Stopping A Bb7 Flexing/best Hydro Disk?

[aener]

So I hear it's a pretty frequent thing to happen when BB7s get older...

The piston that actually moves in to the rotor pushes hard enough that the side with the stationary pad begins to flex over, rather than holding in place and just clamping the rotor.

First off - does anyone know a way of stopping this happening?

I've taken it apart and nothing's broken, put it back together and done the bolts up SUPER tight - but it's still happening.

If no-one knows how to fix it, I'm after advice on hydraulic disks.

Never had one before, so don't know much about them.

Obviously thought "Hope" straight away - but I don't have that much cash.

Was wondering if there's any particularly good-for-trials Magura disks, or Hayes, or anything without Hope's pricetag.

I hear the Bikehut ones are pretty damned decent - but I don't wanna waste this cash. Can anyone confirm this? If so - what model?

Thanks a bunch

[Kieran Morrison]

So I hear it's a pretty frequent thing to happen when BB7s get older...

The piston that actually moves in to the rotor pushes hard enough that the side with the stationary pad begins to flex over, rather than holding in place and just clamping the rotor.

First off - does anyone know a way of stopping this happening?

I've taken it apart and nothing's broken, put it back together and done the bolts up SUPER tight - but it's still happening.

If no-one knows how to fix it, I'm after advice on hydraulic disks.

Never had one before, so don't know much about them.

Obviously thought "Hope" straight away - but I don't have that much cash.

Was wondering if there's any particularly good-for-trials Magura disks, or Hayes, or anything without Hope's pricetag.

I hear the Bikehut ones are pretty damned decent - but I don't wanna waste this cash. Can anyone confirm this? If so - what model?

Thanks a bunch

Bikehut cable discs are awesome, got one sitting right here if you want it. no lever, works fine, no contamination or anything, £10 + postage if your interested?

[aener]

Bikehut cable discs are awesome, got one sitting right here if you want it. no lever, works fine, no contamination or anything, £10 + postage if your interested?

Can you define "awesome" at all? What size is it?

I've got a +20mm disk mount, so would depend on adaptors etc.

I've lost a section of my right index finger, meaning I can't get the same sort of leverage on a front brake. I like piling in to the front wheel quite a lot, too. 203mm BB7 on a mod was OK until it went shit.

If it's as good as that, I might be interested.

[Kieran Morrison]

Can you define "awesome" at all? What size is it?

I've got a +20mm disk mount, so would depend on adaptors etc.

I've lost a section of my right index finger, meaning I can't get the same sort of leverage on a front brake. I like piling in to the front wheel quite a lot, too. 203mm BB7 on a mod was OK until it went shit.

If it's as good as that, I might be interested.

Its 185mm i think, will check tommorow for you mate, it was great, good hold, decent bite and modulation

[Matt Vandart]

Bike hut hydro discs are good.

Tektro also

and shimano are awesome.

They also wont piss oil all over your discs like hope.

Having said that I always use hopes because they are the best when they work.

[Dan6061]

I've never understood why, but my BB7 always feels a lot stiffer with the barrell adjuster on the lever wound right it! I've set it up with the adjuster right in on the lever, then adjusted the lever pull on the red dials, but it was just mush.

Also, when I took my BB7 apart ages ago, I only had 1 ball bearing in the caliper, and saw room for another 2, so I found 2 the same size, and put them in too. The brake felt a lot more solid after that, as it was like the caliper was kept flat when pulling the brake, as apposed to it 'leaning over' on the one BB in there..?

Made sense to me anyway, and I think it payed off!

[aener]

I've never understood why, but my BB7 always feels a lot stiffer with the barrell adjuster on the lever wound right it! I've set it up with the adjuster right in on the lever, then adjusted the lever pull on the red dials, but it was just mush.

Also, when I took my BB7 apart ages ago, I only had 1 ball bearing in the caliper, and saw room for another 2, so I found 2 the same size, and put them in too. The brake felt a lot more solid after that, as it was like the caliper was kept flat when pulling the brake, as apposed to it 'leaning over' on the one BB in there..?

Made sense to me anyway, and I think it payed off!

Thanks for all that. Unfortunately, I've already got it like that/done it already

[Revolver]

I guess you've done all the new cable and stuff.

Rather than going for something you're unsure of, you could get another BB7

[aener]

I guess you've done all the new cable and stuff.

Rather than going for something you're unsure of, you could get another BB7

Have done, yeah.

That's what I thought last time... This is my third, and they've all done the same.

[BlueSmokeyJoe]

If you do decide to go Hope, get yourself on ebay. I bought an 05 (all black/silver bore cap) one that is the 180mm model for £50. Currently running it on a mod and its insane! The bite is incredible and the hold, just as good. Compared to the newer style (which I have on my 26") the older one feels more powerful. The modulation is also great which makes it very easy to roll down stuff, and control the bike for front end moves.

My current set up is all standard (lever/pads/disk) with the only modification being the fork disk tabs being faced to allow the caliper to sit fully perpendicular to the disk

Hope this helps (sorry for the pun )

[Matt Burrows]

Have done, yeah.

That's what I thought last time... This is my third, and they've all done the same.

Is it a new compressionless (linear) outer cable? All cables will get flexier over time, especially linear cables. Is it set up perfectly square, with both pads making full contact with the rotor? Also is the caliper offset correctly relative to the rotor (offset towards the outboard pad with the inboard pad wound in and nearly touching)? Both of those can make a huge difference to how it feels. What lever have you got and does it have adjustable leverage?

Just seems wierd for it to get flexier over time, its not something I've ever noticed or heard of before. I can't think of anything in the caliper which would cause it really, whereas there are lots of other parts to the system which can make a big difference to how stiff it feels. The only problem I have had is the ball bearing races getting worn, which causes the caliper to jam when you pull it hard

At the end of the day a BB7 is always going to be flexy compared to a hydraulic because of the cable. The cable is the biggest source of flex in the system. Its only really a problem if you notice it affecting the power of the brake, which it never has for me. I have my lever set halfway between min and max leverage, so it could be stiffer if I wanted but i find halfway feels much better.

If you do decide on hydraulic I would stick to the trials Hope. Some people will say other brakes perform well, but I think a rider of your ability will be disappointed with anything other than a Hope.

[Krisboats]

Is it a new compressionless (linear) outer cable? All cables will get flexier over time, especially linear cables. Is it set up perfectly square, with both pads making full contact with the rotor? Also is the caliper offset correctly relative to the rotor (offset towards the outboard pad with the inboard pad wound in and nearly touching)? Both of those can make a huge difference to how it feels. What lever have you got and does it have adjustable leverage?

Just seems wierd for it to get flexier over time, its not something I've ever noticed or heard of before. I can't think of anything in the caliper which would cause it really, whereas there are lots of other parts to the system which can make a big difference to how stiff it feels. The only problem I have had is the ball bearing races getting worn, which causes the caliper to jam when you pull it hard

At the end of the day a BB7 is always going to be flexy compared to a hydraulic because of the cable. The cable is the biggest source of flex in the system. Its only really a problem if you notice it affecting the power of the brake, which it never has for me. I have my lever set halfway between min and max leverage, so it could be stiffer if I wanted but i find halfway feels much better.

If you do decide on hydraulic I would stick to the trials Hope. Some people will say other brakes perform well, but I think a rider of your ability will be disappointed with anything other than a Hope.

The 'new' black bb7's are a two piece design that's literally bolted up. The caliper itself becomes more flexible over time and you can visibly see the calliper expanding when you pull the brake. Changing the cable helps reduce the mushiness but the caliper will still expand a tremendous amount.

Mine was like that and then i went to a hope. A decision i should have made a long time ago.

[Matt Burrows]

The 'new' black bb7's are a two piece design that's literally bolted up. The caliper itself becomes more flexible over time and you can visibly see the calliper expanding when you pull the brake. Changing the cable helps reduce the mushiness but the caliper will still expand a tremendous amount.

How do solid metal parts become flexier over time . You do know that aluminium has very low fatigue resistance, surely if it was repeatedly stressed it would just snap?

I've had one of the new BB7s for over 2 years now (as well as countless old models which all snapped). In that time i've snapped numerous pairs of forks, 2 headsets, been through 3 or 4 cables and a few sets of pads. Yes the caliper flexes, yes you can see it flex, but mine is no different to the day I bought it and still performs the same. I've set-up a few new BB7s for other riders and have never thought that they flexed less than mine.

After testing new and old design calipers back to back on my bike, I did notice a difference. But it felt no more than the difference between a standard and a linear cable. It wasn't enough to make me switch back to the old one anyway, as the new one has proved to be way more durable and reliable in my eyes.

[Krisboats]

How do solid metal parts become flexier over time . You do know that aluminium has very low fatigue resistance, surely if it was repeatedly stressed it would just snap?

It's not solid metal though, it's two pieces of solid metal bolted together along one side only.

[aener]

Some people will say other brakes perform well, but I think a rider of your ability will be disappointed with anything other than a Hope.

:$ Thanks!

Both posts...

I have done all that, and the cable's only about two weeks old.

I thought it was a widespread issue. A few people 'round here seem to have had it. After about a year or so the flex just gets crazy. I can pull my lever until the pads engage, then probably another 15/20mm in to the bars. Will go try out another new cable before spending big money on a new brake, but it seemed pretty poo even when I'd just put it on.

Torn between getting another BB7 or a second hand Hope, at the minute.

[Krisboats]

Hope, do it! Best decision ever.

http://www.trials-forum.co.uk/index.php?showtopic=156532

Fairly new, 200mm, good condition. Decent'ish price.

[Matt Burrows]

It's not solid metal though, it's two pieces of solid metal bolted together along one side only.

Ah right I get what you are saying now. So you have found the surfaces start to round over time? Is there any chance the bolts have come loose and caused this? Mine genuinly has no signs of this after 2 years, but then maybe I just don't pull it as hard as you fat Loughborough boys!

I have done all that, and the cable's only about two weeks old.

I thought it was a widespread issue. A few people 'round here seem to have had it. After about a year or so the flex just gets crazy. I can pull my lever until the pads engage, then probably another 15/20mm in to the bars. Will go try out another new cable before spending big money on a new brake, but it seemed pretty poo even when I'd just put it on.

Torn between getting another BB7 or a second hand Hope, at the minute.

That sounds pretty rubbish. Just went out to check mine, on minimum leverage it pulls about 10mm, and on maximum leverage it pulls 15mm, maybe a bit more if I really yank on it. Either way the maximum leverage setting feels awefull, way softer than I would like so I can understand you not being happy with it. Maybe a Hope is the only way unless you can find an old model BB7 in good nick?

[Krisboats]

Ah right I get what you are saying now. So you have found the surfaces start to round over time? Is there any chance the bolts have come loose and caused this? Mine genuinly has no signs of this after 2 years, but then maybe I just don't pull it as hard as you fat Loughborough boys!

I genuinely have no idea what it is. The surfaces rounding slightly might be it, but the bolts on mine at least are done up ridiculously tight. Maybe the bolt /hreads distort slightly? New bolts might be an idea to try.

[p_ruskin]

I have a new style hope if you want it? needs new pads or the pads need a good clean, bleed is good, all good condition. looking for £55