JimB Posted September 23, 2017 Share Posted September 23, 2017 Was riding down the sidewalk at 5pm in Seattle. Approaching an alley a little faster than I normally would - there was a cop there to direct traffic out of the alley (and alley opposite) and he wasn't waving anyone forward. Looked clear. As I was nearing to cross, a car came up the alley - a little faster than he should have. I saw him at the last second. He saw me also. We both stopped. I did what someone here called a "power stop". I leaned back hard and pushed back with my legs. The wheel cut out due to overload/overlean. I ended up on my butt (uninjured). The wheel skidded forward a few feet (also uninjured). The cop commented: "that was a fast stop"! (As I was getting up off the sidewalk.) I'm usually super careful at alleys, coming almost to a stop until I can see it was clear. I guess the cop there gave me a false sense of confidence. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted September 23, 2017 Share Posted September 23, 2017 What wheel? This is important info Only fast wheels (= with strong motors) are safe. Link to comment Share on other sites More sharing options...
JimB Posted September 23, 2017 Author Share Posted September 23, 2017 IPS Lhotz. It's a decent wheel. Not high end, but not crap either. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted September 23, 2017 Share Posted September 23, 2017 1000W, is this right? It's a lot. And still you overpowered it. Or maybe the batteries were the weak part? Link to comment Share on other sites More sharing options...
WARPed1701D Posted September 23, 2017 Share Posted September 23, 2017 Are you sure it was a cut-off and not a loss of traction? Did the wheel spin out as it went down or was it dead? Glad you were OK. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted September 23, 2017 Share Posted September 23, 2017 Hmm, 80 kg rider (= ~100 kg with wheel) at 15 km/h braking to a stop in one second (which isn't short) needs 1736 W of power. 20 km/h makes it 3086 W. So I guess, hard braking can overpower pretty much any wheel. 32 cells on the Lhotz, means 15A per cell for 1000W. (I think that's probably nonsense) Battery might have folded first. No guarantee on these numbers or their interpretation, I'm a noob. -- No idea how much motor power would be needed so the wheel would loose traction on pavement rather than the motor being overpowered. A lot, probably. -- Conclusion: everybody lobby for 5000W nominal wheels with 5000Wh batteries that can go 100 km/h. For safety! Link to comment Share on other sites More sharing options...
Keith Posted September 23, 2017 Share Posted September 23, 2017 59 minutes ago, WARPed1701D said: Are you sure it was a cut-off and not a loss of traction? Did the wheel spin out as it went down or was it dead As @meepmeepmayer says above, it is even easier to overlean a wheel braking than it is accelerating and power demands can be even higher. Accelerating you can be control how far you lean, but when faced with danger you are going to react first and think later. I think it is very easy to overlean in that situation, the reason you will often see me advise newcomers to "not to forget to practice emergency stops" . @JimB, I've done exactly the same thing: riding on the sidewalk with a small closed bodied truck (what we call a van in the UK) parked on the road next to me a women turned straight onto her drive at speed without being able to see if there were any pedestrians there - let alone me on an EUC. I went straight down on my backside, thankfully I was still using a strap at the time so the wheel didn't hit the car (which might have caused something of an insurance nightmare!). Bottom line was that I did stop damn quickly which, I guess was the object of the exercise ?. Oh, and to answer @WARPed1701Ds question, my wheel certainly did not cut out and it did not slide - dry concrete and no rubber marks - I just over torqued it, I.e. leaned further back than it could correct for, it still had power, just not THAT much power. Link to comment Share on other sites More sharing options...
Slaughthammer Posted September 23, 2017 Share Posted September 23, 2017 Outtorquing the IPS lhotz with 80 kg while hard braking is quite easily possible, guess how I know... The motor is actually more of estimated 500W nominal spec. Link to comment Share on other sites More sharing options...
mrelwood Posted September 23, 2017 Share Posted September 23, 2017 Lhotz has a measured peak power of 1200W, which I would think is also the reserve for a short lasting emergency braking. I have felt the Lhotz giving up shortly when braking very fast from something like 10km/h. The one time I fell down on the Lhotz at speed was a long and pretty steep asphalt downhill that had a sudden drop. I was riding at near the max speed (which is 26km/h) and the Lhotz was not able to provide the power needed to brake so I landed on my back. Luckily I only got minor injury. The power limits felt a bit too easy to reach so I upgraded to a KS-16S. Link to comment Share on other sites More sharing options...
JimB Posted September 23, 2017 Author Share Posted September 23, 2017 Hey all, note that I'm NOT blaming the wheel. It did exactly as I would have expected. I have purposely practiced stopping short to the point where the wheel has given out. There's no mystery here. I slammed it HARD into reverse and it buckled. No skidding, batteries were probably at about 75%. Basically, an overlean in reverse. I was reasonably happy with the result - I stopped fast. No skid marks on my pants (inside or out). @mrelwood I start each day down a steep (11 degree) 1/4 mile hill. I ride at ~15 mph, just below the warning beeps, and haven't had a problem with controlling speed. I *do* pay attention to the warnings though and never try to push past them to max speed. Also, yes, I have been lusting after the KS-16S. I just can't bring myself to shell out the cash. I probably need to get 2 years out of the Lhotz, or my wife will give me a hard time. I'm only at 10 months now. Link to comment Share on other sites More sharing options...
steve454 Posted September 24, 2017 Share Posted September 24, 2017 1 hour ago, JimB said: Hey all, note that I'm NOT blaming the wheel. It did exactly as I would have expected. I have purposely practiced stopping short to the point where the wheel has given out. There's no mystery here. I slammed it HARD into reverse and it buckled. No skidding, batteries were probably at about 75%. Basically, an overlean in reverse. I was reasonably happy with the result - I stopped fast. Didn't think that. I've had that happen twice stopping too fast and leaning back too much to try and go backwards. It was a learning experience. These wheels are not super powerful and will give up. Link to comment Share on other sites More sharing options...
Slaughthammer Posted September 24, 2017 Share Posted September 24, 2017 11 hours ago, JimB said: Also, yes, I have been lusting after the KS-16S. I just can't bring myself to shell out the cash. I probably need to get 2 years out of the Lhotz, or my wife will give me a hard time. I'm only at 10 months now. Yes, kinda in the same situation right now, except that my extended battery makes it even harder justifying the purchase of a KS-16s. And then I'll have to deal with that tiny 2.125" tire of the 16S... still waiting on the details of the 2.5" tire mod @mrelwood made. Link to comment Share on other sites More sharing options...
WARPed1701D Posted September 24, 2017 Share Posted September 24, 2017 Its the potential for situations like this that pushed me to get the GForm ski and board shorts with padding for the tail and sit bones. Falling on your backside can be a painful event. Again, glad you are OK and thanks for sharing the experience so we can all learn. Link to comment Share on other sites More sharing options...
LanghamP Posted September 25, 2017 Share Posted September 25, 2017 I had a semi serious situation today whereby I was going down a long and steep grassy hill, with tree roots everywhere, and basically lost control and free wheeled down to the bottom being unable to lean back. I tried to a turn it down but every time I turned "into the wind" so to speak I'd slip or hit a bump, and so it was me bouncing all the way down with my weight completely on my wheels trying to slow down with no success at all. It felt exactly what I imagine a runaway wheel would feel like. This has always been one of my fears and now that it has happened it's every bit scary. You have no control and you're just along for the ride as the wheel accelerates downhill, bumping along and your feet come off the pads. It felt like Wild E Coyote trying to brake, even during the descent. I always trolley my wheel down sketchy descents, going along exactly the path I map out and memorize, and usually a sketchy descent should be absolutely calm as every bit should go according to plan, but this backwards braking simply overwhelmed my skill on the wheel. The pedals never buckled but the wheel felt like it suddenly stopped braking and never got those brakes back. It felt like some ABS was engaged and basically the wheel free wheeled all the way downhill until there was enough traction to "engage" the tire. Link to comment Share on other sites More sharing options...
mrelwood Posted September 26, 2017 Share Posted September 26, 2017 On 24/09/2017 at 1:42 PM, Slaughthammer said: Yes, kinda in the same situation right now, except that my extended battery makes it even harder justifying the purchase of a KS-16s. I'm ever grateful for your superbly documented battery upgrade! Yet it didn't slow me down purchasing the 16S... Trust me, they leap is so monumental that I don't even consider them being in the same genre. It's a different hobby. Just yesterday I took a short trip with the Lhotz. I tend to do a short medium strength braking to make sure my feet are not too forward. While doing this on the Lhotz a bit softer, I darned overleaned the bastard! I was able to hop away and keep upright while the Lhotz run to the bushes. That wasn't even a medium braking for the 16S. The riding experience is so incredibly different with a powerful wheel. On 24/09/2017 at 1:42 PM, Slaughthammer said: still waiting on the details of the 2.5" tire mod @mrelwood made. Dang, I'm sorry I've been lazy! I'll do my best to get it done this week. On 25/09/2017 at 5:30 AM, LanghamP said: You have no control and you're just along for the ride as the wheel accelerates downhill, bumping along and your feet come off the pads. Man, feels horrible just imagining! I hope you get past the scared period soon. This is one of the reasons I made shock absorbers for my 16S. We all have hit sudden bumps or otherwise had our feet slip or lose control. Having shock absorbers can ofcourse hugely increase comfort, but the major gain is that your feet stay on the pedals and your legs don't shake uncontrollably. Unfortunately I still haven't found a great method making them stay in place and not needing continuous adjustment. Link to comment Share on other sites More sharing options...
kasenutty Posted September 26, 2017 Share Posted September 26, 2017 I have an angry Seattle wife too, so my euc fund is in bitcoin ? Link to comment Share on other sites More sharing options...
kour Posted September 27, 2017 Share Posted September 27, 2017 if i come up on some rough patches i squeeze the wheel with my legs! that seems to work most of the time Link to comment Share on other sites More sharing options...
kour Posted September 27, 2017 Share Posted September 27, 2017 On 9/24/2017 at 10:30 PM, LanghamP said: The pedals never buckled but the wheel felt like it suddenly stopped braking and never got those brakes back. It felt like some ABS was engaged and basically the wheel free wheeled all the way downhill until there was enough traction to "engage" the tire. glad you made it ok! although i was kinda hoping you were going to say you parkoured off and then jumped back on to your tottering, not-yet-fallen wheel! Link to comment Share on other sites More sharing options...
LanghamP Posted September 27, 2017 Share Posted September 27, 2017 Just now, kour said: glad you made it ok! although i was kinda hoping you were going to say you parkoured off and then jumped back on to your tottering, not-yet-fallen wheel! I did almost bail but I didn't have a strap. I was going down with the wheel like the captain of the Titanic! Link to comment Share on other sites More sharing options...
kour Posted September 27, 2017 Share Posted September 27, 2017 On 9/23/2017 at 5:21 PM, JimB said: I did what someone here called a "power stop". I leaned back hard and pushed back with my legs. The wheel cut out due to overload/overlean. I ended up on my butt (uninjured). The wheel skidded forward a few feet (also uninjured). yeah, coming up on those blind corners can be risky. what i worry about is my wheel becoming a projectile Link to comment Share on other sites More sharing options...
JimB Posted September 28, 2017 Author Share Posted September 28, 2017 On 9/27/2017 at 8:05 AM, kour said: yeah, coming up on those blind corners can be risky. what i worry about is my wheel becoming a projectile I always use a safety strap. Just a knotted strap looped through my belt. It's not for me, or my wheel; it's to protect others. Link to comment Share on other sites More sharing options...
JimB Posted September 29, 2017 Author Share Posted September 29, 2017 On 9/23/2017 at 4:32 PM, JimB said: @mrelwoodI start each day down a steep (11 degree) 1/4 mile hill. I ride at ~15 mph, just below the warning beeps, and haven't had a problem with controlling speed. I *do* pay attention to the warnings though and never try to push past them to max speed. Well crap! After months with never an issue, coming down the hill fast (just below the warning beeps), I decelerated for my turn a little harder than normal. (I have to turn left up a sloped curb near the bottom of the hill.) I also had an extra 10 lbs of equipment in my backpack that I don't normally carry - which probably contributed. Y'all know where this is going... braking was soft and I ended up on my butt again. I'm riding more cautiously now - that is not a good feeling. Bruised tailbone a bit - that'll be a nice reminder for a while. Link to comment Share on other sites More sharing options...
mrelwood Posted September 29, 2017 Share Posted September 29, 2017 42 minutes ago, JimB said: Well crap! After months with never an issue, coming down the hill fast (just below the warning beeps), I decelerated for my turn a little harder than normal. (I have to turn left up a sloped curb near the bottom of the hill.) I also had an extra 10 lbs of equipment in my backpack that I don't normally carry - which probably contributed. Y'all know where this is going... braking was soft and I ended up on my butt again. I'm riding more cautiously now - that is not a good feeling. Bruised tailbone a bit - that'll be a nice reminder for a while. I hope that you are aware of the possible risk of overvoltage. Going downhill or braking strongly with a full battery will easily overload the battery/BMS due to the degenerative braking. I guess it depends on the device how abruptly this is handled, but worst case scenario is the wheel will just turn off without warning. I would be extremely careful if I had to start downhill with a full battery. Link to comment Share on other sites More sharing options...
JimB Posted September 29, 2017 Author Share Posted September 29, 2017 7 hours ago, mrelwood said: I hope that you are aware of the possible risk of overvoltage. Going downhill or braking strongly with a full battery will easily overload the battery/BMS due to the degenerative braking. I guess it depends on the device how abruptly this is handled, but worst case scenario is the wheel will just turn off without warning. I would be extremely careful if I had to start downhill with a full battery. I use ChargeDoctor, and only charge to about 90%, for exactly the reason you describe. Link to comment Share on other sites More sharing options...
GoinPostal Posted September 30, 2017 Share Posted September 30, 2017 On 9/27/2017 at 8:57 AM, LanghamP said: I did almost bail but I didn't have a strap. I was going down with the wheel like the captain of the Titanic! Which wheel make/model was this? I have yet to overpower a wheel and I'm 250 pounds. I have done pendulum training with my Segway S1, and I have done one emergency downhill "avoid the bastard running the stop sign" evasion on my KS18S. So far, I've never been dropped. Ive fallen twice of my own fault, but never been dropped. Link to comment Share on other sites More sharing options...
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