In Part Three of our article on building a lightweight racing bike, we discussed the work done to lighten the seat and chain ring area. In a few easy steps we converted the bike to single speed, created a solution for tingling testicles and modified the pedals to make them into egg beater pedals.
After having done the wheels in the previous articles, in this article we will look at the small bits that are left on the bike and remove those and then we have the results of our road tests.
This was a shock as the bike reached speeds up to 110 km/h which is the state speed limit. We probably could have pushed it faster but we didn’t want to break the law.
The bike at it's current state of the project.
If you take a look at the above photograph you will note that there is still a lot of stuff that can be removed. As we have converted the bike to a single speed on the front, we can remove the front derailleur, gear cable and it’s associated shifting lever.
You will also note that the handlebars are taped up. This is not very good for aerodynamics so it needs to be removed. Aeroplanes are very shiny and smooth. This is for good aerodynamics. If tape was good, aeroplanes would be wrapped in tape to stop them falling apart wouldn’t they?
So we removed the tape, the plugs in the handlebar ends, and also the brake lever extensions as this was no longer a touring bike but a racer. The reflectors were also removed because we would not be riding at night.
We were going to grind off the dynamo mounting from the front fork, but decided we would need this later on for our road test because of some technical issues, so we left it on the bike. The bell was also removed. Racing bikes don’t need bells.
More Junk, less weight.
After removing all those small articles we have made some considerable weight savings and increased the aerodynamics of the bike at the same time with those shiny smooth handlebars. We also ground the brake pads down a bit to drop some more weight.
We did debate about removing one of the brakes, but in light of the expected speed of this bike, we thought we would need both brakes for stopping.
Riding Apparel
Now that the bike is finished, we need to take a look at riding it. But first we need to look at riding apparel. We need something that is light weight.
We looked at riding naked, but due to solar radiation, the amount of sunscreen applied would probably weigh more than clothes. Standard shorts and a lycra racing top was settled on. A standard bicycle helmet was also settled on even though there was some debate about how much weight it would add. With those egg beater pedals we needed something light and special for footwear.
After weighing up several types of footwear, we decided that due to the heat here we wanted something with good ventilation, so we settled on a pair of thongs. These are extremely lightweight and can double as a social shoe on longer rides when off of the bike and enjoying refreshment.
The finished bike.
Initial Road Testing
At low speed the bike was very responsive and fast. The steering was a little twitchy, but got better as speed increased. It handled bumps very well and absorbed even some of the bigger bumps so you hardly noticed them. It must be a feature of our triple lacing spoke pattern. The bike feels incredibly light when compared to a fully loaded touring bike.
There was a good range of gears with the rear five speed sprocket. Having the large single speed front chain ring made it a little hard to get going from a full stop, but the bike’s incredible light weight more than compensates for this. There was also no indication of tingling testicles on a longer ride. This modification to the seat worked really well and I’d recommend it to any cyclist.
Now to the final part that you have all been waiting for. It’s top speed. Due to state law the speed limit is 110 km/h so we could not go any faster than this without breaking the law.
Now we had an issue in measuring our speed. We did not want to fit a speedo due to the extra weight it would add to the bike. We tried driving a car alongside the bike, but this was incredibly inaccurate as the car would surge ahead and then drop back behind the bike, so we were unable to get an accurate speed reading.
That’s when the dynamo mounting came in handy. We were going to cut it off, but decided to keep it on and tie a rope to it. The other end of the rope we tied to the back of a car. The rope would keep the speed constant between the car and the bike and would allow us to get an accurate reading. While riding around town the speed limit is only 60 km/h and the bike kept up well with the car, so we decided to take it out of town and test it’s top speed.
We took the bike out onto a nice quiet stretch of highway. As the car increased speed over our previous high speed of 60 km/h the bike kept up well. At this higher speed pedalling with the big single speed front chain ring was easy, and the bike handled exceptionally well. We decided to try for a maximum speed reading, and drove the car faster.
The bike kept up with the car without any issues and at the state’s speed limit of 110 km/h we had to back off and not go any faster. This bike is amazingly light and stable and at the speed limit the bike just kept up with the car. Even without a rider on it.
We therefore applied for permission to use the runway at the local airport as this would allow us to get up to the bike’s maximum speed. Unfortunately permission was refused, but permission was granted to use their road as it is private and we shouldn’t have any problems with speed limits. The road also has some hills in it so we would be able to test the hill climbing abilities of the bike.
Crank carrying the extremely light weight bike, ready for the big test.
In the next article we conduct our road test of the bike and run it up to it’s maximum speed. Sadly the bike was destroyed in an extremely freak accident. Luckily Crank who was road testing it was not hurt. Read all about it in the last and final article of this series on building a lightweight racer.
