bike feels spongy

Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

I've lost a total of 53 pounds since I started riding last August so
I'm not sure if what I'm feeling is also due to my weight loss. I can't
tell if the sponginess is coming from my saddle or rear tire but I only
feel it when I'm climbing in the saddle.

Javier

"Javier" wrote: (clip)I've lost a total of 53 pounds since I started riding
last August(clip) I only feel it when I'm climbing in the saddle.
^^^^^^^^^^^^^^^^
I guess we can assume this bike does not have rear suspension.

Since you don't feel it while climbing out of the saddle, that seems to
point to the saddle or your butt. With every pedal stroke, as you push
down, you unweight the saddle. When you were heavier, this may have been
less noticeable. Just a theory.

Put 50 lbs of weight in your pockets, and see whether the problem goes away.
;-)

On 15 Jul 2006 18:11:27 -0700, "Javier" wrote:

Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

I've lost a total of 53 pounds since I started riding last August so
I'm not sure if what I'm feeling is also due to my weight loss. I can't
tell if the sponginess is coming from my saddle or rear tire but I only
feel it when I'm climbing in the saddle.

Javier

Do you have one of those seat stems with the spring in it?

"Javier" wrote in news:1153012287.811361.152160
@s13g2000cwa.googlegroups.com:

Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

I've lost a total of 53 pounds since I started riding last August so
I'm not sure if what I'm feeling is also due to my weight loss. I can't
tell if the sponginess is coming from my saddle or rear tire but I only
feel it when I'm climbing in the saddle.

Javier


This is a little spooky, as the same thing happened to me a few days ago.

It felt so pronounced that I reached under the seat to see if the main nut
was only finger-tight.

I went back checked out the seat rails, and where they embed into the seat,
to make sure there was no failure there. I also fully inflated the tires
again.

And then, today, with about 200% humidity and 87F, I went out and viola, no
shimmy. That was even after clicking up a gear at the end of the climb.

So, there was a lot more perspiration and correctly inflated tires along
with newly laundered riding shorts.

What kind of saddle do you use? Does it have a leather cover, and what
about the shorts? The friction force depends on the normal forces and the
coefficient of friction, so you've got the whole set of empirical
parameters for the coefficient to consider, in addition to the dynamic
factors that could change the normal force.

I have noticed a lot more seat flexing since changing from a Terry CrMo to
a Zero-Y, but that seemed directly attributable to the seat change.

"Javier" wrote:

Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

I've lost a total of 53 pounds since I started riding last August so
I'm not sure if what I'm feeling is also due to my weight loss. I can't
tell if the sponginess is coming from my saddle or rear tire but I only
feel it when I'm climbing in the saddle.

I think wvantwiller is onto the likely cause. The effect of a
slightly loose seatpost clamp will be a "sponginess" (or something
that could well be described with that term, at least). Just grab the
nose and tail of your saddle (not while you're riding though...) and
give it some back/forth and up/down pressure to see if you feel ANY
play (other than the normal flex in the rails).

If you don't see anything there, you might take a close look at your
frame - particularly the chain stays and the seat tube in the bottom
bracket region. Look for cracked paint as an indication of a problem.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Javier ha scritto:

Everything is
tight and nothing seems cracked or loose.

It might be the seat/saddle itself. It might be cracking, ready to
leave you in a rather uncomfortable state away from home.

Sergio
Pisa

Javier wrote:
Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

Examine the frame for cracks.

I've lost a total of 53 pounds since I started riding last August so
I'm not sure if what I'm feeling is also due to my weight loss. I
can't tell if the sponginess is coming from my saddle or rear tire
but I only feel it when I'm climbing in the saddle.

Have you changed your tire(s)? A higher-quality tire can give the illusion
of sponginess.

To confirm that it really is spongy, add water to the rear end and see if
the bike absorbs it. *rimshot*

--
Phil Lee, Squid

Per Phil Lee, Squid:

Examine the frame for cracks.

I didn't want to say it.... but the one time my bike started feeling what I'd
call "spongy", the frame had cracked at the rear dropout.
--
PeteCresswell

"Robert" wrote in message
...
Javier wrote:
Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

I've lost a total of 53 pounds since I started riding last August so
I'm not sure if what I'm feeling is also due to my weight loss. I can't
tell if the sponginess is coming from my saddle or rear tire but I only
feel it when I'm climbing in the saddle. Javier

++ snip ++
Most importantly though, congratulations on being able to get rid of 53
pounds in just under a year. That's a fine performance. And if your frame
is indeed cracked, let's hope it's an old one so that you can feel you're
rewarding yourself for your fitness efforts, by buying a nice replacement.

Cheers, Robert


Ditto on the congrats!

Someone else might have thought of this and I missed it, but...

If you have a sprung seat post, maybe the "heavier you" bottomed out the
spring. Now, with you being 53 pounds lighter, the spring can do its thing
and provide some springiness.

Jerry

"Ohio Jerry" wrote in message
.. .

"Robert" wrote in message
...
Javier wrote:
Last week during my usual climbing ride the rear of my bike felt
"spongy" in other words I felt as if the rear of my bike sinking a
bit
when I put force on the pedals. I got off checked my tires and they
were properly inflated (I pump up before every ride). Everything is
tight and nothing seems cracked or loose.

I've lost a total of 53 pounds since I started riding last August
so
I'm not sure if what I'm feeling is also due to my weight loss. I
can't
tell if the sponginess is coming from my saddle or rear tire but I
only
feel it when I'm climbing in the saddle. Javier

++ snip ++
Most importantly though, congratulations on being able to get rid
of 53
pounds in just under a year. That's a fine performance. And if your
frame
is indeed cracked, let's hope it's an old one so that you can feel
you're
rewarding yourself for your fitness efforts, by buying a nice
replacement.

Cheers, Robert


Ditto on the congrats!

Someone else might have thought of this and I missed it, but...

If you have a sprung seat post, maybe the "heavier you" bottomed out
the
spring. Now, with you being 53 pounds lighter, the spring can do its
thing
and provide some springiness.

Jerry


One other issue that hasn't been touched on is your increased strength.
I've stopped riding for various reasons a number of times over the
years. I found that several frames felt "soft" after I got back in
condition, especially when climbing.

When honking out of the saddle, it can be hard to notice a problem
unless it's severe. As someone else said, check your spoke tension.

Chas.