Odd Crosswind Feeling

[lonelocust]

I'm new to eBikes.  I got a Rad City 5 last month, (lovin' it) and I've put about 1,200km on it.  (And as backstory, when I was much younger, I was quite an avid road biker and have 10's of thousands of km in the saddle.)

Yesterday, I was riding with a strong mostly crosswind (with some headwind) up 30km/hr.  I was trying to make up some time, so I was in PAS 5 and the bike was moving at full-assisted speed.  I got hit by a very strong crosswind gust and I experienced the most disorienting feeling - almost sickening, like a turbulence bump in a plane.  My path didn't deviate much, but it was very noticeable.  For a moment, I thought I was going down into the street.  I'm sure I tipped a good 10º or more, and I've never felt anything like it on a road bike before.

Now, I know it's related to the centripetal force - the wheels trying to maintain a straight, circular path in the face of an external push, and I'm guessing the reason I've never noticed it on a road bike is related to either (A) the more massive wheels, (B) the larger mass of the bike itself, (C) the larger mass of the whole system [bike and rider - as I'm also twice the mass I was when I was younger], (D) the velocity, or (E) some combination of the above.

I guess what I'm curious to know is... Is this a thing others have experienced on eBikes (or any bike, for that matter.)

[Eric7]

Many miles of experience on a road bike here.

Things that contribute to stability.  The Rad bike is heavy compared to a road bike - maybe  a rad is as heavy as 3 road bikes.   The wheels are heavy compared to a road bike.  So there is much more angular momentum with the fat tire, fat rim.  All that make me feel the bike should be more stable.

Not sure:  It goes relatively fast at full-assisted speed as you say (20 mph) which is a lot faster than I would ride.

Instability contributors: Maybe (1) you are wearing more clothes because you were cold because you are not exercising as much at PAS 5 - you had a bigger wind profile (or whatever you call it), (2) the bike has more of a wind profile since everything is bigger relative to a light weight road bike and you are seating more upright.  The rad is not exactly a road racing with a handlebar lower than the seat bike.

[Ddaybc]

Lonelocust, it doesn't completely add up about what you're describing as being caused by a gust of sidewind. I would definitely check the axles to make sure they are both seated correctly and tight. Check your tire pressure as well. I think something is shifting while you're riding.
What you're describing actually sounds a lot like what I used to experience with my old 4X4 truck with huge diameter and wide tires. When the tires rode over a pavement irregularity they would "follow" the irregularity a bit. It made the truck move around on the road as if it was beginning to turn but without any input from me.
The Rad's are heavy bikes and that usually makes them pretty stable. That's why I'm thinking it may have been caused by loose axles or low tire pressure. Maybe even both?
I hope you discover what it was and post it back here.

[Altema]

I ride in high winds often, and consider an e-bike my revenge against the wind for all the times it pushed me around as a child! 
The only thing I would consider an incident, is the time a crosswind gust hit me so hard that I almost went off the sidewalk, but I corrected for it and kept going. It feels a little different than an ordinary bike because it is heavier with a lower center of gravity. While the effect of the wind on your body will be the same, the heavier e-bike will not "move with you" as easily as a 30lb road bike. I have not experienced it, but I imagine it could be slightly disorienting if a person has a sensitive equilibrium.
If there are no problems found with the bike itself, you may need to adapt to the different sensation to get used to it.