Wobbly Crank Bike

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Crank on a bike - Wobbly Crank Bike

Mountain biking can be a dangerous hobby, but the danger doesn’t have to come from untended issues with your bike like a wobbly crank. Riding your bike with a wobbly crank is dangerous, and fixing it should be the first thing on your priority list.

If you ignore a wobbly crank, it could fail on you and cause a crash. Any number of things could have caused your crank to become loose and wobble, but it is essential that you rectify the problem as soon as you notice the wobble in your crank.


Why Does it Happen?

Wear and tear on your bike over time is expected. However, a wobbly crank won’t be the last thing you have to deal with on your mountain bike if you regularly take it to the trails.

You will hit bumps in the road that will cause your bike to malfunction from time to time, and that is just a part of having a physical hobby. Any number of things could have caused your bike crank to wobble.

Some common causes could be that the connection between the crank and the crank spindle is loose, the bottom bracket is loose in the frame, or the bottom bracket bearings are worn.


How Can You Fix it?

Fixing a wobbly crank depends on the diagnosis of the wobble. If the connection between the crank and the crank spindle is loose, then you can tighten the crank.

If the bottom bracket is loose in the frame, then you can remove the cranks and tighten the bottom bracket.

If the bottom bracket bearings are worn, you will need to replace the bearings, or if you have an older cartridge bracket, you will need to replace the entire bottom bracket. In most cases, you should be able to fix the wobble on your own.

In the event that you don’t know what to do, seek help from a professional at a repair shop.


What Tools Do You Need?

Tools will also depend on the diagnosis of your crank’s wobble, but the most basic tool you will need to tighten your wobbly crank bike is an 8mm hexagonal wrench.

This will allow you to either tighten the bolt or remove the crank arm altogether so that you can assess whether or not the problem is elsewhere. A spanner wrench and a flathead screwdriver will help you tighten the cone before replacing your bolt.

This should tighten your wobbly crank bike in the most common case. It should at least last you long enough to get your bike to a repair shop if you decide you need professional help.


How Tight Should Crank Arms Be?

You do not want to over-tighten your crank arms. If you make your crank too tight, you could cause binding.

Binding could cause damage to the crank arm. You will want to ensure that you tighten the crank arms enough so there is no more wobble and the play is eliminated, but not too tight that you have caused binding.


Things You Should Know Before You Start

You should remember that wear and tear on your equipment is normal when participating in a physical activity like mountain biking. You are likely to have issues with your bike over time, but most problems are fixable.

If not by you, then by a professional. If you are going to fix your wobbly crank on your own, ensure you are not over-tightening, and remember that you can always take your bike to a professional repair shop if you are unsure what to do with your bike.


Final Thoughts on Wobbly Crank Bike

It is imperative to your safety to make sure that everything on your mountain bike is working correctly. If you leave a wobbly bike crank unchecked, you could cause serious injury to yourself or your bike.

The last thing you want is to ignore an issue like a wobbly bike crank and end up in a mountain bike crash. Take care to repair any damages you notice on your bike immediately, and cycle safely!

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