Front brake only question: both levers to 1 caliper?

[cheapvega]

Looking to ditch the rear brake on my first hydraulic disc build. Don't need crazy braking power and the front does the heavy lifting anyway. My question is whether I can link both brake levers to the front caliper. I'm imagining some kind of 2 into 1 check valve, and I'm guessing I could only use one lever at a time? If that doesn't work, what could I use to cap off one of the levers so it's not all floppy?

[Butcher]

Not familar with disc brakes on bikes, but if it's a sealed system, then you should be able to run two master cylinders to one caliper.

If, like cars, it has a fluid reservoir, then I don't know how that will be possible. Check valves certainly would not work.

[mikehhhhhhh]

You should be able to just T off a line - that's what you'd do in a car brake circuit when adding a hydraulic handbrake for example.

You'd be able to use both at the same time, you'd just find you got half the travel on each lever (on the assumption of linear actuation, be slightly different for servowave)

Finding a T-block/manifold for your brake lines would be the tricky bit. Easily made, I suppose. I wonder if that's something you might find on recumbant or handicap bikes?

[Vjl]

Not sure that will work! Not sure what will happen when line pressure builds in the unpulled lever. It may damage piston.

[Beebsta]

If that doesn't work, what could I use to cap off one of the levers so it's not all floppy?

If this is the only reason, you could leave like 1-2 cm of brake hose, screw in a tiny regular screw at the end and then fill the brake with oil in regular fashion. Even if you would push the lever, the presure would not be high enough to eject the screw.

[MarkMcM]

I don't think connecting both levers to a single caliper will work. Most bicycle hydraulic disc brakes use a semi-open system. The lever contains a small fluid reservoir (usually an expansion bladder), which is connected to a port in the master cylinder. As the lever is pulled and the master cylinder is compressed, the port to the reservoir closes and the fluid pressure in the master cylinder actuates the caliper. when the lever is released and the master cylinder expands, the port is opened again, allowing extra fluid to enter the system from the reservoir, to make up for brake pad wear. If two levers are connected together, and only one lever is pulled, it may push fluid through the port and into reservoir of the other lever, instead of actuating the caliper.

[jch3n]

My question is just whyyyy? A rear brake is still helpful for modulating speed.

[Sin2000]

Not sure where in the world you are but in the UK it is a legal requirement to have two working brakes on a bicycle - and for good reason. If one fails, you still have an alternative means of stopping.

[cheapvega]

I don't think connecting both levers to a single caliper will work. Most bicycle hydraulic disc brakes use a semi-open system. The lever contains a small fluid reservoir (usually an expansion bladder), which is connected to a port in the master cylinder. As the lever is pulled and the master cylinder is compressed, the port to the reservoir closes and the fluid pressure in the master cylinder actuates the caliper. when the lever is released and the master cylinder expands, the port is opened again, allowing extra fluid to enter the system from the reservoir, to make up for brake pad wear. If two levers are connected together, and only one lever is pulled, it may push fluid through the port and into reservoir of the other lever, instead of actuating the caliper.

I don't know all the ins and outs of bike brakes but this is what I figured. It can work for 1 lever to 2 calipers (like on my motorcycle) but not the other way around unless the system is closed or both levers share a reservoir.

My question is just whyyyy? A rear brake is still helpful for modulating speed.

If I did huge long descents I'd agree on keeping both, but truthfully the only times I use my brakes are at stop signs/traffic lights and when I pull into my driveway. Not a lot of elevation here. And to be honest I don't use the rear brake on my motorcycle much either, even at the race track. Rear brake only seems useful to me as another heat sink on long descents.

[js]

Shimano make an inline brake / 'chicken lever' that works with any of their lines:
https://bike.shimano.com/en-EU/product/ ... 812-R.html

If you don't mind having it away from the lever, but just want to have the option to use the off hand to brake, that could be an option. I've also seen lots of para-riders who do it the other way from what you're asking, to have one lever activating two callipers, so there are ways to split lines with normal levers too.

But I gotta say, I live in likely the flattest place on Earth and I'd never want just a front brake. Fresh rain, loose gravel, off-camber roundabouts, etc - there are way too many reasons to want more control than front-only braking. Nope, nope, nope.

[cheapvega]

IDK maybe I'm being overconfident. But I rode w/nothing but a front brake for years (admittedly on a fixed gear), and literally locked up the front tire on my motorcycle multiple times at a wet race track w/o crashing. Everything on the pedal bike is super tame compared to that. I will use the right brake lever for that muscle memory and practice some hard stops but I think it will be fine. Like my last ride had only about 800ft of climbing over 14 miles. Nothing crazy

[js]

Do you always drink with your left hand? If not, that could have an impact on when you get to drink, especially if you're in a bigger city. Even with two brakes, I still chose my moments to hydrate carefully when I lived in London.

[Karvalo]

IDK maybe I'm being overconfident. But I rode w/nothing but a front brake for years (admittedly on a fixed gear),

That means you had a rear brake...

[wltz]

I guess it could have been worse… From Gumtree UK.


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[usr]

Do you always drink with your left hand? If not, that could have an impact on when you get to drink, especially if you're in a bigger city. Even with two brakes, I still chose my moments to hydrate carefully when I lived in London.

You don't want to brake with only one hand on the bar. I have three days in a hospital missing from my memory and I'm pretty sure that single-handed braking is how they started (operating a camera with the other hand - when you do things like that, keep the fingers off the lever!)