Disappointed w/ Sondors Rockstar power

Howie

New Member
Region
USA
Got my bike March 2022. First off, it arrived with a broken fork and that took three weeks for them to replace. So that sucked. But what also sucks is the power/torque on this thing. Very underwhelming. I'm wondering if something is off in the parameters or if there's an actual problem. From a dead stop, using throttle only (no pedaling) the bike has very little torque/power. I'm not a big guy (5'10" 180lbs) and it takes forever to get up to speed. I can feel the motor struggle and initially, there's a bit of a grinding sensation that I can feel through the pedals. I've got it set up to where I've got nine different pedal assist settings and if I'm pedaling I don't feel the motor doing much unless I'm at like 6 or 7. If I'm on 5 I gotta pedal my ass off in order to get up a hill. There was a lot of hype around this thing and I'm wondering if I'm missing something or if there's a problem? Am I doing something wrong?

Is there a way to get into the controller functions via Bluetooth or directly with a cable? Is it possible to change settings such as unlocking the speed limiter and adjusting throttle voltage, etc etc?
 

tomjasz

Well-Known Member
Region
USA
City
Minnesnowta
In Luna’s early days their hottest selling replacement parts were for the early underpowered motors and inadequate batteries.

They sold a small fortune in upgrades.

A lot of us harp ad infinitum about low end eBike purchases. I realize you made the purchase in good faith. I’m saddened reading this sort of thread. Maybe the really active Sondors blogs and forums can suggest some available upgrades.

I’m hoping you can feel better about your purchase.
 

tomjasz

Well-Known Member
Region
USA
City
Minnesnowta
Yikes! I just read the specs. What gear ratio are you trying to throttle uphill in, from a dead stop?
 

Ken M

Well-Known Member
Yikes! I just read the specs. What gear ratio are you trying to throttle uphill in, from a dead stop?
There is lies the issue. The gear ratio to optimize for the rider and the motor are never the same. The motor would perform best with a small front cog and large diamter rear chain ring so the motor can spin fast and the output torque is magnified. Becasue the drive trail components tend to not be designed for the high combined torque of the Bafang Ultra and rider the OEMs tend to protect the componts by implementing "underdrive" ratios that reduce the torque to the rear wheel. Use the lower gears only if just using the throttle and I'm thinking the performance of the motor should be compelling.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
If this is the Bafang Ultra motor, the issue is not just the gearing, but just as possible is the potential for limiting the motor's performance in the controller setup. Pretty cute rating the 1600w motor for 750w, but if they have the amperage turned back in the setup (should be 30a max) so where it actually tests as a 750w (20a max?), that problem alone could be responsible. Then, there's a whole list of parameters that could be affecting performance. Which brings up the question regarding "can I adjust it?".

If this is the newer CANbus motor, it is NOT adjustable....... not yet anyway. Is this a CANbus motor? Easiest way to tell for sure is the connectors where the display plugs in to the main harness up by the handlebars. If it's a 5 sided affair, not round, it's a CANbus version of the Ultra.
 

tomjasz

Well-Known Member
Region
USA
City
Minnesnowta
Unless the OP shares the gear ratio were just guessing. I had many similar support requests that were gearing issues. The devil will be in the details. Even dumbed down it ought to be a decent climber. But we also don’t know the expected speed.
 

rich c

Well-Known Member
Are you even shifting or just mashing the throttle? Do you start out in your car with the transmission in 5th gear? It would accelerate like a dog too.
 

PedalUma

Well-Known Member
Region
USA
City
Petaluma, CA
@Howie, Were you a cyclist before the purchase of the Rockstar? I am familiar with these bikes. Because even if you are driving a Corvette it will suck if you try to launch from a stop in high gear.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Specs I saw showed it had a 48t in front. I'm running a 49t, and it's not doing too bad a job from the start. Mine is the UART version, and I actually had to dial it back a bit from the factory setting as it was just too agressive for me. Now, it's nothing like wheel spinning from the start, but you had darn sure better be hanging on with both hands....
 

PedalUma

Well-Known Member
Region
USA
City
Petaluma, CA
Even level one is strong. You just need to ride it like its a mid-drive. That means shifting gears. The shifter and Tourney freehub are low quality. I replace a friend's when he ate the cogs a few weeks in. Got him a better chain too. Replacing the shifter was a huge pain because the speed sensor in buried inside the frame, under the battery. He also got a nicer derailleur. Even with the speed sensor it is good to let up on power when selecting a lower gear or it will crunch.
 

theemartymac

Well-Known Member
I've seen a few videos that describe the power of the Rockstar with terms like "not overpowered', and 'manageable'. Right away, that tells you it's not an unrestricted beast.

It is a 90lb FS bike, so not going to pop wheelies like a sur ron. Many reviews reference how noticeable the weight is, and sprocket upgrades are mentioned a lot. If you are a climber and/or enduro style rider, that may be a good start to tighten up the gear ratios and add a little more 'apparent' torque. Even as powerful as the Ultra is, gearing matters for hard launches and punchy acceleration.

I'm surprised they chose to de-rate the ultra for this installation. The platform certainly screams for an unrestricted and maybe even juiced-up option?
 

PedalUma

Well-Known Member
Region
USA
City
Petaluma, CA
I've seen a few videos that describe the power of the Rockstar with terms like "not overpowered', and 'manageable'. Right away, that tells you it's not an unrestricted beast.

It is a 90lb FS bike, so not going to pop wheelies like a sur ron. Many reviews reference how noticeable the weight is, and sprocket upgrades are mentioned a lot. If you are a climber and/or enduro style rider, that may be a good start to tighten up the gear ratios and add a little more 'apparent' torque. Even as powerful as the Ultra is, gearing matters for hard launches and punchy acceleration.

I'm surprised they chose to de-rate the ultra for this installation. The platform certainly screams for an unrestricted and maybe even juiced-up option?
Last year I just went into the display to make it unrestricted. I do not know for '22. You can also put it into metric and tell the display that it has 40% smaller wheels (17").
 

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AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Even level one is strong. You just need to ride it like its a mid-drive. That means shifting gears. The shifter and Tourney freehub are low quality. I replace a friend's when he ate the cogs a few weeks in. Got him a better chain too. Replacing the shifter was a huge pain because the speed sensor in buried inside the frame, under the battery. He also got a nicer derailleur. Even with the speed sensor it is good to let up on power when selecting a lower gear or it will crunch.
I think you meant shift detector?
 

PedalUma

Well-Known Member
Region
USA
City
Petaluma, CA
Yes the shift sensor! You need to remove the battery and it is way down there. There is also a charged capacitor that can knock you on your butt in there. It takes a long needle nose and a needle nose vice grip. To thread the thing you need tandem cable to make a big loop of it to round a tight corner.
 

Mentalist

Member
Region
USA
I’m 6ft 180lbs and the bike takes off to 10mph on pas 1 without issues.
on pas 9 its really torquey and snaps me back..I gotta lean into it. There is no grinding sounds but I greased everything and took half the bike apart. It is very torquey..check for voltage sag or see if you can go to a bike shop to compare.

its too aggressive if anything.
 

Kayakguy

Well-Known Member
Are you even shifting or just mashing the throttle? Do you start out in your car with the transmission in 5th gear? It would accelerate like a dog too.
Actually, dogs can accelerate very rapidly, in my experience. When I was a kid, I had to pass by a yard with a big, angry, unrestrained doberman, who would give chase as I pedaled by. As I strained mightily on my one-speed, I could feel him slashing at my rear tire as I fled. He could really move.

Though my bike (Ariel Rider C Class) has a throttle, it only functions when the PAS is set to zero. Since I got an ebike for exercise, it would make no sense for me not to pedal. If the Sondors is torque sensing, pedaling may bring on more motor power. I find that mine (with a Tongsheng motor) responds proportionally to my input. The more vigorously I pedal, the more the motor puts out.
 
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Mentalist

Member
Region
USA
Actually, dogs can accelerate very rapidly, in my experience.

Though my bike (Ariel Rider C Class) has a throttle, it only functions when the PAS is set to zero. Since I got an ebike for exercise, it would make no sense for me not to pedal. If the Sondors is torque sensing, pedaling may bring on more motor power. I find that mine (with a Tongsheng motor) responds proportionally to my input. The more vigorously I pedal, the more the motor puts out.
It is torque sensing and does bring on more power with pedaling. feels pretty natural aside from the second delay of motor kicking in. But he seems like he’s having some bigger issues if he can feel the motor at only 7pas and up (the throttles output is correlated to the pas setting)