Speed Wobble,,,Concerned?

J

Jerry LM

Active Member
OK, so I am watching Court do a review of the Pedego City Commuter today, a step thru Frame design. I know everyone is enamored with the step thru because of mounting ease but when I see a bike start a wobble as bad as what shows in this and several other videos of his I wonder why these companies have not addressed this issue which to my way of thinking is a Safety Concern.
 
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I would have figured that any no suspension bike going fast over non silky smooth terrain would start to shake a bit at high speed. In the Pedego video he was riding over a sidewalk style path that wasn't perfectly smooth and had constant bumps thanks to the path being seperated into slabs.

I haven't had much experience with riding a step through bike at speed, but do you think that if the Pedego had a step over version, also with no suspension, that it would be noticeably smoother?
 
Jerry, can you post a link so the rest of us can see what you are referencing?
 
Concerned? No

The step-thru frame has been around since the bicycle was invented and has been sorted out. With a "motorcycle background" I would expect you to recognize soft frame geometry and see the potential flex points. You should also know that a wobble can be induced with any two-wheeler.

The sky is not falling.
 
My daughter has a step-thru frame bike. I hit 35 mph going down hill yesterday and nothing happened. No wobble, nothing. Frankly, the upright seating position makes it fun at higher speeds as you really feel the wind. I wasn't even wearing a helmet.....

Now, my 1978 Honda GL1000 with a vetter fairing experienced high speed wobble above 85 mph. That happened to me once and I never went over 80 again on that bike. Scary stuff indeed.
 
I have a step-thru ElectricBikeCompany and have no issues. I would not say there is no flex but nothing that concerns me. This is a heavy bike with sturdy design so likely less of a issue. Court during reviews will mention it and say more or less than what he has noticed in the past on other bikes. Do the research and read the forum and than make the choice. If a step-thru is not needed because of physical issues or just convenience than a higher bar will add more rigid ride.
 
First ebike was an alloy frame step thru cruiser with swept back bars. I'm the only person who has taken it up to 28 mph, but I wasn't aware of any wobble. The bars though, they always make me think I'm playing foosball. It's not a bike for leaning and carving thru turns. The step thru part is a double bar, like the Pedego above. Frame flex at rest? I dunno.

If you ride them at bike speeds, like Class I or Class II, and there's wobble, must be something else wrong. Maybe loose fork?
 
Timpo said:
J....considering Honda Cub or any other scooters have similar frame geometry and still not having wobble issues ....
Click to expand...

I've owned two Honda Cubs: one back in 1965, and the refined 'Passport' version years later. For several years I rode a Vespa an '05 GL200 and '10 GTS300. They all would wobble on certain road conditions and speeds. With 10# on the rear rack, the GL200 would consistently start to wag its head right at 30mph and continue up to 35mph. That stability quirk has been noted at the Modern Vespa forum. The old Cubs had practically undamped suspension and would get into fits of bouncing on their springs and wobbling above 20mph on anything rougher than pavement. Their spindly leading-link front end added to the flex.
 
Citycrosser said:
....my 1978 Honda GL1000 with a vetter fairing experienced high speed wobble above 85 mph. That happened to me once and I never went over 80 again on that bike. Scary stuff indeed.
Click to expand...

The Vetter fairing caused your GL1000 to wobble. The screen's huge frontal area was not very aerodynamically efficient [like a barn door] and was sensitive to turbulence. As well, the heavy weight of the fairing and its mounting assembly shifted the bike's CG forward. It also pre-loaded [compressed] the front forks which not only reduce suspension travel, but it altered the rake/trail. Wind downward force at speed would compress the front suspension, too, and further tweak the bike's geometry.
 
Any bike can experience speed wobble; it is not only step-thru frames. I have had it happen with a very stiff racing bike. But I would say it is more likely to occur with a very upright riding position; because there is less weight on the front wheel.
 
Nova Haibike said:
Any bike can experience speed wobble; it is not only step-thru frames. I have had it happen with a very stiff racing bike. But I would say it is more likely to occur with a very upright riding position; because there is less weight on the front wheel.
Click to expand...

@Nova Haibike is right.
@Jerry LM , without even demo'ing a bike for 5 miles arriving at conclusions is not right. Speed wobble can happen on any bike if your weight is focused on the rear wheel. The moment you assume the riding posture with weight distributed on both wheels, the effect becomes minimal.

People who purchase very upright bikes, cruisers are not wanting to 28mph unlike sporty riders.
 
Jerry LM said “I wouldn't buy a bike that demonstrates a characteristic like this period.” I agree you shouldn’t buy one. Get and ride what YOU like.

I am enjoying my step-thru, and racking up the miles. No issues, and would not hesitate to buy another one.
 
I bought 3 Pedego Platinum Interceptors, the same bike tested in the video above. I saw the video and bought the bike anyway since I rarely if ever ride no handed. After reading this post, I did an experiment. I rode with no hands up to 20 mph on both a smooth paved surface and a slightly rougher trail. I could not duplicate the wobble effect.

I do notice a bit of frame torquing however when making sharp side to side turns. This is typical of many bikes with step through frames and does not affect the performance enough to be a concern IMO.

Please note I'm not disputing or trying to debunk the video, it's an important factor which every rider of this type bike should be aware.

In all fairness, my Interceptor has modifications which may or may not be the reason for the lack of wobble. My bike has mag wheels while the tested bike has spokes. I swapped out the cruiser style handlebars with the BMX type and added a BMX stem & riser.

With over 500 miles on the bike now, I'm pleased with it's performance and don't regret the purchase.
 
Jayvee, thanks for highlighting the speed wobble segment in Court's video! Otherwise, I would never have found it.

Jerry LM, now I see what concerns you, but since I never lean back and ride no-handed on my bikes, I don't see that as an issue for me. Never had the skills to lean back and ride like that.
 
Getting into the habit of frequently putting your weight at the pedal in the down position does not only eases your butt pressure to the seat (esp on the bumps), it also removes the rider weight's pivot point at the highest location and put it into the lowest spot, thus, dissipating the speed wobble phenomenon.
 
Thanks guys some very informative and valuable information here and I appreciated the time you took to reply. I was not trying to down anyones brand or choice or argue I was just concerned when I saw some of the videos.Some say stable some say speed wobble can be induced. The Evelo with the rack mounted battery also had some wobble as a few others.
I plan on laying out 4k for a bike and I just felt that an inherent problem might be avoided. I don't want to experience any kind of instability when cornering or otherwise.
I was also looking at the mag wheels thinking the spokes can cause some weakness in a heavy bike.
I went into this with a open mind and no brand loyalty or prejudice of any kind as I have only ridden standard bikes no motor.
I am after months pretty impressed with the Evelo Aurora as it has huge torque and power, being a step thru as well it seems this frame is very stable, a different design. I am impressed with the no cost returns and four year warranty as well.
If for some reason I don't like the bike I can return with no financial loss whatsoever, I have read return policy and warranty on others and up to 18 to 25% restocking fees? plus shipping? Wow! that's pretty steep on 3k.
I think the power of that bike overcomes the drag of the NuVinci as well and looks like it eats up hills pretty well........
 
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