Are you trying to decide between a thumb or twist throttle for your E-Bike? Does your thumb get overly stressed during long rides and you wish for some twist-throttle relief? Why not have the best of both worlds by converting your thumb throttle to a dual function control. I ride my 1000 watt recumbent 7 days a week for at least an hour a day. (Photo 1) And my thumb would fatigue or cramp up towards the end of many rides. So I designed this little gizmo which allows me to easily shift from thumb to twist or back to thumb again. You’ll need a welder or someone willing to do two small welds for you. This Instructable assumes you have a thumb throttle already installed on your bike. You will also need a bit of tubing, 5" of 1/4" steel rod, and about 4" of ½" x 1/8" flat stock.

Step 1: Make the End Rings.

Find some tubing with an inside diameter that will just barely slide over your handlebar grips. In my case I used a section of tubing from an old cut up bicycle and cut two “rings”, each about 5/8" wide. (Photo 1) The rings should easily slip onto your grip and rotate freely but not have a lot of slop. (Photo 2) With the rings positioned at or near the ends of your grip, measure the distance to the outside of the two rings. Mine was 4" but yours may vary depending on the length of your grips.

Step 2: Connect the End Rings

Cut a length of ½" x 1/8" steel flat stock to the distance you just measured. Then weld the two end rings to the length of flat stock. (Photo 1) Once the welds cool, test fit the rings over your grip to insure they still rotate freely.

Step 3: Fabricate the Push Rod

Next you need a rod or lever that will push against the thumb throttle just as your thumb would normally do. Some quarter inch steel rod about 4" long will fill the bill. Even a quarter inch bolt will work and will be a bit cheaper if you don’t have any steel rod on hand. Bend the steel rod into the approximate configuration shown in the photo. I did the bending in a large vice and slipped a length of tubing over the steel rod to get the necessary leverage to bend the rod. The idea is to bend the steel rod so that one end lays flat on the thumb throttle and the other end can be welded to the flat stock connecting your end rings. (Photo 1) Once you are satisfied with the bends and how they align with the throttle and the end rings, weld the push rod to the end ring bar. (Photo 2) Test fit the push bar to insure it lays centered on the thumb throttle. (Photo 3) You should be able to rotate the mechanism up and out of the way so that you can easily use your thumb to engage the throttle. (Photo 4)

Step 4: Paint and Install

Give your creation a coat of decent paint and slide it onto your handlebar grip. You will quickly note that you need some way to keep the mechanism from sliding off the end of your grip. This can be accomplished in a number of ways. In my case I was already using an “end mirror” which attaches to the end of the handlebar. The mirror mount works perfectly to keep the throttle control in position. (Photo 1) Photo 2 shows the throttle control in the “up” position for using your thumb to press the throttle. Photo 3 shows the throttle control in the “down” position for use as a twist throttle. I’ve been riding with this dual function throttle lever for nearly a year now and would never go back. While it may appear that the 1/2" cross bar would not fit well in your hand it is surprisingly comfortable. It may help that I always wear riding gloves which help cushion the bar but if you position the bar correctly your palm and fingers will wrap right around it and feel quite natural.