COMMON QUESTIONS ABOUT CRANK LENGTH, DISC BRAKES AND SLICK TIRES

And what about crank lengths?

Q: I just got a new bike and it has disc brakes. My problem is, I can’t get this red spacer that is between the pads out. I know it seems so simple, but even with a pair of pliers it won’t budge, and I don’t want to damage anything.

A: There are a few things that could make removing the pad spacer difficult. First, some pad spacers are held in by the pad-retention bolt. You simply remove the bolt and it should slide out, but this style is not normally tight and fairly obvious. The next is to identify if the caliper and brake line are pre-bled but not attached to the lever. If this is the case, the spacer will easily come out as soon as you connect the caliper to the lever. Last is similar, and the brakes may have been bled with the spacer in. The spacer usually also has a clip that attaches to the pad bolt. In this case, you don’t need to remove the bolt, but sometimes it can make it easier.

Q: I have been riding 172.5mm crankarms for over two decades and never thought anything of it. Then, last week on a ride, the group was talking about how at my height (6-foot-1) I need to switch to 175mm. They had a lot of reasons, but they are all pretty set in their ways and still ride 23mm tires. Any insight you have would be much appreciated, because I’m not sure it’s worth the hassle and expense since two bikes have power meters.

A: This question comes at a unique time since we recently began our review of the new Canyon Grizl, which showed up with 170mm cranks instead of the more typical 172.5mm length for us. I’ve always said that it matters less than people make it out to be and really just slightly changes saddle height. Most of my road bikes are 172.5mm, all of my mountain bikes are 175mm, and my e-MTB is 165mm. 

So, in short, I wouldn’t change it unless you are having specific issues and, in most cases, a shorter crankarm would be better. During a pedal stroke on a shorter arm, your hip and knee don’t need to rotate as much. I have also noticed that riders with very aggressive positioning do better with shorter cranks because they have more room between the torso and knees when in the drops. Overall, I would see a professional fitter and have them assess your needs, but if you haven’t had issues in 20 years, just keep rocking what you have.

Q: I just upgraded to a new set of tubeless road tires that are slick (no grooves or tread). Why do they still have a directional arrow, and should I have chosen a tire with some sort of groove?

A: This is a pretty common question, and almost any modern tire has a specific direction that is recommended. This is because as tires evolve, so has the construction of the tire. The layers of the tire are assembled in specific directions to minimize rolling resistance. This is especially important, as the understanding of lower tire pressures offers higher performance results. So, mounting your tires in the correct direction may not be noticeable but will offer better results.

As far as grooves and tread, a slick tire offers the most amount of traction on a paved road. Grooves are a void in rubber contact with the ground, so in ideal conditions, a slick tire is best. A groove could help move water out from under the tire, but the surface area of a road tire is so small that a groove offers very minimal benefits even in wet conditions. In most cases, the grooves are applied as a marketing and psychological sales tactic since the average person relates them to “more traction.” In reality, think of Formula One racing—they will stay on slicks tires till the water is pooling on the track. Remember, this is a bit different when the riding surface is loose, and it’s the reason gravel tires have lugs/knobs.

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