make a softtail into a hardtail?

Steve Knight said:

Anyone know of a bar to replace a shock on my suspension bent? It uses a
standard shock. I find that if I have enough air in it to get rid of the pedal
bounce the rear wheel slams down into all holes very hard. I am about 210 but I
need about 250psi in it to keep the bounce down. If I have about 100 or so PSI
the bounce is gone and no slamming and the lack of the shock is not that big of
a deal.
I don't want to have to spend 300.00 or so for a good shock that would let me
control the problems. So if I could remove the shock and just replace it with a
spacer that would be good. Save some weight too.

Dear Steve,

If you haven't already checked, here are two related sites
that offer calculators about recumbent suspension and pedal
kick-back:

http://www.kreuzotter.de/english/efeder.htm

http://www.kreuzotter.de/english/eschwinge.htm

If you stuff your dimensions into these, they might suggest
a suspension solution or at least a length for the bar that
you have in mind.

If you switch to a bar, you may have to find a machine shop
to get something the right length and strength that will
attach to your particular shock mounts.

Carl Fogel

"Steve Knight" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Anyone know of a bar to replace a shock on my suspension bent? It uses a
standard shock. I find that if I have enough air in it to get rid of the
pedal
bounce the rear wheel slams down into all holes very hard. I am about 210
but I
need about 250psi in it to keep the bounce down. If I have about 100 or so
PSI
the bounce is gone and no slamming and the lack of the shock is not that
big of
a deal.
I don't want to have to spend 300.00 or so for a good shock that would
let me
control the problems. So if I could remove the shock and just replace it
with a
spacer that would be good. Save some weight too.

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

One of these might fit:
http://www.progressivesuspension.com/cvt5.html

They have two stage compression, allowing a stable platform for pedalling
and open up for bigger hits.
There are other versions now too - they're quite common in the MB world.

AndyC

Steve Knight said:

Anyone know of a bar to replace a shock on my suspension bent? It uses a
standard shock. I find that if I have enough air in it to get rid of the pedal
bounce the rear wheel slams down into all holes very hard. I am about 210 but I
need about 250psi in it to keep the bounce down. If I have about 100 or so PSI
the bounce is gone and no slamming and the lack of the shock is not that big of
a deal.
I don't want to have to spend 300.00 or so for a good shock that would let me
control the problems. So if I could remove the shock and just replace it with a
spacer that would be good. Save some weight too.

If the thing slams into holes when you pump it up until it doesn't
work any more, what makes you think that replacing it with a metal bar
will change that situation?

The idea behind the shock is to keep from jarring you when you hit
bumps, since you can't climb out of the saddle on a recumbent. Get
rid of the shock absorber and your body will have to absorb all the
shock instead.

If you want to replace the shock with a metal bar, just get a metal
bar about 1/2" thick (or whatever matches your shock) about the length
of the shock and drill two holes in it.

dkd said:

Steve Knight said:

Anyone know of a bar to replace a shock on my suspension bent? It
uses a standard shock. I find that if I have enough air in it to get
rid of the pedal bounce the rear wheel slams down into all holes
very hard. I am about 210 but I need about 250psi in it to keep the
bounce down. If I have about 100 or so PSI the bounce is gone and no
slamming and the lack of the shock is not that big of a deal.
I don't want to have to spend 300.00 or so for a good shock that
would let me control the problems. So if I could remove the shock
and just replace it with a spacer that would be good. Save some
weight too.

I don't get it. Aren't bents immune from pedal bob from the getgo?

Quoted message said:

If the thing slams into holes when you pump it up until it doesn't
work any more, what makes you think that replacing it with a metal bar
will change that situation?

I was thinking the same thing.

Quoted message said:

The idea behind the shock is to keep from jarring you when you hit
bumps, since you can't climb out of the saddle on a recumbent. Get
rid of the shock absorber and your body will have to absorb all the
shock instead.

If you want to replace the shock with a metal bar, just get a metal
bar about 1/2" thick (or whatever matches your shock) about the length
of the shock and drill two holes in it.

Not only that, but the mounting bolts will undergo far more stress than when
it had the shock, even when it was pumped up rigid. Even worse, the bent
has far more weight on the rear than an upright, putting lots more stress on
the shock mount. Using a block that's much wider than the prior shock mount
would be a good idea, else the mounting bolts may yield and fracture.

All in all, this sounds like a bad idea.

--
Phil, Squid-in-Training

Quoted message said:

On Tue, 17 May 2005 23:22:11 -0700, Steve Knight

Quoted message said:

If you switch to a bar, you may have to find a machine shop
to get something the right length and strength that will
attach to your particular shock mounts.

I figured all I would need to do is take the shock in and have them make a
shaft. but then what do I do without it while they are doing that (G) but if
something was pre made it would be easier.

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

Quoted message said:

They have two stage compression, allowing a stable platform for pedalling
and open up for bigger hits.
There are other versions now too - they're quite common in the MB world.

but a really good shock is spendy. I just can't afford to spend that money. the
lack of a shock is not that big of a deal to me.

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

Quoted message said:

If the thing slams into holes when you pump it up until it doesn't
work any more, what makes you think that replacing it with a metal bar
will change that situation?

it slams into holes because there is no control on the return force. no controls
to slow down the return rate.
going into a hole without it is not a big deal.

Quoted message said:

The idea behind the shock is to keep from jarring you when you hit
bumps, since you can't climb out of the saddle on a recumbent. Get
rid of the shock absorber and your body will have to absorb all the
shock instead.

yes but it is not that big of a deal I did not buy the bike for the shock but
that it felt good to ride. I don't have a problem living without the shock. it
would be fine if I could afford a really good shock. but I just can't see
spending 300 for one.

Quoted message said:

If you want to replace the shock with a metal bar, just get a metal
bar about 1/2" thick (or whatever matches your shock) about the length
of the shock and drill two holes in it.

it needs to have machined holes and flats to work well it needs to be accurately
fitted. length is not the critical thing it's the holes. I don't want to mess up
the mounts.

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

Steve Knight said:

Anyone know of a bar to replace a shock on my suspension bent? It uses a
standard shock. I find that if I have enough air in it to get rid of the pedal
bounce the rear wheel slams down into all holes very hard. I am about 210 but I
need about 250psi in it to keep the bounce down. If I have about 100 or so PSI
the bounce is gone and no slamming and the lack of the shock is not that big of
a deal.
I don't want to have to spend 300.00 or so for a good shock that would let me
control the problems. So if I could remove the shock and just replace it with a
spacer that would be good. Save some weight too.

Go to Walmart and buy a $89 Huffy or Murray with a rear coil shock.
Those things are hard as rocks and compress very little. Swap out the
shocks and your golden!

NC

--

Let the bridges I burn light my way...

On Wed, 18 May 2005 12:33:08 -0400, "Phil,
Squid-in-Training" <[email hidden]>
wrote:

[snip]

Quoted message said:

I don't get it. Aren't bents immune from pedal bob from the getgo?

[snip]

Dear Phil,

Have a look at this recumbent pedal-kickback (pogo effect)
suspension calculator:

http://www.kreuzotter.de/english/eschwinge.htm

On an upright with suspension, pedal bob is more a matter of
the rider stomping up and down on the pedals and the
suspension bobbing in reaction to vertical forces.

On a recumbent with suspension, pedal kickback is more a
matter of the rider pushing horizontally on the pedals and
the tightening chain pulling the two halves of the frame
together.

Carl Fogel

Why not just put 500 PSI in there? That would simulate a metal bar
pretty well.

sunderland said:

Why not just put 500 PSI in there? That would simulate a metal bar
pretty well.

Dear S.,

Unfortunately, 500 psi would also extend the shock to its
upright in-flight position preparatory to landing.

The original poster may not desire a recumbent that imitates
a hot-rod with jacked-up rear suspension.

That much pressure might also lead to failure and deflation,
whereupon the recumbent might switch to imitating a
low-rider.

Carl Fogel

Quoted message said:

On Wed, 18 May 2005 12:33:08 -0400, "Phil,
Squid-in-Training" <[email hidden]>
wrote:

[snip]

Quoted message said:

I don't get it. Aren't bents immune from pedal bob from the getgo?

[snip]

Dear Phil,

Have a look at this recumbent pedal-kickback (pogo effect)
suspension calculator:

http://www.kreuzotter.de/english/eschwinge.htm

On an upright with suspension, pedal bob is more a matter of
the rider stomping up and down on the pedals and the
suspension bobbing in reaction to vertical forces.

On a recumbent with suspension, pedal kickback is more a
matter of the rider pushing horizontally on the pedals and
the tightening chain pulling the two halves of the frame
together.

Your explanation made a lot more sense than the link did. Thanks.

--
Phil, Squid-in-Training

On Wed, 18 May 2005 17:30:43 -0400, "Phil,
Squid-in-Training" <[email hidden]>

Quoted message said:

Quoted message said:

On Wed, 18 May 2005 12:33:08 -0400, "Phil,
Squid-in-Training" <[email hidden]>
wrote:

[snip]

Quoted message said:

I don't get it. Aren't bents immune from pedal bob from the getgo?

[snip]

Dear Phil,

Have a look at this recumbent pedal-kickback (pogo effect)
suspension calculator:

http://www.kreuzotter.de/english/eschwinge.htm

On an upright with suspension, pedal bob is more a matter of
the rider stomping up and down on the pedals and the
suspension bobbing in reaction to vertical forces.

On a recumbent with suspension, pedal kickback is more a
matter of the rider pushing horizontally on the pedals and
the tightening chain pulling the two halves of the frame
together.

Your explanation made a lot more sense than the link did. Thanks.

Dear Phil,

Below its calculator, the Kreuzotter link does explain
things:

"Chain tension generates a torque upon the swingarm, if
pedal kick back is different from zero, because only then
the chain is able to "pull" the swingarm to a different
angle."

http://www.kreuzotter.de/english/eschwinge.htm

It may be a bit Germanic in phrasing, but the main point is
there. It's a recumbent site, so you can't expect much fuss
about uprights, in which the main pedal force is exerted
downward, not horizontally.

Incidentally, the recumbent suspension bobbing is pretty
much a matter of the frame hunching up like an earthworm
each time that the the rider pushes hard against the pedal.

On an upright, this chain-tightening effect is overwhelmed
by the downward force of the rider's leg thrust--the
suspension squashes and spreads out instead of rising up.

Carl Fogel

Quoted message said:

Go to Walmart and buy a $89 Huffy or Murray with a rear coil shock.
Those things are hard as rocks and compress very little. Swap out the
shocks and your golden!

(G) except for the weight added (G)

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

Quoted message said:

Unfortunately, 500 psi would also extend the shock to its
upright in-flight position preparatory to landing.

The original poster may not desire a recumbent that imitates
a hot-rod with jacked-up rear suspension.

(G)

Quoted message said:

That much pressure might also lead to failure and deflation,
whereupon the recumbent might switch to imitating a
low-rider.

I tried it with no air and I got a weird kind of pedal bop not sure if I was
moving or not, it jut felt strange.

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

Steve Knight said:

Quoted message said:

Unfortunately, 500 psi would also extend the shock to its
upright in-flight position preparatory to landing.

The original poster may not desire a recumbent that imitates
a hot-rod with jacked-up rear suspension.

(G)

Quoted message said:

That much pressure might also lead to failure and deflation,
whereupon the recumbent might switch to imitating a
low-rider.

I tried it with no air and I got a weird kind of pedal bop not sure if I was
moving or not, it jut felt strange.

Dear Steve,

With no air, a recumbent with rear suspension should hunch
up just as much or even worse under slow, heavy pedal
forces.

Empty air-shock suspension would offer almost no resistance.

The frame would be sagged as flat as it can go.

So each time the chain tries to pull the rear sprocket and
the front sprocket together, the two halves would hinge
upward at the pivot point.

A solid bar replacing the shock would eliminate this by
locking the two frame halves--no more hunching up like an
inchworm.

As others have pointed out, the solid bar replacement might
end up breaking the mounting points--the frame was
presumably designed for a shock absorber to cushion impacts.

Carl Fogel

"Steve Knight" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

They have two stage compression, allowing a stable platform for pedalling
and open up for bigger hits.
There are other versions now too - they're quite common in the MB world.

but a really good shock is spendy. I just can't afford to spend that
money. the
lack of a shock is not that big of a deal to me.

Fair enough.

"Steve Knight" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Go to Walmart and buy a $89 Huffy or Murray with a rear coil shock.
Those things are hard as rocks and compress very little. Swap out the
shocks and your golden!

(G) except for the weight added (G)

IMHO Lightweight is overrated. Most of us should take pounds off ourselves
before we worry about the weight of the bike.

NC

Quoted message said:

IMHO Lightweight is overrated. Most of us should take pounds off ourselves
before we worry about the weight of the bike.

I am doing both. but my bent is about 37 pounds it needs a diet too (G)

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.