microslice

My wife has a Giant E+1 e-bike. It's supposed to assist up to 28MPH. She was complaining that is was cutting out at 25MPH, so I rode it and verified that's the case.

Anyone else see the same with their Giant E+1 or E+1 Pro?

Buglady

Have you taken it to the shop to make sure there isn't a software or sensor issue? Giant uses a proprietary system, and my shop isn't a Giant retailer so I don't have all the technical details on it, but both Bosch and Shimano STePS pedal assist systems (in which I am certified) have fail-safes in their software that can restrict the assisted speed in the case of software errors or sensors not quite lining up. (Basically, if the system gets inconsistent sensor data, it throttles back to be on the safe side).

A quick update should fix any software glitches, and verify that the speed and torque sensors are both correct.

AnthonyG

It may depend on local legislation. In Australia the law has assist cutting out at 15mph. An e-bike that goes to 20mph is pretty quick and flirting with the law.
25mph is WAY quick for an e-bike.

2old

In many US states, e-bikes are permitted to achieve 28 mph (PAS-only) and still be classified as a bicycle; it's called Class 3, and only allowed on bike lanes contiguous with a road (this is a brief description of Class 3).

microslice

Thanks. I will take it into the shop today and have them update the software.

microslice

28 MPH is legal on non-bike paths. In my opinion, 20 MPH is WAY too slow. I can ride faster than that on my normal bike.

When there is a tailwind I often go over 25 MPH. This is when my wife gets dropped because her bike it not assisting her above 25 MPH. Makes her grumpy :-)

Buglady

So can I... but not uphill, or with a headwind, or with a load of groceries, or when I am having a pain flare, or if I haven't slept well... which is why I bought an e-bike. It's not about how fast you can go, it's what works every day.

microslice

For me, it's about being able to ride with my wife under all conditions and all rides. When there is a tailwind, a slight downhill, or just a fast group ride, 25 MPH is not enough. But 28 MPH is enough under almost all conditions except maybe really strong tailwinds. But that is pretty rare.

I took the bike into the shop and they believe that the motor pulls back on it's assist once it reaches 25 MPH and then completely cuts out at 28 MPH. I hope that's not the case (or that it's configurable).

Todd.

AnthonyG

Well hopefully you can sort it out to work for you yet let me suggest for the record or for the future that if people really want something fast and configurable that they retrofit a Bafang centre drive motor setup rather than an off the shelf bike.
It may not look as neat or professional yet even the base model is configurable from 250 watt all the way to 750-1000 watt depending on what voltage its set to work with. Run it at 52 volt for max performance.

fly135

It might be that the motor doesn't have enough power to go faster. I have a 500W hub drive that unlocked to 28 will only go about 24mph with you pedaling before it runs out of steam.

Buglady

The Bosch and Shimano systems do this, sort of gradually tapering off the amount of assistance as your speed approaches the cutoff, but the way you were describing it didn't sound like that. The motor shouldn't be cutting out entirely. Sometimes you have to shift up or down to find a gear where the assistance is smooth, though.

rm -rf

The local bikeshare e-bikes cut off sharply at 15-16 mph. That's perfect for a bike share, where a lot of riders aren't too experienced.

It has a 3-speed twist shift. The pedal assist is strictly based on cadence, once the rider reaches a spinning cadence, the boost is reduced close to zero. It has full power from the first pedal stroke, so lots of assist at slow speeds. It has a good assist at 14-15 mph, then almost nothing over 16 mph. It's a sharp cutoff.

(I naturally shifted from high gear back to medium or low on a hill climb, but that fast cadence reduced my assist to a minimal amount. Hey! High gear on the climb worked better.)

Perhaps your e-bike is based on cadence? Does the assist cut off if you are in a low spinning gear at a moderate speed? If so, perhaps you need a higher top gear to go faster.

For most riders, I think a 25 mph assist cutoff is reasonable, though.

microslice

That's what we found out. The assist isn't completely dropping off, but unless you're in a gear where you can apply a certain amount of torque, the assistance isn't smooth and it feels like it's cutting out completely.

So....my wife will need to figure out what that cadence/torque value is once she gets above 25 MPH :-)

Leisesturm

I'd love to know where this kind of thinking comes from. What is unreasonable is to think that a speed of 25mph or more is any big deal and should be attained without assist. Assist is needed (by most) at only two extremes of the typical bicycle performance envelope: 1. Grinding up a steep hill OR 2. Sustained speeds above ~15mph on level ground where wind resistance imposes a steep challenge to further acceleration. You would think that severely speed limited (~5mph) e-assists with loads of low end torque suitable ONLY for getting a loaded bicycle and rider up very steep hills and nothing else would become the dominant implementation of e-bike technology. Is it? Nope. To be a practical car replacement (hint: you should want that!) an e-bike should be fast. Unlike Europe America has suburbs. 3 miles is a LONG commute for a Dutch rider. 20 miles (each way) is not an unheard of distance for American bike commuters. Class 3 e-bikes exist because there is a need for them here. In fact, Class 1 e-bikes aren't sold just to get people up hills, they are sold to get them up to 20mph and keep them there for as long as the battery holds out. Even Class 2 throttle systems tout the top end speed (20mph) and not simply how much weight the system can lift. Americans pushed for insane Class 3 top speed of 28mph because when all is said and done, 28mph isn't really all that fast when you have lots of miles to cover. Thinking that it is, and/or that it needs 2 tons (or much more) of metal shielding to be safe at that speed MUST change or we are doomed to a quick death from the degrading effects on everything of the billions of cars we have running around with just one person in them.

Leisesturm

I am researching the Giant and Raleigh e-bikes in particular for a possible purchase soon. Which E+ bike does your wife have? They don't all go to 28mph. They are all in Class 3 which has a top speed limit of 28mph and the e-bike companies have been quietly using the confusion to sell bikes because it takes quite a lot of work to get to 25mph and most people are so scared of even that speed that they don't try to go any faster.

There is an upper cadence limit of 90 to 100 to 120 rpms and it varies by model and motor system. Torque really isn't a factor at those kinds of speeds. Absolutely, the gear matters but again, at those speeds the only gear to be thinking about is the top gear. Period. The model I am thinking about is the Quick E+ and it has a cadence limit of 90rpm and a 42T x 11T top gear. I haven't done the math but if that works out to 28mph (it should) there you are. The Raleigh Redux IE has exactly the same gearing but its motor (Bosch) has a 120 rpm cadence limit. It 'might' be possible to drop down one gear and spin a little faster to hit 28mph and still have assist but its more likely that the rider was already in top gear back at 25mph. FWIW.

Buglady

My experience with a class 1 e-bike (assistance up to 32 km/hr; 20 mph) is that it is plenty fast enough for in-city commuting and errands - and I am not a novice rider afraid of speed! I used to be a roadie who happily took descents at 70km/hr... and I still bomb down the 17th Ave hill at the legal limit of 50km/hr when I am late for work


I have a bike with Bosch mid-drive and my usual cadence is around 80. I spin faster on a road bike, but the geometry of my e-bike is better suited to a touring cadence - it can get a bit bouncy. Bosch designs their systems to be pedaled at 70-90 revolutions per minute, faster than some novice riders may be used to, but nowhere near performance road cadence.


The e-assist isn't helping me ride faster than I used to. It's making it possible for me to ride *consistently,* without exhausting myself, and I am enjoying my rides again. I think that is what a lot of people are getting from pedal-assist e-bikes - a removal of barriers and a sense of enjoyment even if their physical ability isn't what it used to be (or might be on the future).

spartan_262

no, that is not why.

the reason is becuase ebike motors have peak power at 80% of their RPM range. so at 24mph your 500w motor is putting out 500w, but at 28mph its doing only 200w, and at 30mph its at 20w ( basically zero )
as seen on ebike motor simulator.com

also, i have ridden my ebike with a watt meter attaches and i have confirms this.

Leisesturm

You are wrong as well. If you were correct 350W e-bikes could never achieve 28mph but of course many do. In any case, the behavior you describe is NOT true of mid-drive (the o.p.'s bike is a mid-drive)systems because the gear train can lower the torque peak as needed to keep road speed high. Starting at about 12mph and increasing exponentially with added velocity, wind resistance becomes a huge energy sink. Hub motors that do not have gear reductions are doing all they can to keep a bike moving at 28mph. It absolutely is not because they have passed their torque peak and their power output diminishes. Given all that wind resistance if the power were to fall off even a little bit so would the speed and all those scofflaw e-bikes zipping around at 30+ mph that are the bane of BF'ers existence would not be possible. What is true is that at 30mph even an unlocked e-motor simply cannot overcome the wind resistance of any faster speed. Add a bit of downgrade to help the bike out a bit and even a 500W motor might be good for another 5mph. A 750W might even get to 40mph.

spartan_262

i have ridden my ebike with a watt meter attached to my esc and i have confirmed that wattage tappers off from a max of 500w at about 40kmhr. Down to about only 150w at 45kmhr . And at 50kmhr downhill the esc is pulling only 30w,so bassically zero.

to further support my claim, just go to ebike motor simulator.com and u can clearly see ALL ebike motors behave about the same.

Leisesturm

There is a big difference between the cutoff of assist from the motor reaching the legal limit restriction and the decrease in power from a motor reaching the end of its torque curve! You are describing restricted (by law) motors. I am talking about unrestricted motors. The e-bike simulator cannot show you power curves that you cannot legally recreate.

spartan_262

Yet Op is talking about just that......restricted motor. Why u even bring up non restricted motor? Jezz man......

28mph is restriction at full battery voltage.
half voltage or voltage under load would be 25ish mph as to be excpected.

fly135

OK, that is weird. First you tell me I'm wrong. Then you go on to describe why I'm right. LOL! I claimed the motor ran out of steam at 24mph and you claim the motor output drops off above 24mph. Same difference except you were more specific about how it runs out of steam.

Unless of course you were thinking I literally meant "steam".