Fixing Bicycles - Esteban's Bike

Esteban Zambrano working on his bike in July 2011.  Six months later, we still hadn't discovered the real problem with this bicycle....

One bike had been in the shop for months because the coaster brake wasn't braking or accelerating properly.  This yellow BMX style bike, which belonged  to my son, Keegan, when he was young, is now assigned to Esteban Zambrano.  So, in early February, Esteban and I replaced the old coaster hub with a new one.  He happily rode off to try it out, but we both were puzzled when he started having problems before he even passed through the big doors of the shop.  This time, though, I could see that the problem wasn't with the coaster brake hub.  The pedals were moving - but the chain wasn't moving nearly as much.  Hmmm.

So, we pulled apart the one-piece (Ashtabula type) crank and bottom bracket, looking to tighten up the chain ring.  We tightened it as much as possible, and then Esteban gave the bike another test drive.  He made it out the door, but going up the hill behind the shop, the disconnect between the chain ring and the crank returned.  I was tired, it was late at that point, and we just parked the bike and went to dinner, feeling frustrated.

We took the bottom bracket apart several times

Next day, I compared Esteban's bike with another of similar (Ashtabula type) one piece crank - and finally discovered that one important component was missing on Esteban's bike.  The missing part was a stub bolt from the drive side pedal crank that passes through a hole in the chain ring.  This bolt had apparently broken off, because there was an uneven surface left on the pedal crank.  In the days before, I didn't even notice this problem....

So, I got busy with the arc welder and in a short time fashioned a new stub bolt to secure the chain ring in its position.

New stub bolt welded onto the pedal crank to secure the chain ring on Esteban Zambrano's bike, shown in the background.

On the next test drive, Esteban found that he may as well have had a new bike - the difference was astounding!

Subsequently, I did take apart the coaster brake hub that we had replaced on Esteban's bike - and found that it had a cracked brake shoe assembly.  I suspect that the resulting impaired braking action may have caused the operator (Esteban or his predecessor) to exert undo force to get the bike to stop, therefore overstressing the stub bolt and causing its failure.

Fixing bicycles - Donation

Jordan Garcia adjusting the seat on his bike - using our new Park Tools bicycle vice, which is so convenient.

Of all the work the children do in the shop, maintaining the bicycles is what most affects them directly.  You can imagine that each boy is very interested in the condition of the bicycle assigned to him.

Last December, we received a generous gift of about $500 US from a Baptist short-term team from California for bike parts to fix up the bicycles.  Last fall, with all the focus on building things for the fair and other projects, we hadn't kept up with the maintenance on the bikes, so this wonderful gift was very timely.

Felix and Juan Felipe working on Juan's bike.

Felix and I decided one strategic move we could make with the help of the donation would be to equip all the bikes for the smaller kids with coaster brake hubs on the rear wheel.  The smaller kids tend not to have sufficient grip strength nor sufficient coordination to make other braking systems work well.  Also, coaster brakes are very low maintenance, which is attractive when we have so many bikes to take care of.

Ironically, when I went shopping for coaster brake hubs in Bogotá in December, I didn't find any for sale.  The retailers said they expected a new supply to arrive in late January.  So, after I returned from my trip to the US, I tried again and was then able to purchase 6 new hubs at $31,000 pesos ($17.22 dollars) each, made by Velosteel in the Czech Republic.  These hubs are well made - using a Sachs design patented in 1904, but are different than coaster brakes commonly available in the US.

So, we began the process of replacing hubs and in some cases the rims, too, on some of the smaller bikes.  I found that the spoke pattern for a 16" diameter wheel has to be different than that on a 20" wheel, because the rim has only 24 spoke holes, instead of 36.

So, we began the process of replacing hubs and in some cases the rims, too, on some of the smaller bikes.  I found that the spoke pattern for a 16" diameter wheel has to be different than that on a 20" wheel, because the rim has only 24 spoke holes, instead of 36.

Kevin Garcia (left) and William Gomez lacing spokes on this new, aluminum, wheel for William's bike

Julian Garcia (left) and Alberto (right) working on their bikes

Julian Garcia installing the tire on the new wheel for his bicycle