Bike ‘slipped’ when turning corner, twice!

[mohammed]

Hi all, I am trying to figure out what happened when I was riding my e-bike (rear wheel drive) and ‘slipped’ when turning a corner. This happened twice.

First time it happens I was turning right on a mini roundabout (about 10mph) road was slightly wet and I felt like the back wheel slipped, I fell on the side scrapping my derailleur and handlebars, luckily I had a pannier bag on my right so I wasn’t personally injured.

Second time it happens I was turning right again, Road was slightly wet, I was turning right on a junction at about 10-15mph and again I felt like the back wheel slipped. This time my fell on the right (with the bike on top on me) and scrapped my right knee and sprained my left hand. My front light got smashed and front wheel and handle bars were misaligned.

I recently got new tyres (Continental Contact Plus City MTB E-Bike Tyre 27.5" x 2.20) do you think it could be because of these? I feel like it’s something to do with the bike.

I took the bike to my LBS who said maybe it’s because I pedalled around the corner but I’ve turned like this on many occasions.

 

[Tars Tarkas]

Could be a number of things I suppose, but with nothing more to go on, it sounds like operator error. Try slowing down through the curves.

TT

 

[Catalyzt]

Please provide a bit more detail-- I agree with TT, try slowing down. But there could be other factors, or a combination of them, which are contributing to the problem. So the solution may involve solving some of those problems AND changing your riding technique.

By searching your profile, it seems like you are riding an Aventon Level with a modified controller, is that correct?

I'm going to guess that this is a cadence-sensing mid-drive (and NOT a torque sensing mid-drive, please confirm, because some Aventons do have torque sensors) up to 20 MPH with a throttle.

* If you are using throttle while cornering, that may be your answer. Avoid using throttle when cornering.
* If you are pedaling hard, and the mid-drive is delivering a lot of power, that could be the problem as well-- particularly if you have an aftermarket controller. (I think one of your posts suggested that, but didn't have time to read it carefully.) Wildly speculative, though, knowing nothing else about the bike. But your LBS could be right-- if the controller is set up to deliver lots and lots of power when you pedal, it could cause the rear wheel to spoin.
* I read in your posts something about wanting to mount a downtube battery on the rear rack. If you did that, this could be part of or the problem: Bike might not be balanced correctly -- though how heavy could that battery be? Well, I guess if it's 10 pounds or more, could be a factor.
* Tire inflation could be a factor, but your LBS would probably have noticed that. What tire pressure are you running? If it was too high, that could play a role.
* It may be a combination of multiple factors.
* I doubt that it is the tires, unless they are old.

I have Conti extreme contact on both my sports car and my Trek kit bike. On the MX5, they are a dream, some of the best tires for an automobile I've ever owned. On the Trek, they are very good, but mine are not MTB tires, they are a lot thinner than 2.0, and I have to really respect their limits when I am off road or on bad pavement. (The Continental website is really frustrating, and the markings on the tires themselves are really bad, very hard to read the max pressure. There are about 20 different types of "Extreme Contact" tires for bikes. And the listings for car tires are a bit confusing as well! There are a couple of different types of "Extreme Contact" car tires, and you have to really read the fine print to tell them apart.)

Mine are like a gravel bike tire, smooth in the center of the tread, but I've used them on this full-throttle kit bike to climb steep gravel and dirt. Yeah, they do slip a bit, but I expect that, because those are situations where I'm really pushing the tire past what it was designed for.

On my torque sensing mid drive Emtb, with a (low-power) Shimano Steps E5000, I do feel the back end start to break away sometimes on dirt, never on pavement. But one thing about the Shimano setup is there's no delay-- if I feel that I'm losing traction, I just pedal a bit less strenuously, and the motor backs off immediately, so traction returns fast. I have almost dumped the bike a few times cornering hard on hairpin turns on dirt. (And I have dumped it, but only when I was trying to do something that I knew was at the edge of my, and the bike's, capabilities, so I was able to lay the bike down in a fairly controlled way.)

 

[rich c]

Tire quality/compound and inflation can be 2 big factors. There there is road or street condition. Around here the first few hours after a rain can be really slippery because of oil on the streets from leaking cars. Water and oil make for a skating rink.

 

[Gordon71]

I would say the reason is simply going too fast for the conditions.

 

[Tom@WashDC]

Ditto what Gordon71 said. The only time I've slipped while turning was because I was going too fast for the conditions. Dry road, wet road, grass, dirt, heavy gravel, fine gravel, snow, or ice. I've fallen on them all. I was going to fast.

Remember if you are on a wet road there is a fine invisible film of oil on the pavement which makes it slipperier than you would think.

 

[Gionnirocket]

Maybe you need a yellow light

 

[Slaphappygamer]

You got new tires, but did you get new tubes too? Sounds like maybe overinflation. You mention that you’ve successfully made these turns before. Now, after new tires, those same turns are trouble. Since the tires are new, maybe they have some oil/grease from production or packaging. If not over inflated, maybe the new tires need to be degreased. I’m totally guessing, but stranger things have happened and your issue seems to have started after new tires installation.

 

[Tom@WashDC]

Mohammed, didn't you just add a battery to your rear rack? Did the falling happen with the new extra battery on top of the rear rack?

 

[Viking1]

Try to avoid riding on any painted lines as they as less porous than asphalt, thus reduced traction.

 

[sc00ter]

I don't suspect the tires being at fault unless they are old stock (that tire hasn't been out long enough though) and getting hard or your'e running the wrong tire pressure. What I think, as well as others:
You assist kicked in during the turn, breaking traction.
Sewer cap or painted stripe? The motorcycle riders enemy!
Pedal strike? Even the slightest strike can upset handling sometimes.
Going to fast? I can slide my rear Pirelli Angel tire in the rain. My butt still puckers!
Unstable load in your side bag? Heavy load disturbing handling?
Braking in the corner?
I hate falling as much as the next rider but it happens sometimes. I just try to learn why I fell and correct that mistake.

 

[Kayakguy]

I don't suspect the tires being at fault unless they are old stock (that tire hasn't been out long enough though) and getting hard or your'e running the wrong tire pressure. What I think, as well as others:
You assist kicked in during the turn, breaking traction.
Sewer cap or painted stripe? The motorcycle riders enemy!
Pedal strike? Even the slightest strike can upset handling sometimes.
Going to fast? I can slide my rear Pirelli Angel tire in the rain. My butt still puckers!
Unstable load in your side bag? Heavy load disturbing handling?
Braking in the corner?
I hate falling as much as the next rider but it happens sometimes. I just try to learn why I fell and correct that mistake.

It appears yours is the only response to mention braking while turning. I haven't crashed while turning on my ebike, but I did once on a motorcycle. It was during a tight turn down a hill from an alley just as a UPS truck was turning into the alley. I also saw my stepson crash during a turn on pavement while riding a small (16") folding non-ebike, which may have been a contributing factor. During the MSF safety course, we were warned about the danger of braking while turning. You can do it, but very carefully, and certainly not abruptly.