Total brake failure

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BigdummySteve
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Total brake failure

Post by BigdummySteve » Sun Mar 01, 2020 12:53 pm

I’ve just found out that my Dartmoor trip could have been even more dramatic if that’s possible.
Not long after setting off I found the front brake wouldn’t hold pressure, the front lever would slowly come back to the bar. I carried in riding as by pumping it I could get it to work and still had the rear, also due to being mostly underwater, not braking particularly hard.

This morning I’ve had it in the stand, I connected the syringe, bled it then pumped the brake hard looking for the leak. I found it when the hose failed with pop spraying fluid across the kitchen.
The failure point was just after the bar tape and no evidence of any external damage. Following the burst the lever would come straight back to the bar, I suspect that the external cover was all that was providing any pressure transfer.
Considering I hit a maximum speed of 36mph on that ride things could have been very different if I’d needed to brake hard.

Moral? If you have ANY suspicions about your brakes don’t ride until you have checked the system, I consider myself very lucky.

https://flic.kr/p/2izk4iy

https://flic.kr/p/2izmns8
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Bearbonesnorm
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Re: Total brake failure

Post by Bearbonesnorm » Sun Mar 01, 2020 12:58 pm

I once had the pleasure of riding a motorbike on which someone had repaired a split brake line with insulation tape :shock:
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middleagedmadness
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Re: Total brake failure

Post by middleagedmadness » Sun Mar 01, 2020 1:12 pm

Not seen the hose insulation tape scenario but just over the Christmas period got called out to a very large companies trailer with a air leak and brakes locked on , stuck my head under and saw someone had repaired the air tank by wrapping it in insulation tape , told the driver what it was , the reply I got was oh that was done in the workshop before I left this morning :shock:

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htrider
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Re: Total brake failure

Post by htrider » Sun Mar 01, 2020 3:22 pm

There is always the shoe on the back tyre at the chainstay emergency back up brake :???:

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BigdummySteve
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Re: Total brake failure

Post by BigdummySteve » Sun Mar 01, 2020 4:33 pm

New hose fitted, pain in the arse job with dropbars.
Never seen a hose burst before especially mid length.
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ZeroDarkBivi
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Re: Total brake failure

Post by ZeroDarkBivi » Sun Mar 01, 2020 4:42 pm

Hope anchors?

Presumably no indication of external damage to the hose?

Quite bizarre...

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BigdummySteve
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Re: Total brake failure

Post by BigdummySteve » Sun Mar 01, 2020 4:52 pm

SRAM red lever but connected to a Hope RX4 caliper by Hope hose, yes very bizarre, can only put it down to a manufacturing error.
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NewRetroTom
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Re: Total brake failure

Post by NewRetroTom » Mon Mar 02, 2020 2:23 pm

Could the hose have been kinked at some point during installation or use? Just after it coming out of the bar tape could be a risk point for getting folded. You say "no evidence of any external damage" but how can you be sure of that with the hose looking like it does in your photos? Seems very weird for the inner to pop like that!

jameso
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Re: Total brake failure

Post by jameso » Tue Mar 03, 2020 8:36 am

Send the hose back to Hope with a note that you're not "kicking off" etc... See what they say? They may not tell say much but it's good for a manufacturer to understand what can go wrong. Does look odd and it is a serious failure type esp if it was caused by a manufacturing defect. They do happen.

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sean_iow
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Re: Total brake failure

Post by sean_iow » Tue Mar 03, 2020 9:22 am

I can't tell from the picture, but is the inner damaged or just the outer? What fitting have you used on the hose to join it onto the SRAM lever?

The fluid should only be inside the inner clear pipe and not in the outer. If you've used the SRAM fitting onto the Hope hose is there a possibility that the fluid is getting down between the outer layer and the inner hose?
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jameso
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Re: Total brake failure

Post by jameso » Tue Mar 03, 2020 10:17 am

sean_iow wrote:
Tue Mar 03, 2020 9:22 am
I can't tell from the picture, but is the inner damaged or just the outer? What fitting have you used on the hose to join it onto the SRAM lever?

The fluid should only be inside the inner clear pipe and not in the outer. If you've used the SRAM fitting onto the Hope hose is there a possibility that the fluid is getting down between the outer layer and the inner hose?
Good spot, in one pic the inner looks like it's either undamaged or I'm looking through the burst bit toward the back/inside of the inner tube. On a closer look Sean could be right.

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Bearbonesnorm
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Re: Total brake failure

Post by Bearbonesnorm » Tue Mar 03, 2020 10:30 am

My initial thought from simply looking at the picture was that it's become hot ... I'm thinking this isn;t the case but it does look like it's had heat.

RE inner / outer. If fluid has got its way between the two I'd have expected low lever pressure and a fairly obvious leak at the caliper. It looks like the inner reinforcement sheath is also damaged something I wouldn't have expected given that had a leak occured, any fluid pressure between inner / outer would be reasonably low in hydraulic terms.

However, that's simply what I'd expect and what you expect sometimes has no bearing on what actually happened :wink:
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BigdummySteve
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Re: Total brake failure

Post by BigdummySteve » Tue Mar 03, 2020 11:55 am

No heat damage, the outer has been burst by hydraulic pressure, I had to refill the system and keep pumping for it to burst..My expectation was to find a slow leak, initially pressure loss was slow.

hose joined to lever by new SRAM Connectamajig fittings and at the other end by hope barbs and olive, all fittings and hose were new and installed with the new shifters. I even read the instruction for the Connectamajig fittings!
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sean_iow
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Re: Total brake failure

Post by sean_iow » Tue Mar 03, 2020 12:23 pm

But has the inner burst?

I'm intrigued by what might have caused this. I had a Hope hose on a bike that got folded back on itself and creased the outer. Years later it was still in use with no issues other than the obvious damage to the outer. In the end I changed it as I couldn't stand seeing it but it never failed.
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touch
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Re: Total brake failure

Post by touch » Tue Mar 03, 2020 12:54 pm

The end of the bar tape is prime location for clamping things to the handlebars and pinching cables. Have you (or whoever had the bike before you) had aero bars, handlebar harness, light clamps or garmin mount fitted there?

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BigdummySteve
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Re: Total brake failure

Post by BigdummySteve » Tue Mar 03, 2020 4:49 pm

touch wrote:
Tue Mar 03, 2020 12:54 pm
The end of the bar tape is prime location for clamping things to the handlebars and pinching cables. Have you (or whoever had the bike before you) had aero bars, handlebar harness, light clamps or garmin mount fitted there?

no, only thing has been a Velcro strap from a stem cell and hose failed beyond where it sits. I think ill cut the outer sleeved off tonight and investigate further..
There's a place up ahead and I'm goin'
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wriggles
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Re: Total brake failure

Post by wriggles » Tue Mar 03, 2020 4:54 pm

It would be interesting to get Hopes opinion on this. Not something I have ever seen before.

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sean_iow
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Re: Total brake failure

Post by sean_iow » Tue Mar 03, 2020 5:00 pm

I have seen a Hope hose fail before... I used a section with an old gear cable through it and a solderless nipple as an emergency throttle cable on a mate's Mk 3 Ford Cortina estate once :lol: I assumed he'd use it only to get from my workshop back to his on the other side of the Island. It's all I could find lying about.

He kept using it for months before the cable wore through the inner at a tight bend :roll:
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MuddyPete
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Re: Total brake failure

Post by MuddyPete » Tue Mar 03, 2020 7:02 pm

BigdummySteve wrote:
Tue Mar 03, 2020 4:49 pm
I think ill cut the outer sleeved off tonight and investigate further..
Noooooooo! :o

That'll destroy any evidence the manufacturer may find important to its problem resolution process.

Sending it back for the manufacturer to investigate will help it understand the problem. Your "bad luck" could be a precursor to someone else's "bad event". :???:

And they may even send you something nice for your efforts :-bd
May you always have tail wind.

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BigdummySteve
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Re: Total brake failure

Post by BigdummySteve » Tue Mar 03, 2020 8:24 pm

Oops good point, but too late, I only kept a 12” section where the burst was and upon investigation the liner is perfectly intact so it remains a mystery.
There's a place up ahead and I'm goin'
Just as fast as my feet can fly

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