Posts Tagged ‘bike mechanics’


Tool of the Week #7 – Spoke Wrenches and Truing Stands

Wednesday, August 14th, 2013

This week, we’re discussing spoke wrenches and truing stands. Both are integral tools to making and keeping your bicycle wheels running round and straight!

 

Spoke Wrenches

Spoke wrenches are used during the building and repair of bicycle wheels to adjust the tension of the wheel’s spokes. Spokes are connected on one end to the wheel’s hub and on the other end to the spoke nipple. The nipple and spoke are both threaded, so the spoke and nipple can be screwed together to secure them just like a nut (the nipple) and bolt (the spoke). Spoke wrenches are sometimes called nipple wrenches, as it’s actually the spoke nipples (the “nuts”) that are turned to adjust the tension of the spokes.

 

Spoke wrenches, just like other types of wrenches, come in different sizes. For the Park Tool wrenches used in the Bike Kitchen, the size is visible based on the colour of the wrench.

Black are for 0.127” (3.23mm) nipples.
Green are for 0.130” (3.30mm) nipples.
Red are for 0.136” (3.45mm) nipples.
Blue wrenches are for 0.156” (3.96mm) spoke nipples.

By adjusting the spoke tension using spoke wrenches, a wheel that is wobbly or “out of true” can be brought back into alignment. When a wheel is out of true, spokes on one side or section may be more tight than those on the other side or another section, resulting in part of the wheel being pulled out in one direction or more. Out of true wheels are not as strong as perfectly true wheels, and can make it difficult to perfectly adjust the brakes due to the wobble.  Sometimes the rim is bent or unable to be trued and must be replaced.

 

We’re not going to get into the nitty-gritty of wheel truing here, but here’s a quick overview to get you started.

There are four aspects of wheel truing:

1. Lateral true: This is the side-to-side wobble that can be seen when the wheel spins.

2. Radial true: This is the up-down type of wobble from a wheel that is not perfectly round. It can be felt as a bump for each wheel rotation when the bike is ridden.

3. “Dish” or rim centering: This is how centered the wheel is in relation to the hub.

4. Tension: This is the tightness of the spokes. It can be tested by plucking each spoke: the front wheel spokes should all sound the same, while the rear wheel spokes should sound the same as those on the same side.

 

Fixing an out of true wheel is typically done using a truing stand. The truing stand holds the wheel steady while being trued and makes is easier to gauge in which way(s) the wheel is out of alignment. Before putting a wheel in the stand, the wheel is removed from the bicycle and the tire and tube are removed from the wheel so it’s just the hub, spokes and rim. See the previous post on tire levers for tips on removing tires!

When truing, it’s important to remember that the spokes and nipples have a standard right-hand thread, but you are looking at the nipple from the bottom. This means that turning the spoke wrench on a spoke clockwise loosens it while counter-clockwise tightens it.

If you noticed your wheel is out of true in one or more of the ways described above, come into the Bike Kitchen. The mechanics can show you in more detail how to true your wheel to get your wheel rolling straight and strong again!

 

*Thanks to howstuffworks.com for the photo of spoke anatomy

 


 

Tool of the Week #6 – Pedal Wrenches

Wednesday, August 7th, 2013

 

This week, we’re talking about pedal wrenches, which are used on the bicycle’s pedals to remove and to install them.

About bicycle pedals: Pedal threads are different on each side, to prevent the pedals from loosening while riding. The right-side pedal has a right-hand thread which removes counterclockwise and installs clockwise. The left-side pedal has a left-hand thread (reverse threaded), and therefore tightens and loosens in the opposite direction. As discussed in a previous post, left-hand threads slope up to the left, while right-hand threads slope up to the right.

   

How to use pedal wrenches:

To remove pedals:  Removing pedals is a common occurrence on volunteer nights in the Bike Kitchen when stripping bikes to recycle the parts. Pedal wrenches have a 15mm opening but are typically longer than a normal wrench so more leverage force can be applied.

1. Shift the chain to largest chainring, to help prevent cuts from the chainring teeth.

2. Move the crank arm, the arm the connect the pedals to the bicycle, so it is pointing straight ahead.Place the wrench in line with the crank arm, or a little above. This positioning helps to eliminate the rotation of the cranks when you are trying to unscrew the pedal. Try the wrench and the cranks in different positions until you find the sweet spot.

3. The first movement of unscrewing the pedal is the most dramatic. After that it gets easier and you can hold the pedal wrench in the same position while turning the crank so the pedal is pedaling forward. Keep turning the pedal until the pedal is completely removed from the crank arm.

Tip: If the pedals are well stuck, spray some WD40 in to help loosen them.

 

To install pedals: Pedal wrenches can be used to tighten pedals as well.

Make sure that you are putting the left pedal on the left crank and the right pedal on the right! Start the pedal into the crank by threading with your hands first to ensure that it engages easily. As with removal, you can use the wrench to hold the pedal still while pedaling the cranks backwards and installing the pedal fully.

 

 


 

Tool of the Week #5 – Cable Pullers

Thursday, August 1st, 2013


Today, we’re exploring cable pullers. Cable pullers pull cables tight for adjustment of derailleurs and brakes. They are also called “4th hand” tools, as they allow you to do the work of two hands with just the one tool, as if you had an extra hand. (The “3rd hand” name was already taken by another tool).


How to use: The tool has two sides, one that pinches the cable and one that provides leverage for pulling. To use, place the cable to be adjusted in the slots.  The short slot should be towards the bicycle part to be adjusted, while the end of the cable comes out of the long slot where it’s pinched. Leave a little bit of space between the tool and the brake so you can loosen or tighten the cable as needed. Once in place, grab the cable by squeezing the tool with one hand until the short slot comes in contact with the brake. With your other hand, loosen the fastener. Then use the tool to tighten or loosen the cable as needed: to tighten, simply squeeze the tool further; to loosen, release. When the cable is adjusted, tighten the fastener with your other hand. Release the tool and check your adjustment. Readjust as needed.

Ride on!