Dura Ace Scandium Rims and Grabby Brakes

[SteveT]

I have a pair of Dura Ace 7801SL wheels with the Scandium rims, and
right out of the box, they have always been very "grabby" for want of
a better word. It's similar to the feeling I get with my old Volvo
when the brake disks get warped - kind of a pulsing braking action.

The wheels are true and out-of-round looks good, and they ride great,
except when braking. To get rid of the grabby feeling, I cleaned the
rims very thoroughly, even used a scouring pad and some solvent to
make sure any oils etc. were removed. I changed the pads to Kool-
stops salmon color, and lastly, I gave the pads quite a bit of toe-in
to make sure the front of the pads contacted long before the rear
portion. All of this helped and the braking is smoother, but they
just don't feel as smooth as my Ksyriums or any Mavic rim I have.

I have a feeling that because the rim material is so thin that the
rims could be distorting at the spoke locations, ie. affecting the run-
out and creating a pulsing under braking. Don't know anyone else who
has these rims, but everyone I've talked to who has the standard 7800
aluminum rims doesn't have this problem.

Any ideas or suggestions on how to fix this would be appreciated.
Thanks,
Steve

 

[[email protected]]

Steve Turner writes:

> I have a pair of Dura Ace 7801SL wheels with the Scandium rims, and
> right out of the box, they have always been very "grabby" for want
> of a better word. It's similar to the feeling I get with my old
> Volvo when the brake disks get warped - kind of a pulsing braking
> action.

> The wheels are true and out-of-round looks good, and they ride
> great, except when braking. To get rid of the grabby feeling, I
> cleaned the rims very thoroughly, even used a scouring pad and some
> solvent to make sure any oils etc. were removed. I changed the pads
> to Kool- stops salmon color, and lastly, I gave the pads quite a bit
> of toe-in to make sure the front of the pads contacted long before
> the rear portion. All of this helped and the braking is smoother,
> but they just don't feel as smooth as my Ksyrium or any Mavic rim I
> have.

> I have a feeling that because the rim material is so thin that the
> rims could be distorting at the spoke locations, ie. affecting the
> run- out and creating a pulsing under braking. Don't know anyone
> else who has these rims, but everyone I've talked to who has the
> standard 7800 aluminum rims doesn't have this problem.

> Any ideas or suggestions on how to fix this would be appreciated.

I would try cleaning the rims either by the ride-through-a-mud-puddle
with the brakes applied lightly as a scrubber, or to wet the rim with
dish detergent as a wetting agent and dust the brake surface with
Bon-Ami cleanser and ride the brakes before rinsing off the residue.

Pulsating is not a material characteristic but rather one of
contamination. Right now, I'm riding a Mavic anodized rim on the
front wheel that adsorbs moisture and squeals horribly until I get it
hot from a couple of hard brakings. Then all is silent and the brake
works as one would expect of good brakes.

Jobst Brandt

 

[JeffWills]

>
> Any ideas or suggestions on how to fix this would be appreciated.
> Thanks,
> Steve

Well, a suggestion: ditch the Kool-Stop salmon pads in favor of their
black pads. The additional friction of the salmon pads *could* be
making the action *too* sensitive and less able to be modulated.
(Jobst will probably want me burnt at the stake for this.)

However, it worked for me- I've had a couple bikes that I had a
horrible time with when I installed salmon pads- noise, uncontrollable
shuddering, on/off braking action. I tried everything I knew and I
couldn't get them to work properly. I switched them to the black pads
and it all went away. After a couple weeks of using the black pads, I
switched back to the salmon pads and had very good braking from the
start.

This was on two very different bikes, but with the same kind of rims:
Velocity "Aero" unmachined silver. I think Velocity roughens the
surface. I think that using the black pads did the same thing as
Jobst's Bon-Ami-and-dish-soap technique, which is to say they polished
the rim through any surface roughness or contamination.

Jeff

 

[Donald Gillies]

Jagwire makes a nice soft 40 mm black brake pad/holder for $0.70/ea
and as a bonus the pad fits in many vintage pad holders including
campagnolo, dia-compe, weinmann, etc. You might try a set of these in
your brakes to see if they fix the problem.

http://www.biketoolsetc.com/index.c...&tc=Pads-BMX/Juvenile/Utility&item_id=JW-207N

- Don Gillies
San Diego, CA

 

[SteveT]

Couldn't decide which fix to try, so I tried both. But instead of
applying the dishwashing soap and then sprinkling on the Bon-Ami, I
mixed the two together in a cup and applied the resulting paste with a
brush. Rode up and down the streat a couple of times with the brakes
on, then washed off all the soap and changed the pads out to Kool-Stop
black. Seems to have done the job. Absolutely no shudder from the
front brake, and only the smallest hint of shudder from the back.
However, I think after a while I'm going to try the Dura Ace pads
again because the "weird" shape of the Kool-Stop pads makes them hard
to adjust for toe-in.

-Steve T
-------------------------------------------------------------------------------------
On May 7, 8:30 pm, JeffWills <[email protected]> wrote:
> > Any ideas or suggestions on how to fix this would be appreciated.
> > Thanks,
> > Steve
>
> Well, a suggestion: ditch the Kool-Stop salmon pads in favor of their
> black pads. The additional friction of the salmon pads *could* be
> making the action *too* sensitive and less able to be modulated.
> (Jobst will probably want me burnt at the stake for this.)
>
> However, it worked for me- I've had a couple bikes that I had a
> horrible time with when I installed salmon pads- noise, uncontrollable
> shuddering, on/off braking action. I tried everything I knew and I
> couldn't get them to work properly. I switched them to the black pads
> and it all went away. After a couple weeks of using the black pads, I
> switched back to the salmon pads and had very good braking from the
> start.
>
> This was on two very different bikes, but with the same kind of rims:
> Velocity "Aero" unmachined silver. I think Velocity roughens the
> surface. I think that using the black pads did the same thing as
> Jobst's Bon-Ami-and-dish-soap technique, which is to say they polished
> the rim through any surface roughness or contamination.
>
> Jeff

 

[Qui si parla Campagnolo]

On May 20, 10:56 pm, SteveT <[email protected]> wrote:
> Couldn't decide which fix to try, so I tried both. But instead of
> applying the dishwashing soap and then sprinkling on the Bon-Ami, I
> mixed the two together in a cup and applied the resulting paste with a
> brush. Rode up and down the streat a couple of times with the brakes
> on, then washed off all the soap and changed the pads out to Kool-Stop
> black. Seems to have done the job. Absolutely no shudder from the
> front brake, and only the smallest hint of shudder from the back.
> However, I think after a while I'm going to try the Dura Ace pads
> again because the "weird" shape of the Kool-Stop pads makes them hard
> to adjust for toe-in.
>
> -Steve T
> --------------------------------------------------------------------------- ----------
> On May 7, 8:30 pm, JeffWills <[email protected]> wrote:
>
> > > Any ideas or suggestions on how to fix this would be appreciated.
> > > Thanks,
> > > Steve
>
> > Well, a suggestion: ditch the Kool-Stop salmon pads in favor of their
> > black pads. The additional friction of the salmon pads *could* be
> > making the action *too* sensitive and less able to be modulated.
> > (Jobst will probably want me burnt at the stake for this.)
>
> > However, it worked for me- I've had a couple bikes that I had a
> > horrible time with when I installed salmon pads- noise, uncontrollable
> > shuddering, on/off braking action. I tried everything I knew and I
> > couldn't get them to work properly. I switched them to the black pads
> > and it all went away. After a couple weeks of using the black pads, I
> > switched back to the salmon pads and had very good braking from the
> > start.
>
> > This was on two very different bikes, but with the same kind of rims:
> > Velocity "Aero" unmachined silver. I think Velocity roughens the
> > surface. I think that using the black pads did the same thing as
> > Jobst's Bon-Ami-and-dish-soap technique, which is to say they polished
> > the rim through any surface roughness or contamination.
>
> > Jeff

Gonna try hard to not slam your buying decision, but geeezzz, how much
were these wheels? Ya gotta wash and grind and switch pads, on a new
wheelset right utta the box...didn't shimano test these things? Is
having some 'dirt' in the aluminum actually making this product
better?

Once more I scratch my head in wonder, applaud the marketing
department.

 

[SteveT]

You're preaching to the choir given that these are the only pre-built
wheels I have now and all my other wheels : training, commute, and
tandem, are 32+ spoke wheels that I built myself. But I got them for
not much more than good set of hubs, rims and aero spokes would have
cost me. They do roll nice and they ride better than Ksyriums, but
I'm pretty dissapointed in the quality control. Not only did I have
problems with brake shudder, but they were out of true and way
undertensioned when I recieved them. Probably the last set of pre-
built wheels I'll ever get, and not nearly as much satisfaction as
building them yourself.

---------------------------------------------------------------------------------------------

On May 21, 5:18 am, Qui si parla Campagnolo <[email protected]> wrote:
> On May 20, 10:56 pm, SteveT <[email protected]> wrote:
>
>
>
> > Couldn't decide which fix to try, so I tried both. But instead of
> > applying the dishwashing soap and then sprinkling on the Bon-Ami, I
> > mixed the two together in a cup and applied the resulting paste with a
> > brush. Rode up and down the streat a couple of times with the brakes
> > on, then washed off all the soap and changed the pads out to Kool-Stop
> > black. Seems to have done the job. Absolutely no shudder from the
> > front brake, and only the smallest hint of shudder from the back.
> > However, I think after a while I'm going to try the Dura Ace pads
> > again because the "weird" shape of the Kool-Stop pads makes them hard
> > to adjust for toe-in.
>
> > -Steve T
> > --------------------------------------------------------------------------- ----------
> > On May 7, 8:30 pm, JeffWills <[email protected]> wrote:
>
> > > > Any ideas or suggestions on how to fix this would be appreciated.
> > > > Thanks,
> > > > Steve
>
> > > Well, a suggestion: ditch the Kool-Stop salmon pads in favor of their
> > > black pads. The additional friction of the salmon pads *could* be
> > > making the action *too* sensitive and less able to be modulated.
> > > (Jobst will probably want me burnt at the stake for this.)
>
> > > However, it worked for me- I've had a couple bikes that I had a
> > > horrible time with when I installed salmon pads- noise, uncontrollable
> > > shuddering, on/off braking action. I tried everything I knew and I
> > > couldn't get them to work properly. I switched them to the black pads
> > > and it all went away. After a couple weeks of using the black pads, I
> > > switched back to the salmon pads and had very good braking from the
> > > start.
>
> > > This was on two very different bikes, but with the same kind of rims:
> > > Velocity "Aero" unmachined silver. I think Velocity roughens the
> > > surface. I think that using the black pads did the same thing as
> > > Jobst's Bon-Ami-and-dish-soap technique, which is to say they polished
> > > the rim through any surface roughness or contamination.
>
> > > Jeff
>
> Gonna try hard to not slam your buying decision, but geeezzz, how much
> were these wheels? Ya gotta wash and grind and switch pads, on a new
> wheelset right utta the box...didn't shimano test these things? Is
> having some 'dirt' in the aluminum actually making this product
> better?
>
> Once more I scratch my head in wonder, applaud the marketing
> department.