unstable e-bike

pagheca

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Hi Folks,

I've had a Trek Powerfly 7 FS for about a year, and I've always felt it was a bit unstable, with a tendency to wobble. I never fell off, but I always feel a bit unsafe, especially on very steep roads, respect to the past, when I had just a standard bike.

Is it because of this ebike model, or because it's much heavier, or maybe stability is against maneuverability, or maybe because I'm just... older (64)?
 
mhhh... this is difficult to do for me for several reasons.

Do you know of any specific criteria to understand if a bike is a good or bad fit for someone?
 
mhhh... this is difficult to do for me for several reasons.

Do you know of any specific criteria to understand if a bike is a good or bad fit for someone?
Hope this helps, i'll leave a couple links,




 
Thanks for all the answers and suggestions, guys.

I have checked the size and it is correct. I have also lowered the tyre pressure. I wonder if it could be a problem with the rake of the front suspension of this particular model, or something like that.

My previous bike was a Trek FX 7200 and I don't think I ever experienced this feeling.
 
I think it may be just the wrong style of eBike for the type of riding you want to do.
(LINK WITH IMAGE, FOR REFERENCE)

I bet you were attracted by the full suspension, or maybe it was just what was available.

Full suspension mountain bikes are designed for tight single track trails through the woods and on mountains. With jumps. The steering geometry (such as the rake angle you mentioned) and handlebar leverage are designed so it can turn quickly, which in turn leads to it feeling less stable than you're expecting.

I think you probably should just sell it and buy a bike that's more suited to your style. If you're after a very stable ride on the street, check out the cruiser style eBikes by Electra. The front wheel is raked out more; it's so stable (and a bit long) that making a 90° turn on the sidewalk without hitting the grass is a challenge. But stability? It has it in spades:


A side feature of this bike is that since the crankset is forward of the seat tube, your feet are out front a bit more and you don't need to raise the seat so high to get full leg extension. You can still get both feet on the ground. Electra refers to this as "Flat Foot Technology". They sued Trek for copyright infringement and Trek figured out it was cheaper to just BUY Electra than to settle the lawsuit.

I bought the above-linked bike for my wife and she loves it, except that she can't make the tight turns that I can on my commuter bike.
 
The complaint about unstable is a bit vague. While I'm new to E-Bikes, my background is desert race and dirt bikes. "If" what your riding/driving is unstable, are you pushing the limits of the bike beyond it's design. If you have a full suspension bike, is the suspension tuned to you and your riding style as well as the terrain? Fork position and handlebar width, are also be part of stability on dirt as well as street.

I have two Ebikes. An Aventure2 and a Turbo Levo. The Aventure is a hardtail, heavy bike with a moderate front fork design. Its great for street cruising and a mild dirt. If I take it to a moderately rough road or a trail, its very unstable. This is due to the weight with no rear suspension. The rear of the bike is difficult to control. The front fork dampening is also poor. The bike was not designed to be ridden like that.

My Levo on the other hand will ride very well, beyond my capabilities. It did take me a bit to fine tune the suspension. Out of the box, it was ok but the suspension didn't exactly match my riding and required fine tuning. Part of my tune was moving the fork forward 2 degrees (if it was a car I would call it caster).

Bottom line is, if your bike doesn't match you but is the right size, it may not be as stable as you like.
 
With those long stays in the back (I'm looking at how much space there is between the front of the back tire and the frame), and the sorta kinda conservative 67 degree head tube angle, this bike looks like its meant more for medium trails than hardcore stuff. As an aging cyclist myself, I can see the desire to buy something capable but only so for lesser things than you once rode.

measurements etc.:


It may be you can fix this, but you have to be ready to throw money at parts and understand you might fail. You have to be comfortable swapping parts around on a bike, and familiar with working on them in general. If not then don't mess with it. Go to a bike shop and have them work with you on fitment.

Is your reach on this bike shorter than it was on another that you were comfy on? A longer stem could help, but again it may not so there's that 'might fail' thing. Myself, I have a half-dozen stems I can try out in my garage parts bins, but not everyone has that resource. Instead, for something like a stem experiment, try a cheap one for ten bucks that is good enough for a few mild rides. If the solution works get a proper quality part matching that spec.

The handlebars are 750mm wide. Go wider. On paper at least, on an mtb wider bars increase comfort, stability and steering leverage. Pay attention to the rake (the rearward angle at the handgrips). According to the linked specs above, your bars are 750mm with a 15mm rise. Did your other bike you liked better have a bigger rise vs. your saddle height? If that bike is still around, looking at the two side by side will be helpful. If the Powerfly has your body leaning over differently, less rise or more in addition to more length could be helpful (also I've gotten great results from short 45-degree stems that only lift by a centimeter or two. Ritchey made the ones I use).

Go really wide, too. I just looked at JensonUSA and an 820mm bar is available for $69.00. If it turns out 820mm is too wide, handlebars have hashmarks on them so you can cut them shorter. The one I am looking at is marked to go all the way down to 720mm. The point being its a whole lot easier to cut excess material off than it is to add it on.

But before you spend Dime One on replacement parts, dig into your suspension specs and make sure its tuned for your body weight. Check the manual for your rear shock and make sure the sag etc. is set right. Then experiment with damping settings to see if that makes any difference. Fiddle with the air and damping settings on the front. I'm skeptical that 'wobbliness' can be caused by suspension as for my bikes at least suspension tuning is about perfecting the up/down and to me wobbly is a side to side affair. BUT multiple things together can all contribute, so throw all the spaghetti at the wall.
 
Probably a bad bike.We have 3 electric bikes (wtva ,rad mini 2, and a ariel rider grizzly) They all work great. I bought my wife a 3 score , 3 wheeler.It was stated it would do 30 mph.Well at 10 mph it almost shook you off the seat and when turning your feet hit the front tire.I returned it and shortly later they designed a different 3 wheeler.So I believe you have a poorly designed bike or was put together incorrectly
 
Hi Folks,

I've had a Trek Powerfly 7 FS for about a year, and I've always felt it was a bit unstable, with a tendency to wobble. I never fell off, but I always feel a bit unsafe, especially on very steep roads, respect to the past, when I had just a standard bike.

Is it because of this ebike model, or because it's much heavier, or maybe stability is against maneuverability, or maybe because I'm just... older (64)?
Hi Folks,

I've had a Trek Powerfly 7 FS for about a year, and I've always felt it was a bit unstable, with a tendency to wobble. I never fell off, but I always feel a bit unsafe, especially on very steep roads, respect to the past, when I had just a standard bike.

Is it because of this ebike model, or because it's much heavier, or maybe stability is against maneuverability, or maybe because I'm just... older (64)?
One possibility is a loose or improperly seated head set. This has happened to me; could also be your fork if suspension is unequal.
What tires are you riding? Stays are a possible. My first ebike was a Juiced CCS with asymmetric stays that kept getting worse until
it became completely unridable
 
mhhh... this is difficult to do for me for several reasons.

Do you know of any specific criteria to understand if a bike is a good or bad fit for someone?
For a start can the operator ride it without it feeling wobbly? Bring it to a bike shop that sets folks up properly. You could be too far forward, too far back, and all sorts of adjustments in between. If you're a do it yourself type just google bike set up, there are toons of guides out there.
 
51 pounds is a lot to sling around, when compared to a nice equivalent mt bike without motor.

At that weight, anything that is even a little amount 'off spec' gets magnified. Take it to a competent Trek dealer for a check. Sounds like you know what you have been doing.

edit: many good suggestions above. probably i missed something [apols], but: Is the suspension up to firmly supporting the total load?
 
Looooots of stuff to read, understand and apply: thanks a lot, e-bike people! :love:

I will take the bike to the only dealer on the island tomorrow (holiday here today) for a full check and fine tuning. I have a pretty tough job and not too much time to spend at home, although I have good technical skills but not many tools as I moved all my life around the world.

I tried to tune the suspension. I change the set-up quite often according to the situation. I used my ebike to drive mainly off-road. The problem, which is more of a feeling to be honest, occurs at low speeds and on very steep gradients (30%). Here there is a typical way of building old tracks, the "camino real", used a long time ago to herd goats and sheeps. They are very steep and covered with badly cut and sharpened stones, often in bad condition due to lack of maintenance. That's where I had the most problems, partly because of my age (almost 65) and my weight (90 kilos, but I'm losing weight).

I'll let you know how the dealer will respond. Thanks again to everybody that commented here.
 
Hi Folks,
today I had the chance to swap with a friend that own an almost identical bike. We both felt ok with the "other" bike. We discussed at length this instability issue and came to the conclusion that is probably just the fact that I was used to much lighter acoustic bikes, plus my age. We rode over very hard terrain, road, steep hill up and down, gravel and also sand (so much fun, wow!), and everything looks OK.
 
This afternoon I went for a 1.5 hour ride up the mountain with a friend. Maybe because I am getting fitter, maybe because of this discussion, I felt much more balanced and confident. Today something really unlocked in myself. I tried to ride faster, uphill and downhill. Especially uphill I used longer gears so I could stand up on the bike. I realised - don't laugh... - that on an ebike you have to use longer gears to stand up, otherwise the motor makes difficult to balance on the pedal.

It was super adrenalinic: I really had a lot of fun on this nice track in the woods. The guy who usually rides with me is a bit more scared than me when it comes to very steep descents, so at one point we had to take a detour and get back.

But doesn't matter: each time I realise that this two-wheel thing is probably the best investment I have made in the last ten years. Wow! :love:

p.s. and on the way back I did my very first stair... :cool:
 
I went for a short ride early this morning and I felt again "unlocked". I think I have not been aggressive enough on my rides, that was the problem.

Today I went down the hill to sea level and back and I felt everything was fine. In the past I did not use the gears enough. Now I attack every steep climb much faster with a higher gear. The climb was 395m in 4.82km, part of which was 14% on very rough terrain.

I am also trying to improve my balance. Stuff like that:

 
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