After getting smacked by Bambi 18 months ago and ultimately loosing my right leg below the knee, I'm trying to figure out how to get a thumb brake set up. I've seen some use a m/c off of a kids mx bike and whittle a lever assm. I think that using an atv bend handlebar might allow me to mount the m/c on the backside of the bar on the l/h side. I can then get a brake line fabbed in the correct length to the caliper.
I still enjoy getting out on the trails but a few instances made it REALLY clear that I need to get a rear brake asap.

 

I would go with a recluse clutch or get a new bike with an automatic transmission. Put the brake where the clutch is.
I don't think you will be able to use your thumb for any significant force.
The down side, is you loose engine braking....

 

GpTech LLC - Thumbrakes

 

Damn dude, respect for getting back on the bike! Can only imagine the recovery, but it's awesome to hear you're back on the horse!

 

Those GP thumbbrakes look good. One model will lock the rear wheel. That would be nice in the dirt on right handers where heavy braking is required.
But... if you lock the rear wheel, how do you pull the clutch at the same time?

 

Go flattrack style, but opposite side - Left side brake and shift.

 

Recluse with lever brakes does it all. You can keep a small clutch lever (positioned under the new brake lever)for use when you want it. Engine braking functions normally as long as engine RPM was above idle before you "chopped" the throttle. Otherwise, you have to "blip" the throttle first before engine braking is restored..

Oops, rekluse has no part number for the KLX250S.. http://efmautoclutch.com/ may be the only choice..

 

GpTech LLC - Thumbrakes

Check with GPtech.com they are more used for road racing but offer sever different styles.
Must respect for the remount!

 

Heck yeah, a GpTech BILLET HANDLEBAR+ EFM would certainly do it.. But you'll be spending $1k.

 

This is what you want. It is a duel lever. You pull the clutch lever in to disengage the clutch, pulling it further applies the rear brake. Expensive but...
Clake Pro Lever |