Can i just flush out old brake hoses when changing oils...???

I would use dish detergent and hot water to flush them rather than brake cleaner, then flush them again with DOT fluid. Brake cleaner is normally used externally, not internally.

Are you sure it wouldn't be safer to hoover them out rather than flush them DrP 😂

I'd use brake cleaner, usually it's either IPA or butane/pentane so will do a better job of cleaning out oil than soapy water, then blow it dry with compressed air.

Are the hoses the same size or do they have compatible connectors?

Are you sure it wouldn’t be safer to hoover them out rather than flush them DrP 😂

LOLZ!!

TBH, I'll probably just remove the calliper and lever, leaving just the hose, then using some syringes pump a bunch of DOT oil through...
That'll work, right...

DrP

EDIT:
"Are the hoses the same size or do they have compatible connectors?"

They seem to! It's an olive at either end, rather than the classic eyelet thing...
OOH... compressed air blast sounds good too.. cheers

Do you know that the Tektro hoses are compatible with DOT fluid? DOT fluids are nasty shit and will quickly knacker seals that are only spec'd for Mineral oil. I'd not risk putting DOT into a previously mineral oil hose unless I was 100% sure, flushed or not.

Ive done this replacing Shimano with SRAM on every bike I've owned. Just taken the bits off the ends and carried on. Bled enough fluid through with DOT 5 and it all works, plus,
No hospital food
No visit to the dentist
Everything works.

It might not be what Elon/Spaceboy might do but, here we are.

DOT fluids are nasty shit and will quickly knacker seals that are only spec’d for Mineral oil.

It's usually the other way around. Mineral oil can knacker seals designed for DOT fluid. However, there are seals that are compatible with both. It's not a case of "will", it's a case of "can."

DOT fluids are nasty shit and will quickly knacker seals that are only spec’d for Mineral oil.

..but there are no seals in a bit of hose... only in the working ends...

And all HOSES seem to be sold for shimano/SRAM anyway - it's just the caliper/lever with seals and moving gubbings...

DrP

Whilst it'll probably work, is it really worth the risk for a few quid and an extra half an hour? Get yourself a barb connector to join the old and new hoses to pull the new one through.

..but there are no seals in a bit of hose… only in the working ends…

Granted, but there is some kind of polymer liner. Material compatibility is not a straightforward science, I was just pointing out a potential issue that no one else has raised. My cousin has a Citroen 2CV that a garage put DOT fluid in the brake system that was designed for LHM (which is mineral). They picked up the tab for replacing all the callipers and master cylinder a few weeks later.

Sounds like rickmeister has genuine experience though so likely a non-issue.

You don't need very much of the wrong fluid to completely bork your caliper seals.

I've seen it happen on cars (my job) at less than 1% contamination.

I would buy new hoses, and sell the old hose with the old brakes, just for peace of mind.

FWIW the hoses are just hoses, they come off a reel the size of an elephant in a factory in which ever country your brakes were made.

The issue can be some materials can absorb a small amount of what ever is in them. Dunno if it'll happen with brake fluid, especially with the pressures/temperatures you see in there. But you might get some weird contamination effects.

TBH, i'd just swap them for the cost of ~3m of hose of the reel somewhere, especially if you've got all the fittings to hand.

I suspect by the time you flushed them thoroughly you could have just pulled a new hose through..

May also be worth noting that Tektros have their own type of barb, which comes with a rubber seal fitted. I'd probably get a new hose.

Chop up the old hose into relevant short lengths, and sell on with small amounts of surplus mineral oil as the DrP ear syringing kit.

FWIW the hoses are just hoses, they come off a reel the size of an elephant

African elephant or Asian?

I have just flushed through with dot 5 when replacing my Shimano brakes with Hope brakes,never had any issues.

I have just flushed through with dot 5 when replacing my Shimano brakes with Hope brakes,never had any issues.

DOT 5 fluid is silicone based. I think you mean DOT 5.1, which is glycol based. You can mix DOT 5.1 with DOT 4 or DOT 3 fluids, but none of those can be mixed with DOT 5. AFAIK, Hope use DOT 4/5.1, not DOT 5.

The tektro hoses are really horrible, stiff, plasticky things. Ive never tried, but I feel like they won't play nicely with the SRAM olive and barb connectors. You definitely don't be able to use the tektro fittings; they're a completely different shape.
For the sake of the price of a barb connector, just pull new ones. It'll almost certainly be less hassle.

FWIW I use Dot 5.1 not 5 as I said above.... also the red connectors and barbs are available on Wish etc for a fraction of the price for a pack of 10 and I reckon they are identical...

Cheers all...
I've got new barbs and olives etc ...
But.. I'm NOT going to be lazy and have ordered new hose...

Thing is on ebikes it's a HUGE faff as all hoses and cables from front to back are clamped/glued/bolted to all the battery and motor gubbins.. so not just a case of pulling through...
Sigh!

DrP

Thing is on ebikes it’s a HUGE faff as all hoses and cables from front to back are clamped/glued/bolted to all the battery and motor gubbins.. so not just a case of pulling through…

Don’t tar all e-bikes with the same brush… I asked exactly the same question as you and got the same answers. The new hose just pulled straight through my Rise without any of the extra faff I was expecting.