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-   -   Mtn bike w/ hydraulic brakes -- one lever to two brakes? (http://www.bikeforums.net/adaptive-cycling-handcycles-amputee-adaptation-visual-impairment-other-needs/882253-mtn-bike-w-hydraulic-brakes-one-lever-two-brakes.html)

mconlonx 04-06-13 09:38 AM

Mtn bike w/ hydraulic brakes -- one lever to two brakes?
 
Looking for a solution for someone with multiple left hand finger amputations.

He can work a shifter on the left side OK--still has thumb--but definitely not a brake.

I know we could swap over to cable actuated disc brakes and go with either a cable splitter or one of those two-cable brake levers.

Anyone know of solutions for hydraulic brakes?

centralks 04-06-13 09:13 PM

If you went to a good auto parts store with the fittings they could make you a y fitting to split one line to the front and back but then you would be locking the rear brake as it would be getting the same line pressure as the front. You could try to switch to a very poor pad in the back to counter this. Maybe...

Or, buy another right side lever and cut most of it off to use one finger on it for the rear. I broke my left wrist once and ran my motorcycle with the front brake, clutch, and throttle all on the right for a while.

mconlonx 04-07-13 07:17 AM

Quote:

Originally Posted by centralks (Post 15479002)
If you went to a good auto parts store with the fittings they could make you a y fitting to split one line to the front and back but then you would be locking the rear brake as it would be getting the same line pressure as the front. You could try to switch to a very poor pad in the back to counter this. Maybe...

Or, buy another right side lever and cut most of it off to use one finger on it for the rear. I broke my left wrist once and ran my motorcycle with the front brake, clutch, and throttle all on the right for a while.

Research tells me that a simple Y or T fitting won't work -- effectively halves the travel and pressure being applied at each caliper. Probably would need an aftermarket, maybe motorcycle?, lever and master cylinder, where the piston is x diameter with y stroke = same force a bike brake lever applies x 2.

I was just brainstorming a double-lever solution like you mention this AM. He's running Shimano brakes, which should have easy reach adjustment... so maybe just moving one further inboard and futzing with the reach adjust on both would be a first option...

tigat 04-10-13 06:48 PM

Magura makes a hydraulic caliper brake system that converts a traditional cable into hydraulic by feeding it into a compressor box mounted on the stem. Front and rear cables from the levers attach on the sides and each has a dedicated cylinder. Pricy and not specced for disks, but the principle looks like it might work for two cables off a single lever or through a splitter.

Bezalel 04-17-13 02:56 PM

Quote:

Originally Posted by centralks (Post 15479002)
...but then you would be locking the rear brake as it would be getting the same line pressure as the front. You could try to switch to a very poor pad in the back to counter this. Maybe...

Maybe using different disc sizes can be used to get the right balance of braking power.

hotbike 04-22-13 11:27 AM

Put the front brake handle on the right, and install a Coaster Brake on the rear wheel.

tigat 05-11-13 06:44 AM

Update to earlier post
 
Quote:

Originally Posted by mconlonx (Post 15476982)
... I know we could swap over to cable actuated disc brakes and go with either a cable splitter or one of those two-cable brake levers.

Anyone know of solutions for hydraulic brakes?

After earlier posting on the Magura cable to hydraulic converter for rim brakes, I stumbled upon the TPR Parabox. Appears to be a similar concept to the Magura (front and rear cables into the box mounted under the stem, hydraulic lines out), but specifically mated to their disc brakes and less expensive than the Magura. As a one handed rider who spent 30 years wrestling a big steel frame to a halt with first a single front brake, and later pulling two cables with a bar mounted lever and splitter, often with a trail a bike in tow, the notion of stopping more efficiently with boosted effort is somewhat attractive. If it can be accomplished without changing the nature of the bike (coaster brake on back), or trying to understand how to balance a fairly complex fluid pressure equation, all the better. Would love to see, hear what you can come up with.

esther-L 05-27-13 04:19 PM

There are some solutions listed at http://www.mtb-amputee.com/bikemodifications.htm for modifying brake and gear controls on bicycles. There are some examples for putting both brake controls on 1 side of the handlebars.

Honza 06-22-13 04:46 AM

What about Hygia Multi http://www.hygia.com.tw/prod-brake01-4.htm?

zaroba 06-25-13 04:48 PM

Quote:

Originally Posted by centralks (Post 15479002)
If you went to a good auto parts store with the fittings they could make you a y fitting to split one line to the front and back but then you would be locking the rear brake as it would be getting the same line pressure as the front. You could try to switch to a very poor pad in the back to counter this. Maybe...

Would just need to restrict the flow of hydraulic fluid to the rear brake so it has less force.

Similar to how cars work. The single brake pedal in a car brakes all 4 wheels, but it's something like a 70/30 split in power between the front and rear brakes. Not enough to lock the rear wheels, but enough to aid in stopping and aid in braking while cornering. Only really notice it if it's not working and it gets fixed, car will suddenly stop a lot faster with the same pressure on the brake pedal and will feel smoother when corning while braking.


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