ADVrider

Go Back   ADVrider > Bikes > Trials
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 07-02-2013, 08:17 PM   #1
lamotovita OP
Ageing Adventurer
 
lamotovita's Avatar
 
Joined: Oct 2007
Location: WA/AZ, USA
Oddometer: 1,421
Fork Spring Rate

Can you tell me what a is typical spring rate, or range of spring rates for a modern trials bike?
I'm working on a trail bike and just looking for another reference point. I can't recall seeing a spring rate published anywhere.
__________________
Beaten paths are for beaten men.
lamotovita is online now   Reply With Quote
Old 07-02-2013, 08:31 PM   #2
klx_dude
Gnarly Adventurer
 
klx_dude's Avatar
 
Joined: Jan 2012
Oddometer: 100
Go onto racetech site and click on there spring rate calculator. Gives standard rates for the bike u select

Sent from my GT-I9300T using Tapatalk 2
klx_dude is offline   Reply With Quote
Old 07-02-2013, 08:35 PM   #3
lamotovita OP
Ageing Adventurer
 
lamotovita's Avatar
 
Joined: Oct 2007
Location: WA/AZ, USA
Oddometer: 1,421
Quote:
Originally Posted by klx_dude View Post
Go onto racetech site and click on there spring rate calculator. Gives standard rates for the bike u select

Sent from my GT-I9300T using Tapatalk 2

Not Trials bikes.
__________________
Beaten paths are for beaten men.
lamotovita is online now   Reply With Quote
Old 07-08-2013, 11:25 PM   #4
mung
Studly Adventurer
 
Joined: Apr 2008
Location: Idaho
Oddometer: 543
Spring rates

My 04 Raga had .30 springs stock and now I use .40 mountain bike springs for my 250 pounds.Look at Beta USA under BYOB in the suspension section and it suggests spring rates for your riding weight.
mung is offline   Reply With Quote
Old 07-09-2013, 11:15 AM   #5
motobene
Motoing for 43 years
 
Joined: Mar 2013
Location: Wichita Mountains SW Oklahoma
Oddometer: 1,017
Trials bikes are interesting as compared to my years of setting suspension up on fast off road bikes. Modern trials bike base settings tend to apply across a very wide range of riders, so spring rates tend to fall out of relevancy. Modern bikes generally have stiff enough springs to get by with, even with heavier riders. What is super relevant, however, is the affect setup has on steering characteristics.

The role of spring rate and preload, front and rear in handling characteristics, is often not well understood, and riders, thinking the rear end should sit up higher for more travel, will crank up rear spring preload and end up messing up the bike's steering characteristics. Then they wonder why they take so many points zigzagging in sections. "I just need to get better", they'll say to themselves.

The last three used bikes I helped set up were a Beta Rev 3, a 4RT, and a Beta 300 4T. All were jacked up in rear preload, causing over steer. Over steer from ground reaction torques wanting to suck the bike deeper into turns by decreasing the turn radius. It has to do with rake and trail and bike lean... all to complex to write about here. But you've all felt those bikes that felt hyper and wanted to tuck under in turns?

I set up bike attitude (pitch)/steering feel first making sure the grip position (bar rotation) is correct to modern trials, that is, more forward so the rider's body isn't being pushed back, but not so far forward as to increase over steer (grip position and steering action and reaction torques are related). Then I ride the bike on flat concrete to feel steering reaction torques. If you lean into a turn and the bike wants to steer into a decreasing radius and even tuck under, that's over steer.

I set rear preload and fork preload and position in triple clamps for close-to-neutral reaction torques. Often I leave the shock preload alone unless it's been messed with (the factories center on ~80kg rider -180 pound riders). When I find over steer, which is more often than not, I increase fork spring preload and/or put the fork caps level with the top of the triple clamps. Then I observe riders turning to make sure I'm matching the settings to their weight and style.

I set bikes up with a very slight tendency to over steer during good bit of lean in a turn, but otherwise on flatter turns I prefer neutral steering or even some under steer. Under steer is when a bike wants to steer slightly out of a turn and straighten up. Much less crazy to track the steering that way than when the bike isn't trying to steer itself into turns, acting hyper, and adding points to your game.

motobene screwed with this post 07-09-2013 at 11:56 AM
motobene is offline   Reply With Quote
Old 07-09-2013, 11:39 AM   #6
Sting32
Trials Evangelist
 
Joined: Oct 2009
Location: Minneapolis, Ks
Oddometer: 1,279
Quote:
Originally Posted by motobene View Post
Trials bikes are interesting because the base settings with a few tweaks will work across such a wide range of riders, and the modern bikes generally have stiff enough spring to get by, even with heavier riders.

At most I've had to up spring preload and position forks lower in the triple clamps for handling purposes: to reduce over steer tendencies (front end wants to tuck under and wash in turns). In fact riders should take care when upping the shock spring preload to not negatively affect bike attitude and steering characteristics.
When I was NOT as "good a rider" I wanted stiffer springs, this mean I could keep my skidplate off of things, even though I was heavier than others on same bike (years are important, at least with Gasgas IMHO). We're talking about 1 inch or so, that I could sag the rear, not as much affected by fronts, more than my dad who weighed at least 60lbs less than I DID. We both would increase the pre-load on the front fork springs, up until about the 2008 Raga we got.

Dad didnt need to add spacers anymore on the front, he never used the stiffer rear springs. I on the other-hand, I being semi athletic (yet fat but pretty heavy even for my size) nearly 275lbs, at the highest point. So I bought 2 forks springs from Lewissport, which were supposedly 10% stronger each. 2 almost was too stiff. Plus I had the stiffer spring for the rear Sachs shock, that I had rebuilt and revalved. Anywho, I recall I sold one of the pair of fork springs, to a buddy. He as at least 250, novice rider heading to amature on a short fuse (riding well).

THen I also started to lose weight, but the time I lost 25 lbs, the spring was still WAY too stiff. BUT! Here's the deal, You don't notice too stiff so much, especially since the old days I always wanted the front to not sag hardly at all. I didn't realize how stiff the front had become, until I was competing in winter on very slippery rocks and mud, I mean SLIPPERY STUFF! On dry ground and rocks with traction, I was beating my peers just fine, never felt there was any problem with my setup per se. you hit a pebbel sized rock on the mud path, it stopped you because shocks didnt compress at all, etc.

Now I weigh in at 199lbs. I have even recently had to reduce preload on rear shock spring preloads (stock shock spring on the 2011 Reiger) compared to what I started with a few months ago, when I was above 210, and I haven't modified the front forks from stock since I left that 08 raga.

You want the softer suspension IMHO, as long as it doesn't BOTTOM out or BIND up suspension at full compression, on a 2ft or 3 ft drop of any kind, IMHO. if it hits bottom of travel, things are not right, and IMHO you can find yourself bending and breaking things that are then given a lot harder "tug" on or against when this happens

Even with Raga being a light guy, in comparison, the bike at stock settings sould hold a 180-230lb rider without much mods, other than adding turns to the rear spring preloader, and maybe adding 1/4 - 1/2 inch to the spacers in the front spring setup. what I we used to DO, was take original spacer out, replace with ones that were longer, made from PVC pipe. I dont do this anymore but if I was above 220 I might I dunno, I like softer setup now. ALSO, there was a limit to how much you can add from stock spacer length though, I cannot recall that VALUE, better ask JSE or someone at Trails Central for that kind of technical info, I know I never added more than 1/2 inch per side... when you add that much, there is a BIG difference if the springs are not SHOT!
Sting32 is offline   Reply With Quote
Old 07-09-2013, 09:04 PM   #7
neilking
Gnarly Adventurer
 
Joined: Mar 2008
Location: Austin, TX
Oddometer: 430
This is the best explanations I have ever read! As far as on topic, I can only think of a couple things to add. I can really only comment on stock Beta spring rates specifically. I set rear preload and bar rotation as a compromise between traction and turning characteristics. I find rolling the bars forward increases foot pressure and rear sag, too far forward and steering gets twitchy, too far back puts too much pressure on the front and makes drop offs harder. I find that the one size stiffer (8.0kg) rear spring works well for me(185lb). This way I can run less preload actually making the initial action of the rear shock softer than stock, then it stiffens up nicely further in the stroke helping prevent bottoming out. I'm able to rotate my bars a little more forward to get more weight on the pegs.

Quote:
Originally Posted by motobene View Post
Trials bikes are interesting as compared to my years of setting suspension up on fast off road bikes. Modern trials bike base settings tend to apply across a very wide range of riders, so spring rates tend to fall out of relevancy. Modern bikes generally have stiff enough springs to get by with, even with heavier riders. What is super relevant, however, is the affect setup has on steering characteristics.

The role of spring rate and preload, front and rear in handling characteristics, is often not well understood, and riders, thinking the rear end should sit up higher for more travel, will crank up rear spring preload and end up messing up the bike's steering characteristics. Then they wonder why they take so many points zigzagging in sections. "I just need to get better", they'll say to themselves.

The last three used bikes I helped set up were a Beta Rev 3, a 4RT, and a Beta 300 4T. All were jacked up in rear preload, causing over steer. Over steer from ground reaction torques wanting to suck the bike deeper into turns by decreasing the turn radius. It has to do with rake and trail and bike lean... all to complex to write about here. But you've all felt those bikes that felt hyper and wanted to tuck under in turns?

I set up bike attitude (pitch)/steering feel first making sure the grip position (bar rotation) is correct to modern trials, that is, more forward so the rider's body isn't being pushed back, but not so far forward as to increase over steer (grip position and steering action and reaction torques are related). Then I ride the bike on flat concrete to feel steering reaction torques. If you lean into a turn and the bike wants to steer into a decreasing radius and even tuck under, that's over steer.

I set rear preload and fork preload and position in triple clamps for close-to-neutral reaction torques. Often I leave the shock preload alone unless it's been messed with (the factories center on ~80kg rider -180 pound riders). When I find over steer, which is more often than not, I increase fork spring preload and/or put the fork caps level with the top of the triple clamps. Then I observe riders turning to make sure I'm matching the settings to their weight and style.

I set bikes up with a very slight tendency to over steer during good bit of lean in a turn, but otherwise on flatter turns I prefer neutral steering or even some under steer. Under steer is when a bike wants to steer slightly out of a turn and straighten up. Much less crazy to track the steering that way than when the bike isn't trying to steer itself into turns, acting hyper, and adding points to your game.
__________________
74 TY 80, 175 and 250 no longer at Brewtus's house
86 TLR200
95 Sportster 1200
13 Factory Beta 250
neilking is online now   Reply With Quote
Old 07-09-2013, 09:10 PM   #8
neilking
Gnarly Adventurer
 
Joined: Mar 2008
Location: Austin, TX
Oddometer: 430
Forgot to say, I pretty much leave the front alone, just add a couple clicks of damping from zero. Aso add a little to the rear to keep it planted, much more important than having it off the ground.
__________________
74 TY 80, 175 and 250 no longer at Brewtus's house
86 TLR200
95 Sportster 1200
13 Factory Beta 250
neilking is online now   Reply With Quote
Old 07-09-2013, 09:23 PM   #9
neilking
Gnarly Adventurer
 
Joined: Mar 2008
Location: Austin, TX
Oddometer: 430
This is the best explanations I have ever read! As far as on topic, I can only think of a couple things to add. I can really only comment on stock Beta spring rates specifically. I set rear preload and bar rotation as a compromise between traction and turning characteristics. I find rolling the bars forward increases foot pressure and rear sag, too far forward and steering gets twitchy, too far back puts too much pressure on the front and makes drop offs harder. I find that the one size stiffer (8.0kg) rear spring works well for me(185lb). This way I can run less preload actually making the initial action of the rear shock softer than stock, then it stiffens up nicely further in the stroke helping prevent bottoming out. I'm able to rotate my bars a little more forward to get more weight on the pegs.

Quote:
Originally Posted by motobene View Post
Trials bikes are interesting as compared to my years of setting suspension up on fast off road bikes. Modern trials bike base settings tend to apply across a very wide range of riders, so spring rates tend to fall out of relevancy. Modern bikes generally have stiff enough springs to get by with, even with heavier riders. What is super relevant, however, is the affect setup has on steering characteristics.

The role of spring rate and preload, front and rear in handling characteristics, is often not well understood, and riders, thinking the rear end should sit up higher for more travel, will crank up rear spring preload and end up messing up the bike's steering characteristics. Then they wonder why they take so many points zigzagging in sections. "I just need to get better", they'll say to themselves.

The last three used bikes I helped set up were a Beta Rev 3, a 4RT, and a Beta 300 4T. All were jacked up in rear preload, causing over steer. Over steer from ground reaction torques wanting to suck the bike deeper into turns by decreasing the turn radius. It has to do with rake and trail and bike lean... all to complex to write about here. But you've all felt those bikes that felt hyper and wanted to tuck under in turns?

I set up bike attitude (pitch)/steering feel first making sure the grip position (bar rotation) is correct to modern trials, that is, more forward so the rider's body isn't being pushed back, but not so far forward as to increase over steer (grip position and steering action and reaction torques are related). Then I ride the bike on flat concrete to feel steering reaction torques. If you lean into a turn and the bike wants to steer into a decreasing radius and even tuck under, that's over steer.

I set rear preload and fork preload and position in triple clamps for close-to-neutral reaction torques. Often I leave the shock preload alone unless it's been messed with (the factories center on ~80kg rider -180 pound riders). When I find over steer, which is more often than not, I increase fork spring preload and/or put the fork caps level with the top of the triple clamps. Then I observe riders turning to make sure I'm matching the settings to their weight and style.

I set bikes up with a very slight tendency to over steer during good bit of lean in a turn, but otherwise on flatter turns I prefer neutral steering or even some under steer. Under steer is when a bike wants to steer slightly out of a turn and straighten up. Much less crazy to track the steering that way than when the bike isn't trying to steer itself into turns, acting hyper, and adding points to your game.
__________________
74 TY 80, 175 and 250 no longer at Brewtus's house
86 TLR200
95 Sportster 1200
13 Factory Beta 250
neilking is online now   Reply With Quote
Old 07-09-2013, 10:03 PM   #10
lamotovita OP
Ageing Adventurer
 
lamotovita's Avatar
 
Joined: Oct 2007
Location: WA/AZ, USA
Oddometer: 1,421
Quote:
Originally Posted by mung View Post
My 04 Raga had .30 springs stock and now I use .40 mountain bike springs for my 250 pounds.Look at Beta USA under BYOB in the suspension section and it suggests spring rates for your riding weight.
Thanks for the info. The Beta site lists springs in the .8-.9 range, so I'm guessing that Beta either rates their springs as a pair, or only uses one spring. Anybody know?

I've never changed fork spring rate on a Trials bike even though I frequently change them on other bikes. That's why I don't know what rates are used. I'm working on softening up the front end of a trail bike and just want to compare the rate of Trials bike springs to what I'm using.
__________________
Beaten paths are for beaten men.
lamotovita is online now   Reply With Quote
Old 07-10-2013, 12:02 AM   #11
DrKayak
Retro Rider
 
DrKayak's Avatar
 
Joined: Mar 2010
Location: Shingle Springs CA
Oddometer: 737
Quote:
Originally Posted by lamotovita View Post
Thanks for the info. The Beta site lists springs in the .8-.9 range, so I'm guessing that Beta either rates their springs as a pair, or only uses one spring. Anybody know?
.
My new Evo only uses one spring on the front. Just got the Evo. I rode a stock Techno for 2 years. I never touched the suspension, just rode it. Did hard trail riding too and it never bottomed.

This Evo came with 3 sets of springs. I would have left it stock after my Techno experience. Now I have too many choices. The previous owner has the stiffest spring in it Rated to 250+ rider. I am 190lbs. Still I get a ton of movement in the suspension, does not feel that stiff and it does not seam to over steer as motobeam describes. Guess I will leave it as is for now.
__________________
2011 690 Enduro R
2013 Beta Evo
07 450 EXC
04 FZ1
DrKayak is offline   Reply With Quote
Old 07-10-2013, 01:32 PM   #12
neilking
Gnarly Adventurer
 
Joined: Mar 2008
Location: Austin, TX
Oddometer: 430
Sorry for the double postong. Don't know how that happened.
__________________
74 TY 80, 175 and 250 no longer at Brewtus's house
86 TLR200
95 Sportster 1200
13 Factory Beta 250
neilking is online now   Reply With Quote
Old 07-24-2013, 01:36 PM   #13
motobene
Motoing for 43 years
 
Joined: Mar 2013
Location: Wichita Mountains SW Oklahoma
Oddometer: 1,017
Quote:
Originally Posted by neilking View Post
This is [one of] the best explanations I have ever read!
Well, thanks, Neil! Motobene is me, your friendly, shorts-wearing, gimpy competitor

I was reminded recently just how important bike setup is. I had my former Econo here as well as the 'new' `11 Raga. I think I mentioned in my post about the affect grip placement (bar rotation) has on bike attitude and handling.

Riding the two bikes back and forth, I just could not get the Raga to thread as precisely through rocks and turns as well as the Econo. Given the money I spent on the Raga, it was disturbing me because any one of us can trade places in our class with just a few points. I thought it might have been the bike pitch/attitude/front-rear preload), but those seemed right for my weight, stance, and other variables. What was causing me to lose a touch of steering acuity?

I found it was grip position (bar rotation). Grip position and angle interact with preload and bike pitch (attitude) which affects steering. I was somewhere between one and two degrees of error, bars rotated back. I thought it was just the Raga bend. The error created slight under steer and vagueness.

When I made the minor correction it was eye opening. I could stay on line like the Econo. I might not have caught that without a long term well set up bike to compare to.
motobene is offline   Reply With Quote
Old 07-24-2013, 03:21 PM   #14
Sting32
Trials Evangelist
 
Joined: Oct 2009
Location: Minneapolis, Ks
Oddometer: 1,279
Bar rotation makes a good bit of difference for sure, for us who aren't experts (hopping and big objects). When I rotate forward I find I can hop rear over easier, then struggle a slow-normal *line*... amazes me to see master's with bars even farther forward than I have even *tested* lol. My issue is strenght I thought but absolutely not sure.

Sent from my SCH-I535 using Tapatalk 2
Sting32 is offline   Reply With Quote
Old 07-24-2013, 04:02 PM   #15
Twin-shocker
Beastly Adventurer
 
Joined: Jan 2012
Oddometer: 1,673
Quote:
Originally Posted by motobene View Post
Well, thanks, Neil! Motobene is me, your friendly, shorts-wearing, gimpy competitor

I was reminded recently just how important bike setup is. I had my former Econo here as well as the 'new' `11 Raga. I think I mentioned in my post about the affect grip placement (bar rotation) has on bike attitude and handling.

Riding the two bikes back and forth, I just could not get the Raga to thread as precisely through rocks and turns as well as the Econo. Given the money I spent on the Raga, it was disturbing me because any one of us can trade places in our class with just a few points. I thought it might have been the bike pitch/attitude/front-rear preload), but those seemed right for my weight, stance, and other variables. What was causing me to lose a touch of steering acuity?

I found it was grip position (bar rotation). Grip position and angle interact with preload and bike pitch (attitude) which affects steering. I was somewhere between one and two degrees of error, bars rotated back. I thought it was just the Raga bend. The error created slight under steer and vagueness.

When I made the minor correction it was eye opening. I could stay on line like the Econo. I might not have caught that without a long term well set up bike to compare to.
Bar position does make an awful lot of difference, and in many cases moving the bar mounts themselves forward a little will improve a bike enormously.

The stock position is a compromise, and means its often necessary to move the bars forward to help improve control. Factory riders have bar mounting position adjusted to suit them perfectly, but this is something thats relatively easy to do, if you use S3 adjustable clamps.
Twin-shocker is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 06:19 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014