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Ah the joys of brake bleeds. You shouldn’t be feeling much pressure when pushing through from the syringe. I’ve made that mistake before, so just make sure the bleed port is sufficiently open.
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Had the exact struggles when doing my first hydraulic disc brake bleed, too. Although in my case the results (amount of leakage) were not as drastic, as I'm pretty neurotic when it comes to carrying out maintenance procedures. So for example, I always keep an eye on the hose on the caliper end so it doesn't pop out (I made a note of the connection being flimsy very early on, so I knew it was something to be observed throughout the process).
In the end, what I do is I have the syringe on the caliper end resting on a chair similar to what's shown in your picture, and then play with the height of the workstand so that the syringe rests on the chair without too much tension on the hose, so it doesn't get disconnected so easily on those moments when you can't support the hose with your hand. I know it's a faff and I could probably rig up something to make the bleeding easier (I saw an interesting setup by Free to Cycle on YouTube, which involved using a spray bottle of some sort hanging from the wheel through a metal wire).I also learned the required torque for the hose fastening the hard way, as I noticed some brake fluid on the hose after the first ride. Carefully tightened the hose fitting slightly more and it fixed the leak. I must say I'm still very careful tightening the fastenings when assembling a new brake system, but I think I've gained some confidence now. It especially pays to be cautious on the lever end as stripping the threads on the lever will be much more expensive compared to the caliper. But I have never had leaks from the lever end, even though I'm pretty sure the torque I've set by feel on the fitting is below the recommended torque setting.
Oh, and actually there is a tool bit from Shimano which you can attach to a torque wrench and it appears to be not too costly (https://r2-bike.com/PRO-Adapter-Open-End-Wrench-8-mm-fuer-1-4-Mount). I think the keyword for this type of bit is "crowfoot wrench".
Anyway, it's usually only the first bleed that's the most laborious but after filling the system and doing the first bleed, the Shimano brakes are extremely easy to maintain (if properly bled the first time, they might actually go perfectly fine for two years or more without any maintenance, though they recommend a bleeding to be done once a year). You only connect the partly filled funnel on the lever end and pump the hose to get some air bubbles out, which is basically a 5-minute job.
Edit. also wanted to add that my front and rear have a different bite point even though they should be properly bled and IIRC, I've read similar reports from Shimano users (which is obviously no proof that it would not be a user error...)
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cheekysnaker
coast_turtle
@scarlet
Hydraulic brakes. This is my first (road) set, and I've sort-of been looking forward to them/sort-of dreading it too. And I was right to... Like all things new, it was a complete pain first time around, and I'm not 100% happy.
The hoses were through a few days ago, cut to length and connected both ends. Well. I thought so. The front brake was first; being a shorter run, and pretty much vertical, I thought it would be easier. To get the fluid in/bleed, I have a funnel-cup thing for the lever port, and a syringe and tube for the lower port. I filled both with 20ml mineral oil, and the antics began.
To cut a long and frustrating story short, I probably got half the oil on the floor via a number of booby-traps; the hose pops off the caliper bleed nipple far too easily, and generally once you are squeezing oil at pressure into the system. Sometimes when you are looking at the funnel thing, so you don't spot until half a syringe of oil is soaking your sock. There are torque settings for the hose fastenings, but show me the open-ended torque wrench? So, I thought I had the rear hose properly screwed into the caliper. Apparently not. I discovered when I had filled the non-drive-side chainstay with mineral oil and it started coming out of the BB hole. And the bubbles, the neverending bubbles!
Anyways. I have some lever now. Sadly, the bite point isn't quite the same; the front has a longer pull. But I'm going to leave it for a few weeks, wait for any air to hopefully rise to the top and repeat this wonderful job again.
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