Cyclocross fork vibration

Matthew Eash said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

Thanks for all help,

Matt

Hi.

Are the brakes snug on the mounting posts? No flex?

Is there much of the post of the cantilever pad exposed between the
pivot and the pad? This can cause flex too.

Is the headset properly adjusted? Too loose a headset can cause your
symptoms.

Those are three things that I have experienced that could cause the
juddering besides improper toe-in.

Cheers from Peter

Matthew Eash said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

Thanks for all help,

Matt

What you experience is the brake grabbing because the flex of the
steerer applies the brake. Converting to a V-brake ( mini_v or with a
V-dapter etc) , a crown mounted cablestopper or a powerhanger
(www.m-gineering.nl/pwrhanger.jpg) will probably cure it

--
/Marten

info(apestaartje)m-gineering(punt)nl

Matthew Eash said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

Thanks for all help,

Matt

I'd try a longer straddle cable. Reducing the brake's mechanical
advantage can reduce grabbiness.

Matthew Eash said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

Thanks for all help,

Matt

My bet would be a stiffer fork. I have a Pace carbon fork that is not so
stiff in the for-after direction and experience the same problem. I had
this withe several brakes and pads on it. So I concluded it's the fork.
It's not that bad, so I live with it.

Lou
--
Posted by news://news.nb.nu (http://www.nb.nu)

Matthew Eash said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

Thanks for all help,

Matt

Fork flex issue. If you are near Yellow Jersey, talk with Andrew Muzi. He knows these things and sells Soma, et al.
We have experienced similar issues with lighter forks on our tandem. We now put up with heavier but stiffer steel forks with steel steerers on both 26" MTB and 700C tandems. Once I learned this lesson, I also stick with stiffer forks (Especially stiffer steerers) on all the bicycles we own.

Matthew Eash wrote:
<snip stuff about fork shurdder/chatter/judder>

Getting a steel fork was the only way I got it down to a manageable
level. I tried 2 carbon/canti forks and both suffered from this badly.
No amount of adjustment helped. I would try V brakes instead of
cantis as well though.

Pete

I had not thought of substituting in a different type of brake. I can try
that right away -- I have a couple of bicycles with v-brakes around and can
swap one in to test. Long term, I understand that the "travel" is wrong --
the v-brakes require more cable travel that what the STI levers can provide,
but for a test, that may not matter.

I am not adverse to changing to a steel fork, but that is more involved than
switching brakes, so I think I'll try the brakes first.

Sounds like I am not the first one with this problem, anyway 🙂

Thanks, and I'll keep you posted.

Matthew

"Matthew Eash" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross
style bike) that I use for fitness and commuting. It uses a Winwood
carbon cross fork, Mavic Askium wheels, with Cane Creek SCX-5
cantilever/cross brakes. Right now it has black Kool-Stop pads. I
originally choose the cross style brakes and/or bike so I could run fatter
tires -- lots of great rails to trails in Wisconsin 🙂 I don't need huge
mud clearance -- not a real cross rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY
when it happens. The vibration seems to come in the front to back (as
opposed to the side to side) direction, like the front brake is grabbing
and releasing, grabbing and releasing.

....

On Sat, 19 May 2007 21:30:09 -0500, "Matthew Eash" <[email hidden]>

Quoted message said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

First, they sorta all do that to some extent or another - obviously some worse
than others, but mostly it's a manageable problem. A lot of variables in the
cross-bike-fork-shudder problem. First, a good set of cant's on clean, dry rims
can stop the bike so hard that it tends to bounce on the fork. THat's a lower
cyclic rate than shudder, just mentioning it because when you get to that point
there's nothing left to fix.

To my eye and experience what's happening is that the length of cable that goes
from the hanger to the straddle runs in parallel with the steerer. Under heavy
braking the steerer flexes and the canti studs on the fork blades move back
effectively tightening the brake cable and putting on more brake - at some point
the pads lose grip and the fork and steerer spring back returning the brake to
the tension that you applied. This results in a cyclic tension - relax pattern
that we feel as shudder. Closest things to a sure cure is either mounting the
hanger on the fork crown like Redline does or convert to a travel agent and V-
brake combination.

The other option is to just not brake that hard unless you need to. With a road
bike the limit is going over the bar, with a cross bike the limit is when the
fork shudder starts to annoy you. Maybe you've got it worse than I ever had it,
but I've never experienced shudder bad enough to bother me off the pavement and
on pavement it's never been worse than an annoyance. I still really like my
travel agent and V-Brake combo.

Ron

RonSonic said:

On Sat, 19 May 2007 21:30:09 -0500, "Matthew Eash" <[email hidden]>

Quoted message said:

This group has helped in the past, so...

I have a Soma Fabrications Double Cross 56cm (a steel frame cyclocross style
bike) that I use for fitness and commuting. It uses a Winwood carbon cross
fork, Mavic Askium wheels, with Cane Creek SCX-5 cantilever/cross brakes.
Right now it has black Kool-Stop pads. I originally choose the cross style
brakes and/or bike so I could run fatter tires -- lots of great rails to
trails in Wisconsin 🙂 I don't need huge mud clearance -- not a real cross
rider.

Under moderate to hard front braking, the front end of the bike "shudders"
and vibrates a lot -- enough to make me back off the brake IMMEDIATELY when
it happens. The vibration seems to come in the front to back (as opposed to
the side to side) direction, like the front brake is grabbing and releasing,
grabbing and releasing.

I had the LBS guy who built the bike (and who sure seems to be a good
mechanic) take a couple of looks at it. He is an experienced cross rider
and says he has seen similar issues before. He tried different brake pads
(black vs. salmon) and slightly different toe-in settings, but it didn't
really change much.

I originally choose the cross style brakes so I could run fatter tires --
lots of rails to trails in Wisconsin 🙂 Any insight into alternative things
to try would be greatly appreciated -- different brakes, forks, whatever. I
googled the issue, and found one similar complaint from a Winwood user --
not a lot of information besides that.

First, they sorta all do that to some extent or another - obviously some worse
than others, but mostly it's a manageable problem. A lot of variables in the
cross-bike-fork-shudder problem. First, a good set of cant's on clean, dry rims
can stop the bike so hard that it tends to bounce on the fork. THat's a lower
cyclic rate than shudder, just mentioning it because when you get to that point
there's nothing left to fix.

To my eye and experience what's happening is that the length of cable that goes
from the hanger to the straddle runs in parallel with the steerer. Under heavy
braking the steerer flexes and the canti studs on the fork blades move back
effectively tightening the brake cable and putting on more brake - at some point
the pads lose grip and the fork and steerer spring back returning the brake to
the tension that you applied. This results in a cyclic tension - relax pattern
that we feel as shudder. Closest things to a sure cure is either mounting the
hanger on the fork crown like Redline does or convert to a travel agent and V-
brake combination.

The other option is to just not brake that hard unless you need to. With a road
bike the limit is going over the bar, with a cross bike the limit is when the
fork shudder starts to annoy you. Maybe you've got it worse than I ever had it,
but I've never experienced shudder bad enough to bother me off the pavement and
on pavement it's never been worse than an annoyance. I still really like my
travel agent and V-Brake combo.

Ron

A slightly further take off on this would be that if they are rim brakes
and not disks then any irregularity like rust, dirt, a weld seam or
other tricky thing might cause you to lock up when you don't expect it.
As a long time motorcycle rider I prefer double disks up front but that
may not be practical without spending more that the basic bike is worth.
A side note is to never try to stop hard with the front brake of gravel
or dirt unless you want to be eating it. I learned that the hard way a
few times.
Bill Baka