Whats that clunking, check your battery

My Bulls Evo 3 27.5+ hardtail developed a sound which at first I thought was a loose headset and then possibly a damaged fork, thought I would share this story to help others.

I first noticed a defined 'clunk' sound when lifting the front tire to clear a curb. I first noticed this after flipping the stem to lower the handlebar.

Since I had just changed the stem, the first thought was a loose headset. I also thought that having the stem without any spacers below might be causing issues in getting the headset tight so I ordered the smallest headset spacer I could find to put under the stem and installed it. I could have sworn this fixed the issue.

So all seemed well.

Much of my rides dont really need a suspension fork so probably 75% of my rides are with the fork locked out. About two weeks ago, the fork was 'not' locked out and as I dropped off a curb I heard a horrendous clunk sound. When I got home I noticed the shock only had about 20psi in it (130psi is where I set it to). My thought was that the 'clunk' was the shock bottoming out. So the front shock is not holding air well (lbs is fixing it as I write this) but that doesnt appear to be the problem as the suntour shock has also specific parts(secondary spring) to handle bottoming out.

This bike (and probably any bulls bike with the brose system) has some adjustable bracket stuff at the front of the battery you can adjust to make the battery fit tighter and this appears to be the issue.


New Member
Thanks for the information. I have the same bike (BULLS E-Stream Evo 3 27.5+ hardtail). I'll have to check it out.

Had you ever removed the battery before the 'clunk' sound? I've always recharged with the battery still in the bike, never removed it.