What speed should the bosch stop assisting?

colinb

New Member
Hi,

I'm the proud owner of a Felt Bruhaul. Its great, apart from some parts that look like they were designed by a different company. i.e. the chain guide. Anyway, I've modified it and things are better.

My Question

What speed should the assist cut off at. It says in all the documentation "up to 20mph" before I modified the chain guide it wouldn't assist past 18.5. I got it so it was just about assisting at 19.6mph, however when I checked it against GPS the speedo was very optimistic at factory settings. and the trip distance was over by half a mile on a 9 mile trip.

I reduced the circumference from 1990mm to 1942mm the speedo now reads correctly and the trip distance is spot on. My commute is exactly 9miles. The issue is the assist now stops at 19.3mph and its almost non existent after 19mph. I don't know if there is a PID controller or something but with the extra weight and big tires it just needs to assist a bit more to achieve 20mph. Is this something a dealer can adjust or has FELT just not set it up correctly?

Thanks
 

Scooteretti

Active Member
Hello Colinb,

When you say you modified the chain guide can you give some specifics on what you changed?

So just to make sure, you have calculated the exact circumference of your wheel and inputed that into you console (Intuvia, Purion etc...) correctly? How did you measure the circumference?

If all was done correctly, I suggest a call to your dealer or to Felt technical support as this speed indicator can be affected by what the factory set the drive unit specs at for the bike (rare there is an issue but anything is possible). Once configured at the factory only the manufacturer or Bosch can flash the settings / setup of the drive. They will be able to pull out the motor configuration for you and assist in getting that corrected.

The Bosch drive systems are pretty darn precise and when it's set for 20MPH it's almost always spot on. Of course this is if all the parameters are entered correctly.

Keep us posted on your progress.


Will
 

colinb

New Member
Thanks for the response.

I ride a 100 miles a week so plenty of chance to check accuracy against my Garmin. So I never measured the circumference, but I do reset both the bike and my watch before I set off and it is perfect now 1942 setting for both actual speed and distance. The factory setting was actually larger than the schwalbe estimate (1980mm) and its on a wider rim than normal plus my 230lb + kid + luggage.

With regards the guide, it is a bit of a joke. It was mounted too high and to close to the frame. In gears 6-10 it really dug into the bottom of the guide. Even in first it dug into the bottom of the guide. I made some spacers and moved it down and away from the frame. It doesn't touch the chain at all now in 6th. Still clears the chain stays. I know why they did it, to clear the running boards if fitted. But I don't have them. It really needs to be a floating jockey wheel (my next project). It was under so much load and the chain almost cut through on one end after 300 miles. Must of cost quite a few watts as its on the drive side.

Looks like I'll set up an appointment at my local bike shop.
 

MLB

Well-Known Member
Not so. Mine and every other Haibike I know of cuts out at just over 19mph. The law is LESS THAN 20 mph. The Haibike forum has several discussions about this, very common and certainly seems to be "normal".
My Easy Motion also cuts out well below 20 mph.
 

colinb

New Member
Hi MLB

I totally agree what the law says, however the BOSCH manual states the following:-

  1. As soon as you stop pedaling when in normal operation, or as soon as you have reached a speed of 20 mph, the assis- tance from the eBike drive unit is switched off. The motor assistance is automatically re-activated as soon you start pedaling again and the speed is below 20 mph.


    I love my bike and its perfect for my family I just want things to do what they say they should. 1mph adds up over the year. My journey to work is actually slightly slower on my ebike compared to my Tern VergeX but i can breath and don't need a shower. The return journey is all up hill through and much quicker on the FELT
 

pxpaulx

Well-Known Member
Not so. Mine and every other Haibike I know of cuts out at just over 19mph. The law is LESS THAN 20 mph. The Haibike forum has several discussions about this, very common and certainly seems to be "normal".
My Easy Motion also cuts out well below 20 mph.

Even your easy motion? Both the easy motion bikes I've owned previously went over 20mph with me pedaling (both hub versions). My sduro pretty strongly ends assist when 20 is hit. I've noticed my new bulls brose bike stays to lay off at 19mph...I wouldn't mind if 19 were actually 19 on it though, my GPS reads about 18mph when the brose cuts out!
 

MLB

Well-Known Member
Hi MLB

I totally agree what the law says, however the BOSCH manual states the following:-

  1. As soon as you stop pedaling when in normal operation, or as soon as you have reached a speed of 20 mph, the assis- tance from the eBike drive unit is switched off. The motor assistance is automatically re-activated as soon you start pedaling again and the speed is below 20 mph.


    I love my bike and its perfect for my family I just want things to do what they say they should. 1mph adds up over the year. My journey to work is actually slightly slower on my ebike compared to my Tern VergeX but i can breath and don't need a shower. The return journey is all up hill through and much quicker on the FELT

LOL, if you search, one of the threads is titled "I want my 1mph" and I am the author. o_O
 
I think that you are splitting hairs. Why stress over such a small margin. I bet the odometer in your car/truck/mini-van is far less accurate and you live with that.