Mix'n'match calipers and rotors?

Duncan Smith

Mostly I've been v.happy with Juicy-7s, except for a particular one on
the front of my MTB - for some reason it's never been much cop.
Initially an air bubble percolated up tp the caliper and I took it to
the LBS (Pitsford cycles) so they could bleed it (I've never bled
brakes myself) and it came back very spongey with almost no stopping
power - they tried again and it made a marginal improvement but was
still, quite frankly, a load of rubbish.

Winter came and passed and the bike wasn't used much, but now it's
racing season, I thought I'd treat myself to a new brake, a Magura
Mantra SL - after a couple of commutes to work on the road and the
recommended 'quick stop x 30' wear-in period, the rotor's now warped
out of recognition, wheel wouldn't turn and after removing the wheel,
it wouldn't even go back in until the rotor was removed (an emergency
measure to get me to work).

Reading around it seems the Mag's rotors are a bit flimsy for the sake
of a few grams weight saving.

So I was wondering could I just use the Mag SLs with an Avid Rotor
which will stay true for more than 60M?

Another thing I found with the Mags was a dissapointingly low reach/
bite point on the lever (even with the reach adjustment screw fully
adjusted) - there's no caliper adjustment like there is on the Avids,
so does that mean that there's just not enough oil in the system?

Additionally, I've ordered a bleed kit for the Avids, hopefully I can
do a better job than the LBS.

Regards,

Duncan

Doki

"Duncan Smith" <DSmith1974@googlemail.com> wrote in message
news:25d4447f-2550-427c-a126-7e64f3b22138@24g2000hsh.googlegroups.com...
> Mostly I've been v.happy with Juicy-7s, except for a particular one on
> the front of my MTB - for some reason it's never been much cop.
> Initially an air bubble percolated up tp the caliper and I took it to
> the LBS (Pitsford cycles) so they could bleed it (I've never bled
> brakes myself) and it came back very spongey with almost no stopping
> power - they tried again and it made a marginal improvement but was
> still, quite frankly, a load of rubbish.
>
> Winter came and passed and the bike wasn't used much, but now it's
> racing season, I thought I'd treat myself to a new brake, a Magura
> Mantra SL - after a couple of commutes to work on the road and the
> recommended 'quick stop x 30' wear-in period, the rotor's now warped
> out of recognition, wheel wouldn't turn and after removing the wheel,
> it wouldn't even go back in until the rotor was removed (an emergency
> measure to get me to work).
>
> Reading around it seems the Mag's rotors are a bit flimsy for the sake
> of a few grams weight saving.
>
> So I was wondering could I just use the Mag SLs with an Avid Rotor
> which will stay true for more than 60M?
>
> Another thing I found with the Mags was a dissapointingly low reach/
> bite point on the lever (even with the reach adjustment screw fully
> adjusted) - there's no caliper adjustment like there is on the Avids,
> so does that mean that there's just not enough oil in the system?
>
> Additionally, I've ordered a bleed kit for the Avids, hopefully I can
> do a better job than the LBS.

Should work fine, unless they're considerably thicker. That said, I've had
julies for a while and had no problems with disks warping except for when
I've crashed them into things... Floating rotors don't warp through heat
BTW, so that may be an option (ie,the £37 ones on chain reaction).

Paul Boyd

Doki said the following on 01/05/2008 12:46:

> Should work fine, unless they're considerably thicker. That said, I've
> had julies for a while and had no problems with disks warping except for
> when I've crashed them into things... Floating rotors don't warp through
> heat BTW, so that may be an option (ie,the £37 ones on chain reaction).

A question about the floating rotors - how much do they float? What I
mean is, will they constantly be flapping about rubbing on the brake
pads, or is it just a very small,tight movement?

--
Paul Boyd
http://www.paul-boyd.co.uk/

Dave Larrington

In news:-sGdnXnVFbnHRYTVRVnyjAA@plusnet,
Paul Boyd <usenet.is.worse@plusnet> tweaked the Babbage-Engine to tell us:
> Doki said the following on 01/05/2008 12:46:
>
>> Should work fine, unless they're considerably thicker. That said,
>> I've had julies for a while and had no problems with disks warping
>> except for when I've crashed them into things... Floating rotors
>> don't warp through heat BTW, so that may be an option (ie,the £37
>> ones on chain reaction).
>
> A question about the floating rotors - how much do they float? What I
> mean is, will they constantly be flapping about rubbing on the brake
> pads, or is it just a very small,tight movement?

Not sure why they call 'em floating at all, TBH. I've got some of the
soi-disant floating Hope rotors:

http://www.hopegb.com/photos/mm4ffT.jpg

on one bike and they're bolted just as firmly to the hubs as any of the
others. They look cool, though, and make a nice pinging noise as they cool
down :-)

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
I am the Disgruntled Employee; I am the New Face of Labour
Relations.

Duncan Smith

>
> Should work fine, unless they're considerably thicker. That said, I've had
> julies for a while and had no problems with disks warping except for when
> I've crashed them into things... Floating rotors don't warp through heat
> BTW, so that may be an option (ie,the £37 ones on chain reaction).

Thanks I'll have a play about with a few combinations. My Maggy rotor
now resembles a deep rice bowl rather than a flat disc - I think it
will need replacing - but for future reference, how do people return
their rotors to true after a warp? Does a wrench and a felt tip
suffice?

I found this nifty looking tool in the States

http://www.utahmountainbiking.com/fix/diskrotortrue.htm

Don't know if there's anything similar here in the UK?

Regards,

Duncan

Doki

Duncan Smith wrote:
>> Should work fine, unless they're considerably thicker. That said,
>> I've had julies for a while and had no problems with disks warping
>> except for when I've crashed them into things... Floating rotors
>> don't warp through heat BTW, so that may be an option (ie,the £37
>> ones on chain reaction).
>
> Thanks I'll have a play about with a few combinations. My Maggy rotor
> now resembles a deep rice bowl rather than a flat disc - I think it
> will need replacing - but for future reference, how do people return
> their rotors to true after a warp? Does a wrench and a felt tip
> suffice?
>
> I found this nifty looking tool in the States
>
> http://www.utahmountainbiking.com/fix/diskrotortrue.htm
>
> Don't know if there's anything similar here in the UK?

For minor dings I use an adjustable spanner. If I've had a big crash it's a
waste of time trying to get it within tolerances so I just buy another from
the fatherland.

Doki

Paul Boyd wrote:
> Doki said the following on 01/05/2008 12:46:
>
>> Should work fine, unless they're considerably thicker. That said,
>> I've had julies for a while and had no problems with disks warping
>> except for when I've crashed them into things... Floating rotors
>> don't warp through heat BTW, so that may be an option (ie,the £37
>> ones on chain reaction).
>
> A question about the floating rotors - how much do they float? What I
> mean is, will they constantly be flapping about rubbing on the brake
> pads, or is it just a very small,tight movement?

Have a look at this:

http://www.carbibles.com/brake_bible.html

It's about car and motorbike brakes but the same applies to bike brakes.

Paul Boyd

Dave Larrington said the following on 01/05/2008 15:55:

> Not sure why they call 'em floating at all, TBH.

....and Doki said the following on 01/05/2008 16:07:

> Have a look at this:
> http://www.carbibles.com/brake_bible.html


Thanks both - that answers that!

--
Paul Boyd
http://www.paul-boyd.co.uk/

Rob Morley

In article <67u3v6F2qd0i4U1@mid.individual.net>, Dave Larrington
smert.spamionam@privacy.net says...

> Not sure why they call 'em floating at all, TBH. I've got some of the
> soi-disant floating Hope rotors:
>
> http://www.hopegb.com/photos/mm4ffT.jpg
>
It's the grommetty things holding the rotor to the spider that allow a
bit of movement.

Duncan Smith

>
> For minor dings I use an adjustable spanner. If I've had a big crash it's a
> waste of time trying to get it within tolerances so I just buy another from
> the fatherland.

The bowl shaped rotor caused quite a stir at the LBS - they'd never
seen or heard of anything like it. I swapped the flimsy Martar SLs
for an Avid 7 and got the £50 difference back in my pocket.

Even before the rotor warped, I wasn't all that impressed with the
Martar's breaking power or reach adjustment when compared to the
Avid. Unless you're a nutter for weight saving and don't mind keeping
the rotors true then I reckon Avid's are a better bet, easy to fit,
fun to bleed, greater stopping power - more bang for your buck!

Cheers,

Duncan

Doki

Duncan Smith wrote:
>> For minor dings I use an adjustable spanner. If I've had a big crash
>> it's a waste of time trying to get it within tolerances so I just
>> buy another from the fatherland.
>
> The bowl shaped rotor caused quite a stir at the LBS - they'd never
> seen or heard of anything like it. I swapped the flimsy Martar SLs
> for an Avid 7 and got the £50 difference back in my pocket.
>
> Even before the rotor warped, I wasn't all that impressed with the
> Martar's breaking power or reach adjustment when compared to the
> Avid. Unless you're a nutter for weight saving and don't mind keeping
> the rotors true then I reckon Avid's are a better bet, easy to fit,
> fun to bleed, greater stopping power - more bang for your buck!

I've got some 2006 or so vintage Julies on my bike, and I can't say I've got
any issues with them. They've handled long peak district descents without
issue, and I'm not a light man. Braking power is easily enough to lock
wheels at either end, and bite is fantastic.

It may be possible that the pads weren't bedded correctly on yours - if
they're not (and it's fairly hard to do right, compared to most), magura
pads tend to bite very poorly - perhaps this happened to you and caused you
to drag the brakes more than usual?