My wife has a new ebike, the BSP Musa,. It had some wobble as shown in the video. This is on ECO, with a 82kg rider and about 5kg Weight in the carrier bags. I can evoke this easily with accelerating and then lowering my pedale power, at that moment it starts to wobble /oscillate.
With about 15kg Weight on the carrier the bike is doing this non stop with an amount that you almost can't keep under controller even with both hands on the handlebar.
The headset bearings are smooth and without play, the front wheel is not perfectly true, so I will get that straightened by the dealer under Warrenty.
Is there anything else I can do regarding fork settings or tyre pressure?
It happens on perfectly smooth roads.
Thanks!
by 76-scighera
21 Comments
have the same problem with the bike my mother drives and i have not found any solution. So I think the problem is the form of the Bike itself. sorry for broken Englisch
i have had this on my ebike for years now.
I’m also interested in the answer!
A top tube.
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Weight distribution..? Try leaning foreword a little more or load the front with cargo.
That should not happen on any bike, E or otherwise. Get your “head tube” adjusted, it’s too loose. A tiny bit of misadjustment, either too loose or too tight, will cause problems.
Double check that the headset is properly preloaded. Just hold the front brake down and with your other hand hold onto the headset and then push the bike back and forth. If you feel it move then it needs more preload tension. Barring that, maybe the wheels are dished poorly (not centered)?
You should just return the bike if it’s not just a loose headset. People blaming the lack of a top tube seem to not understand that most bikes on earth do not have top tubes and don’t do this.
You said the headset bearing are smooth, but just to double check. When you grab the front brake and try to rock the bike there is no play?
Take that shit back to the shop. It’s a design flaw and dangerous
This should not happen.
My recommendation would be to have a shop check the alignment of the frame. This is a flaw of bikes when the rear triangle of the bike is welded twisted or off center (or both) relative to the midline of the bike. It can also happen if the head tube is not perpendicular to the ground.
Lastly and less likely, is that this can happen with bent or twisted fork legs. But unless the bike has been crashed I wouldn’t suspect that right away.
Do you have a suspension fork? If yes the tubes have too much play and it is a design failure. It‘s at least my experience with small budget e-bike.
If you have already set your tyre pressure normally using a calculator. [https://axs.sram.com/guides/tire/pressure](https://axs.sram.com/guides/tire/pressure)
Try reducing the front tyre pressure a little more.
Check the front brakes do not rub.
It may just be that the weight is too high up that acceleration reduces the weight distribution of the front wheel causing the twitchy/wobble.
The torque coming from the motor will be consistent and still engages a-time after you stop pedalling.
No mechanical cyclist would laydown that kind of torque without holding the handlebars.
Your bike is an upright seated geometry which distributes the weight further back and high aswell.
Or it could be all these factors above.
Cheap suspension fork and not enough trail. It’s bad design and “catalogue” engineering. Some ebike company built a frame then grabbed a fork but never tested it with real riders or weight to the rear of the bike. You could probably solve it with a different fork with more trail or greater rake, but if it’s new return it and get something that’s been vetted.
Is this a cargo bike? Does it do the same thing when you have weight in the back? My cargo bike will have speed wobble when totally empty, no wobble when carrying 20 lbs or more.
You can install a damping bearing in the headset to take some of this away. The Cane Creek Hellbender 70 Visco is an example
This is a geometry issue, too much weight on the front wheel. Keep your hands on the bars or buy a new bike.
My bike does this, just keep your hands on the bar.
It’s called a speed wobble.
The weight on the front is much lower than the rear; that’ll give you this wobble, and why it only happens when you don’t touch the bars.
Technically it could be an issue somewhere, but a lot of the time it’s just how it is with some bikes. If you don’t trust it, take it back to the shop and ask the techs.
Edit: try without the carrier bags fitted and see if the issue is gone / less, then you know for sure it’s a weight distribution thing.
Looks to be a low-step model without a top tube. They’ll flex like crazy and even a little unbalance in front wheel setup will cause that. A rigid bike (aka with top tube) would be stable.
The wobble is in the front but the issue may very well likely be in the rear wheel spokes and not tensioned correctly.
If purchased from shop, bring back and have them test ride it. I can say 9/10 what I am seeing in video, its a spoke or two in the rear.
Otherwise bring to a shop have them do the above.
I had this on my old 12+ year hybrid bike (none electric). It was okay when it was new, I noticed the wobble when it was about 10 years old. I fixed it by checking the tire spokes and tightening them (both front and back wheels), but after about a year or so it came back again. By then I already have other bikes so I just stopped riding it.
You know what meant. 🙂 when the axles are parallel to the ground steering axis should form a 90 degree angle with the ground when viewed from the front. If it’s not, issues like this wobble can occur.