear suspension. If there were, though, they still wouldn't have a place to put their feet.

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Bio: Engineer making renewable energy products for African entrepreneurs.
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