is this possible?

[neanderthal]

was wondering if there is a softail out there with a drum rear brake. would the brake stay be connected to the axle? and as far as linkage goes for the brake pedal? how would you go about that since there will be play with the wheel moving.

 

[TwoManyXS1Bs]

What kind of softtail, like the floating monoshocks?

Well, consider the forces involved. Stopping the total weight of 500 to 700 lbs (depending on bike design/weight and rider), plus a realistic max .85 drag coefficient for street tires, puts max stopping force around 400-550 lbs. Roughly saying that wheel is 2-ft diameter, that means 400-550 ft-lbs of torque on brake to stop (or slow). The xs rear brake drum backing plate torque rod pin is about 1/2 foot from axle center, so it sees double the force, about 800-1100 lbs. Rough it out to 1000 lbs and add typical 100% safety margin, then the torque pin and its mounting point need to handle 2000 lbs of force, in the direction of rotation of the wheel. Best done with torque bar in tension, not compression (risk of buckling).

Now the geometry. Notice how the stock bike's forward end of the brake rod is very close to the swingarm pivot point? This minimizes brake deflection during suspension travel.

You could affix the backing plate torque pin to the swingarm, but it would have to be adjustable to allow chain adjustment.

Is this what you were looking for?

 

[TheRealSpinner]

If he wasn't looking for that, I was; I just didn't know it yet. Thanks!

 

[TwoManyXS1Bs]

Yew betcha...

 

[XSLeo]

All the stock bikes are softails of a sort, nit like Harley's softtail with hidden shocks but still a soft tail.
Most had drum brakes. If you look at the stock rear brake, one end of the strut hooks to the brake plate, one hooks to the swingarm. This holds the brake plate from turning while using the brakes. It also holds the brakes in place as the suspension moves. It also allows the axle to move while adjusting the chain tension.
Just set up your brake the same way.
Leo

 

[neanderthal]

i guess i should have been a more specific about the type of hard tail. i was think of this guy. could you use an axle spaces to double as a break stay? theres no play in the axle so no adjusting ever. it has a chain tensioner on the other side. but what about the foot slack when it moves around? i was thinking a cable might work? just toying around with the idea mostly. i think the shocks would look better on the bottom side of the frame.

 

[JR Roxx]

I'm confused LOL

 

[TwoManyXS1Bs]

Wow, that's interesting, kinda like a mini-swingarm. Notice how the caliper shares the mount post with the shock, plus a link-rod to the axle spacer. A drum setup like this would be an interesting challenge. The backing plate could be attached similar, to the shock mount post. To ensure zero undulation to the brake actuating lever, could mount a belcrank, pivoting on the mini-swingarm pivot point. Everything should orbit/pivot about the mini-swingarm pivot point...

 

[XSLeo]

I'm a bit confused myself, in the first post he asked about a softail, a few posts later he is talking about a hardtail.
In the pic its kinda a half breed thing. Looks kinda like the new springers that have the spring and shock down by the wheel instead of up at the top.
Leo

 

[neanderthal]

well it is a softail. just not a traditional one leo. its not a hard tail. the axle is in place no adjustments needed, a hard tail look with a softail touch. it pivots at the hardtail's end. almost like two mini swing arms on each side. which is attached to a rocker arm. the rock arm holds the axle in place and acts as a shock mount. they used a disc so play with fuild works, im concerned about mechanic brake play when you go over a bump or pot hole. and there the foot control to worry about as well. just trying to throw so ideas around.

two many yeah i think we are on the same page. my concern is that if the swing arm opens, it activate the brake, and once it hits the ground itll put the bike off. or maybe if you hit a speed bump itll step on the break. or if the tire is in the air i wont be able to use the brake safely. good call on the break stay being part of the shock mount. Thanks


side note: didnt realize i called it a hard tail in the post that i posted a photo...sorry guys

 

[TwoManyXS1Bs]

Yeah, a belcrank/linkage would be too complicated/busy. Your idea of brake cable solves all that...

 

[neanderthal]

Ok great. Thanks twomany

 

[warbird]

looks like a zero engineering type9 multilink rear kinda.

 

[jdizon]

Rad concept. Similar to the Zero Engineering type 9 bike.

 

[neanderthal]

yeah thats neat, ill have to do some research on that. i like the one i posted because it looks more like a tradition hard tail.

 

[jdizon]

Well this is how it looks installed. Looks like a traditional hard tail to me

yeah thats neat, ill have to do some research on that. i like the one i posted because it looks more like a tradition hard tail.

 

[neanderthal]

oh yes i was picturing it in my head a little different. thanks for the photo. that gets the head going.

 

[jdizon]

oh yes i was picturing it in my head a little different. thanks for the photo. that gets the head going.

No problem! That Zero-eng bike is a beauty in my eyes!

 

[warbird]

i don't know Jdizon, I've been following your builds, they look pretty awesome to me

 

[jdizon]

i don't know Jdizon, I've been following your builds, they look pretty awesome to me

Thanks man. Appreciate that