Cold Weather = Stiff Forks?

SPOODZILLA

Got a new bike over christmas with a basic rockshox xc28 fork on it. Found the fork very stiff everytime I went out on it , to the point that I was convinced something was wrong with it and sent it off to sram for a look over. It came back, re-installed it, gave it a few bounces and it was very plush and responsive. Took it out for a test ride and it started stiffening up again, to the point that it practically stopped moving. Brought it indoors and had a bounce on it after an hour or so, super responsive again. After the same results 5 nights on the run I have decided this night and day difference is down to the fork oil viscosity when cold, it seems to start to stiffen at anything under 10c. Do rockshox think cyclist only go out in the summer? Or do I need to send it back for further testing? I've searched the net for similair stories but have only found a couple of people reporting similar results, which suggests my fork problem is not so common.

Chunkers1980

You spent an hour indoors 'bouncing on it', if that's true that's quite sad.

benpinnick

Never heard of forks stiffening that much when cold due to oil viscosity, although it could happen I guess (except elastomer ones). I dont think the basic XCs even have compression damping, so it would only slow up on rebound anyhoo. More likely they use metal bushes which are contracting and 'grabbing' the legs.

nicklouse

it is what happens to low end forks that have elastomers in them to help control the motion when they dont have proper damping.

in use they will warm up and move better after some time on each ride.

SPOODZILLA

I was hoping they'd warm up with use or at least keep warm through friction, but yesterday I went from a 20c office to -1c canals/woodland and they just got stiffer and stiffer to the point that after 20 mins I thought the lockout was on. Never had this on the rebas/toras I've used previously. Time to complain again I think.

nicklouse

SPOODZILLA wrote:

I was hoping they'd warm up with use or at least keep warm through friction, but yesterday I went from a 20c office to -1c canals/woodland and they just got stiffer and stiffer to the point that after 20 mins I thought the lockout was on. Never had this on the rebas/toras I've used previously. Time to complain again I think.

complaining will get you no where. it is what the forks do. the reson your Rebas never did is because they have proper damping. (and are a whole different level of fork) the XC28 are cheap basic entry level forks.

1mancity2

SPOODZILLA wrote:

I was hoping they'd warm up with use or at least keep warm through friction, but yesterday I went from a 20c office to -1c canals/woodland and they just got stiffer and stiffer to the point that after 20 mins I thought the lockout was on. Never had this on the rebas/toras I've used previously. Time to complain again I think.

Ride rougher terrain

SPOODZILLA

Thanks for the replys chaps. I accept the fork is at the budget end of the market, but it should still work in the cold? Bit warmer today and it shows, fork is much more responsive.

Re rougher terrain, I do at the weekends, woods and canals is my commute. Though 4 miles of 5 inch deep frozen mud littered with horse tracks, bike tracks and genrally chopped up shook me to pieces with no suspension :-)

1mancity2

SPOODZILLA wrote:

Re rougher terrain, I do at the weekends, woods and canals is my commute. Though 4 miles of 5 inch deep frozen mud littered with horse tracks, bike tracks and genrally chopped up shook me to pieces with no suspension :-)

Just thought the rougher you ride the quicker the fork should hopefully loosen up and stay loose

allen.coulson

I think that it should work. Elastomers are basically rubber compounds and agreed that there is a thermal effect it is not so sensitive over a 20deg C range. I think this may just be a running in effect.

nicklouse

allen.coulson wrote:

I think that it should work. Elastomers are basically rubber compounds and agreed that there is a thermal effect it is not so sensitive over a 20deg C range. I think this may just be a running in effect.

Nope it is the temp change. and is why they are only now found on cheap forks.

benpinnick

This is true about elastomers, but aren't the XC28 coil sprung?

Chunkers1980

These appear to be:

http://www.chainreactioncycles.com/Mode ... elID=67884

Dirtydog11

It's a common problem with RockShox forks that use the Turnkey damper .

Rockshox advise using lighter oil during colder months.

Coil sprung or air sprung, it doesn't matter it's the "Turnkey" damping system that causes the issue.

benpinnick

Dirtydog11 wrote:

Coil sprung or air sprung, it doesn't matter it's the "Turkey" damping system that causes the issue.

FIFY.

Dirtydog11

benpinnick wrote:

Dirtydog11 wrote:

Coil sprung or air sprung, it doesn't matter it's the "Turkey" damping system that causes the issue.

FIFY.

386ka

Yes, use lighter oil in colder weather. I have had the same problem with Dart 2, which are basically the same but rebranded I think. These have rebound and remote lockout. They were very stiff, until I serviced them and used lighter oil. I think they use 5wt, 2.5, 3 will be fine.

Try it, it will make a lot of difference.

obido

I have the same issue!

I just bought a Rockshox xc28. I have only used it three times and in the range -5 to -10C it only takes about 10 min or so before it goes rock solid with 0 dampening.

I have used basic low end forks for a long time but never experienced anything like this before

nicklouse

obido wrote:

I have the same issue!

I just bought a Rockshox xc28. I have only used it three times and in the range -5 to -10C it only takes about 10 min or so before it goes rock solid with 0 dampening.

I have used basic low end forks for a long time but never experienced anything like this before

been like this for years.

My Judys from 2001 did this. BUT the Jetts from 1999 did not as they were oil damping.


ALL Elastomer damped forks do it.

obido

Do I risk any damage it if I ride it stiff?

eg. is the force mitigated on a small or big area when it is stiff due to cold. I have no problem riding it stiff but don't want to break a completely new fork.

Neal_

I'm not sure how you would feel about replacing the oil in the damper yourself on new forks but if you're happy doing it then replace it with Red Line Lightweight suspension fluid (which is very stable across a wide temp range) or silicone oil (which is even better but may be hard to source). Rock Shox 5W fork oil is 15.9 cSt @ 40C so you want an oil close to this viscosity.

Thread below shows it works although only on Reba's but it should still be an improvement.

http://forums.mtbr.com/shocks-suspensio ... 62486.html

nicklouse

obido wrote:

Do I risk any damage it if I ride it stiff?

eg. is the force mitigated on a small or big area when it is stiff due to cold. I have no problem riding it stiff but don't want to break a completely new fork.

Makes no difference.

nicklouse

Neal_ wrote:

I'm not sure how you would feel about replacing the oil in the damper yourself on new forks but if you're happy doing it then replace it with Red Line Lightweight suspension fluid (which is very stable across a wide temp range) or silicone oil (which is even better but may be hard to source). Rock Shox 5W fork oil is 15.9 cSt @ 40C so you want an oil close to this viscosity.

Thread below shows it works although only on Reba's but it should still be an improvement.

http://forums.mtbr.com/shocks-suspensio ... 62486.html

But as there is an elastomer in the spring the abov will change nothing.

386ka

obido wrote:

I have the same issue!

I just bought a Rockshox xc28. I have only used it three times and in the range -5 to -10C it only takes about 10 min or so before it goes rock solid with 0 dampening.

I have used basic low end forks for a long time but never experienced anything like this before

If they have TurnKey damper in them, then using lower oil weight will make them better in the cold. So, if you can, and have a TurnKey damper, service them.

Neal_

nicklouse wrote:

Neal_ wrote:

I'm not sure how you would feel about replacing the oil in the damper yourself on new forks but if you're happy doing it then replace it with Red Line Lightweight suspension fluid (which is very stable across a wide temp range) or silicone oil (which is even better but may be hard to source). Rock Shox 5W fork oil is 15.9 cSt @ 40C so you want an oil close to this viscosity.

Thread below shows it works although only on Reba's but it should still be an improvement.

http://forums.mtbr.com/shocks-suspensio ... 62486.html

But as there is an elastomer in the spring the abov will change nothing.

Where's the elastomer in the spring? I can't see it in the below exploded view



http://www.mountainbikes.net/mtbikes/pr ... 0202103411

benpinnick

We established that the forks weren't elastomer a while ago, I think Nicklouse is losing his mind.

Neal_

It happens to the best of them...I blame Wiggle.

So the answer is to service them and use lighter fluid in the damper.

supersonic

The basic entry level XC28 that is found OE on some bikes does not have a Turnkey damper. SRAM do not list the fork, but show pics of it. The Dart 2 and 3 layout above is a different fork.

You can actually buy it in some places, it does not have magnesium lowers, and can be seen to have no adjusters on the right hand leg.

The spring is a coil with an elastomer section.

Neal_

Ah right. SRAM's site isn't the best, I couldn't even find a technical manual for the XC range!

So do we know if it's the basic XC 28 on the OP's bike? He mentions lockout so does that mean it's got the turnkey damper?

jasonsedy

yeah i have the xc28 and it is completely locked out within minutes when the weather is even a little bit cold. WTF?