brianinc-ville

Hi, all. Advise me on bleeding hydraulic brakes, particularly the front brake, on a front-loading cargo bike? I'm about to try it for the first time with my Douze, and I'm concerned that because the bike is too big to put on a repair stand or pick up and move around, I won't be able to get the brake lines at the optimal angles to get all the bubbles out. How do you do it?

cxwrench

Don't overthink it, just bleed the brake. You can always remove the caliper and put it on the ground and take the lever off the bars and hold it as high as you can get it. It's not critical.

Iride01 

It also helps to get the brake manufacture's instructions. Shimano's will be found here..... https://si.shimano.com/#/

And for video and other documentation, this place does a great job of telling you how to do it.

https://www.parktool.com/blog/repair-help

Random vid's on youTube, even some of the best produced are done by those that really shouldn't be allowed near a bike with a tool in their hand.

But how much help do you think you are going to get since you don't tell us what brake you have, brand and model of bike or any details. My hydraulic brakes may not be your hydraulic brakes. They only work on the same principle. They don't have the same design.

brianinc-ville

Thanks, but that's not the point. All the directions you link there are for normal bikes. As I mentioned, I'm talking about a Douze cargo bike here -- which is a bakfiets-style frame, more than 8 feet long in total, with a very long brake hose running to the front wheel.

Iride01 

Why would a very long hose matter? It might require you to waste more fluid trying to push any air in the lines out.

veganbikes

No real difference unless you have a non-standard brake but I cannot believe that Douze would use something non-standard, they use Bosch motors and make what look to be a nice product from what I remember seeing when I last looked. I think you can just do it like a normal bike that is what we do at the shop with all the similar bikes.

brianinc-ville

No, it's a standard brake (Tektro Gemini). When you're doing a front-brake bleed on a cargo bike, do you usually have to take the hose entirely off the bike, in order to get the air out of it? Or can you get by with just taking the caliper off and taking the hose off the fork?

veganbikes

No we don't generally take a hose off we try to do the path of least resistance. I would say if you didn't have a proper stand to put it into (we are lucky as we have the electronic lift stands from Park at the workplace) then yes I might consider removing the caliper as cxwrench said but I don't know that I would worry a ton about that. We certainly don't and we want to make sure these bikes leave safe plus having to take them back in and store them and work on them is a pain and a lot of these folks aren't super near the shop or aren't near enough they are comfortable riding.

When in doubt ask the local shop that sold it to you and see if they can help out, save you some hassle and headache. I personally don't mind bleeding brakes but for a big cargo bike I would not want to do it at home, those things are heavy and my stand can't really handle it at home and I don't have the set up for the park stand nor the money.

Iride01 

When bleeding brakes on a motor vehicle they have much longer and much wider brake lines. Yet the air bubbles still get pushed down the brake lines and out the lower and further away caliper body. At least they did when I was DIYing my own vehicles 20 years ago. Maybe the physics involved isn't the same, which I highly doubt. <grin> But we also could push the fluid from the brake calipers to the master cylinder too. So if one way didn't work the other would.

Probably on your brakes you can do that too. But first, find the procedure recommended for your brand of brakes and brake lever. Hopefully they are the same brand so there won't be a conflict of design that might make one way of bleeding them ineffective.