Speed Limitations

[Bmac4007]

First time poster, long time reader. Trying to learn all I can as I try to figure out my first purchase. Because of the price and the generally positive comments I have read, I’m really thinking about the RadCity. I have seen comments that once you hit 20 (maybe it’s 25) mph, the bike brakes itself, even on a downhill. My question is whether or not this is how all bikes work? It seems like that would be the case but I don’t want to make assumptions. Thanks for any feedback.

 

[6zfshdb]

I'm not aware of any ebike that applies brakes when it hits max speed. The motor controller on most ebikes simply cuts off power to the motor when the programmed limit is reached. You can pedal the bike faster if you provide enough force or coast down hill.

BTW, welcome to the forum! You've come to the right place to ask questions.

 

[Bmac4007]

Thanks for the response and the info. Makes sense. The motor cutting off is not unique to the RadCity or the Rad brand, correct?

 

[AHicks]

Good question!
First, you need to understand that all production e-bikes will have an upper speed limit imposed on them that's handled electronically. In the US, some are limited to 20mph, while others (Class 3 bikes) are limited to 28 mph.

Then, you need to factor in the fact that the Rad City has a direct drive rear hub motor. These direct drive motors are able to use a feature called "regen" that works a lot like engine braking in a car or truck while driving in BIG hills. It's not going to stop you, but it can create drag, enough where it can help control your speed.

In your down hill scenario, the power to the motor was cut off at about 20 mph electronically. If the hill is big enough, the bike will continue to build speed even with no power. That's when the "regen" comes into play, it's turned on electronically, in an attempt to prevent the bike from building so much speed that it becomes dangerous.

Not all bikes can do that. If you look at the Rad Rover for instance, it's powered by a gear driven rear hub (this vs. the City's direct drive rear hub). These use an internal clutch that allows them to free wheel while coasting. Because of that, there is no way for "regen" to work. Mid drive bikes are not able to use the regen feature as well.

So to answer your "cutting off" question, it's about the type drive system the bike is equipped with first. Then, it's about the features programmed into the bike's controller. So though this feature is not unique to the Rad City, not all bikes will do or are able to do this.

 

[Browneye]

See if you can find a local demo for RadPower bikes - they are setting them up around the country. RadPower is enjoying good success and have a reasonably good reputation - but you're kind of on your own if you have them ship you one instead of buying a bike from your local bike shop.

Some good friends got a pair of them - a city and a rover, and they like them just fine, had them just a short time. I have not gotten to try the direct-drive hub on the city - would be interesting to compare it to the geared hub we have on wife's bike, which works very well BTW - effortless riding, good range, very quiet. I may have that opportunity this weekend, will post back if so, and get some more feedback comment from them as well.

 

[GregGritton]

Good question!
In your down hill scenario, the power to the motor was cut off at about 20 mph electronically. If the hill is big enough, the bike will continue to build speed even with no power. That's when the "regen" comes into play, it's turned on electronically, in an attempt to prevent the bike from building so much speed that it becomes dangerous.

The "regen" should only be turned on when you apply the brakes. However, even when regen is turned off, direct-drive motors are always connected to the wheel and thus will always have some drag. This drag works against you as you go faster, but is smaller than the drag experienced when "regen" is actually activated by the brakes.

 

[AHicks]

Though I would tend to agree with you at lower speeds, I think at higher speeds, say those of around 25mph where motor power has been cut off, regen may be applied regardless of the brakes being on or off. Several have reported that to be the case with their Rad City bikes.

I have an'18 Rad City, and though I did have occasion to use the regen feature by partial brake application, I never had it going fast enough to see what happened going down really big hills that would have me going fast enough where it might come on by itself.

Today, my City still looks like a City, but about all that is still OEM is the frame and the front wheel. Everything else has been changed, at least once! -Al

Edit: This thought regarding the regen coming on by itself at higher speeds, applies to the Rad product only.

 

[Bmac4007]

Appreciate the responses and patience with my lack of knowledge! I’ll get there.

 

[AHicks]

I thought it was a good question because it covered so much country. If there's something you don't get, don't be shy, ask away!

 

[Browneye]

Ah...got to ride the RadCity today, and a RadRover - both are very nice bikes.
For me personally, I don't care for 'fat bikes', they just seem over the top to me. And they are very bulky and like riding a freight train.
The City, much more refined, has 2.3 tires so surely not 'skinny', and while the direct drive hub isn't what I would call 'snappy', oh my it is SOOO smooth. And plenty fast.
I don't know if it would be any speed demon up hills, but as a commuter/city urban casual bicycle I think it's a hit. Very nicely done. A lot of nice features, the half-twist throttle I liked better than I thought I would, it's comfortable, the ride is great. I would buy one for the wife in a heartbeat.

For me the Giant is still my first choice so far, very happy with it. It's much lighter than all of them, the assist more well integrated, but it's a class 1 so it's limited to 25kph, and it's quite a bit more money than the others.

So our friends that got a pair of RadPower bikes - also got their friends to buy a pair, so there were six of us on a 12 mile loop today, we had a ball.
Three of them were RadRover bikes, the City, wife's Roll, and my Giant. Once you get those RadRovers going they haul ass pretty darn good.

I was favorably impressed with the RadCity. I would buy one myself. It's a veritable bargain, and now $1299.
BTW, they got $250 off for two with the demo discount coupon. Going to find a demo depot rental place and try them out is a great introduction and a helluva savings.

EDIT: I had a hard time telling what size wheels the City had, actually had to look up the spec. They look like 700c or 28" wheels, but they're 26's, with 2.3" width. And likely lends to the price point. IMO it's a perfect bike for a lady, just slightly limited for a man - the latter I think belongs on 700c wheels, depending on their size and height. JMHO

 

[AHicks]

Browneye,
Not going to say that some won't be able to make a good case for them, but agree with you on the whole fat tire thing. They don't do much for you regarding battery charge range either.

Regarding the "City" wheel size, I bought it because it was on 26" wheels, and love it for that reason. So to your thought regarding 26" being appropriate for size and height, I would add "age". With the seat set at the correct height, this 6'2" old man has a much easier time getting on and off this bike. I sold a nice 29'er conversion I had done for just that reason! It was comfortable while I was on it, but geez, getting on and off, especially on uneven ground, left me anxious when having to stop.

When dealing with hills and heavier riders, the City would be a REALLY great bike with a gear driven rear hub option. At that point you would have a serious home run....

 

[Bmac4007]

I bought the RadCity 19” for me and the white step through for my wife. Put them together with really no problems and I am no bike mechanic. I live in the Louisville metro area so it was chilly last night but we had to test them. My wife went along with my idea for the purchase but I know she was skeptical.
She is a skeptic no longer. We had a blast and can’t wait to ride again. I did notice that on my bike, the front wheel does not spin as freely as on her bike. I assume the brake is rubbing? When riding there was a definite high pitch sound from the front. I looked at the web site and it talks about a break in period if the wheel spins freely but I did not find any info on what to do if it does not. I emailed them and will look again today when I have more time. Any thoughts are appreciated.

 

[Browneye]

Your pads may well need to be adjusted. They should not rub on the disc. Easy fix.

This vid may be just what you need...

Here's the one for hydraulic discs: