Bike Friday HaD: Footrest and Rear Support Installation

Ever since I set up the Bike Friday Haul-A-Day cargo bike, it has been in the "Young Riders" mode, with the wraparound bar to hold the kids behind. 

At that time, the footrests were not installed, as my kid could not reach it anyway. Also, I was not carrying anything that needed to be supported by the footrests. Therefore the footrests were left out to save some weight.

Recently, I found that my kid has grown tall enough, such that his feet can now reach the footrests. Therefore, it was time to put on the footrests! There will be no need to tuck the legs into the side pockets of the side bags any more.

Metal footrests installed onto the bike!

No tools needed, as there is a spring loaded ball that fits into a hole on the frame.

After fitting one side in, the other end also needs to be slotted into the frame. This is a bit difficult as the shape of the footrest and frame don't fit together exactly. A bit of knocking and bending is required to join them up.

Each side of the footrest weighs about 700 grams, so putting on the pair adds 1.4 kg to the bike. It is a lot, but not as much as you think when the whole bike already weighs 20 kg.

Once the footrests are installed, my kid can actually climb on and off the bike by himself, using the footrests to step up. However, the wraparound bars are in the way. Therefore I decided to remove the wraparound bars.

Previous setup, with the wraparound bars for the kid or kids to hold.

Wraparound bar removed from the bike. There is a shim at the front clamp area that changes the diameter from 22.2 mm to 25.4 mm (approximated values).

No more wraparound bars!

It is necessary to give the kid something to hold on to while they are riding behind. At the front of the rear seat, a handlebar can be installed (separate post to be written), while a backrest should be added behind for some support and safety.

There is a rear crossbar that links the two diagonal struts at the back. I plan to reinstall this crossbar to act as the backrest.

Crossbar linking the left and right end of the wraparound bar together.

I noticed that the diagonal struts are not very rigid, as it is not fixed to a solid part of the frame. As shown below, the diagonal struts are fixed to the metal plate of the seat, which means that it can flex a lot upwards and downwards.

When the wraparound bars are present, it is not an issue as the wraparound bar stiffens up the whole structure. Now, with the wraparound bars removed, I need to find another way to stiffen up the rear diagonal struts.

As shown, the diagonal struts are bolted to the metal plate only, while the metal plate is itself bolted to the frame.

Diagonal struts are fixed to the thin metal plate only. Pulling up or down on the diagonal struts causes the metal plate to flex up and downwards alarmingly.

Bottom view. Diagonal strut fixed to the metal plate with a normal nut and bolt (right side), while the metal plate is fixed to the frame via a bolt that threads into the boss on the frame (middle of picture)

I considered using an additional metal part to stiffen up the end of the metal plate, but it didn't seem that it would be effective.

Then, I had a better idea, which was to move the diagonal struts forward, such that it bolts directly into the frame, together with the metal plate. Slightly longer bolts are required to ensure full thread engagement.

Moved the diagonal struts forward from the end of the metal plate, so that the bolts are secured directly to the threaded boss on the frame.

By doing so, the rigidity of the diagonal struts are greatly improved, since it is not affected by the metal plate's bending any more. 

Next question, how do I install the horizontal crossbar to the diagonal struts, since the wraparound bar is no longer present?

I found that the clamp diameters of the diagonal struts and horizontal crossbar are about 22.2 mm in diameter, which is the same as the diameter at the end of flat handlebars. It is a standard diameter for grips, brake levers and shifters. What I need is just two short tubes of diameter 22.2 mm.

You could just cut the ends off an unused flat handlebar, but I didn't have an unused one lying around. Then, I found that I could just get a cheap diameter 22.2 mm tube from Taobao and cut it to my preferred length.

Here is a 400 mm long, 22.2 mm diameter straight tube! It is actually a seatpost for a kids bike, but strange that it is so long for a kids bike.

Using the tube, I cut two lengths of 100 mm each, as I measured it to be roughly what I need.

Here is how it is fixed! The short tubes act as a link between the diagonal struts and the horizontal crossbar. The clamp diameters fit perfectly. Credit to Bike Friday for using standard clamp and tube diameters.

View from the top. You can set the position of the crossbar to be more forward or rearward as you wish. I used cable tie to fix some foam around the crossbar for more comfort as it is quite slim.

When the bike is placed vertically, the bike rests on the upgraded roller wheels and the cushioned end of the frame as seen here. It used to rest on the ends of the wraparound bars but they have been removed.

I set the length of the short tubes so that they don't touch the ground, as the diagonal struts are not strong enough to support the bike's weight. However, they do act as a stabilizer, as they prevent the bike from tilting too far over.

As a final step, I found some cheap plastic handlebar plugs from Decathlon, which can be trimmed to plug the ends of the short tubes. I have some fancy wedge type bar end plugs, but they are too big to fit into the ends of the short tubes.

With both ends of the short tubes plugged, mostly for aesthetic purposes.

This modification is not completed! The handlebar for the kid has not been installed yet. That will be shown in the next blog post.