More hydro questions

[benb]

I need to replace the brakes on my son's Trek. It's less than two years old but Trek substituted some no-name brakes during the pandemic. If they'd broken faster it sounds like we might have got Tektro or Shimano replacements under warranty, but we got ~18 months out of them. FWIW both master cylinders are leaking.

I got some SRAM brakes to put on. Not amazing, but I have them on my bike as well, so the commonality is good and there was no way I was putting $400-500 of brakes on a $700 bike he's going to outgrow in a few years.

Now here is the dumb thing.. my son's Trek has internal hose routing for the rear brake. I am seeing everything saying you can actually just cut the hose and route the whole thing with fluid in the hoses.

I haven't dug into this yet but is it likely I can actually route the hose back through the frame without leaking fluid into the frame? This bike came with mineral oil but the new brakes are DOT, I certainly don't want DOT fluid inside the frame where I can't clean it. Is it likely I can route it with the olive/barb in place? That would make it seem more realistic to not spill much.

Overall I think this is super stupid a sub-$1000 MTB has internal routing. It's geared such you can't really even cruise along at 20mph. Aero is zero concern on a recreational level MTB. A lot of the reports on the failing brakes on these are that the factory did a crappy job taking the brakes apart to route the internal cable, a lot of people seem to suspect the factory got the brakes pre-filled and bled and took them apart for routing and didn't replace the barb/olive and then damaged the cheap master cylinder putting it back together.

Thought about letting the dealer do this but it was hundreds of dollars of labor and closer to a month of waiting.

edit: The other thing is SRAM wants the cable shortening done at the lever end.. but the frame seems like it's designed to have things routed the other way. Maybe I get lucky and this frame has a full sleeve.

[.RJ]

You likely cant get the hose through the frame without removing the olive, but you could drain it first before pulling it through and I wonder if shimano or sram has a plastic hose plug for this.

You probably want to fish a cable into the hose and pull it with the hose out of the frame, leaving the cable in place as a guide for routing the new hose. If they route around the BB you'll probably need to remove that too.

Yay internal cables.

[Mark McM]

Originally Posted by benb

I need to replace the brakes on my son's Trek. It's less than two years old but Trek substituted some no-name brakes during the pandemic. If they'd broken faster it sounds like we might have got Tektro or Shimano replacements under warranty, but we got ~18 months out of them. FWIW both master cylinders are leaking.

I'm confused - isn't the Trek Warranty on parts and accesories 2 years? If the bike is less than 2 years old, and the brakes failed due to a defect in materials or worksmanship, shouldn't they be repaired under warranty?

https://www.trekbikes.com/us/en_US/warranty_policy/

[prototoast]

My first choice would be to just get some mineral oil brakes and leave the hose in place.

But barring that, internal routing kits usual include an insert that plugs up the hole while you pull the hose through.

[yinzerniner]

For what you're describing it's a pretty easy swap.
See this vid:
https://youtu.be/p0LZYtdXuhk

Since the adapter is solid, you won't be mixing fluids, nor will you lose that much since the hole will be plugged.

If you want to follow SRAM's suggestion to shorten at the lever, then leave the SRAM hose attached to the SRAM caliper, then cut off roughly 1/2" from both the caliper end of the existing hose and also the lever end of the new SRAM hose. Use the adapter mentioned in the vid to connect the two ends of the hose, then pull through at the front of the bike. Disconnect the adapter, then add a new sram barb and olive, then install into the lever.

Very easy on MTBs, and you'll lose a tiny amount of DOT fluid if done correctly. Kate Copeland's mechanic did in on course:
https://www.instagram.com/reel/CO8wh...JiY2I4NDBkZg==

[benb]

Originally Posted by Mark McM

I'm confused - isn't the Trek Warranty on parts and accesories 2 years? If the bike is less than 2 years old, and the brakes failed due to a defect in materials or worksmanship, shouldn't they be repaired under warranty?

https://www.trekbikes.com/us/en_US/warranty_policy/

I think it might be 2 years since we bought it... not necessarily 2 years of riding.

I'm not going to deal with months of waiting for Trek and/or the shop right in the middle of riding season anyway.

I just ordered one of those Reverb stealth barb connectors, what a great idea. That should make it super easy. Thanks.

[JMT3]

What I have done with replacing internal brake lines is to disconnect at the lever. Cut off the barb and tape a strong string to hose. Put a round tooth pick in the hose and break it leaving enough you can grab it. Pull it thru from the caliper side with the caliper disconnected. Remove the hose from the new brake at the lever side. With two people feed the hose from the caliper mount area and have someone pulling on the string that you should have taped to the new line. Mount the caliper and brake lever. Trip the hose to proper length and insert new olive and barb, mount to lever and bleed the system according to the brake manufacture instruction.

It’s easy and a 15 to 20 minute job taking your time!

[batman1425]

Got to your local big box store and get some screw caps. They'll be in the specialty parts bins in the hardware isle and come in a bunch of different sizes. They have good stretch so you can undersize them and get a tight fit on the end and last time I picked some up, they were 4-6/$1 depending on size. For some extra insurance put a wrap of electrical tape around the end and onto the hose and you're set, route away.

[Dave]

12 gauge copper wire worked to plug the end of my SRAM hoses.

[tkbike]

Mineral oil brakes SUCK in cold climates...

[tkbike]

Sorry for posting this to the wrong forum, ignore but true if you ride in -0 temps.

[benb]

I finally got time to do this. Did I beat the shop by that many days if I'd waited? Not really sure. But now I have everything, and my son and I have the same setups so future stuff is simple. Cost of tools and their labor would have been about the same and now I've done my bike too so I'm ahead. I had to wait for the 2nd brake to come in for his bike and then we were away for memorial day.

The internal routing & resizing was easy. The double sided threaded barb connector was great. Not spilling fluid with the SRAM calipers that don't have "bleeding edge" was terrible/impossible. I get the impression the only learned skill there is containing the spills. I did spill quite a bit less on the 2nd bike but WAY more than other stuff I bled in the past. I used to do my motorcycles and not spill a drop.. Just a cap with no valve might be light but it's the lamest design I've seen in terms of spills. I am curious if the weight of the newer bleeding edge system is lower than the traditional moto-style valves. SRAM levers seem finicky to bleed compared to previous stuff I did. The park bleed kit is very nice though. I am really curious about which kinds of caliper bleed setups are patented or what not that causes this to not be a totally solved problem like it seems to have been on automotive/motorcycle for a very long time.

I need to get some more barbs & collars and resize my MTB. It looks stupid now that I set my son's up to size. Trek didn't size either of our bikes at all, just tons of excess hose. His bike was $700, mine was $3k, I wonder what price point they size hoses at. At $5k and up I would think it's ridiculous not to size the hoses.

This forced me to get the kit and so I did my bike too. The Fluid was still quite clean and was not discolored from absorbing water after a year. No change in tint from fresh fluid. But it definitely needed a bleed, maybe it always did.