The rowing trike: a workout on the go

This week, we first added a brake to the rowing trike’s front wheel. Then, we built an improvised seat for the person who pulls on the handle to propel the bike by welding a straight tube in between both sides of the rear of the frame. This improvised seat was surprisingly robust and more comfortable than expected.

Next, we verified that the bike is able to support two people without collapsing. However, we noticed that the rowing handle would not retract after pulling on it. The retraction mechanism we built last week used a spring, but it wasn’t strong enough. Fortunately, tying a wheel’s tube from the frame to the drive train solved this issue.


The last step was to weld a few more tubes to support the bike and ensure its robustness. The rowing trike is shown below.


See a video here:


266 Finishes their “Awesful” Bike

It’s been an exciting week for Team 266 because we rode our finished bike, survived to tell about it, and looked like we were having fun safely enough to intrigue passers-by to ride as well!


The first time we rode the bike, it was really difficult because our tires were deflated. (Spoiler alert: it never got much easier) We removed the tubes from the tires to find and patch most of the holes by listening for escaping air or looking for air bubbles in a bucket of water.


Fixed tires made it easier to move the bike with the hand pedals, but it was still terrifying to steer and balance. We attributed this to the top heaviness of the bike, so we tied weights to our foot handle bars with ropes and zip-ties and took it outside for some testing!


It was still a challenge to ride, but it was somehow fun seeing how much further we could pedal before we toppled over into the slush and fielding off the funny looks and comments we received. Riding the bike is like patting your head and rubbing your tummy since you pedal forwards with your feet and backwards with your hands, but that makes it so much cooler when both are done at once. The bike also had a unique way of marking it’s riders.


We decided the weights should be a permanent feature, so we welded some possibly-rider-impaling bent steel pieces to either sides of the foot handlebars to hold the weights in a less sketchy fashion than ropes and zip-ties.

Bike whiskers

The welding required some awkward angles, so we quickly realized how comfortable the welding room floor is.


We also added a a real handlebar (piece of steel pipe welded to the frame) to help with steering.

Some parting words:

Building bikes is cool. Building super-challenging-to-ride and wacky-looking bikes is even cooler. Check out a video of our bike and if you ride it, please come off in one, alive piece because our grade is dependent on all riders’ survival.

Video link!!

Thank you to Jack, Izzy, Rango, and Jarrod for fearlessly attempting our challenging bike, anyone in the shop who had to listen to George Ezra’s Budapest with us on repeat (we got to around three hours), and the lady outside who told us “sure it is, girls” when we told her our contraption was a bike.






The Elliptical Bike in all its rolling glory!!!!!

This week, we were finally able to put all of the parts of our bike together! First, we had to weld on supports for our angle brackets so that they would be stable for the pedals. We did this by drilling a hole through the middle of a plate and then cutting it in half. This created a nice gap for the tube that we were able to weld to. Also, we had to add a foot plate to the pedals so that the elliptical motion could be executed by the rider. We did this by attaching a piece of hard plastic to our pedals and the horizontal connecting rod attached to them. Also, to avoid slipping, we originally planned to create a sort of toe box for your foot to go into but found that that would require a lot of time and effort so decided to go ahead and use Rango’s original suggestion of gluing sand paper to the foot plate. This has worked beautifully so far. Thanks Rango! The biggest part of the week was getting the bike itself put back together since all of it’s pieces fit into a plastic box for 3 weeks. Luckily, with some help from Jarrod and Izzy, the bike is all in one connected piece and has not fallen apart yet. We had(are having) a small issue with a hole in the back inner tube but it is small enough that the bike remains rideable for a couple hours after filling it with air. Our current potential fix is a piece of gorilla tape that we put on the hole. Overall, we found that the feeling we get when we ride the elliptical bike really makes us feel like we’re floating so our original idea of a floating bike has, in a way, been fulfilled. Some potential things we would do if we had more time would be to add a hinge in the frame because it is very long so that it could be unlocked when we want to turn the bike around and make life a bit easier. Another fun idea we had was to make the elliptical bike a 2 person bike because it doesn’t appear to require enough coordination yet and watching people make fools of themselves is funny. Finally, this class has been a lot of fun and we are pumped that our bike works! Thanks to everyone who helped us and answered our clueless bike questions!






Elliptical Bike – The Elliptical Part: Pedals!

This was a big week for the elliptical bike. After extending the frame last week it was time for us to convert our cardboard model of the pedals into something rideable. The first step, for me at least, was realizing that although we had only looked at one cardboard model, we actually needed two pedals to make a bike which meant 2 matching pieces for every part.

Our first issue was determining how to attach things in a way that they would still be able to rotate. This was solved by flattening both ends of our attaching tubes and using bolts, nuts, bushings, and nylon spacers so that the parts weren’t rubbing or running into each other.

Pivot Point 1:

We took advantage of the bearing within the bike’s original pedals and used that as our built-in pivot point to start constructing our elliptical pedaling frame. This first step was a matter of attaching our first metal rod to the existing pedals.

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Pivot Point 2:

Now the other end of the rod attached to the pedal needs to be attached to the left bar of our elliptical frame. It took some finagling to figure out the best way to pin the two metal rods together. Problems we ran into were:

  1. The cylindrical portions of the rods were still bumping into each other; couldn’t achieve the small angle of rotation our bike would require.
  2. The gray rod kept sliding along the length of the nylon bushing, which is one direction we did NOT want it to move in.

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So, we flattened the end of one rod more, and fixed the spacing between the two rods by filing down a bushing and inserting two nylon spacers: Much better!

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Witness the evolution of the elliptical frame:IMG_1021IMG_1026   IMG_1031      IMG_1035 01b8bb1f6afd404d6db4e35ae4b4df280e2ddcdc69017149c37f8ac6929a4ad7775246e1015c3cdd1192

We still need to do some adjustments to make sure everything moves smoothly but as of now we have two semi-stable rotating pedals! Before someone can actually ride the bike, we need to put longer bolts on each joint and use locknuts so that the bolts will not unscrew as we pedal. Additionally, while the angle brackets appear to be working out very well in terms of alignment, they need to be reinforced so that they don’t bend and/or break off. Our plan for that is to weld to flat pieces across the two brackets to essentially make a box.

Rowing Trike: Building the Drivetrain

Previously, on AIBD…

We decided to build a tricycle that is propelled with the same mechanism used in a rowing machine, and last week, we built the trike’s frame.


Recall that riding the rowing trike will require two people: one person to steer the trike and another person to propel the trike by pulling on a handle that is connected to the drive train.


The rowing trike’s drive train should be designed such that

  1. the bike moves forward when a person pulls on a handlebar,
  2. the handlebar automatically retracts when a person stops pulling, and
  3. the handlebar can move back and forth for at least three feet.

These requirements attempt to emulate the type of motion observed in an indoor rowing machine.

Making the main axel

Most of the drivetrain’s components are placed in an axel that is attached to both sides of the rear of the trike. We tried to align the axel with its axis of rotation as much as possible.

First, we took apart two cranksets and removed the chainrings and the cranks. Then, we welded steel pipes to each crankset with a jig that aligned these components.



Since we intended to attach the drum to another pipe, we cut this piece in a half.


The main axel at the end of this week is therefore made from both pieces as well as the pipe that contains the drum.

Making the drum

To obtain a reasonable gear ratio, we decided to build a drum with two chainrings and a thin steel rod. Surprisingly, taking apart a rusty chainring was the hardest part of this step. We weren’t able to take it apart even with a hammer, so we resorted to more elegant and refined techniques.


Having all the parts, we welded together the drum.

The handlebar

We used an angle grinder to carve a slit into a tube that serves as the handlebar. A rope was then attached to the handlebar using a rivet.


To connect the rope to the drivetrain, we built a roller.


Issues for next week

There are a few issues that we’ll address next week. In particular,
the trike needs a seat for the rower, and the seat should ideally slide,

  1. the trike needs a brake,
  2. the trike needs a seat for the rower, and the seat should ideally slide, and
  3. the trike needs to be able to support the weight of two people.

Week 3: 266’s Questionably Functional Bike

This week, Team 266 turned the bike that made everyone laugh into the bike that made everyone’s arms sore.  Going off of our frame from last week, we fixed up a few small problems and mainly worked on making our bike rideable.

The first problem we encountered was that the front wheel and the rear wheel that sat on top of it needed to be tensioned together so that they would always stay in contact and be able to drive the bike.  We decided  to add a slotted piece of steel to either side of the wheels that allowed us to push down on the top wheel and tighten down the bolts, which effectively kept the wheels together.

In progress, welding the slotted beams
In progress, welding the slotted beams
Slotted beam with cutout to make space for the axle
Slotted beam with cutout to make space for the axle

It still wanted to come misaligned when the bottom wheel was turned backwards, but we decided not to worry about that because it’s pretty impossible to ride the bike backwards anyway.

Our second problem was that the bike took a huge amount of power to move.

Click here to watch Jarrod struggling
Click here to watch Izzy struggling

One factor was the size of the sprockets in the top drivechain, but we decided that the main factor was that all three tires were very deflated, which led us to our third problem.

Neither of us were bike people before AIBD, so of course, we didn’t know a thing about fixing tires.  After some Googling and Youtubing and asking-Jack-for-help-ing, we learned how to find the leak in the inner tube and used the tire patch kit.  (solution to this problem still in progress…)

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Finally, a sincere statement: we are good people.  We do not want our riders to mount the bike with two functional eyes and to dismount with less than that. We hacksawed off the unintentional weaponry on the top bike and covered it with a cushy sock, and the bike should be safe to ride, at least with respect to eyes.


After we tested our bike, however, it became clear that our bike is quite a challenge to ride.  It requires hand-eye coordination, good balance, short stature, extreme bravery, Iron Man arm strength, and the ability to pedal backwards with hands and forwards with feet (not actually).  We’re thinking of asking potential riders to submit a resume and cover letter detailing why they are qualified to ride our bike.

On the plus side, it’s a great door opener.

(Shoutout to Jarrod and Izzy for being our beta riders)

Rowing Trike: Building the Frame

Previously, on AIBD

Last week, we decided to build a tricycle that is propelled with the same mechanism used in a rowing machine (see below).

contracted extended

Additionally, we decided that the rowing tricycle would require a second person who is exclusively in charge of steering (that is, a coxswain).

Dismantling old bikes

Our objective this week was to build the frame of the rowing trike. The first step, which ended up being surprisingly difficult, was to take apart three old and rusty bicycles. We got all bicycles from the AIBD instructors, who bought a dozen rusty bicycles from the Cambridge police auction. We were lucky enough to find two bicycles with identical bodies that we eventually used for the rear wheels of the trike. The pictures below show the most important pieces  that we used to build the rowing trike.

An empty bike frame that will become the back right part of the rowing trike.
An empty bike frame that will become the back right part of the rowing trike.
An empty bike frame that will become the back left part of the rowing trike.
An empty bike frame that will become the back left part of the rowing trike.
An empty bike frame that will become the front part of the rowing trike.
An empty bike frame that will become the front part of the rowing trike.

We then proceeded to remove the seat stay and the chain stay from the black frame and to remove the paint from areas we intended to weld. Side note: angle grinders are awesome.


Building a jig

Before welding the trike together, we built a jig to try to align the two rear frames as much as possible and to make sure they’re not too close together or to far apart. We also put the trike’s wheels back on to help us properly align the connection between the front and the back of the trike.


Then, with the jig in place, we began to weld parts of the rowing trike together.

Hello Weld

The first few welds were quite the learning experience: it turns out that using a heat setting that’s too high burned holes in the tubes we were using. Fortunately, Jack was around to show us how to patch up the holes and, as a bonus, how to avoid inhaling toxic fumes–we we were about to use a random piece of scrap metal to cover the holes, but Jack noted that it was a scrap of galvanized steel, which has zinc and emits nasty fumes. Thanks Jack!  Our first few welds were gigantic, disgusting, and ugly, but they appear to be robust.

Finishing the frame (almost)

After the initial welds, we realized our jig didn’t properly constrain one important part of our frame. Since the transmission for the rowing bike depends on connecting the cranksets of the two rear bikes via an axle, we needed to make sure that the cranksets lined up so that they would be able to spin together. We achieved this by removing the cranksets from both bikes and sliding a tube through each of the bottom brackets. The tube was approximately the size of the inner diameter of the bottom brackets, with just a little bit of wiggle room so that it would only be able to spin if the bikes were properly lined up. When we first used this tube it revealed that our initial jig did not line up perfectly. Luckily the remedy for this misalignment was just a few hammer blows in some key places on our frame.


The (almost) final trike is shown below.


The trike is currently missing a seat for the person in charge of propelling it. It’ll be easier to determine how to best position this seat after taking into account the driving mechanism that we’ll build next week.

Elliptical Bike – Elongating the Frame

This week, our goal was to elongate the overall frame of our bike!

Purpose: for the elliptical pedaling mechanism we decided on last week to not interfere with the turning of our bike’s front wheel, which will be critical to the bike’s steering.

Plan: we needed our bike’s front wheel to be displaced 13″ forward (about the radius of one bike wheel)

So, we dismantled the remainder of our original bike to isolate the bike frame:


And cut it apart to replace the curved rods in the middle with 28″ steel rods (original straight length was 15″, so +13″ = 28″)


We had to wire brush the paint off of the ends we would be welding together, to avoid paint fumes during welding:


The Welding Process: We decided, after checking out Jack’s steel tube stock, that 1″ steel tubes would fit best inside of our existing, hollow bike frame pieces. However, although this was almost a perfect fit for the upper tube, our lower tube’s original diameter was about 1.5″, which meant that we had some crushing to do! (Apparently the pretentious word for this is “swaging.”) So we cut about 1-1.5″ slits in the original bike frame ends, and crushed it circumferentially as best we could in the shop’s vise grip. Once we were satisfied that we had minimized the gap between the original bike frame and our steel tube stock, we pushed the tubes together into our desired position, and WELDED.





Finally, just to check if we  achieved our goal of creating tolerance for our front wheel to turn:




266 Tackles the Frame

This week, we made the new wacky bike frame we designed from two beach cruiser bikes. To do this, we first needed to strip both of the bikes so we could work with their frames.

One half of 266 gets soaked on the trek to shop :(
<3 Kroil

We braved torrential and cold downpour to come into the shop Sunday and got right to work. Stripping the bikes was challenging because they were so rusty and we quickly learned that we liked Kroil because it removed the rust we didn’t like, making it easier to remove bolts, but we didn’t realize this soon enough because we ended up stripping some parts on the crank shaft of one bike. We released some anger over this situation by hitting that spot with a hammer and metal rod (strategically of course in hopes of removing the pedals), but it didn’t work, so we chose a replacement bike.  Lesson learned: add Kroil, add Kroil, add Kroil!

Our next challenge was removing the unique crank sets on both of our bikes. We didn’t have a bike tool on hand for this, so we used pliers to loosen and then slide the crank arms out.


With bare bike frames, we lay them out to visualize how we would attach them. The below picture is the front of our bike without the blue bike’s rear wheel.


Next, we cut off the extra pieces of the red bike frame that we wouldn’t be using in the bike, learning how to use the hack saw and the angle grinder in the process.

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We spent a lot of time practicing our welding (or practicing welding over the holes we made while welding). While our early welds didn’t look very pretty, most were strong enough to survive our hammer test. We couldn’t resist using the hammer again, so we tested the strength of our welds by hitting the pipe with hammers.


The next course of action was to bend pipe into feet handle bars. We don’t have superman strength though, so Jack offered to bring up a pipe bending machine to bend our tube at a 4 inch radius. It still took a lot of strength and some extra assistance to bend our tubes. Pipe Bending



Photo Jan 11, 9 46 26 PM
Grippy tape: the real mvp

Once our two pieces were bent, we had to angle grind the ends so they would fit nicely onto the curved pipe that is the fork. Before, welding, we used the belt sander to remove the paint from the fork since paint fumes are nasty. Then, more welding!

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The foot handlebars were a success!



We also modified the back triangle of the red bike so we could attach it onto the handlebar spot of the blue bike. This involved welding two new support bars (the unpainted ones in the photo) and removing the head tube. We had removed the head tube so we could insert the screw that attached the handlebar component, but unfortunately we welded the pieces together backwards so we can’t get the screw in.


When it was attached to the handlebar location, the red piece slipped right into the head tube of the blue bike. The wheels were at the perfect angle so they touched. We just need to attach them along either sides with some long, thin metal rods so they don’t become misaligned.


We found out then that we had two issues that needed to be resolved. The first was that our chain for the hand pedals was rubbing up against one of the support bars we added to the red frame. The fix wasn’t too bad: we removed the bar and added a new bar, positioned away from the chain, so it wouldn’t rub.

The second issue was that since we did some backwards welding, the screw to attach the red bike to the blue bike in the head tube wouldn’t fit. We decided to flip the inside components so it screwed on from underneath. This required flattening and  angling various tubes so the angle was correct for an upside down screwing in.

Our upside down handlebar setup

We encountered a minor issue while welding the angled nut to the pipe for the angle when we forgot to remove the screw we had put inside both to hold them in place for welding. But it’s ok, the screw did not have to take up residence inside the head tube because we sawed off the one end and the other was short enough that it fell out.

In the process of evicting the screw


Our wacky bike seems to work. We attached the hand pedals and crank shaft and it does go forward when backwards hand pedaled. The balance is just sketchy, so the bike is not ready to be ridden yet.






Bike Ambulance for Northern Uganda


The Team and The Idea

Jon and I met this at the first class on Monday, but because of some scheduling issues I didn’t realize that I would be working with him until Wednesday. Luckily, Jon already had an idea of what he wanted to produce, and I was happy to work on it with him.

Jon has been working at Bikes Not Bombs for 30+ years loading up recycled bikes into containers to be shipped to different countries in Africa where mobility is needed. He shared stories with me about how paramedics in an African country had received a lot of funding from the Gates Foundation only to realize they didn’t have the means to travel to the areas where medical attention was needed. It was only with a shipment of bikes from BNB were they able to do their jobs. Thus, there is a great need for human-powered mobility, and Jon had identified one aspect of medical mobility that is still not fully met in Northern Uganda: the ambulance.

Due to the terrain, narrow footpaths, and remoteness, it’s often difficult for those who need to be taken to a clinic or hospital for urgent medical attention to actually get there. Jon proposed we try to come up with a bike ambulance that could be powered by both rear and forward riders with a gurney for a patient in between. According to Jon, there are some specific details that needed to be taken into account in designing such a bike ambulance:

    • Narrow footpaths- meaning the vehicle needs to be very narrow
    • Unpaved terrain- meaning a very strong frame, wheels, and suspension
    • Inclines- maybe something to push the vehicle
    • Ugandans can be very tall- maybe a gurney that can accommodate someone as tall as 6’6″
    • and probably a few more things that I’m forgetting

A quick google search revealed a bike ambulance is not a new idea, but one that meets all of the above criteria might be




So Jon drew up a sketch of what he was imagining. And we went back a forth a bit with some sketches (Jon’s sketches still to come):





And we picked out a couple of discarded frames to begin seeing what we’re working with. I rushed to to some welding training and shop training. And we’re on our way!



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