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After some time, I go back to publishing a more technical-themed post for my Towards the Bikend initiative. I renamed this section of the project as INSTRUCTIONS BEFORE USE. Before getting down to our focal points, a quick summary.
Towards the Bikend is a project that includes the publication of various posts, all centered on the theme of the "bike world". In the past, I had published a few posts, but never too formal. Instead, I decided to give a more structured face, finding myself disassembling an old road bike from top to bottom, and thinking I could show - with the help of some photos taken during the different passages - a "sketch" of how to proceed. However, the project plans to go beyond this boundary through contents that concern multiple aspects of the bike world, from homemade training methods to local initiatives, perhaps also passing through training itineraries.
For today's episode, I decided to talk about my experience in DISASSEMBLING a CRANKSET. Today, I will show you my experience with the first part of the disassembly process, which is the one aimed at removing the crankset from a bike.
In the meantime, let's define it. The CRANKSET is the portion of the bike essentially formed by the cranks, the crowns, the various connection points between these elements, and what allows them to be linked and blocked. I tried to simplify the concept in the photo, I hope it is understandable.
The crankset is mounted on the bike at the level of the bottom bracket area, the area where most of the metal tubes (or other material) that make up the bicycle frame converge. The PEDAL is setted on the crank arm, at the furthest end from the bottom bracket. I tried to schematize everything in the image below. Try to imagine positioning yourself behind the bike and looking forward: you should see the various components roughly like in the image.
And now let's move on to the practical side. IMPORTANT!: Consult a specialized technician and the specific manual to use the correct assembly or disassembly process. This is just a summary that can serve as a more practical and less schematic approach than a technical book.
The crankset that I had to take apart was a SHIMANO Ultegra model. First, I focused on the crank arm from the left side of the bike, the one where there are no chainrings. As you can see, there are two screws that I have highlighted.
We have to loosen the screws with the help of a suitable hex wrench.
Once the first has been loosened a little, we have to 180-degrees turn the cranck-arm (because the other screw will have the head on the opposite side and that's why you saw it smaller in the previous images). Let's unscrew this second screw a little too.
Then, I took a screwdriver and looked at the crank-arm from the side. It should be noted that in the area of the screws the crank-arm has a small cut in which you will have to insert a tiny screwdriver or other tools: inside that space, there is a small piece of metal, technically called a "Safety Pin". We need to push it slightly to one side and let it pop out halfway.
The pin must move easily. If it doesn't, we need to further loosen the screws holding the crank arm tightly, the ones seen previously.
In my case, I have completely removed the screws and the pin to clean everything, but it is not necessary to completely remove pins or screws to extract the crank arm: just loosen them firmly.
The next step is to use a specific tool to unscrew the cap that you can see on the side of the crank arm.
In the photo below you can see this cap whose shape is specific for each manufacturer brand (and sometimes even beyond).
Below, you can see the crank arm and the cap, as well as the turned outward safety pin.
In the image below, I show where the specific tool fits. These tools can be turned by hand, with a hex wrench, or even with a wrench, depending on the strength with which the cap was previously mounted.
Once partially unscrewed, the cap will look like this.
I finished loosening it and removed it. Aside from the filth that abounds in my case, what you see above is approximately what you will find yourself in front of. I gently pulled - and then with increasing force - the crank, in order to extract it. You can loosen the screws that hold it in place further if you still feel it is too anchored.
The result will be very similar to the one in the image below.
Now: the result just seen could be different depending on the type of bottom bracket that is mounted on the bike. In this perspective, there may be further steps to be performed with different tools that I, having not performed, cannot show you. For most of the cases of racing bikes around 1500-2000 euros that I have seen, the crankset is completely removable without too much more difficulty.
In my case, it was necessary to remove some bearings and gaskets that were positioned between the frame and the crank arm that was recently extracted.
Once this is done, it is necessary to push on that metal tube that protrudes through the frame: it is nothing more than the connecting axis between the right side and the left side of the crankset. I used my fingers because the elements were already quite mobile.
To overcome unpleasant inconveniences, while we are pushing the crankset axis, it is sometimes useful to place a hand on the opposite side, as shown in the figure. This prevents the crankset from coming out abruptly on the opposite side.
And again the crankset, ready to be pulled out completely.
Let's move to the opposite side of the bike... grab the crank arm... pull slightly towards us... et voilà, extracted crankset.
Once the extraction is finished, the disassembly is not finished. In the Shimano Ultegra case, like many other crankset models, the chainrings are fixed on the cranks, so they will have to be separated manually. We will see in a future episode how to finish the disassembly process.
PROMPT: if you want to remove everything, I strongly recommend that you remove the pedal from the crank arm before removing the crankset from the bike. There are cases in which the pedal is extracted quite easily anyway, but others in which the oxides make this operation almost impossible, if not with more expensive tools with less accessible cost than a common hexagonal wrench.
Having said that, I greet you and make an appointment for the next episode of the Towards the Bikend initiative. If you are interested, every week I will also publish routes and activities that I do on my bike. Check out the #bikend tag if you want to know more.
