oscillation

Jon Blake said:

Would appreciate the group's wisdom on this.

Symptom: smooth road, no wind, 19-20 mph, 80-85 cadence produces slight
wobble/oscillation. I'm thinking headset adjustment - too tight/too loose?

Frame alignment has been checked. Headset is old style Campy road. No
brinlling (sp?), new ball bearings.

Seat 1cm too high?

How full are the spines on your clogs?

Balls in races might be upside down.

Consider buying a brooks saddle.

Might be close-coupled for a lively feel, springy yet dead-on.

I hope this helps.

Franklin said:

Jon Blake said:

Would appreciate the group's wisdom on this.

Symptom: smooth road, no wind, 19-20 mph, 80-85 cadence produces
slight wobble/oscillation. I'm thinking headset adjustment - too
tight/too loose?

Frame alignment has been checked. Headset is old style Campy road. No
brinlling (sp?), new ball bearings.

Seat 1cm too high?

How full are the spines on your clogs?

Balls in races might be upside down.

Consider buying a brooks saddle.

Might be close-coupled for a lively feel, springy yet dead-on.

I hope this helps.

Who's this guy?!? :-D

Dude, this is Tech. Scowl and be serious, dammit. HTH

TNX for your response. Let me respond to each so others may have more
ideas.

Franklin said:

Jon Blake said:

Would appreciate the group's wisdom on this.

Symptom: smooth road, no wind, 19-20 mph, 80-85 cadence produces slight
wobble/oscillation. I'm thinking headset adjustment - too tight/too loose?

Frame alignment has been checked. Headset is old style Campy road. No
brinlling (sp?), new ball bearings.

Seat 1cm too high?
Saddle height is same as it has been for decades, definitely not too

high, no bouncing at 100+ rpm

Quoted message said:

How full are the spines on your clogs?
Don't understand. Do you mean worn cogs?
Balls in races might be upside down.
Balls loose, no retainer
Consider buying a brooks saddle.
Have been using same saddle without symptoms.
Might be close-coupled for a lively feel, springy yet dead-on.
Yes, it's more a crit bike than long tourer. But, I've ridden this bike

for several decades without these symptoms.

Quoted message said:

I hope this helps.

More advice/opinions most welcomed.

- Jon

Bill Sornson said:

Franklin said:

Jon Blake said:

Would appreciate the group's wisdom on this.

Symptom: smooth road, no wind, 19-20 mph, 80-85 cadence produces
slight wobble/oscillation. I'm thinking headset adjustment - too
tight/too loose?

Frame alignment has been checked. Headset is old style Campy road.
No brinlling (sp?), new ball bearings.

Seat 1cm too high?

How full are the spines on your clogs?

Balls in races might be upside down.

Consider buying a brooks saddle.

Might be close-coupled for a lively feel, springy yet dead-on.

I hope this helps.

Who's this guy?!? :-D

Dude, this is Tech. Scowl and be serious, dammit. HTH

We should start reflexively saying, "Who are you?" to the random/FNGs like
Mike Press's handle was doing a while back with "What are you talking
about?" 😉
--
Phil Lee, Squid

Two-wheeled systems are susceptible to vibrational modes
which can depend on the energy storage/release characteristics
of every flexible and/or massive object attached to them.

The resonance depends on speed because of the way a bike
remains upright; it's essentially always out of balance, but constantly
correcting between left and right leans. At a certain speed, this
corrective oscillation matches the resonant frequency of the hinge
and spring system (the bike and rider) and, as all resonances do,
builds until it reaches some other limit, if there is another limit.
If there isn't, something breaks or the bike oscillates with an
amplitude that includes the ground.

And it gets weird when you try to guess how to cause or prevent
it.

For instance, if you lower the air pressure in your /rear/ tires you
may
change the resonant frequency of the system in such a way that
your /front/ end vibrates at a speed in your normal range. At least,
that's what it feels like. The whole bike is actually contributing
to that vibration.

There are ways to design these resonant frequencies out of the range
of speeds you're likely to encounter; and ways to critically damp every
mode of vibration in the system so that it never vibrates, but it'd be
too complicated and expensive a process when designing a bicycle.
It's really the kind of thing you'll do to a building or a bridge. For
anything else, you'd test it, and if a vibration occurs, just try a few
different parts until you find a combination where the problem is
gone or acceptable.

And as soon as someone customizes their new bike, it all changes.

--Blair

"Jon Blake" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

TNX for your response. Let me respond to each so others may have more
ideas.

Franklin said:

Jon Blake said:

Would appreciate the group's wisdom on this.

Symptom: smooth road, no wind, 19-20 mph, 80-85 cadence produces

slight

Quoted message said:

Quoted message said:

Quoted message said:

wobble/oscillation. I'm thinking headset adjustment - too tight/too

loose?

Quoted message said:

Quoted message said:

Quoted message said:

Frame alignment has been checked. Headset is old style Campy road.

No

Quoted message said:

Quoted message said:

Quoted message said:

brinlling (sp?), new ball bearings.

Seat 1cm too high?
Saddle height is same as it has been for decades, definitely not too

high, no bouncing at 100+ rpm

Quoted message said:

How full are the spines on your clogs?
Don't understand. Do you mean worn cogs?
Balls in races might be upside down.
Balls loose, no retainer
Consider buying a brooks saddle.
Have been using same saddle without symptoms.
Might be close-coupled for a lively feel, springy yet dead-on.
Yes, it's more a crit bike than long tourer. But, I've ridden this

bike

Quoted message said:

for several decades without these symptoms.

Quoted message said:

I hope this helps.

More advice/opinions most welcomed.

- Jon

Additional suggestions:

Rule out riding style before looking for mechanical causes.

Have someone ride behind you to watch how smoothly you're pedaling. You
may be unconsciously bouncing when you pedal at a higher cadence.

Also long stems on short wheel base bikes with steep angles can cause
some squirrelly handling problems, especially down hill at high speeds.

Chas.

Jon Blake said:

Would appreciate the group's wisdom on this.

Symptom: smooth road, no wind, 19-20 mph, 80-85 cadence produces slight
wobble/oscillation. I'm thinking headset adjustment - too tight/too loose?

Frame alignment has been checked. Headset is old style Campy road. No
brinlling (sp?), new ball bearings.

TIA - Jon

yes, check the headset, wheel bearings, etc. but what kind of frame is
this? sounds like old steel with "standard" tube diameters. you'll be
much better served by a modern frame with oversize tube - the bigger the
better, especially in large frames. it makes the structure /much/ more
torsional oscillation resistant.

jim beam said:

yes, check the headset, wheel bearings, etc. but what kind of frame is
this? sounds like old steel with "standard" tube diameters. you'll be
much better served by a modern frame with oversize tube - the bigger the
better, especially in large frames. it makes the structure /much/ more
torsional oscillation resistant.

It also makes it ride like pneumatic tires hadn't been invented...

--Blair

Blair P. Houghton said:

jim beam said:

yes, check the headset, wheel bearings, etc. but what kind of frame is
this? sounds like old steel with "standard" tube diameters. you'll be
much better served by a modern frame with oversize tube - the bigger the
better, especially in large frames. it makes the structure /much/ more
torsional oscillation resistant.

It also makes it ride like pneumatic tires hadn't been invented...

--Blair

where'd you get that idea blair? i invite you to ride my big piped
aluminum bianchi ev3 with curved rear stays. it's a good deal more
comfortable than any steel frame i have.

jim beam said:

Blair P. Houghton said:

jim beam said:

much better served by a modern frame with oversize tube - the bigger the
better, especially in large frames. it makes the structure /much/ more
torsional oscillation resistant.

It also makes it ride like pneumatic tires hadn't been invented...

where'd you get that idea blair?

Cannondale.

Quoted message said:

i invite you to ride my big piped
aluminum bianchi ev3 with curved rear stays. it's a good deal more
comfortable than any steel frame i have.

Interesting. Do you have a steel Bianchi?

--Blair

Blair P. Houghton said:

jim beam said:

Blair P. Houghton said:

jim beam wrote:
> much better served by a modern frame with oversize tube - the bigger the
> better, especially in large frames. it makes the structure /much/ more
> torsional oscillation resistant.
It also makes it ride like pneumatic tires hadn't been invented...

where'd you get that idea blair?

Cannondale.

Quoted message said:

i invite you to ride my big piped
aluminum bianchi ev3 with curved rear stays. it's a good deal more
comfortable than any steel frame i have.

Interesting. Do you have a steel Bianchi?

--Blair

yes sir, i do.