Choosing the best tooth count on front gear

Claus C.

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I’m converting an old bike to an eBike using the Bafang 750 watt mid drive BBS02. Which tooth count is the best for the longest distance?

The bike is currently equipped with a triple front gears 48, 38 and 28 tooth rings.

I typically bike routes ranging from 20 to 60 miles on rails-to-trails paths, so therefore mostly level. My total stop time is usually below 5 minutes (only for cross traffic).

For my cadence my normal gear setting is the 48 tooth and gear 6 out of 7 on the back. It is extremely rare that I ever use the 28 tooth gear. And only infrequently downshift to the 38 tooth gear.

My cadence is about 60 rpm and my average speed is about 13 to 14 mph. I’m not looking for super speeds in excess 25 mph. But I would like to increase my range to 100 miles which means I would be looking to use the minimal motor assist as possible.

The bike tires are 26”
 

Hoggdoc

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View attachment 2457View attachment 2458I’m converting an old bike to an eBike using the Bafang 750 watt mid drive BBS02. Which tooth count is the best for the longest distance?

The bike is currently equipped with a triple front gears 48, 38 and 28 tooth rings.

I typically bike routes ranging from 20 to 60 miles on rails-to-trails paths, so therefore mostly level. My total stop time is usually below 5 minutes (only for cross traffic).

For my cadence my normal gear setting is the 48 tooth and gear 6 out of 7 on the back. It is extremely rare that I ever use the 28 tooth gear. And only infrequently downshift to the 38 tooth gear.

My cadence is about 60 rpm and my average speed is about 13 to 14 mph. I’m not looking for super speeds in excess 25 mph. But I would like to increase my range to 100 miles which means I would be looking to use the minimal motor assist as possible.

The bike tires are 26”
I think the 48 tooth would be a good starting point. I think you'll find with the motor assist you will be riding much faster with your RPM and gearing choice. You will be surprised how is all works when put together.

You may want to consider upgrading to disc brakes on your build as the power of the motor system will easily overpower your current brake system. Keep us informed on your build process as many here will be interested in following.
 

Claus C.

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Just an update on my progress. I opted for the 46 tooth but should have gone with the 48 or larger 52 tooth. But first a little about my build. The package took longer to arrive than expected. It should have been 4 days shipping but turned out to be a week and a half mostly due to FedEx.

For my first ever experience converting a bike into an eBike it was surprisingly easy. I followed the easy instructions to check that what I wanted was going to fit on my bike. With little to go on I ordered a slightly smaller sprocket than the bike originally had. I may upgrade that in the future.
I didn’t have the tools to pull the old cranks on the bike but a friend had them and helped me get them off.
I followed the assembly instructions on the manufactures website as well as another YouTube video. Between the two it was very easy to complete the installation. While the videos suggested it should only take a couple of hours for me it took most of a day to complete because I wanted to make sure I did it correctly. The only problem I had was not tightening the 8 mm crank bolts enough. The video warned you to not over tighten the bolts lest you strip them. On my first ride the left peddle fell off about 10 miles into the ride.
I had not installed the optional shift sensor before my first ride, but I was glad I bought it. I can see how it will protect my chain and gears. It has now also been installed. The instructions say you need to split the chain. If you don’t have a front derailleur or if you don’t plan to use the old derailleur then you don’t need to split the chain. I am not comfortable adjusting the gear alignment, but to install the shift sensor you need to remove the cable. I had my friend adjust the gears when done. All in all I’m very pleased with the installation. I found I can out peddle the motor on the first 7 out of 9 assist levels but on 8 and 9 I’m just spinning the peddles while the motor does most of the work. That is why I think I will install a larger front sprocket.
 

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Hoggdoc

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Location
Longview, WA.
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Just an update on my progress. I opted for the 46 tooth but should have gone with the 48 or larger 52 tooth. But first a little about my build. The package took longer to arrive than expected. It should have been 4 days shipping but turned out to be a week and a half mostly due to FedEx.

For my first ever experience converting a bike into an eBike it was surprisingly easy. I followed the easy instructions to check that what I wanted was going to fit on my bike. With little to go on I ordered a slightly smaller sprocket than the bike originally had. I may upgrade that in the future.
I didn’t have the tools to pull the old cranks on the bike but a friend had them and helped me get them off.
I followed the assembly instructions on the manufactures website as well as another YouTube video. Between the two it was very easy to complete the installation. While the videos suggested it should only take a couple of hours for me it took most of a day to complete because I wanted to make sure I did it correctly. The only problem I had was not tightening the 8 mm crank bolts enough. The video warned you to not over tighten the bolts lest you strip them. On my first ride the left peddle fell off about 10 miles into the ride.
I had not installed the optional shift sensor before my first ride, but I was glad I bought it. I can see how it will protect my chain and gears. It has now also been installed. The instructions say you need to split the chain. If you don’t have a front derailleur or if you don’t plan to use the old derailleur then you don’t need to split the chain. I am not comfortable adjusting the gear alignment, but to install the shift sensor you need to remove the cable. I had my friend adjust the gears when done. All in all I’m very pleased with the installation. I found I can out peddle the motor on the first 7 out of 9 assist levels but on 8 and 9 I’m just spinning the peddles while the motor does most of the work. That is why I think I will install a larger front sprocket.
Nice job. So are you happy with the overall performance of the bike? Do you feel the need to get into the setup and fine tune any parameters of the system?

Oh how about the brakes do your feel they are adequate for the speed of the bike?
 

Claus C.

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Nice job. So are you happy with the overall performance of the bike? Dp you feel the need to get into the setup and fine tune any parameters of the system?

Oh how about the brakes do your feel they are adequate for the speed of the bike?
Thanks. I was very happy with the kit. It was as if the kit was made specifically for my bike a Diamondback Outlook. I watched a number of installation videos before purchasing the kit and remembered a few things not highlighted in the two videos I used to guide me. For example after you insert the motor into the bottom bike frame bracket you attach a small bracket to the motor and then tilt the motor forward and up before tightening it in place. This is not shown on the official installation video. Another small confusing point is the installation of the speed sensor, the official video says one thing and shows something else. At first I was installing it on the wrong side of the bike. This is when I opened a second video.
 
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