C
Clyde
Guest
Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
tell the difference when riding?
Clyde
tell the difference when riding?
Clyde
- Status
D
David L. Johnso
Guest
On Fri, 14 Nov 2003 20:02:35 +0000, Clyde wrote:
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
In that your body would be higher up with the lower drop, yeah. The whole geometry is
changed by that.
--
David L. Johnson
__o | If all economists were laid end to end, they would not reach a _`\(,_ | conclusion. --
George Bernard Shaw (_)/ (_) |
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
In that your body would be higher up with the lower drop, yeah. The whole geometry is
changed by that.
--
David L. Johnson
__o | If all economists were laid end to end, they would not reach a _`\(,_ | conclusion. --
George Bernard Shaw (_)/ (_) |
M
Mike Beauchamp
Guest
What if the headtube is 1CM higher, same toptube length.. same stem and seatposts are both properly
adjusted...
Mike http://mikebeauchamp.com
"David L. Johnson" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 14 Nov 2003 20:02:35 +0000, Clyde wrote:
>
> > Between 2 bikes, the same except for bottom bracket drop, one is 65mm,
the
> > other is 75mm, could you tell the difference when riding?
>
> In that your body would be higher up with the lower drop, yeah. The whole geometry is changed
> by that.
>
> --
>
> David L. Johnson
>
> __o | If all economists were laid end to end, they would not reach a _`\(,_ | conclusion. --
> George Bernard Shaw (_)/ (_) |
adjusted...
Mike http://mikebeauchamp.com
"David L. Johnson" <[email protected]> wrote in message
news:[email protected]...
> On Fri, 14 Nov 2003 20:02:35 +0000, Clyde wrote:
>
> > Between 2 bikes, the same except for bottom bracket drop, one is 65mm,
the
> > other is 75mm, could you tell the difference when riding?
>
> In that your body would be higher up with the lower drop, yeah. The whole geometry is changed
> by that.
>
> --
>
> David L. Johnson
>
> __o | If all economists were laid end to end, they would not reach a _`\(,_ | conclusion. --
> George Bernard Shaw (_)/ (_) |
M
Mike S.
Guest
"Mike Beauchamp" <[email protected]> wrote in message
news:[email protected]...
> What if the headtube is 1CM higher, same toptube length.. same stem and seatposts are both
> properly adjusted...
>
> Mike
Probably only if you're trying to pedal around corners...
Mike
> http://mikebeauchamp.com
>
> "David L. Johnson" <[email protected]> wrote in message
> news:[email protected]...
> > On Fri, 14 Nov 2003 20:02:35 +0000, Clyde wrote:
> >
> > > Between 2 bikes, the same except for bottom bracket drop, one is 65mm,
> the
> > > other is 75mm, could you tell the difference when riding?
> >
> > In that your body would be higher up with the lower drop, yeah. The
whole
> > geometry is changed by that.
> >
> > --
> >
> > David L. Johnson
> >
> > __o | If all economists were laid end to end, they would not reach
a
> > _`\(,_ | conclusion. -- George Bernard Shaw (_)/ (_) |
> >
>
news:[email protected]...
> What if the headtube is 1CM higher, same toptube length.. same stem and seatposts are both
> properly adjusted...
>
> Mike
Probably only if you're trying to pedal around corners...
Mike
> http://mikebeauchamp.com
>
> "David L. Johnson" <[email protected]> wrote in message
> news:[email protected]...
> > On Fri, 14 Nov 2003 20:02:35 +0000, Clyde wrote:
> >
> > > Between 2 bikes, the same except for bottom bracket drop, one is 65mm,
> the
> > > other is 75mm, could you tell the difference when riding?
> >
> > In that your body would be higher up with the lower drop, yeah. The
whole
> > geometry is changed by that.
> >
> > --
> >
> > David L. Johnson
> >
> > __o | If all economists were laid end to end, they would not reach
a
> > _`\(,_ | conclusion. -- George Bernard Shaw (_)/ (_) |
> >
>
B
Bruce
Guest
I have two bikes with that difference - about one cm - in BB height. I notice the difference when
mounting and dismounting. Since I use Speedplay pedals, even the low BB height of 26.3 cm (10 3/8" )
doesn't scrap the pedals around corners. But while riding I can't quite tell the difference. I feel
slightly lower compared to other riders, so I get a better draft and I can't see over them as
easily. But that's a very small difference, so I might not actually notice it.
-Bruce
"Clyde" <[email protected]> wrote in message news:[email protected]...
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
>
> Clyde
mounting and dismounting. Since I use Speedplay pedals, even the low BB height of 26.3 cm (10 3/8" )
doesn't scrap the pedals around corners. But while riding I can't quite tell the difference. I feel
slightly lower compared to other riders, so I get a better draft and I can't see over them as
easily. But that's a very small difference, so I might not actually notice it.
-Bruce
"Clyde" <[email protected]> wrote in message news:[email protected]...
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
>
> Clyde
P
Paul Hays
Guest
On Fri, 14 Nov 2003 12:02:35 -0800, Clyde wrote (in message
<[email protected]>):
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
>
> Clyde
>
>
Here's a Rivendel Bicycles article about the relationship between bb height and handling:
http://tinyurl.com/v2y0
<[email protected]>):
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
>
> Clyde
>
>
Here's a Rivendel Bicycles article about the relationship between bb height and handling:
http://tinyurl.com/v2y0
C
Charles Berista
Guest
On Fri, 14 Nov 2003 20:02:35 GMT, "Clyde" <[email protected]> wrote:
>Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
>tell the difference when riding?
>
>Clyde
My mountain bike ( cannondale jekyll) has a rear shock adjustment that changes the BB height
1+ inches .. and also changes the head tube angle.... so it is hard to tell which has the
greater impact.
in the cross country mode.. the BB is at it's highest point and the head tube angle is 70 degrees..
good for navigating switchbacks, etc.
in the freeride mode the BB is at it's lowest and the head tube angle is about 68 degrees... greater
stability on rocky downhills.
I set mine "in the middle".. because in the freeride mode, I hit the pedals on rocks, etc and in the
cross country mode... I endo when going off steep drops,e tc.
charlie
>Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
>tell the difference when riding?
>
>Clyde
My mountain bike ( cannondale jekyll) has a rear shock adjustment that changes the BB height
1+ inches .. and also changes the head tube angle.... so it is hard to tell which has the
greater impact.
in the cross country mode.. the BB is at it's highest point and the head tube angle is 70 degrees..
good for navigating switchbacks, etc.
in the freeride mode the BB is at it's lowest and the head tube angle is about 68 degrees... greater
stability on rocky downhills.
I set mine "in the middle".. because in the freeride mode, I hit the pedals on rocks, etc and in the
cross country mode... I endo when going off steep drops,e tc.
charlie
S
Simon Brooke
Guest
Charles Beristain <[email protected]> writes:
> My mountain bike ( cannondale jekyll) has a rear shock adjustment that changes the BB height
> 1+ inches .. and also changes the head tube angle.... so it is hard to tell which has the
> greater impact.
>
> in the cross country mode.. the BB is at it's highest point and the head tube angle is 70
> degrees.. good for navigating switchbacks, etc.
>
> in the freeride mode the BB is at it's lowest and the head tube angle is about 68 degrees...
> greater stability on rocky downhills.
>
> I set mine "in the middle".. because in the freeride mode, I hit the pedals on rocks, etc and in
> the cross country mode... I endo when going off steep drops,e tc.
OK, my Jekyll is currently 'in the middle' as well. As a matter of interest, is there anyone out
there with a Jekyll _not_ in the middle? I certainly would not want my BB any lower, because, as you
say, you'd spend too much time bouncing pedals off rocks.
--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; gif ye hes forget our auld
plane Scottis quhilk your mother lerit you, ;; in tymes cuming I sall wryte to you my mind in Latin,
for I am nocht ;; acquyntit with your Southeron ;; Letter frae Ninian Winyet tae John Knox datit 27t
October 1563
> My mountain bike ( cannondale jekyll) has a rear shock adjustment that changes the BB height
> 1+ inches .. and also changes the head tube angle.... so it is hard to tell which has the
> greater impact.
>
> in the cross country mode.. the BB is at it's highest point and the head tube angle is 70
> degrees.. good for navigating switchbacks, etc.
>
> in the freeride mode the BB is at it's lowest and the head tube angle is about 68 degrees...
> greater stability on rocky downhills.
>
> I set mine "in the middle".. because in the freeride mode, I hit the pedals on rocks, etc and in
> the cross country mode... I endo when going off steep drops,e tc.
OK, my Jekyll is currently 'in the middle' as well. As a matter of interest, is there anyone out
there with a Jekyll _not_ in the middle? I certainly would not want my BB any lower, because, as you
say, you'd spend too much time bouncing pedals off rocks.
--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; gif ye hes forget our auld
plane Scottis quhilk your mother lerit you, ;; in tymes cuming I sall wryte to you my mind in Latin,
for I am nocht ;; acquyntit with your Southeron ;; Letter frae Ninian Winyet tae John Knox datit 27t
October 1563
Z
Zog The Undenia
Guest
Clyde wrote:
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
>
> Clyde
>
>
You could at traffic lights ;-)
> Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could
> you tell the difference when riding?
>
> Clyde
>
>
You could at traffic lights ;-)
B
B
Guest
>Between 2 bikes, the same except for bottom bracket
>> drop, one is 65mm, the other is 75mm, could you tell the difference when riding?
yes B
(remove clothes to reply)
>> drop, one is 65mm, the other is 75mm, could you tell the difference when riding?
yes B
(remove clothes to reply)
C
Clyde
Guest
Remarkable!
"B" <[email protected]> wrote in message news:[email protected]...
> >Between 2 bikes, the same except for bottom bracket
> >> drop, one is 65mm, the other is 75mm, could you tell the difference when riding?
>
> yes B
>
> (remove clothes to reply)
"B" <[email protected]> wrote in message news:[email protected]...
> >Between 2 bikes, the same except for bottom bracket
> >> drop, one is 65mm, the other is 75mm, could you tell the difference when riding?
>
> yes B
>
> (remove clothes to reply)
C
Charles Berista
Guest
On Sat, 15 Nov 2003 10:05:02 GMT, Simon Brooke <[email protected]> wrote:
>OK, my Jekyll is currently 'in the middle' as well. As a matter of interest, is there anyone out
>there with a Jekyll _not_ in the middle? I certainly would not want my BB any lower, because, as
>you say, you'd spend too much time bouncing pedals off rocks.
I had a bad experience with my jekyll's settings. One day I decided to try the full freeride
position as we were heading out to a very technical area with lots of big rocks to climb up and
down. The big ring took such a beating ( did not have a rock ring on).. that I stopped and took a
minute to put it into full X/C position. The I rode down a very steep rock face and at the bottom,
the front wheel just dug in and sent me flying. The head tube angle in the X/C position makes it so
the front wheel does not want to ride over stuff that normally i would just float over. After that,
I put it in the middle, took off the big ring and put a 32 bash ring on in it's place. I've been
happy since.
I'd like to go back to the full freeride position, but I think I would have to re-learn pedalling ..
otherwise I'd hit every rock that i pass by <G>
I have the "5 & 5" jekyll.. Max TPC+ shock in front and 5" travel in the rear - I love it. I have a
scalpel for racing.
charlie
>OK, my Jekyll is currently 'in the middle' as well. As a matter of interest, is there anyone out
>there with a Jekyll _not_ in the middle? I certainly would not want my BB any lower, because, as
>you say, you'd spend too much time bouncing pedals off rocks.
I had a bad experience with my jekyll's settings. One day I decided to try the full freeride
position as we were heading out to a very technical area with lots of big rocks to climb up and
down. The big ring took such a beating ( did not have a rock ring on).. that I stopped and took a
minute to put it into full X/C position. The I rode down a very steep rock face and at the bottom,
the front wheel just dug in and sent me flying. The head tube angle in the X/C position makes it so
the front wheel does not want to ride over stuff that normally i would just float over. After that,
I put it in the middle, took off the big ring and put a 32 bash ring on in it's place. I've been
happy since.
I'd like to go back to the full freeride position, but I think I would have to re-learn pedalling ..
otherwise I'd hit every rock that i pass by <G>
I have the "5 & 5" jekyll.. Max TPC+ shock in front and 5" travel in the rear - I love it. I have a
scalpel for racing.
charlie
J
Jim Adney
Guest
On Fri, 14 Nov 2003 20:02:35 GMT "Clyde" <[email protected]> wrote:
>Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
>tell the difference when riding?
The main difference is the pedal clearance when cornering.
-
-----------------------------------------------
Jim Adney [email protected] Madison, WI 53711 USA
-----------------------------------------------
>Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
>tell the difference when riding?
The main difference is the pedal clearance when cornering.
-
-----------------------------------------------
Jim Adney [email protected] Madison, WI 53711 USA
-----------------------------------------------
B
Bvm
Guest
I could definitely tell the difference, but could live with either. Unless you're going off-road and
hitting your pedals in corners, then lower is better--lower center of gravity.
On Fri, 14 Nov 2003 20:02:35 GMT, "Clyde" <[email protected]> wrote:
>Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
>tell the difference when riding?
>
>Clyde
hitting your pedals in corners, then lower is better--lower center of gravity.
On Fri, 14 Nov 2003 20:02:35 GMT, "Clyde" <[email protected]> wrote:
>Between 2 bikes, the same except for bottom bracket drop, one is 65mm, the other is 75mm, could you
>tell the difference when riding?
>
>Clyde
T
Ted Bennett
Guest
BVM <[email protected]> wrote:
> I could definitely tell the difference, but could live with either. Unless you're going off-road
> and hitting your pedals in corners, then lower is better--lower center of gravity.
I keep hearing this, but I am skeptical.
A higher center of gravity makes a bike more stable, not less. The natural frequency is slower and
therefore requires slower inputs.
You can think of a bike as an inverted pendulum, pivoted at the ground. Try balancing a short stick
and a long one on the palm of your hand and you will see what I mean.
This can also be demonstrated by how much of a learning curve is required for a low racer and a
tall bike.
--
Ted Bennett Portland OR
> I could definitely tell the difference, but could live with either. Unless you're going off-road
> and hitting your pedals in corners, then lower is better--lower center of gravity.
I keep hearing this, but I am skeptical.
A higher center of gravity makes a bike more stable, not less. The natural frequency is slower and
therefore requires slower inputs.
You can think of a bike as an inverted pendulum, pivoted at the ground. Try balancing a short stick
and a long one on the palm of your hand and you will see what I mean.
This can also be demonstrated by how much of a learning curve is required for a low racer and a
tall bike.
--
Ted Bennett Portland OR
J
Jay Hill
Guest
Ted Bennett wrote:
> BVM <[email protected]> wrote:
>
>
>>I could definitely tell the difference, but could live with either. Unless you're going off-road
>>and hitting your pedals in corners, then lower is better--lower center of gravity.
>
> I keep hearing this, but I am skeptical.
>
> A higher center of gravity makes a bike more stable, not less. The natural frequency is slower and
> therefore requires slower inputs.
>
So a bike whose rider is 10 feet off the ground can make a, say, 45 degree turn faster than a
bicycle whose rider is at normal height?
> BVM <[email protected]> wrote:
>
>
>>I could definitely tell the difference, but could live with either. Unless you're going off-road
>>and hitting your pedals in corners, then lower is better--lower center of gravity.
>
> I keep hearing this, but I am skeptical.
>
> A higher center of gravity makes a bike more stable, not less. The natural frequency is slower and
> therefore requires slower inputs.
>
So a bike whose rider is 10 feet off the ground can make a, say, 45 degree turn faster than a
bicycle whose rider is at normal height?
T
Ted Bennett
Guest
Jay Hill <[email protected]> wrote:
> Ted Bennett wrote:
> > BVM <[email protected]> wrote:
> >
> >
> >>I could definitely tell the difference, but could live with either. Unless you're going off-road
> >>and hitting your pedals in corners, then lower is better--lower center of gravity.
> >
> > I keep hearing this, but I am skeptical.
> >
> > A higher center of gravity makes a bike more stable, not less. The natural frequency is slower
> > and therefore requires slower inputs.
> >
> So a bike whose rider is 10 feet off the ground can make a, say, 45 degree turn faster than a
> bicycle whose rider is at normal height?
I doubt it. When I wrote about stability I was thinking about riding in a straight line, where each
lean of the bike must be corrected in order to not turn. The shorter the height of the mass, the
higher the frequency of the excursions which must be corrected.
This thread began with a question about stability effects of a higher or lower BB. Within the range
found on virtually all "normal" bikes, the stability effect is very small. Pedal strikes are another
matter entirely and is a good reason for higher BBs on, for example, a criterium bike.
On most bikes, the centroid is at a similar height to that of a pedestrian and that is a factor in
learning to balance a bike. For a much lower centroid, such as on this:
http://www.wisil.recumbents.com/wisil/gritters/20-20-lowracer-side.jpg which requires smaller,
higher-speed steering inputs. Not easy at all at first, but luckily humans readily train and adapt.
For a tall bike, the higher centroid needs slower inputs which are easier to learn, once you get up
there, that is.
Any single track vehicle doesn't really go straight. Careful observation will show that both wheels
follow a sinusoidal path, the frequency inversely related to the centroid height and directly
related to the mass.
--
Ted Bennett Portland OR
> Ted Bennett wrote:
> > BVM <[email protected]> wrote:
> >
> >
> >>I could definitely tell the difference, but could live with either. Unless you're going off-road
> >>and hitting your pedals in corners, then lower is better--lower center of gravity.
> >
> > I keep hearing this, but I am skeptical.
> >
> > A higher center of gravity makes a bike more stable, not less. The natural frequency is slower
> > and therefore requires slower inputs.
> >
> So a bike whose rider is 10 feet off the ground can make a, say, 45 degree turn faster than a
> bicycle whose rider is at normal height?
I doubt it. When I wrote about stability I was thinking about riding in a straight line, where each
lean of the bike must be corrected in order to not turn. The shorter the height of the mass, the
higher the frequency of the excursions which must be corrected.
This thread began with a question about stability effects of a higher or lower BB. Within the range
found on virtually all "normal" bikes, the stability effect is very small. Pedal strikes are another
matter entirely and is a good reason for higher BBs on, for example, a criterium bike.
On most bikes, the centroid is at a similar height to that of a pedestrian and that is a factor in
learning to balance a bike. For a much lower centroid, such as on this:
http://www.wisil.recumbents.com/wisil/gritters/20-20-lowracer-side.jpg which requires smaller,
higher-speed steering inputs. Not easy at all at first, but luckily humans readily train and adapt.
For a tall bike, the higher centroid needs slower inputs which are easier to learn, once you get up
there, that is.
Any single track vehicle doesn't really go straight. Careful observation will show that both wheels
follow a sinusoidal path, the frequency inversely related to the centroid height and directly
related to the mass.
--
Ted Bennett Portland OR
B
Bvm
Guest
On Sun, 16 Nov 2003 17:57:59 GMT, Ted Bennett <[email protected]> wrote:
>BVM <[email protected]> wrote:
>
>> I could definitely tell the difference, but could live with either. Unless you're going off-road
>> and hitting your pedals in corners, then lower is better--lower center of gravity.
>
>
>I keep hearing this, but I am skeptical.
Well, you can test it fairly easily on the same bike. Let's say you usually use 175 cranks. Get some
170's or shorter. If the difference is 5mm, then that is close to raising your BB by 5mm for
cornering. Try cornering and you will have more stability and can carve a tighter line, though only
a little bit. I used to race BMX bikes over 20 years ago, and this was a fairly big issue. On road
bikes, I usually ride in a straight line for long periods of time and the tires are relatively
skinny, so the benefit, while real, is probably not going to cut much time off your trip.
>BVM <[email protected]> wrote:
>
>> I could definitely tell the difference, but could live with either. Unless you're going off-road
>> and hitting your pedals in corners, then lower is better--lower center of gravity.
>
>
>I keep hearing this, but I am skeptical.
Well, you can test it fairly easily on the same bike. Let's say you usually use 175 cranks. Get some
170's or shorter. If the difference is 5mm, then that is close to raising your BB by 5mm for
cornering. Try cornering and you will have more stability and can carve a tighter line, though only
a little bit. I used to race BMX bikes over 20 years ago, and this was a fairly big issue. On road
bikes, I usually ride in a straight line for long periods of time and the tires are relatively
skinny, so the benefit, while real, is probably not going to cut much time off your trip.
P
Peter Cole
Guest
"Ted Bennett" <[email protected]> wrote in message
news:[email protected]...
> BVM <[email protected]> wrote:
>
> > I could definitely tell the difference, but could live with either. Unless you're going off-road
> > and hitting your pedals in corners, then lower is better--lower center of gravity.
>
>
> I keep hearing this, but I am skeptical.
>
> A higher center of gravity makes a bike more stable, not less. The natural frequency is slower and
> therefore requires slower inputs.
Low bottom brackets are common on touring bikes because it makes it easier to put a foot down while
in the saddle. The trade off is more pedal strike risk when cornering. The effects on handling are
negligible.
news:[email protected]...
> BVM <[email protected]> wrote:
>
> > I could definitely tell the difference, but could live with either. Unless you're going off-road
> > and hitting your pedals in corners, then lower is better--lower center of gravity.
>
>
> I keep hearing this, but I am skeptical.
>
> A higher center of gravity makes a bike more stable, not less. The natural frequency is slower and
> therefore requires slower inputs.
Low bottom brackets are common on touring bikes because it makes it easier to put a foot down while
in the saddle. The trade off is more pedal strike risk when cornering. The effects on handling are
negligible.
- Status
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