So I thought it might be good to have a category in our blog about specific mechanical problems we face and solutions. Unfortunately we won’t have time to document too much specifically, but when we have the chance we will!
I had been noticing while riding that if I took my left hand off the handlebars, there would be a slight wobble in the front. I have an American mechanic friend, Michael, that works at a great shop in Beijing called Motorway (摩德威 in the 798 art district). He’s incredibly knowledgeable and also very honest. I’ve been bringing my bikes to him for nearly a year now, and it’s nice being able to walk away from a shop confident in the job that’s been done rather than worrying something is going to come loose from the bike 5 minutes after riding away.
Anyway, thought it would be worth asking him about it and see what I could have a mechanic take a look at when I had the chance. He gave me a very detailed answer that listed out all the possibilities and how to diagnose. Here is his answer in full below:
The wobble could be caused by a few different things. Usually, it’s the steering head nut that needs to be tightened. Sometimes, it can be the steering head bearings that are worn out. To check this, you would have to lift the front wheel off the ground somehow and just very slowly turn the handlebars from the center position (pointing straight ahead) to maybe like 10 degrees left then right. You have to do this slowly with a fine touch or you won’t feel anything. If there is a problem, you will either feel some drag or a click. That means the bearings are toast.
If you turn it back and forth and it feels really loose, then the nut just needs to be tightened.
The other possibility is that the suspension is not set-up correctly for the load you are carrying. If the back is set too soft and you put a heavy load on the bike (another passenger, a lot of gear) it will make the rear drop a lot and the front will almost lift off the ground. This will make the front “loose” and can cause it to wobble. You would especially see this when you accelerate because the rear will drop when you get on the gas. I’m thinking this might be your problem because I’m guessing nobody set up the suspension for you and the shock spring(s) might be too weak for the load you’re carrying anyway. The way to help this is to stiffen the spring(s) by adjusting the pre-load to a harder position, if that’s even possible on this bike. You can also check if this is the problem by trying to shift your weight forward as much as possible as you’re riding the bike or putting a bag on the tank to add some weight to the front. If the wobble goes away, then that’s your problem.
The other option is that it could be caused by the condition of the tire or the surface of the roads you are riding on. If the tread is worn unevenly or if the roads aren’t entirely smooth, it can cause some wobble.
In the case of our bike, it looked like the likely culprit was the suspension as guessed by Michael. Either way, some great tips worth remembering!