Frozen BB7 Caliper?

[sean_iow]

On my ride to work this morning I went to brake and the rear lever wouldn't move. I didn't want to try too hard to move it so nursed it to work with just the front brake. Once at work I had a look and a good pull got the brake on but it didn't release. I managed to move the arm on the caliper back again by hand but it was very stiff. That was at 08:00. I've just been down to the bike shed now at 09:30 (which is actually an outbuilding and warmer than outside as the heat comes through the wall from next door) and it's back to normal and working fine and returns under the power of the spring.

Could it have been frozen? My Garmin said the temp was 0 when I left home and that dropped to -2 by the time I got to work. Anyone else had a similar problem and is there anything I could do to stop it happening again? It's a BB7 Road if that makes any difference and the bike is only ridden on the roads.

[atk]

I've not had them freeze but I have had the hook(?) which traps the inner cable not seated correctly and it's "lip" catch on the body of the calliper when braking, preventing the arm from returning. Same symptoms as you've described, "fixed" itself initially but then came back. Resolved by removing, cleaning and fastening it all back up (+ new inner cable for the hell of it).

[cycleofaddiction]

I suppose it's possible if moisture had got in but cable actuated disc's have always been preferred by some cold weather racers on the Iditarod & Arrowhead!

[sean_iow]

The arm was stiff to move and didn't return fully when I moved it by hand. As I worked it back and forward it got a bit easier to move but still wouldn't return on it's own. Having left it for a bit it now seems fine. I'll have another look at lunch time and if there's noting obvious I guess it's a careful ride home (only 10 miles so not too bad) and then I'll have a proper look and give it a clean and check over.

Luckily I didn't try pulling the lever too hard when I noticed on the ride in as the rear brake would of been locked on and that would of been interesting as I was doing 25mph in the traffic down hill and was only trying to take the edge of the speed as I was catching the queue of cars in front of me. They were stuck behind a tractor and we all ended up doing 15 mph for the last couple of miles on the flat, which made all their dodgy overtakes to get by me earlier all the more pointless as we all got to town at the same time

[whitestone]

There's a BB7 stripdown here - https://plus.google.com/photos/+IhabAwa ... 4583211921

[Trail-rat]

always worth stripping down bb7s and coating moving parts in copperslip.

the threads will sieze up otherwise.

[sean_iow]

Cheers all, looks like I've got some maintenance to do. The bike was new in August and has only done 1000 miles (1006 according to strava) but as the weather is only getting worse it will be time well spent. I'll either be in the cold shed with the head torch (no elec out there) or I could wait until I'm a Celebrity is on and the wife is distracted and sneak it into the Kitchen

[Zippy]

I've had issues before with moisture/ice within cables reducing ability to actuate cable controlled brakes.

I've solved this by being a hydraulic brakes only type person...

[Trail-rat]

significantly more hydraulic brake issues brought on by commuting in winter based on sample size of a shop mechanics worth of work :D - the salt infused road grime eats the caliper and piston.

a dab o copperslip as a preventatitve measure on threads and some light grease in the outers should give you year round braking reliability.

[ScotRoutes]

It's a mystery to me. I've commuted over several cold winters with BB7s and had no problems. My Fatbike also has BB7s and has been out in some pretty severe weather, including camping in conditions so cold there was no running water.

Are you using continuous outers?

[sean_iow]

Are you using continuous outers?

Bit embarrassing that I had too look for a pic of the bike to answer that It's the first bike I've bought new and it just came in a giant cardboard box. Yes it has continuous outers. I didn't think it was the cable but don't know why I thought that and I guess that's the most likely thing to freeze up. I first started single-speeding years ago after having had my gears freeze up twice on a ride due to a frozen cable so should of thought that.

I'll head down to the shed at lunch time to have another look and it's an excuse to look at the bike

I realised the other day that despite the cold and the damp now winter's coming that the worst thing about commuting to work by bike is not heading out into the weather but arriving at work, because at that point I'm then at work and not out on a bike ride

[chris n]

I had this on BB7s last winter. Chainstay mounted brake - then the cable exits downwards and water can get into the outer, especially if the rubber boot on the end is damaged or missing. Grease the cable and refit the seals.

[sean_iow]

I've had a better look at it and the cable does run downward from the caliper so any water would run into the outer. The cable then runs down the chain-stay and under the BB so there is a low point for any moisture to collect. The brake is now free but the action doesn't feel very smooth so I'll grease the inner and hopefully that will improve the action and keep the water out.

Apologies for the poor phone camera picture.

[MarkW]

I had the very same problem on my cable disc commuter this morning! Haven't had a chance to check it out yet.

[sean_iow]

I had a look at the caliper last night but didn't do anything to it as I had an idea to check out to hopefully confirm the exact cause of the issue.

Got the bike out of the shed this morning and both brakes were fine, outside temp of below freezing and a hard frost. Rode off down the road and at the first junction which is only half a mile from home the back brake lever wouldn't move. A quick check of the caliper showed the arm was free and could be moved by hand. Finished the ride with one brake and once at work gave the lever a harder pull and the brake came on... and stayed on which I guessed it would which is why I didn't try it at the side of the road. The lever returned ok so it's definitely the cable which is freezing.

I'll fit a new inner at the weekend and use plenty of grease and hopefully that will fix the problem. I'm trying to avoid fitting a new outer as well as I'd have to re-tape the bars. The bikes only 3 months old so the rubber boots at the caliper are in good condition so I guess it's just the way the cable is routed to finish going uphill at the caliper.

[Cheeky Monkey]

I'm trying to avoid fitting a new outer as well as I'd have to re-tape the bars

You could trim the outer to keep the section under the tape and "re-join" new outer with one of those in-line tension adjusters. Just a thought / potential bodge if grease etc doesn't sort it.

[Bearbonesnorm]

Middleburn cable oilers have always done the trick for me - might not be easy to find now though.

[Gari]

I had the same problem at the weekend with mine, fine when stood still but froze when riding for a while. Pulling the inner out and giving the outer a good squirt of WD40(with the little red nozzle/tube thing) will help as it disperses water.
With regard the outer cable replacement, I fit all my cables on drop bars with inline adjusters. That way I have adjusters, plus I don't need to replace the outer that is wrapped, just from the adjusters to the brakes.



Folks above just beat me to it, those cable oilers work well too.

[sean_iow]

Splitting the outer cable after it comes out from under the bar tape is a good idea. The Middleburn cable oilers look like the favourite at the moment. I've found some on the web and ordered them but whether they are really in stock or just an out of date website we'll find out, fingers crossed as they would be a good thing to have anyway to keep the cable running freely. If no longer available I'll have to make one or something similar.

[sean_iow]

Just a quick update on the frozen brake. It's taken this long to get the right weather conditions to know (hopefully) it's cured.

I changed the inner (easier to fit a new one than try and get an old one back in) and when I fitted the new one I coated it in oil as I threaded it into the outer and also greased under the rubber boot at the calliper end. That was early December but I didn't want to post I'd fixed it until I was sure.

It's taken until now for the bike to have been ridden in the rain/on wet roads to make sure the cable was getting wet and then have a morning commute where the temperature was below freezing. Rode in this morning and the Garmn said 0 deg and the brake still worked fine It must of been moisture in the outer at the low point which was freezing and stopping the cable moving. Now it's well oiled and the grease under the boot at the calliper end should also help keep the water out.

[Mariner]

I have had two bits of SRAM kit go wrong recently.
My forks were found to have been overfilled with oil from new and a BB7 actuator arm detached itself.
The nut on the actuator is supposed to be threadlocked and torqued and has a lock washer.
Looks like SRAM may have a QA problem.

[Pickers]

My forks were found to have been overfilled with oil from new

Count yourself lucky. My Rebas had pretty much bugger all. Knackered in short order.