ST1 loosing power & speed

Cupid

Member
Has anyone experienced loosing power/speed one day with your ST1?

As I started to ride today and the bike's top speed when pedaling at same torque was about 3.5 mph less.
It felt like, I had rear flat tire (checked tire pressure and it was all good) Bike felt heavy and sluggish.
Its not battery in cold weather situation issue - as temperature was much colder past week than today.

Perhaps malfunction in the cpu or torque sensor?
With the same pedal strength: I am at 23-24 mph vs. 27-28 mph that I used to get before.
Its just not the speed, the bike feels heavier and doesn't have the kick and power that it had before.

Any ideas?
 

Cupid

Member
Doing some reading on the forum, could it be the Pulse issue? ( REAR BRAKE sensor ) Issue is constant and is not intermittent.
Its just stuck sluggish mode.
 

Operator7

Active Member
I'm a new ST1 owner... the only thing I've noticed so far is that often times when I'm at a complete standstill, as soon as I push down on the pedal I get a lot of assistance - but a few times recently, there was no assistance at all, and one time I actually had to play with the bike for like 10 seconds waiting for the power assist to come on at all. What woke it up seemed to be when I shifted gears a couple times, but it was troubling.
 

Cupid

Member
I was instructed to take battery out and to power cycle.
Have done that but didn't have chance to do long ride test yet.
Will find out by this weekend.
 
I was instructed to take battery out and to power cycle.
Have done that but didn't have chance to do long ride test yet.
Will find out by this weekend.
I have experienced what sounds like the same problem. Tried turning the bike on/off. Removed battery. Tried my other two batteries. No difference. It has happened to me in all four power settings, and happens on longer rides on level or mostly level ground where I am happily cruising along at 18-20 mph in ECO or CITY. It's never happened going up a steep hill fortunately.

My bike is at the dealer now. Had a long conversation with the mechanic yesterday and he's discussing back and forth with Stromer. Another person on the forum reported that changing the brake sensor solved it for him. My mechanic isn't totally sold on that solution. Of course when he rides my bike, he never encounters what I have encountered probably 10-15 times over 900 miles--all of a sudden it feels like I am pulling a 100-lb. trailer. Generally, it goes on for several miles then everything goes back to normal. I weigh 225, and with a few accessories and the bike combined, we tip the scale at 300 lbs. so losing power is a major issue. Hope to have it resolved shortly and will report back.
 

opimax

Well-Known Member
I had 2 ST1 s, my wife's bike was about 2-3 mph faster, I traded in for ST2, either motor or torque sensor or torque sensor adjustment would be my guess
 

Theelf

New Member
Hi
New forum member and thought I would jump into this too as I appear to have same problem
I have an ST1 and have almost 2oook on it. I was mostly for commuting so by and large travel the same route and the same hills every day.
No problems for almost a year and then about 6 weeks ago started having the power go out completly while riding up a steep hill at the end of the day

Have tried the break sensor disconnect trick suggested in the owners manual but issue still occurs. My bike shop -a Strommer dealer- have tried cleaning the break sensor. To no avail.
Today they replace the torque sensor. This too did not fix the problem and the power dies at the same place on the same hill all the time.
If I stop reboot and start to go the assist us intermittent. The following day works perfectly on the way to work, then dies again on the way home
Very frustrating. Frustrating too as their are no steep hills around my dealer so after each "fix" have to ride to almost home to see if problem is fixed!

Very frustrating !!


Still dealers suggestion going to try adjusting the power settings and see if that helps. Will update here when I know
 

bluecat

Well-Known Member
This is not a SOP - but might be a useful procedure. Taking 'another battery' means: Drop in at your Stromer-dealer and exchange your battery with one of his batteries from a demo-Stromer. You may adapt these test according your current situation. The outcome will help your Stromer-dealer to identify the source of the error.
 

Cupid

Member
After removing the battery and doing power cycle; that fixed my issue. Luckily mine wasn't a complicated issue.
 

toon

New Member
Yes, I did experience the same thing riding yesterday. And a few times before in the 5000 km I did with my st1. Mostly it went away after a few km. But ysterday it didn't go away. Hope tomorrow it will be over. If not I'll try the power cycle trick. Keep you posted.
 

Cupid

Member
It happened again on my ride this morning. This time it happened in the middle of my ride. Perhaps when I go over a bump, the battery connection gets affected to cause issue with control unit.
After taking the battery out and doing power cycle, it fixed the issue.
 
This is not a SOP - but might be a useful procedure. Taking 'another battery' means: Drop in at your Stromer-dealer and exchange your battery with one of his batteries from a demo-Stromer. You may adapt these test according your current situation. The outcome will help your Stromer-dealer to identify the source of the error.
Thanks. I have three batteries--two purple, one gold. Have had the problem with each of the three batteries so don't think that's the issue.
 
I have experienced what sounds like the same problem. Tried turning the bike on/off. Removed battery. Tried my other two batteries. No difference. It has happened to me in all four power settings, and happens on longer rides on level or mostly level ground where I am happily cruising along at 18-20 mph in ECO or CITY. It's never happened going up a steep hill fortunately.

My bike is at the dealer now. Had a long conversation with the mechanic yesterday and he's discussing back and forth with Stromer. Another person on the forum reported that changing the brake sensor solved it for him. My mechanic isn't totally sold on that solution. Of course when he rides my bike, he never encounters what I have encountered probably 10-15 times over 900 miles--all of a sudden it feels like I am pulling a 100-lb. trailer. Generally, it goes on for several miles then everything goes back to normal. I weigh 225, and with a few accessories and the bike combined, we tip the scale at 300 lbs. so losing power is a major issue. Hope to have it resolved shortly and will report back.
Quick update on my ST1. After some consultation with Stromer's tech rep, they decided to replace the gears on the rear hub. They explained why, though I honestly don't recall what the reasoning was. Looked the bike over thoroughly and suggested I take the bike and see if there was an improvement, especially before the weather gets colder and wet. I have ridden it about 150 miles since getting it back--just hit 1000 miles since I bought it in June. The first time out, on a 29 mile ride, I had the pulsing issue for about 7-8 miles. So I was disappointed, but have ridden 125 miles since then on all sorts of terrain and with each of my three batteries, and it's been fine, so it continues to be an intermittent thing. Only problem I had was yesterday--stopped to switch out batteries on a 45 mile ride, and when I put it in the LED in the control unit was completely dead--though the headlight (powered by the bike battery) worked. Disconnected the main cable to the control unit, reconnected, and it fired right up.

So, the saga continues but I continue to enjoy my rides and hope to get some more in before winter sets in.
 
Sorry I haven't kept up re: the intermittent and unpredictable "pulsing issue" on my ST-1. But I do have some positive updates to share.

As you can see above and from 3-4 previous postings, I had the issue since I got my bike in June. My dealer, who worked through Stromer's tech people to resolve the matter tried: 1) replacing the gears, 2) the handlebar control unit, and 3) the motor. Nothing changed--still had the pulsing/sometimes total power drop off issue.

So I took the bike back to the dealer again. The mechanic there (great guy) checked back with Stromer. Based on other accounts I'd seen here, I kept nudging for a check of the torque sensor and wiring. This time they replaced most of the wiring and the torque sensor both. I did a 32 mile ride from 0-31 mph (down a long steep hill), up and down hills and on long flat bike trails using two different batteries, and for the first time since last summer, had no issues at all. The only hesitation I feel from the motor happens as I go down a hill and at the bottom immediately start to pedal up the next hill--just for a second the bike seems to need to figure out that you want the motor to kick in and help out on the climb. It's really not an issue at all. I am heading out to do another 25 miles or so today to test it again, but I am very encouraged and I would recommend to anyone with similar intermittent power problems to start by taking a hard look at the torque sensor and the wiring.

If I don't post again, all is well. Thanks for everyone's interest and support.
 

Cupid

Member
I purchased my Stromer ST-1 from a dealer far away. Is this sort of repair under warranty and do you think local Stromer dealer would be able to look into it?
 
I purchased my Stromer ST-1 from a dealer far away. Is this sort of repair under warranty and do you think local Stromer dealer would be able to look into it?
Absolutely covered by warranty. Any good Stromer dealer/mechanic should be able to work through it. It may take a few attempts, trying this and that, process of elimination. I would really nudge the repair person to do two things: 1) first, carefully go over the bike and consider the possible causes, and 2) consult the Stromer tech reps. They will have a lot more experience across the entire network of Stromer dealers and should be a real asset.

It might be premature, but if I had to guess what's wrong, I'd say it's the torque sensor or an intermittent wiring issue. Will be interested to hear how it turns out. Good luck.
 

Cupid

Member
What's the proper process to initiate the repair? Contact Stromer for them to refer stromer dealer near me? or for me to take the bike to nearest Stromer dealer?
 
What's the proper process to initiate the repair? Contact Stromer for them to refer stromer dealer near me? or for me to take the bike to nearest Stromer dealer?
I would call the dealer and talk to their mechanic first, then take the bike in when they're ready to get into it. I'd share what you've heard about possible causes but wouldn't focus too much on any one thing--that way they'll be more likely to contact Stromer and get to the real issue quicker. The dealer is compensated for warranty work by Stromer so they should have no hesitation carrying out the work.
 

BarronakaB

New Member
I recently bought a Stromer ST1 (2017 model) new from an authorized dealer near me and am having the same intermittent power issue. It's frustrating because I notice it, but of course it doesn't surface when it is at the shop. I ride 7 miles to work everyday on a full charge, no issue. Then, some, but not all days, my commute home has the power issue (feeling sluggish, losing about 1/3 power, lower top MPH). I power cycle and its resolved. They have done a thorough tune up, and we have tried swapping the battery. No resolution yet. We are now doing another test by swapping the computer console to see if that resolves it. We have not tried replacing the torque sensor or wiring. I know it's been a while, but if anyone else has been able to resolve this issue I'd love to hear about it.
 

Rincon

Active Member
I recently bought a Stromer ST1 (2017 model) new from an authorized dealer near me and am having the same intermittent power issue.
I had the same problem with one of my 2016 ST2 bikes: Intermittent slowing, sluggishness. The next time it happened I immediately stopped and recalibrated the torque sensor. Problem solved. It hasn’t happened again.

That’s the short story. The actual symptoms were interesting. When it got sluggish, I could change power levels between 1, 2, and 3 and feel no difference. Switching to level zero, power off, felt the same as 1, 2, and 3. If I tried to accelerate in level zero, then I knew I was riding an unpowered 60lb bike. In 1, 2, or 3 it was easier to accelerate than with zero, but there was no difference between the three powered levels.

Recalibrating the torque sensor fixed it for me. Good luck.
 
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