A few disc brake questions

Aug 14, 2019
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I'm planning a future project and have some disc brake questions. Things to consider in my plans,

First it's not planned to be more than an occasion rider, basically a fairground queen, or ride around the immediate neighborhood.

It will be a trike, each back wheel will weigh between 12-15 lbs.(18 x 9.5 x 8 tires), so figure 40-50 lbs. of rolling weight, I have no idea how much the entire bike will weigh, but it's going to be pretty heavy.

I'm not sure if I will run a front brake. I will have to move the BB forward quite a bit, so I need to get the front wheel forward. My options are a bent springer (I don't trust putting a brake on it), or an extended triple tree style, with disc brake. To use the TT style fork, I will need to rake the head to keep the frame where I want it, I'm not sure I want to do that on this bike. Most of the weight will be over the rear wheels, and I plan to run a very narrow 20" front tire.

My idea is to use two brakes on the rear axle. I'm hoping I can find a way to mount the rotors to each wheel hub, so even the non drive wheel will aid in braking.

I hope some of you can help me with the following questions.

1- What is the bolt circle diameter of the rotor screws?

2- If I can mount the brakes to both wheels, can a double cable lever be used to activate both brakes. My concern would be them working equally/ staying in "balance".

3- Would hydraulic be a better choice to have equal back brakes? If they could run off a tee at the rear axle, will one lever power both brakes adequately?

4- Would you be concerned with having a front brake with what I've described so far?
 
Jul 30, 2013
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Far from an expert, but it looks like a BCD of either 44mm or 48mm are most common.
bcd.jpg

Just an opinion, but cable actuated disks might be very tough to synchronize. The hydraulic system you describe ought to self-balance and, in theory, alleviate that concern, while it introduces another...a single point of failure. I can't provide all the answers, but at least you're asking the right questions.
 
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Apr 20, 2009
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Had a tadpole trike at one time with 2 separate brakes, one on each side. Stopped fine, even though prone to doing stoppies. That wouldn't be a problem with the paired wheels in the rear.

edit: if pulling to one side squeeze the other side harder.
 
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Most trikes only have a front brake, you could probably set up a disc brake hub as a mid-drive. Use a rear wheel hub and make whatever drive wheel fixed. Either way, you'll need a way to mount disc calipers. You could also use a axle from say a shifter cart that has a rear disc.

Most triple tree style forks are adjustable so you can raise and lower the fork legs. Also wondering why are the wheels going to be so heavy?
 
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