Choosing a Front Shock

Hey Guys,

A few years ago I bought an Avanti Hammer (2002 Model) and rode and
rode it all around the palce and had a great time, over the course of a
few years everything has been replaced and now the only original parts
on it are the front shocks and the front wheel. Yes even the frame was
replaced when it developed cracks, the supplier replaed it with a
Specialised Stumpjumper (hardtail).

So my question is, now I have an 05 Stumpjumper and some old Rock Shox
Judy XC forks and looking to upgrade them. When specialised make their
bikes, is the frame designed around a specific shock? Would I not be
getting the best out of the bike if I went for another brand? The
retail version comes with 90mm Fox forks, would it make much difference
if I put a pair of 80mm Rock Shox SID's on there?

I have had a search through this groups of past postings, and I came up
with all these responses about the advantages of shocks and whether
they are actually worth it! I never thought the discussion was so
current and there are still people out there who ride fully rigid biks
on trails!! But then the date on the postings was 93/94.

Any advice would be greaqtly appreciated
Thanks

spdr wrote:
Hey Guys,

A few years ago I bought an Avanti Hammer (2002 Model) and rode and
rode it all around the palce and had a great time, over the course of a
few years everything has been replaced and now the only original parts
on it are the front shocks and the front wheel. Yes even the frame was
replaced when it developed cracks, the supplier replaed it with a
Specialised Stumpjumper (hardtail).

So my question is, now I have an 05 Stumpjumper and some old Rock Shox
Judy XC forks and looking to upgrade them. When specialised make their
bikes, is the frame designed around a specific shock? Would I not be
getting the best out of the bike if I went for another brand? The
retail version comes with 90mm Fox forks, would it make much difference
if I put a pair of 80mm Rock Shox SID's on there?

Frames are designed around specific amounts/ranges of fork travel, and
of course are also made with a certain level of abusability in mind, to
which the fork should also be appromximately matched. And there's also
headset/steerer compatibility.

The biggest reasons why this all matters is its effect on head tube
angle, trail, and BB height. It affects most of the other measures of
the bike's geometry by some amount as well, but not very much.

Some frame-only suppliers spec an exact travel length for a frame, many
spec a range, and some say use anything. This is debatable, but most
likely the ones that say use anything aren't being duly anal.

Putting the SID on will probably be fine.

I have had a search through this groups of past postings, and I came up
with all these responses about the advantages of shocks and whether
they are actually worth it! I never thought the discussion was so
current and there are still people out there who ride fully rigid biks
on trails!! But then the date on the postings was 93/94.

Any advice would be greaqtly appreciated
Thanks

On Sun, 29 Jan 2006 17:49:09 -0800, Nate Knutson wrote:

spdr wrote:

A few years ago I bought an Avanti Hammer (2002 Model) and rode and
rode it all around the palce and had a great time, over the course of a
few years everything has been replaced and now the only original parts
on it are the front shocks and the front wheel. Yes even the frame was
replaced when it developed cracks, the supplier replaed it with a
Specialised Stumpjumper (hardtail).

So my question is, now I have an 05 Stumpjumper and some old Rock Shox
Judy XC forks and looking to upgrade them. When specialised make their
bikes, is the frame designed around a specific shock? Would I not be
getting the best out of the bike if I went for another brand? The
retail version comes with 90mm Fox forks, would it make much difference
if I put a pair of 80mm Rock Shox SID's on there?

Frames are designed around specific amounts/ranges of fork travel, and
of course are also made with a certain level of abusability in mind, to
which the fork should also be appromximately matched.

Actually it should be well matched, because...

The biggest reasons why this all matters is its effect on head tube
angle, trail, and BB height. It affects most of the other measures of
the bike's geometry by some amount as well, but not very much.

The rule of thumb is, a degree of head angle for every half inch of fork
height. Of course this varies with adjustment (sag), but you want to keep
it as close as possible.

Measure the length of your fork, axle to crown, and find one that's as
close as possible. This isn't hard because most forks with the same
purpose are about the same length anyway.

And there's also
headset/steerer compatibility.

Almost all forks these days have standard 1 1/8" steerers.

Some frame-only suppliers spec an exact travel length for a frame, many
spec a range, and some say use anything. This is debatable, but most
likely the ones that say use anything aren't being duly anal.

Putting the SID on will probably be fine.

If your Judy is 80mm travel, the 80mm SID is probably the same height. So
if you like how your bike handles now, this would be a good swap. A
taller fork will make your bike more stable but slower to react, a shorter
one the opposite.

Matt O.

On 29 Jan 2006 16:13:48 -0800, "spdr" wrote:

So my question is, now I have an 05 Stumpjumper and some old Rock Shox
Judy XC forks and looking to upgrade them. When specialised make their
bikes, is the frame designed around a specific shock?

TTBOMK, no, though they may optimize the geometry for forks with a
certain set of specs that may only be closely filled by a limited
selection.

Would I not be
getting the best out of the bike if I went for another brand? The
retail version comes with 90mm Fox forks, would it make much difference
if I put a pair of 80mm Rock Shox SID's on there?

Look at the distance from the crown to the axle. If it's close to the
same on both, there should be no real problem IMO.

I have had a search through this groups of past postings, and I came up
with all these responses about the advantages of shocks and whether
they are actually worth it! I never thought the discussion was so
current and there are still people out there who ride fully rigid biks
on trails!! But then the date on the postings was 93/94.

Looking at the bikes that pound through the trails of a nearby public
park, there are still folks running through the weeds and woods on
unsuspended bikes today. They're decidely in the minority, though.
My personal opinion is that you are best served by choosing the bike
which fits your riding style, your expectations, and the terrain where
you'll use it.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

On 29 Jan 2006 16:13:48 -0800, "spdr" wrote:

Hey Guys,

Clip

So my question is, now I have an 05 Stumpjumper and some old Rock Shox
Judy XC forks and looking to upgrade them. When specialised make their
bikes, is the frame designed around a specific shock? Would I not be
getting the best out of the bike if I went for another brand? The
retail version comes with 90mm Fox forks, would it make much difference
if I put a pair of 80mm Rock Shox SID's on there?

Any advice would be greaqtly appreciated

Thanks

I have used the Englund Air Cartridges in a Judy XL and
find them to be terrific.

You basically throw everything inside the Judy away and install these
cartridge units. You will need a shock pump if you don't have one.

They were simple to set up and adjust and have worked great for almost
two years now. They were known to leak down over a period of time,
but I have not noticed this to any great degree.

If your bushings are good, you can put some STP or the like into the
legs for lube and install these cartridge units and be trouble free.

I like them and highly recommend them to anyone with a Judy..

See the URL below:

http://www.ekosport.com/ta_intro.shtml

Bob F.

On Mon, 30 Jan 2006 09:17:24 -0500, Bob Flumere wrote:

I have used the Englund Air Cartridges in a Judy XL and find them to be
terrific.

You basically throw everything inside the Judy away and install these
cartridge units. You will need a shock pump if you don't have one.

They were simple to set up and adjust and have worked great for almost
two years now. They were known to leak down over a period of time, but
I have not noticed this to any great degree.

If your bushings are good, you can put some STP or the like into the
legs for lube and install these cartridge units and be trouble free.

Good call on the STP. I use Phil Oil in addition to the usual grease.

I like them and highly recommend them to anyone with a Judy..

See the URL below:

http://www.ekosport.com/ta_intro.shtml

Those things were great as long as they didn't leak. Some did, some
didn't. Mostly they were a great solution a decade ago, when adjusting
your spring rate meant buying *way* overpriced replacement springs from
Rockshox, etc. For a little more money, the Englunds gave you infinite
adjustability and considerable weight savings. An old Judy SL with
Englunds is lighter than anything but the most exotic carbon fiber SID.
The damping isn't as good as with the best hydraulic units, but it's at
least as good as stock. A Judy with Englunds really is a poor man's SID.

Personally I use coil springs and a White Bros. cartridge, the same fork
for almost 10 years now. I overhaul it once or twice a year, and rarely
have to touch the cartridge.

If you have an old Judy and can find a good deal on Englunds, I can
recommend them too. But these days you can find such good deals new
forks, that it probably isn't worth the trouble. I see brand new Psylos
and Dukes on eBay for $150. The seals in these are way better than the
Judy's so they're more trouble free, they're stiffer, and overall better
performing.

Matt O.

So my question is, now I have an 05 Stumpjumper and some old Rock Shox
Judy XC forks and looking to upgrade them. When specialised make their
bikes, is the frame designed around a specific shock? Would I not be
getting the best out of the bike if I went for another brand? The
retail version comes with 90mm Fox forks, would it make much
difference if I put a pair of 80mm Rock Shox SID's on there?

05 Stumpjumper is designed around a 100mm fork. Also, there's technically
no 90mm factory Fox fork. And all this talk about the handling changing on
you is really imperceptible for small changes of 10mm or less. The
suspension itself will make more of a difference in the feel. The reason
that there are so many variables, with the preload, air or coil, sag,
damping, etc. that there's no hard or fast rule on MTB geometry. What I'm
trying to say is that the shock itself is going to dictate how the bike
rides, not whether it's a 80 or 100mm fork.

Put on whatever you'd like between 100 and 80... It's getting hard to find
80's unless it's a race fork. I'll bet you it'll handle pretty much the
same as what you have now, unless your Judy's one of the real old,
elastomer-thats-now-turned-into-putty 63mm forks.

--
Phil, Squid-in-Training