Rear hub vs mid drive

Deacon Blues

Well-Known Member
Also what is it like to ride an ebike with a Gmac powering it because of the regeneration?

I didn't notice the regen on the HillEaster until I was coasting down a steep hill. I wasn't going anywhere near as fast as I thought I should be going and thought the brakes were sticking. After talking to the shop owner, who was along for the test ride, I realized it was the regen in action.
With the GMAC motor there is always a bit of power consumed to cancel out the drag from the regen.
 

AHicks

Well-Known Member
Timpo, regarding the battery, the stock RAD is good enough for MY needs! I'm not building this bike to be the ultimate, best available, or to set a new land speed record. It's way more about FUNCTIONAL, meeting my needs. I ride for sport. Would I like to have a 52 volt? Sure! Do I need it? Nope..... Nor do I need more Ah. A 20 mile ride is about all I'm good for (my butt won't let me go much further!). There's no need for a heavier battery than the one 14 Ah battery Rad uses on my bike. No upside to lugging around the extra weight of a 17 or 20Ah battery for my purposes. The 14Ah will let me ride for up to a week as it is!

As far as proprietary, so what? It's not THAT proprietary. If I want to put a generic battery on it, it might take me an hour. The battery rack, the thing that makes this battery proprietary, is held in place with 3 screws. How long do you think it's going to take to remove that and install a new rack - the one that's going to ship with a new battery? That's a non event, here anyway. Internet hogwash....

I've been riding the bike, equipped with a stock '17 Rad battery, and the MAC 12t motor (very similar to the GMAC) for over a year now. I LOVE it. I have an easy 35 mile range with much time spent in rolling hills. Noteworthy is the fact I have the controller set to limit available power to the MAC at 1100 watts or so. That setting provides all the power I need to crest the biggest hills - and it's super efficient! Also noteworthy is that I weigh 315 lbs, and rarely ride at speeds over 15mph. The novelty of going faster has long since worn off. My time is spent mostly in PAS 1, with 2 and 3 used as wind and hills make them necessary.

Regarding speed, the GMAC's are available in 2 different windings. The 8 turn and the 10 turn. The 8 turn would likely work out better for those riding at 25 mph frequently. It's designed to be more efficient with the motor turning at a higher rpm. All that is spelled out on the Grin site. The 12t wind, like I have now, isn't available from Grin for the GMAC. Their standpoint is that the 10t will equal the 12t performance in the majority of circumstances. OK fine. I bought the 12t for it's low speed ability, as that best describes how my bikes are ridden.

Regarding the GMAC regen, it's capable of locking up the rear tire if just turned "on". That's why they made the variable regen/brake set up. This is WAY different than the regen on any bike made previously, to my knowledge anyway. That's what makes this drive a game changer. Yes, it is fed some power when coasting, but the regen available, used when stopping if not in the hills, more than makes up for the tiny bit used to make it feel like it's coasting. That little bit of power used coasting is customizable by the user too. -Al
 
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Timpo

Well-Known Member
Timpo, regarding the battery, the stock RAD is good enough for MY needs! I'm not building this bike to be the ultimate, best available, or to set a new land speed record. It's way more about FUNCTIONAL, meeting my needs. I ride for sport. Would I like to have a 52 volt? Sure! Do I need it? Nope..... Nor do I need more Ah. A 20 mile ride is about all I'm good for (my butt won't let me go much further!). There's no need for a heavier battery than the one 14 Ah battery Rad uses on my bike. No upside to lugging around the extra weight of a 17 or 20Ah battery for my purposes. The 14Ah will let me ride for up to a week as it is!

As far as proprietary, so what? It's not THAT proprietary. If I want to put a generic battery on it, it might take me an hour. The battery rack, the thing that makes this battery proprietary, is held in place with 3 screws. How long do you think it's going to take to remove that and install a new rack - the one that's going to ship with a new battery? That's a non event, here anyway. Internet hogwash....

I've been riding the bike, equipped with a stock '17 Rad battery, and the MAC 12t motor (very similar to the GMAC) for over a year now. I LOVE it. I have an easy 35 mile range with much time spent in rolling hills. Noteworthy is the fact I have the controller set to limit available power to the MAC at 1100 watts or so. That setting provides all the power I need to crest the biggest hills - and it's super efficient! Also noteworthy is that I weigh 315 lbs, and rarely ride at speeds over 15mph. The novelty of going faster has long since worn off. My time is spent mostly in PAS 1, with 2 and 3 used as wind and hills make them necessary.

Regarding speed, the GMAC's are available in 2 different windings. The 8 turn and the 10 turn. The 8 turn would likely work out better for those riding at 25 mph frequently. It's designed to be more efficient with the motor turning at a higher rpm. All that is spelled out on the Grin site. The 12t wind, like I have now, isn't available from Grin for the GMAC. Their standpoint is that the 10t will equal the 12t performance in the majority of circumstances. OK fine. I bought the 12t for it's low speed ability, as that best describes how my bikes are ridden.

Regarding the GMAC regen, it's capable of locking up the rear tire if just turned "on". That's why they made the variable regen/brake set up. This is WAY different than the regen on any bike made previously, to my knowledge anyway. That's what makes this drive a game changer. Yes, it is fed some power when coasting, but the regen available, used when stopping if not in the hills, more than makes up for the tiny bit used to make it feel like it's coasting. That little bit of power used coasting is customizable by the user too. -Al
Hmm okay maybe I misunderstood something? 😕

When you said you want a GMAC, I thought you were looking for high performance.
To get a most out of GMAC, you would want a high drain rate battery.

If you just need a little more boost, without changing too much on Rad Rover, I think Bolton kit would be the best bet.
Somebody on this forum (Feliz or Dewey) said that he got a Bolton kit, without upgrading the motor to Bolton 750W (retained the stock Rad 350W motor), he still saw a significant gain in performance.
 

AHicks

Well-Known Member
Hmm okay maybe I misunderstood something? 😕

When you said you want a GMAC, I thought you were looking for high performance.
To get a most out of GMAC, you would want a high drain rate battery.

If you just need a little more boost, without changing too much on Rad Rover, I think Bolton kit would be the best bet.
Somebody on this forum (Feliz or Dewey) said that he got a Bolton kit, without upgrading the motor to Bolton 750W (retained the stock Rad 350W motor), he still saw a significant gain in performance.

<<<To get a most out of GMAC, you would want a high drain rate battery.>>>

What if I were after only enough performance to get the job done? That I have NO interest in maximum available?

You missed something alright. Starting with the fact I was unhappy with the performance available with my existing bike using a 1500w direct drive, have already installed a MAC 12t, and the fact the bike is equipped with a 12 fet 35a KT controller and display already (likely exceeding Boltons specs, but otherwise very similar) and that I've been riding this bike for a year. I have a pretty good idea of what's available performance wise using a standard RAD battery.....

Not interested in taking a step backwards performance wise with this new bike.

You're missing the fact that performance, to some of us, is NOT about how fast a bike will go. While that may have been a factor 40 years ago, any more that novetly has worn off (been there, done that, no longer have that "need for speed"). Now I'm WAY more interested in how the bike accelerates from a stop for instance, if it will climb a big hill with a reasonable amount of assistance from me, or it's ability to provide all around "peppy" performance. That coupled with a proportional regenerative braking system is what I'm after with the GMAC conversion.....
-Al
 

Timpo

Well-Known Member
<<<To get a most out of GMAC, you would want a high drain rate battery.>>>

What if I were after only enough performance to get the job done? That I have NO interest in maximum available?

You missed something alright. Starting with the fact I was unhappy with the performance available with my existing bike using a 1500w direct drive, have already installed a MAC 12t, and the fact the bike is equipped with a 12 fet 35a KT controller and display already (likely exceeding Boltons specs, but otherwise very similar) and that I've been riding this bike for a year. I have a pretty good idea of what's available performance wise using a standard RAD battery.....

Not interested in taking a step backwards performance wise with this new bike.

You're missing the fact that performance, to some of us, is NOT about how fast a bike will go. While that may have been a factor 40 years ago, any more that novetly has worn off (been there, done that, no longer have that "need for speed"). Now I'm WAY more interested in how the bike accelerates from a stop for instance, if it will climb a big hill with a reasonable amount of assistance from me, or it's ability to provide all around "peppy" performance. That coupled with a proportional regenerative braking system is what I'm after with the GMAC conversion.....
-Al
I don't know.. when I hear people wanting a GMAC or Bafang Ultra, almost always they're looking for performance gains.

But if you're interested in GMAC just because of their built quality and whatnot, I can understand that too.
 

AHicks

Well-Known Member
I don't know.. when I hear people wanting a GMAC or Bafang Ultra, almost always they're looking for performance gains.

But if you're interested in GMAC just because of their built quality and whatnot, I can understand that too.

Yes, performance gains. Big ones. But not necessarily those involving top speed....

Build quality sure, but also efficiency and low speed abilities. Think truck, tractor, or trials bike maybe. They are set up and used for their low speed abilities. The absolute best are not fast by anyone's imagination.
 

opimax

Well-Known Member
A better reaction sensor is a “performance gain” also. Wanting to go up up hills without slowing down as much or putting in the effort of my old legs I want to use on that hill at above 26 Is important instead of seeing 40 mph on flats
 

Thomas Jaszewski

Well-Known Member
While
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the GNAC hs some nice features The MAC is a better value IMO. Calculated with a 5% grade
 

AHicks

Well-Known Member
MAC is a better value no doubt - until you factor in the GMAC features, which are not showing on those charts! GMAC is all about the variable regen/braking. If you have no need for/interest in these, the MAC will work just fine. I'll be the first to admit that. It's a really great drive.

GMAC brings a whole new meaning to regen though. Some use it in favor of a rear brake! Too, it's actually able to replace a significant amount of power into the battery. Chart not able to factor in the GMAC features as regarding consumption I don't believe.
 
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BigNerd

Active Member
So I finally tested my rear hub drive Espin Sport up a long incline to see what the 500w motor was capable of. Now, I'm over 250lbs so I was scared I was going to push it because from what I've read here, mid drives are better for heavier riders.

To my surprise, it worked like a champ... even in just PAS 1 this formerly "I don't want to ride it" uphill path that is just over a mile long was nothing for the Bafang motor... didn't even need to go to PAS 2 or 3 but tried it just to see what's what. At PAS 3, I could easily get over 15mph which for uphill is impossible.

So while I was worried about a rear hub drive not being enough for my big body... turns out, it's okay. I just don't know if it can handle a steeper incline or longer one... I only used the power for about 2/3 of the path but as I said, didn't hear any crying from the back of my bike. :)

One plus for rear hub that some mid-drives don't have is the throttle... went back halfway down to see how my non-ebike partner was doing and from the stop... I could throttle a little bit so I could sync up pedaling on the incline since I forgot to gear down.
 

CityExplorer

Active Member
You don't say what the elevation was over that distance, so no one can really get a sense of what kind of hill you are talking about.

The steeper inclines is where the hub motor will suffer on most bikes. For real mountain biking the mid drive is still preferable in most cases. There are designs that can narrow the gab. There are always tradoffs.
 

BigNerd

Active Member
You don't say what the elevation was over that distance, so no one can really get a sense of what kind of hill you are talking about.

The steeper inclines is where the hub motor will suffer on most bikes. For real mountain biking the mid drive is still preferable in most cases. There are designs that can narrow the gab. There are always tradoffs.

Sorry... according to All Trails it looks like it maxes at 7% but that’s still steep enough to make me not want to ride it with a non ebike. I actually tried it yesterday with my regular MTB as my kid used the ebike and while I can do it, it’s not fun at all.

There is another shorter incline with a 12% grade and I’ll try it out one day but I think it should be ok.

I understand that mid drives are better for mountain biking and real torque but what I’m trying to say is for casual bikers on paved trails that are not too steep or too long, a rear hub is capable enough.

I hope my next one will be a mid drive but it all depends on weight/price.