[Closed] Fitting New hose and bleed (any difference?)

I would imagine if it's a new brake the fluid should be alright. You should be able to tell by the colour of the fluid that comes out when you start bleeding.

I done similar to an old set of sram brakes a few months ago, needed to extend the hose after I bought them. You could definitely tell the fluid was old. Because it was a new hose I made sure to bleed top to bottom and bottom to top a few times to make sure there was no more air in the system, seems to have worked for me.

The brakes are a few years old but still new and were sealed but is it best to bleed by putting the funnel in the brake lever and pouring mineral oil in to drain down and get rid of the oil in the system first before disconnecting the hose and fitting the new hose. I was thinking just switch the hose over first and then drain the system from brake lever down to caliper into waste bottle, then syringe new fluid in via the caliper and wait till emerges in the funnel then finish the bleed off. Does this sound right, I think its just the fact that I have gotta install a new hose that is causing me some doubt in how I go about the bleed, in which I order I do it.

I would switch the hose over first, it's going to create a huge void of air anyway. Then bleed till old fluid comes out. Don't think you would get all the old fluid out anyway if you did it the other way, and it would be a waste of fluid.

Thanks for the advice, yes I have just had a skim through a few old posts on here and seen a lot of conversation about being careful when pushing the pistons back. I think these are a pretty low end set of brakes, but I heard they work pretty well when set up right so hopefully that is the case. Is there any difference between starting by pouring oil into the funnel at top and letting the oil out through the bottom from the caliper valve or injecting the oil via the syringe into the caliper and going upwards and out into the funnel? As its a new brake system I am assuming the oil will be clean as it has just been left since it left the factory. I guess the key is to not let any air bubbles remain in the system and to get the fresh oil in and the older oil flushed out.

It won't really make any difference. I would just fit the new hose, then fit the funnel to the lever and let fresh fluid gravity bleed through to the caliper. Making sure that the hose is vertical will help a lot. If the lever is still spongy after that, then bleed bottom to top and top to bottom to get out any remaining air bubbles.

Yes, on the video for the bleed kit it starts with letting fresh fluid gravity bleed down to get the oil out via the caliper end and then goes on to show it being syringed in via the caliper and out through the funnel. When adding oil through the funnel side is it needed to press the brake lever or just let the oil flow through. I noticed at the end on the video they press the lever in with a full funnel which is like a mini bleed right?

The brakes are a few years old but still new and were sealed 

As its a new brake system I am assuming the oil will be clean as it has just been left since it left the factory

In theory brake fluid should be replaced roughly every two years regardless of mileage, it can still absorb water from the atmosphere even if sealed inside a braking system.
In practice I've never done this and never had a problem but if I was bleeding anyway for another reason like you are I would do it.

Do not pump the lever while you are gravity bleeding. There's a transfer port in the master cylinder that allows fluid to flow from the reservoir to the master cylinder. As soon as you pull on the lever, the master cylinder piston moves and closes off this port. Having this port closed will stop the flow of brake fluid that you need for gravity bleeding.

If you really can't get a good firm lever feel after bleeding with syringes, you can try squeezing the lever with the bleeder on the caliper closed to pressurize the system, then opening the bleeder to expel fluid, then closing the bleeder before releasing the lever. This will generate much more pressure than a syringe so will get any troublesome air bubbles out of the hose and caliper. You must close the bleeder before releasing the lever though, otherwise it'll just suck air back into the system. Much easier with two people than trying to do it yourself though. Using a strong rubber band or something to clamp the lever might work if you have to do it yourself.

In theory brake fluid should be replaced roughly every two years regardless of mileage, it can still absorb water from the atmosphere even if sealed inside a braking system.

With DOT fluid, the fluid can absorb water, which is dispersed through the fluid. This lowers the boiling point of the fluid. I'm skeptical about the claims that a sealed brake system will allow moisture in, and I've used DOT brakes for many years without flushing the fluid. However, if I was racing DH or riding in the Alps, I would flush the fluid every few months just to make sure it was in absolutely tip-top condition.

The OP has Shimano brakes, which use mineral oil. This does not absorb moisture like DOT fluid. The benefit of this is that you can store the fluid for a long time after opening the bottle. The disadvantage is that, if water does get into the system, it won't disperse throughout the system like with DOT fluid. It will probably collect at the lowest point, which is the brake caliper. That is also the hottest part of the system, so having water collecting there will result in brakes boiling at a much lower temperature than with DOT fluid.

That's all theoretical though, I doubt that any water will be getting in unless you pressure wash your bike and point the nozzle directly at the seals on the caliper or master cylinder. The idea that you will die if you don't replace the fluid every year is a massive exaggeration.

However, tiny specs of debris will collect in the fluid over time as the master cylinder seals, pistons, and bores wear. Replacing the old, dirty fluid with fresh fluid is a sensible thing to do if you're bleeding them anyway.