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[LiveandLetDrive]

The highway overheating (when maintaining >80mph for >10 miles) is a mild nuisance and probably needs some real aero work to design a good duct for better cooling with the current motor design.  However I spent this last long weekend in Mendocino National Forest doing some serious off-road riding and for the first time ran into motor overheating off-road.  It only happened on very extended, non-stop hill climbing  (valley to mountain top).  On the highway I've depleted a significant majority of my battery before it overheats but in the hillclimb case I've only used maybe 25% before I get torque limited to the point I can't make it up the next climb and to me that means it is a significant functional limit.  That being said, it seems like the low-speed hillclimb case could easily be improved by, most simply, strapping on a couple 12V computer case fans and wiring them into the bike's 12V system (or having a removable plug run to my power outlet.)  It gets dirty down there so I might try to find something more weatherproof but I thought it was worth a shot with the ones I already have lying around.

Has anyone else taken any steps to deal with overheating?

[Richard230]

It is too bad that there isn't enough room to install a fan next to the motor belt pulley.  You could probably cobble together a plastic ducting system that would deal with cooling at high speeds, but overheating at slow speeds would likely require a fan of some sort.  I would think that computer fans wouldn't blow enough air to be very effective.     There are likely plenty of other cheap 12V DC electric motor options that could be found to power a fan from the 12V accessory outlet.

[BrianTRice@gmail.com]

For what it's worth (people reading this forum who are prospective buyers), overheating is not nearly as much of an issue in the Pacific Northwest as in California and the Southwest. We're more interested in heated gear right now, really.

[NoiseBoy]

Are you sure its the motor? General consensus is that the controller reaches thermal limit first.  That would be a lot easier to cool with fans so worth a try.

[DesignerDan]

Are you sure its the motor? General consensus is that the controller reaches thermal limit first.  That would be a lot easier to cool with fans so worth a try.

I keep seeing people say this on this forum but from my personal expirence this is completely false. My motor controller NEVER gets "hot". Even after a long strecht of highway speed when it's 90 degrees here in Florida, that thing is still only stilghtly above ambient temperature. It's designed exceptionally well.

The motor is definitely the thermal limit. It always always always runs much hotter than the motor controller.

I too think liquid cooling would be a great way to make the bike less susptible to the motor running too hot. The Tesla model S motor only weighs 90 lbs and puts out 400 horse power. This could not have been done without liquid cooling.

I do however respect Zeros philosophy of simplicity. The is less that can go wrong with air cooling and it's probably easier/cheaper to make.

[LiveandLetDrive]

I used to have motor, controller, and battery temps showing on the app but I eventually whittled it down to the motor as the others never reached any significant temp.  (I'm on an FX, could vary by bike.)  I didn't have the phone on when I was hillclimbing but I'd be surprised if it was suddenly another component.

As for cool temps, the difference between 30F and 70F isn't much compared to the ~230F limit, it might buy you some time but not a lot.  Mostly mornings these days I'm riding in at ~50F.  I am concerned I'll hit the limit even faster once it's 80F+ this summer!

It cools down pretty quickly when you keep the power off for a moment, so I think even a smallish amount of airflow could make a significant difference.  Also I already have about a dozen computer fans from 60mm to 120mm lying around so I might as well give them a shot!  Unfortunately the mega-hills are far from home so I can really only test the highway overheating.  I have some pretty extreme roads (CA-130 up Mt. Hamilton to Lick Observatory) in my backyard but temp has never been a problem there, probably because speeds are higher and power isn't quite as constant.  I have been to Hollister OHV area yet, maybe there are some continuous climbs there but probably not Mendocino Ntnl Forest level.

Indeed liquid cooling makes all the difference for these edge cases, and keeps things more evenly cooled which is good for longevity.  Not so easy to add to an existing finned case though, and I am riding the line close enough with my warranty I don't need to be disassembling the motor!

[Marshm]

I have had issues with liquid cooled bikes on offroad hill climbs.  In 1st or 2nd gear the speeds are low, and winding thru the trees not much cross wind.  When I stopped I was spewing coolant out the overflow so I dumped my water bottle on it, which cooled it down to stop the overflow.  I thought it might crack the aluminum radiator but it didn't.  I think a fan is needed for the radiator because offroad can be so slow yet my rpm was way high.  I sometimes wind it up in 1st gear to reduce risk of stalling because the hill is not just a smooth straight line.  I turn a blind corner around a tree and I see a 1 foot tall vertical step in front of me.  You have to react quickly.  No place to let off throttle or you may slow down and get stuck.  Once you stop on a hill like that, you may never get going again. 

With my example above, how do you think an electric bike would work.  With the FX, the rpm would be low going slow due to direct drive.  However, the steep hill might require a lot of throttle?  Were your hills climbs fast or 1st gear type of slow stuff?  Airflow in my example is very poor.  For gas bikes, the water cooled bikes let you know they are hot, but the air cooled ones do not.  I suspect the air cooled bike is really hot also, but just no liquid to overflow. 

[LiveandLetDrive]

This climb was nearly 10 miles of continuous uphill, mixed between ridgeline steady climbing and very steep technical hillclimbs of the sort that if you lost momentum you're out of luck.  I've found that electric makes these significantly easier as as long as you don't lose traction entirely you can just give it the necessary throttle and it just goes.  No stalling or lugging or wrong gears obviously, just point and shoot.  On the bad side that encouraged the bad habit of plodding up extremely steep climbs quite slowly which meant high torque and low airflow.  So some technique improvement would help but that's only the difference between 5mph and 10mph, it's still going to be low airflow.

Yeah, that is when air-cooled bikes start warping, and a good time to have a temp sensor!


I've been on the dirt less than 10 times and the guys I was riding with more like 20 years, so I wasn't exactly keeping up but they all enjoyed the FX when they tried it out though they were less impressed with my overheating and having to head back before they were out of gas!  Even in that extreme terrain I got a half day out of the packs (and had a second set to swap in), so I found that to be okay.



I've been to the mountain top:


Back home with the supermoto setup back on:

[trikester]

I'm surprised by this. All of my Klamath Forest rides are from 4300' climbs to 5300' climbs and I've done them on my 2012 DS and my 2013 FX and never had the motor overheat. These are pretty much steady climbs with some steep pitches thrown in and steep switchbacks. Air temp in the 60 to 70 degree range.

My moving averages (from GPS) are from about 14 mph to 17 mph for the entire rides which includes the downhill back to the start so the uphill ave would be slower than those.

I wonder what the difference is?

Next June I will climb Pike's Peak on the trike (at an easy pace) and it will be interesting to watch my motor temp. The motor on the trike appears to run cooler than on my FX (same motor). When I was building the trike I wondered if it would cool better or worse than the bike. It seems to be better. The controller may be in worse shape because the air goes more cross wise on the fins than on the FX.

Trikester

[WindRider]

I live at the end of a 1,000 foot climb up 2 1/2 miles of steep dirt road.   Air and liquid cooled motorcycles, and my old Jeep Cherokee, all heat up on this climb in the summer when ambient temps are 80 -100 deg F. 

My ZeroDS did not seem to be bothered at all by this and the temp light never came on during the climb even at temps above 100 degrees F.  I suspect my FX will be OK as well this summer. 

The motor heating is probably driven by time of the climb, amount of current going through the motor, and air flow.   I suspect that LieAndLetDrive had a throttle position closer to WOT than I do on my commute home.   

I have found the cooling on Zero motorcycles to always be sufficient for my riding style and demands and generally better than air and water cooled bikes in the same circumstances.   On hot days in traffic it is really nice to ride a Zero as there is no heat thrown on the rider at idle. 

[LiveandLetDrive]

trikester,

These climbs were similar, from 1600' camp to around 5000' peaks.  We started from the valley in the center of this map up to the surrounding peaks.

https://www.google.com/maps/@39.3396092,-122.6557539,13z/data=!5m1!1e4

Unlike the roads shown, the trails took quite direct routes!  It may have been some combination of the trails themselves being steeper than yours on average perhaps, more sustained riding as there were no breaks from start to top, faster pace as I was trying to keep up with some quite skilled and aggressive riders on capable bikes, or maybe the short but steep climbs were more intense and high-torque.  The steep sections were severe enough to require getting right up on the bars and modulating the throttle to keep from lifting the front wheel and falling a long way off the back.  Or could be your motor gets better airflow.

Regardless it took quite the extreme circumstance to create this kind of overheating but if I can stick a fan on it and expand the envelope a bit, I'm all for it.  I actually accidentally rode to work today with a 120mm computer fan sitting loose in the gap between the motor and my right foot!  Didn't bounce out somehow.

[trikester]

Yeah, the difference could have been any of those things or combinations. My guess would be for the riding speed to be the main difference, since I was just cruising up the hills. Also I did have some very steep pitches but none so steep that I had to lean far over the bars. However, I used to mountain bike these areas and I was never able to climb those same steep ones, even though I had a very low "granny gear".

I'm betting on the climbing speed being the main difference in the heating of our motors. When I'm at Pike's Peak, and I cruise up on my trike, I know for a fact that my motor will be way cooler than the guys who are racing. 

Trikester