Bike build issues (disc brake woes)

[lavi]

Yo. I need some pointers/advice. Hold the snark plz. I know, rim brake is better. However, this is an AR bike where I go between 700c and 650b, thus the disc use.

My frame routes the rear brake through the (T47) bb. I was hoping to use mech disc, Klampers. Rest of the group is Red AXS.

The routing through the bb has the brake housing making some tight turns. I currently cannot get the brake cable to go all the way through the housing. Running the cable from rear to front ends up with what feels like there's going to be lots of drag on the cable. That's if I can even get the cable in properly. Bummers.

So, any thoughts/ideas/tip/tricks on getting the cabling to work?

Else, I may have to punt and go hydro. Not my pref, but it is what it is.

[icepick_trotsky]

Have you tried running the cable through the housing first and then feeding them through the frame together?

[weaponsgrade]

I'd try segmented housing as it allows for tighter turns.

[batman1425]

^^ This. If that doesn't do, may have to go hydro.

[lavi]

Originally Posted by icepick_trotsky

Have you tried running the cable through the housing first and then feeding them through the frame together?

Nope. I could try that, but would have to pull the crank and bb apart to get back in there.

Originally Posted by weaponsgrade

I'd try segmented housing as it allows for tighter turns.

Gracias. That's an option to try before going hydro.

[mtechnica]

Housing above or below the spindle? Is the drag around the BB area or the chainstay?

[slowpoke]

As an aside, if you're still going to route the rear brake cable through the BB, be careful that it doesn't rest against the crank spindle. I've seen a few photos where the housing has worn a groove into the spindle.

[Mark McM]

Originally Posted by slowpoke

As an aside, if you're still going to route the rear brake cable through the BB, be careful that it doesn't rest against the crank spindle. I've seen a few photos where the housing has worn a groove into the spindle.

Some BBs have sleeves over the spindles specifically to prevent that. Campagnolo calls their BB sleeve an "EPS cable guide". This sleeve has large holes in it so it doesn't keep out dirt or water, it just prevents hoses/housings/cables from contacting the spindle.

[Mark McM]

Originally Posted by mtechnica

Housing above or below the spindle? Is the drag around the BB area or the chainstay?

I was going to ask the same thing. My (one and only) bike with cables/hoses run through the BB shell runs them over the BB, which seems to provide a straighter, smoother run.

[lavi]

Originally Posted by mtechnica

Housing above or below the spindle? Is the drag around the BB area or the chainstay?

Housing is below the spindle. When initially figuring things out, having the housing go over the top seemed like more of an issue. Pretty sure cable is hanging up at the BB as that's where all the bends are.

Originally Posted by slowpoke

As an aside, if you're still going to route the rear brake cable through the BB, be careful that it doesn't rest against the crank spindle. I've seen a few photos where the housing has worn a groove into the spindle.

Ya. This is a Sram T47 bb...so there's a sleeve. Without the sleeve, there'd be lots more room in there for routing. Then there would definitely be the issue of the housing rubbing the spindle.

Originally Posted by Mark McM

I was going to ask the same thing. My (one and only) bike with cables/hoses run through the BB shell runs them over the BB, which seems to provide a straighter, smoother run.

I may need to rip it apart and see what else I can sort. It did seem a harder route over the top. The hole in the bb shell is smaller than the chain stay. The hole is a rectangle shape...but oriented more towards the base of of the bb shell. So the lower route is likely the necessary route.

[XXtwindad]

Originally Posted by lavi

Yo. I need some pointers/advice. Hold the snark plz. I know, rim brake is better. However, this is an AR bike where I go between 700c and 650b, thus the disc use.

My frame routes the rear brake through the (T47) bb. I was hoping to use mech disc, Klampers. Rest of the group is Red AXS.

The routing through the bb has the brake housing making some tight turns. I currently cannot get the brake cable to go all the way through the housing. Running the cable from rear to front ends up with what feels like there's going to be lots of drag on the cable. That's if I can even get the cable in properly. Bummers.

So, any thoughts/ideas/tip/tricks on getting the cabling to work?

Else, I may have to punt and go hydro. Not my pref, but it is what it is.

Caveat: this is (hopefully) not snark. Just a middle-aged Roleur’s opinion.
You’ve already committed to winning ugly. Discs are very high-functioning but are an aesthetic blight. Think of them as the braking equivalent of the late Eighties Detroit Pistons. They will get you to the finish line (bottom of the hill) seamlessly. They’re just no fun to look at.

So, why not go “Full Laimbeer” and go hydro?

[mtechnica]

On both of my bikes I had to run the hose under the spindle, they're both hydraulic though. The tightest bend IMO on my bikes may be where it comes out of the chainstay and into the caliper. I'd try what others said and run the inner cable first then put the whole thing through. And hey, at least the BB is threaded not a press fit! lol...

[lavi]

Originally Posted by XXtwindad

Caveat: this is (hopefully) not snark. Just a middle-aged Roleur’s opinion.
You’ve already committed to winning ugly. Discs are very high-functioning but are an aesthetic blight. Think of them as the braking equivalent of the late Eighties Detroit Pistons. They will get you to the finish line (bottom of the hill) seamlessly. They’re just no fun to look at.

So, why not go “Full Laimbeer” and go hydro?

Oh I hear ya. I'm not afraid to "Laimbeer" the **** out of this thing. I was just hoping to go mech disc. On top of that, I'm incredibly inpatient when it comes to this stuff. I just got done waiting for the frame. Now, I want it built and get some miles on the pig.

Main issue is that going hydro means dealing with the dearth of frigging parts. First world problem for sure!

Originally Posted by mtechnica

On both of my bikes I had to run the hose under the spindle, they're both hydraulic though. The tightest bend IMO on my bikes may be where it comes out of the chainstay and into the caliper. I'd try what others said and run the inner cable first then put the whole thing through. And hey, at least the BB is threaded not a press fit! lol...

True. Before I punt to hydro, I'll pull the thing apart and try that. I do think there's going to be some big time cable drag. So, I may also try the jagwire linked solution too.

If those attempts fail, hydro here I come.

[charliedid]

Hydro yo.

Originally Posted by lavi

Yo. I need some pointers/advice. Hold the snark plz. I know, rim brake is better. However, this is an AR bike where I go between 700c and 650b, thus the disc use.

My frame routes the rear brake through the (T47) bb. I was hoping to use mech disc, Klampers. Rest of the group is Red AXS.

The routing through the bb has the brake housing making some tight turns. I currently cannot get the brake cable to go all the way through the housing. Running the cable from rear to front ends up with what feels like there's going to be lots of drag on the cable. That's if I can even get the cable in properly. Bummers.

So, any thoughts/ideas/tip/tricks on getting the cabling to work?

Else, I may have to punt and go hydro. Not my pref, but it is what it is.

[Clean39T]

I wonder if you could dremel some relief in the sleeve so that it keeps the hose off the spindle, but just barely. I've seen some sleeves that are concave instead of straight across. Campy uses what looks more like a cage to keep EPS wires off the spindle.. Just a thought.