Advice on bike purchase disaster

"Michael Warner" <[email hidden]> schreef in bericht
news:[email hidden]...

Quoted message said:

Hi folks,

I have a large '04 carbon Giant TCR1, which I love, and I
took a mate who was looking to upgrade from a Tiagra-level
alloy bike in to check out the '05 range. The TCR C1 now has
10-speed Ultegra and carbon brakes at the same price, thanks
to the exchange rate, damn it :-)

Anyway, he bought a medium TCR C1 about a week ago, and
found that it develops a lethal wobble when descending
at a mere 50km/h or so. I've read about wobbles but never
seen one before, and I couldn't believe it. He's about 5'8"
and 63kg, I'm 6'1" and 79kg - I've never felt any trace of
instability on mine, and neither have several other people
I ride with who have TCRs of various sizes. He found that putting
as much weight as possible on the drops helps, but not much.

He took it back to the shop, and they fitted a shorter stem and
tightened the headset, but it didn't make a significant difference
(although the factory stem was a little on the long side for him
anyway). He went back again and they said they'd (a) get
someone else who rides a medium Giant to try it (b) change
the frame (?). However, they also said they wouldn't let him
return it. Ouch. Like other shops around here where I've asked, they
don't allow test rides beyond the block.

Understandably, he's pretty unhappy, and I'm a bit embarrassed
because I recommended it, and introduced him to the sales guy
who now refuses to take it back. I suggested today that he call Consumer
Affairs and find out what his rights are before any real confrontation
with the shop, but I'd like to know what others have learned about
wobbles, consumer rights regarding bikes (we're in SA) and how to deal
with this situation, where a bike is simply useless for a particular

rider.

Quoted message said:

Thanks,

Michael

--
bpo gallery at http://www4.tpgi.com.au/users/mvw1/bpo

The google words are bike and shimmy. Using these words will bring you a
wealth of 13,000 hits.
Bikes shouldn't shimmy

--
Posted by news://news.nb.nu

Michael Warner said:

Hi folks,
Anyway, he bought a medium TCR C1 about a week ago, and
found that it develops a lethal wobble when descending
at a mere 50km/h or so. I've read about wobbles but never
seen one before, and I couldn't believe it. He's about 5'8"
and 63kg, I'm 6'1" and 79kg - I've never felt any trace of
instability on mine, and neither have several other people
I ride with who have TCRs of various sizes. He found that putting
as much weight as possible on the drops helps, but not much.
--
bpo gallery at http://www4.tpgi.com.au/users/mvw1/bpo

Not sure if this is relevant to you ...

My LBS guy used to own a carbon framed Giant and described the same problem but at faster speeds (70+ km/h) going downhill. He fixed it by changing the carbon stirrer on his fork to an alloy one.

Koon

Koon Yong said:

Not sure if this is relevant to you ...

My LBS guy used to own a carbon framed Giant and described the same problem but at faster speeds (70+ km/h) going downhill. He fixed it by changing the carbon stirrer on his fork to an alloy one.

Koon

This is quite possible, but might be expensive. Some people think shimmy can be relieved by taking a little weight _off_ the saddle when the shimmy starts - stand on the pedals just a bit and see if that reduces the wobbling.

If shimmy persists, please see your LBS.

Ritch

Bert L said:

The google words are bike and shimmy. Using these words will bring you a
wealth of 13,000 hits.
Bikes shouldn't shimmy

What I want to know is if the problem lies with bike or rider?
Get someone who knows what they are doing to ride it and see if they
notice any odd behaviour.
How true are the wheels? Are the wheels in the dropouts properly? Is
there any brake rub? Is the frame straight? Is the road smooth? Is he
used to descending it? Is he pedaling or coasting when it happens?

hippy

"Michael Warner" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Hi folks,

I have a large '04 carbon Giant TCR1, which I love, and I
took a mate who was looking to upgrade from a Tiagra-level
alloy bike in to check out the '05 range. The TCR C1 now has
10-speed Ultegra and carbon brakes at the same price, thanks
to the exchange rate, damn it :-)

Anyway, he bought a medium TCR C1 about a week ago, and
found that it develops a lethal wobble when descending
at a mere 50km/h or so. I've read about wobbles but never
seen one before, and I couldn't believe it. He's about 5'8"
and 63kg, I'm 6'1" and 79kg - I've never felt any trace of
instability on mine, and neither have several other people
I ride with who have TCRs of various sizes. He found that putting
as much weight as possible on the drops helps, but not much.

He took it back to the shop, and they fitted a shorter stem and
tightened the headset, but it didn't make a significant difference
(although the factory stem was a little on the long side for him
anyway). He went back again and they said they'd (a) get
someone else who rides a medium Giant to try it (b) change
the frame (?). However, they also said they wouldn't let him
return it. Ouch. Like other shops around here where I've asked, they
don't allow test rides beyond the block.

Michael

as always sheldon, with the help of jobst, may have the answer.
tell him to try a light grip and either pedal or rest his leg aginst the top
tube.

http://www.sheldonbrown.com/brandt/shimmy.html

Michael,
If the shop will change the frame, isnt that a suitable solution. You mate
gets a bike that works and the shop gets the sale.

"Michael Warner" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Hi folks,

I have a large '04 carbon Giant TCR1, which I love, and I
took a mate who was looking to upgrade from a Tiagra-level
alloy bike in to check out the '05 range. The TCR C1 now has
10-speed Ultegra and carbon brakes at the same price, thanks
to the exchange rate, damn it :-)

Anyway, he bought a medium TCR C1 about a week ago, and
found that it develops a lethal wobble when descending
at a mere 50km/h or so. I've read about wobbles but never
seen one before, and I couldn't believe it. He's about 5'8"
and 63kg, I'm 6'1" and 79kg - I've never felt any trace of
instability on mine, and neither have several other people
I ride with who have TCRs of various sizes. He found that putting
as much weight as possible on the drops helps, but not much.

He took it back to the shop, and they fitted a shorter stem and
tightened the headset, but it didn't make a significant difference
(although the factory stem was a little on the long side for him
anyway). He went back again and they said they'd (a) get
someone else who rides a medium Giant to try it (b) change
the frame (?). However, they also said they wouldn't let him
return it. Ouch. Like other shops around here where I've asked, they
don't allow test rides beyond the block.

Understandably, he's pretty unhappy, and I'm a bit embarrassed
because I recommended it, and introduced him to the sales guy
who now refuses to take it back. I suggested today that he call Consumer
Affairs and find out what his rights are before any real confrontation
with the shop, but I'd like to know what others have learned about
wobbles, consumer rights regarding bikes (we're in SA) and how to deal
with this situation, where a bike is simply useless for a particular
rider.

Thanks,

Michael

--
bpo gallery at http://www4.tpgi.com.au/users/mvw1/bpo

Michael Warner wrote:
<snip>

Quoted message said:

Understandably, he's pretty unhappy, and I'm a bit embarrassed
because I recommended it, and introduced him to the sales guy
who now refuses to take it back. I suggested today that he call Consumer
Affairs and find out what his rights are before any real confrontation
with the shop, but I'd like to know what others have learned about
wobbles, consumer rights regarding bikes (we're in SA) and how to deal
with this situation, where a bike is simply useless for a particular rider.

Thanks,

Michael

If it does turn out to be a problem with the bike that cannot be fixed
with the things other people have suggested, check out what Giant's
warranty policy is like. You may be able to contact them directly or
through recommended dealers.

My coach busted his Trek frame 2 years ago, which supposedly have a
lifetime guarantee. Original LBS told him where to go, so he took it to
another who sent it off and got him a brand new frame.

T

Dunno whether it will help your friend, but in my experience, shimmy (especially downhill shimmy) is generally cured by not gripping the bars so tightly. This is especially common with people who haven't been riding for long, especially if they haven't ridden a light bike before.

Regards,

Suzy

Koon Yong said:

Michael Warner said:

Hi folks,
Anyway, he bought a medium TCR C1 about a week ago, and
found that it develops a lethal wobble when descending
at a mere 50km/h or so. I've read about wobbles but never
seen one before, and I couldn't believe it. He's about 5'8"
and 63kg, I'm 6'1" and 79kg - I've never felt any trace of
instability on mine, and neither have several other people
I ride with who have TCRs of various sizes. He found that putting
as much weight as possible on the drops helps, but not much.
--
bpo gallery at http://www4.tpgi.com.au/users/mvw1/bpo

Not sure if this is relevant to you ...

My LBS guy used to own a carbon framed Giant and described the same
problem but at faster speeds (70+ km/h) going downhill. He fixed it by
changing the carbon stirrer on his fork to an alloy one.

shimmy, or speed wobbles, or any other name for increasing amplitude
(resonance) vibrations can be stopped by changing almost anything.
Every system has a frequency at which it will resonate, and any
change in the system will alter that frequency. I've heard stories of
bikes having uncontrolable resonance with something as simple as
a seatbag with 50g in it, that goes away when the seatbag
is removed.

Whatever's making the bike resonate will probably be trivially easy to
fix, all it will take is a very minor shift in weight distribrution.

Your LBS may not have a very good understanding of resonance,
but it'll be easy to fix.

Quoted message said:

Koon

Another opinion:

http://www.bikefanclub.com/forum/showflat.php/Cat/0/Number/3914/page/0/view/collapsed/sb/5/o/all/fpart/1

might be worth checking

Mower

Carl Brewer said:

shimmy, or speed wobbles, or any other name for increasing amplitude
(resonance) vibrations can be stopped by changing almost anything.
Every system has a frequency at which it will resonate, and any
change in the system will alter that frequency. I've heard stories of
bikes having uncontrolable resonance with something as simple as
a seatbag with 50g in it, that goes away when the seatbag
is removed.

Whatever's making the bike resonate will probably be trivially easy to
fix, all it will take is a very minor shift in weight distribrution.

Your LBS may not have a very good understanding of resonance,
but it'll be easy to fix.

Quoted message said:

Koon

There's been quite a bit of debate in UK/euro forums regarding giants and 'shimmy' (and maybe here too sometime last year?)

maybe a common design/setup 'characteristic'
Your friend's lower weight may be a factor too

last year i got carbon (alu steerer) forks and lighter wheels on my 853-steel-is-real frame.
Previously had heavier-aero rims and straight-steel forks
Rake was identical

The difference in handling was huge!
Far lighter but 'shimmy' is very easy to get now if i take my weight off the bars (no hands ip salute for me the day i finally nail a win 🙄 )

I reckon the straight forks were awsome for descending on too BTW.
[censored] over 3 hours tho...

F"wanted. bigger lungs"Dutch

Flyingdutch said:

last year i got carbon (alu steerer) forks and lighter wheels
on my 853-steel-is-real frame.
Previously had heavier-aero rims and straight-steel forks
Rake was identical

Quoted message said:

The difference in handling was huge!
Far lighter but 'shimmy' is very easy to get now if i take
my weight off the bars (no hands ip salute for me the day
i finally nail a win 🙄 )

Was the crown race to dropout length the same? Most of the stock 700C carbon forks around the place are 365mm long. Steel forks vary a lot, but are often a centimetre or more longer.

Bringing the front end down by a centimeter adds around half a degree to your head tube angle, which will make the steering faster.

My audax bike (700C, 72.5 degree head tube, 45mm rake carbon forks with 1" carbon steerer) is solid as a rock. Steering is nicely neutral, and I've done a couple of 400s and a 600 on it without excessive complaint. I can ride it no-hands for ages with no wobbles.

My old fixed wheel (700C, 73 degree head tube, 48mm rake Tange steel forks) is full-on deadly. It's not so bad as long as you've got a hand on the bars, but it's really hard to ride no hands.

Regards,

Suzy

hippy said:

What I want to know is if the problem lies with bike or rider?
Get someone who knows what they are doing to ride it and see if they
notice any odd behaviour.

My thought exactly. Double check the bike, as below, but also rider input (or lack of it) could be the cause.

Didn't Jazmo have a wobble problem with his new bike?

hippy said:

How true are the wheels? Are the wheels in the dropouts properly? Is
there any brake rub? Is the frame straight? Is the road smooth? Is he
used to descending it? Is he pedaling or coasting when it happens?

hippy

Quoted message said:

Didn't Jazmo have a wobble problem with his new bike?

That was fear, I think we saw some more of that last night, but I think
he was more worried about damage to the bike. Hey I did offer him my
commuter MTB but he would have to ride it with panniers. Now that would
be a crit worth watching. Kind of like the bicycle equivalent of that
racing in the UK with caravans attached.

DaveB

"Michael Warner" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I just want to know what shop it was from!
Cheers
Gemma

I know of 2 guys around my area with the same problem. Both were told the
same thing...pretty much "bad luck".
I would suggest somebody who has first hand experience of the problem and
who is getting no help from the place of purchase should contact Bicycling
Australia magazine and Ride magazine with a written letter may get some sort
of reaction.... and possible help

Peter

Gemma_k said:

I just want to know what shop it was from!

I bet :-)

I'm not going to name them, in case it prejudices matters. I have no
idea who reads this group.

--
bpo gallery at http://www4.tpgi.com.au/users/mvw1/bpo

On Wed, 16 Mar 2005 22:01:39 +1030, Michael Warner wrote:

Thanks for the replies, everyone. We're going out into some
hilly country tomorrow to experiment with the new frame
and various riding adjustments. The idea of adding weights
etc to the bike is interesting - we'll use full water bottles :-)

--
bpo gallery at http://www4.tpgi.com.au/users/mvw1/bpo

suzyj said:

My audax bike (700C, 72.5 degree head tube, 45mm rake carbon forks with
1" carbon steerer) is solid as a rock. Steering is nicely neutral, and
I've done a couple of 400s and a 600 on it without excessive complaint.
I can ride it no-hands for ages with no wobbles.

My old fixed wheel (700C, 73 degree head tube, 48mm rake Tange steel
forks) is full-on deadly. It's not so bad as long as you've got a hand
on the bars, but it's really hard to ride no hands.

Steeper head angle with more fork rake is not a good combination. This will
push the tyre contact point forward towards the steering axis, reducing the
caster of your front wheel. The fixed wheel would be much betterwith a fork
with minimal rake.

Cheers
Peter