dclash Posted June 22, 2018 Share Posted June 22, 2018 Hello! I started commuting to work in March on a Gotway MCM4-HS 340Wh which has a 800W nominal motor. I am considering upgrading to another Gotway but am not sure which model will solve my current problems. The hill is 0.4 miles long with an average grade of 15% and a maximum grade of 20%. The rest of my main commute is a flat 3.0 miles for a 6.8 mile round trip. Every trip that I make involves this hill. Down hill data points: 1. If the battery is charged to 100% then the wheel immediately hits the over-voltage warning (i.e. I have to walk). 2. If the battery is charged to 90% then the over-voltage warning occurs at about 9MPH. 3. If the battery is charged to 80% then the over-voltage warning does not occur at 15MPH. Up hill data points: 4. If the battery is charged to 90% before returning home then the up hill speed is approximately 9MPH before an under-voltage warning. 5. If the battery is not charged to 90% before returning home then the up hill speed is much slower before an under-voltage warning. Once I learned the limits, I now ride slow enough to avoid falling or damaging the wheel. I would like to avoid the over/under voltage warnings, not have to charge before returning home, and have a higher uphill/downhill speed. I made a spreadsheet so that I could compare my current wheel to others that I want to consider: VoltageCharge/cell 4.2 VoltageNominal/cell 3.6 Model Serial Parallel Ah/cell Current/cell VoltageCharge VoltageNominal Wh MotorPower MotorCurrent BatteryCurrent BatteryPower MCM4 340 16 2 2.9 8.0 67.2 57.6 334 800 13.9 16.0 921.6 MCM5 800 20 3 3.5 10.0 84.0 72.0 756 1500 20.8 30.0 2160.0 Tesla 1020 20 4 3.5 10.0 84.0 72.0 1008 1900 26.4 40.0 2880.0 ACMv2 1600 20 6 3.5 10.0 84.0 72.0 1512 1900 26.4 60.0 4320.0 Msuper V3S+ 20 6 3.5 10.0 84.0 72.0 1512 2000 27.8 60.0 4320.0 I suspect that the over/under voltage warnings are due to the fact that my current wheel is only 2P. The MCM5 800 is only 3P so I am worried that it might struggle with the hill as well. The Msuper V3S+ seems to provide the best margin at 6P. Does anyone have a similar data point for a 15% to 20% grade hill with these wheels? The attached image is from DarknessBot where I charged to 90%, slowly rode down the hill, waited for the voltage to stabilize, rode back up the hill, and waited for the voltage to stabilize. Link to comment Share on other sites More sharing options...
Marty Backe Posted June 22, 2018 Share Posted June 22, 2018 Very thorough - you win the prize for the most analytical approach to an EUC purchasing decision I can only speak to the practical aspect of your problem. Of course you won't be able to avoid the overvoltage problem at the beginning of your day. But simple undercharging will solve that. Key bit of missing data - what's your riding weight? All things being equal, the MCM5 will scream up that hill with no issues unless you start the ride at 20-percent battery. Obviously (to me) the other listed wheels will have no issues, but they probably won't 'scream' to the same extent of the MCM5. The nature of all 18-inch wheels will make the MSuper unpleasant to use for the uphill ride. The ACM2 and Tesla will have no difficulties. Assuming that your riding weight isn't 250-pounds, if you want the cheapest solution, go with the MCM5. If you have other needs, use those to establish the criteria for evaluating which of the other wheels would best fit your needs. They will all work for you without requiring any walking. Link to comment Share on other sites More sharing options...
dclash Posted June 23, 2018 Author Share Posted June 23, 2018 I had a feeling that I forgot something 175lb with protective gear and laptop backpack. I went too inexpensive on the first wheel so I do not want to make that mistake again. If I could ride the hill at 15 to 20 MPH then fewer cars would pass me and I would feel safer. Standard bicycle speed/power calculators using nominal numbers predicted that the MCM4 would reach about 9MPH which matches my GPS measurement. Those calculators predict 16MPH for the MCM5 and 19MPH for the others. When you say that the MCM5 will scream, do you mean that it might have a higher uphill speed? > The nature of all 18-inch wheels will make the MSuper unpleasant to use for the uphill ride. Could you explain what you mean by unpleasant? I was starting to think that the MSuper would be a good choice since I would not have to second guess on the battery again. The 14 inch MCM4 bounces a lot on uneven concrete on other parts of my commute so I thought an 18 inch wheel might help with that aspect. The MCM4 feels small for my leg length at times so I thought the height of the Tesla or MSuper would help in that area. Link to comment Share on other sites More sharing options...
Marty Backe Posted June 23, 2018 Share Posted June 23, 2018 2 hours ago, dclash said: I had a feeling that I forgot something 175lb with protective gear and laptop backpack. I went too inexpensive on the first wheel so I do not want to make that mistake again. If I could ride the hill at 15 to 20 MPH then fewer cars would pass me and I would feel safer. Standard bicycle speed/power calculators using nominal numbers predicted that the MCM4 would reach about 9MPH which matches my GPS measurement. Those calculators predict 16MPH for the MCM5 and 19MPH for the others. When you say that the MCM5 will scream, do you mean that it might have a higher uphill speed? > The nature of all 18-inch wheels will make the MSuper unpleasant to use for the uphill ride. Could you explain what you mean by unpleasant? I was starting to think that the MSuper would be a good choice since I would not have to second guess on the battery again. The 14 inch MCM4 bounces a lot on uneven concrete on other parts of my commute so I thought an 18 inch wheel might help with that aspect. The MCM4 feels small for my leg length at times so I thought the height of the Tesla or MSuper would help in that area. Yeah, "screams" means fast. Did you happen to see my MCM5 Mountain Stress Test video? The larger diameter wheels require more lean when climbing steepish hills. This means you'll generally be squeezing the sides of the wheel to get enough leverage to force the wheel uphill at a faster speed. This can be tiring on the legs. "Unpleasant". I'm just about exactly your same riding weight. All the wheels that you listed (I own them all) can do what you want. So I'm going to tell you that my favorite all-around wheel is the ACM2. Better electronics, more powerful motor, tough axle, etc. With the battery you will never have undervoltage issues. It has seemingly endless battery reserves and is very powerful. You may want to try different wheels for variety buy you will never outgrow the ACM2. The MSuper, having the same basic motor and battery, will feel less powerful than the ACM2 because of the larger diameter wheel. Yes, the 18-inch wheel will be more comfy on the road, but the larger diameter wheels are just not ideal hill climbers. I prefer the ACM2 over the Tesla because of the greater versatility. But if you're certain that you don't want the added range, the Tesla will certainly work too. Due to it's lighter weight and different drive electronics, it's more sprightly than the ACM2. All of the above is one mans opinion - mine Maybe others to can offer a counterpoint for you to consider. Link to comment Share on other sites More sharing options...
Arbolest Posted June 23, 2018 Share Posted June 23, 2018 1 hour ago, Marty Backe said: The larger diameter wheels require more lean when climbing steepish hills. This means you'll generally be squeezing the sides of the wheel go get enough leverage to force the wheel uphill at a faster speed. This can be tiring on the legs. "Unpleasant". ... The MSuper, having the same basic motor and battery, will feel less powerful than the ACM2 because of the larger diameter wheel. Yes, the 18-inch wheel will be more comfy on the road, but the larger diameter wheels are just not ideal hill climbers. I tend to agree with @Marty Backe on this one. The new MSupers (Teslarized and X) are wickedly fast/powerful and will be nothing but a treat to ride for most of your commute, but for most of your uphill journey you're going to either be leaning forward an uncomfortable amount, or gripping the side-pads and torquing the wheel forwards a bit. Like Marty said, that's just the nature of the larger wheels -- because of the distance of the pedals from the center of the wheel, you have less torque you can apply and therefore have to work a bit harder, and this is felt particularly strongly when you're going uphill and have to keep your center of mass farther forward just to stay upright, much less move forward... Link to comment Share on other sites More sharing options...
Keith Posted June 23, 2018 Share Posted June 23, 2018 9 hours ago, dclash said: If the battery is not charged to 90% before returning home then the up hill speed is much slower before an under-voltage warning. Welcome to the forum. I have to second @Marty Backe‘s comment that this is the best analysis of what wheel to buy I have ever seen as well. Do have a watch of Marty’s hill climb videos: https://www.youtube.com/channel/UCQeDQAr2JgTSSujXThdlWxg As actually seeing them in action might help you to decide. Finally, whilst you are still using your current wheel, why not charge it at work to 100%. A 340Wh wheel ought to easily make a 6.8 mike round trip OK if the hill is around the 3 mile mark and it will be low enough on the return leg to work to not over charge going down. You won’t need to worry about charging to less than 100% if you start drawing power within a few hours of charging it - especially if you are going to be replacing it soon anyway. Link to comment Share on other sites More sharing options...
The Fat Unicyclist Posted June 23, 2018 Share Posted June 23, 2018 15 minutes ago, Keith said: Finally, whilst you are still using your current wheel, why not charge it at work to 100% That's exactly what I do... My commute (home to work) is 1 km down a steep hill, followed by 3 km across the valley floor. With a loaded weight of over 250 lb (I pack big lunches) and a 340 Wh battery. So when I get to work (and after my batteries have rested) I charge to 100% . Then I ride home (and do not charge). Then to work again (regenerating power on the downhill). And (for me at least) that makes it truly free energy too! As a side comment, with more or less the same conditions, my uphill trip home uses 2.5 times the power of my regenerative downhill trip to work... Link to comment Share on other sites More sharing options...
meepmeepmayer Posted June 23, 2018 Share Posted June 23, 2018 20mph on a 15% average upwards incline... woot, that going to HEAT the wheel!! I'd get a Kingsong 18L for that, or the msuper X, due to their better electronics (KS is better anyways, and the msX and 100V Monster have the new GW boards, not sure about the MCM5). If you really want to go that fast uphill, it's not only about how many P you have, but the electronics. Honestly, that's pushing it a bit about what one should and should not do with current wheels, though 0.4 miles (600m) will be ok (you'd really have to start thinking if it was 1 mile or so). If you go for more normal speeds uphill (25km/h = 15mph or less), any of these current wheels will easily do (4P still can't hurt, I guess, or maybe it does not matter). So as you want to go fast uphills/have reserves there (which is the biggest limiting factor here), I'd say msuper X or 18L. Get all the ooomp you can. -- Tiny correction: the msuper V3(s+) has a 1500W motor, they upgraded it to the 1900W Tesla motor, and the msuper X is the one with the 2000W motor. 12 hours ago, Marty Backe said: All the wheels that you listed (I own them all) can do what you want. Must feel nice to be able to casually throw that around "Oh yea, I have all of these wheels lol" Link to comment Share on other sites More sharing options...
WARPed1701D Posted June 23, 2018 Share Posted June 23, 2018 Another reason to consider the 18S is the seat. Many people say they can get much more leverage on the wheel for uphill climbs and acceleration when seated. Link to comment Share on other sites More sharing options...
meepmeepmayer Posted June 23, 2018 Share Posted June 23, 2018 Ooops, I meant to write 18L, not sure how much difference there is between the electronics between the newer 18L and the 18S. But you make a good point with the 18S. It's the secret commuting champion. Link to comment Share on other sites More sharing options...
WARPed1701D Posted June 23, 2018 Share Posted June 23, 2018 4 minutes ago, meepmeepmayer said: Ooops, I meant to write 18L, not sure how much difference there is between the electronics between the newer 18L and the 18S. But you make a good point with the 18S. It's the secret commuting champion. I'm hoping the 18S shell gets the L's motor and board upgrades. Not sure how the body will handle the 84v battery configuration though. Link to comment Share on other sites More sharing options...
Marty Backe Posted June 23, 2018 Share Posted June 23, 2018 1 hour ago, meepmeepmayer said: <snip> Must feel nice to be able to casually throw that around "Oh yea, I have all of these wheels lol" I only threw that statement in there to add a little authority to what I was saying, that all the wheels would work from personal experience Link to comment Share on other sites More sharing options...
mrelwood Posted June 24, 2018 Share Posted June 24, 2018 On 6/23/2018 at 2:15 AM, dclash said: The MCM5 800 is only 3P so I am worried that it might struggle with the hill as well. I don’t think you need to worry that much about the amount of parallel cells in the battery. Simply a hefty amount of Wh capacity will do the trick for you. You know, 340Wh is nothing today, it’s when a battery is almost empty... Regarding the planning, these guys are right, you have done excellent groundwork! And about the models you consider (I’ve seen Marty ride them all), my preference would easily be the Msuper (X), but the hill resistance of an 18” is going to be quite pronounced since you ride that long, steep uphill every single day. I’d choose a 16”, as to me all 14” wheels are too unstable and bump-intolerant. Link to comment Share on other sites More sharing options...
WARPed1701D Posted June 24, 2018 Share Posted June 24, 2018 10 hours ago, mrelwood said: I don’t think you need to worry that much about the amount of parallel cells in the battery. Simply a hefty amount of Wh capacity will do the trick for you. You know, 340Wh is nothing today, it’s when a battery is almost empty... The two are related. You can't add more Wh without adding more parallel packs or increasing voltage. A larger battery will be able to absorb much more overcharge current from regeneration breaking and more parallel packs will mean each parallel pack will be under less stress during both current draw and supply. With the larger battery pack you could also charge to a much lower % and operate in a smaller % range overall. This allows plenty of headroom in both directions for voltage drop going up the hill and regen going down. Personally I think a 16" wheel with at least a 4P battery system and a >1500W motor is the best option for the OP. If Inmotion get their firmware issues resolved then the V10 would be a good option otherwise if feeling brave and wanting to risk a Gotway the new ACM would work nicely. Apart from the 18S in seated mode I don't think Gotway has a good offering for this use case right now. The 16S at 1200W would likely struggle to maintain a good speed going up. Link to comment Share on other sites More sharing options...
dclash Posted June 25, 2018 Author Share Posted June 25, 2018 Thank you for all of the feedback. I was surprised that the 18 inch wheels are that much harder to ride uphill. I will watch a few of Marty’s videos now that I know what to look for. I was impressed that the MCM4 was able to do as well as it did. This hill is part of a race here that has 13 of the steepest hills in the city: https://en.m.wikipedia.org/wiki/Dirty_Dozen_(bicycle_competition) I will try Canton St after I upgrade Link to comment Share on other sites More sharing options...
Jerome Posted June 25, 2018 Share Posted June 25, 2018 41 minutes ago, dclash said: Thank you for all of the feedback. I was surprised that the 18 inch wheels are that much harder to ride uphill. I will watch a few of Marty’s videos now that I know what to look for. I was impressed that the MCM4 was able to do as well as it did. This hill is part of a race here that has 13 of the steepest hills in the city: https://en.m.wikipedia.org/wiki/Dirty_Dozen_(bicycle_competition) I will try Canton St after I upgrade god bless you and good luck! Link to comment Share on other sites More sharing options...
meepmeepmayer Posted June 25, 2018 Share Posted June 25, 2018 Dude, be careful. You want to ride the country's (world's) steepest street on a euc? It's very likely going to work because it is only short, but be aware you can literally fry your electronics this way (constant longer extreme incline). Then you fall on your face and have a heavyweight and broken wheel to carry somewhere. You can NOT 100% expect current wheels to "work or warn" (that is, push them into any situation and expect either a warning or the wheel to do what you want without problem), at least I don't think so yet. Not sure. Here's an example with an older wheel: I know how exciting it is to push your wheel into crazy inclines (that's how I fried mine, also an older 1st revision ACM, with the thinnest cables, 8 minutes up an uninterrupted 15-20% grade), and I'm not saying there will be a problem, especially with these short steep climbs and the latest wheels. Just be aware that this is (was?) a thing and don't overdo it. These short city hills can hardly become a problem, but there's no 100% guarantee. Link to comment Share on other sites More sharing options...
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