Respring for Big Rider?

[kpaul]

Someone mentioned in another thread that if you're a big guy then you should respring the bike, as it's already at its limits with just a larger rider. I'm pushing about 280 at 6'4" and if it's as important as indicated, I would like to have the bike resprung to suit my weight and possibly a pillion if possible.

I'm not sure where to start, is this doable on my own (I've installed an exhaust but that's about it) or should I bring it in to a mechanic? And if anyone can recommend a kit, I would appreciate it. Thanks!

 

[SANGER_A2]

Someone mentioned in another thread that if you're a big guy then you should respring the bike, as it's already at its limits with just a larger rider. I'm pushing about 280 at 6'4" and if it's as important as indicated, I would like to have the bike resprung to suit my weight and possibly a pillion if possible.

I'm not sure where to start, is this doable on my own (I've installed an exhaust but that's about it) or should I bring it in to a mechanic? And if anyone can recommend a kit, I would appreciate it. Thanks!

Hyperpro springs are designed for a weight about 2-3 clicks more than the stock. I had the stock on 2 and the Hyper pro on 0 and it was a bit too bouncy. Better with more weight on the back. If you have the stock spring on max reload and it's just a bit too bouncy, the Hyperpro would allow a bit more stiffness for a low cost. Otherwise you'd have to buy a full shock setup by Ohlins etc for massive amounts of money. Much better though! You'll need someone with a machine to swap the springs over though.

You can also put heavier oil in the front forks to help with the damping (the stock is 5w, 10-15w would make a big difference.

 

[Mancolt]

Racetech also makes springs that are cheaper than Ohlins. I've been leaning towards the Hyperpro's though because I have no plans to race or ride on the track. Only carry my big @$$ (same exact size as you) and maybe a pillion. I'm curious to see what other users post for this.

I'm hoping Hyperpro is a viable, effective option for guys our size. If not, my next choice would be Racetech. If neither or those are an option, I guess I'll be sticking with stock rear maxed out and maybe just change the front fork oil...I will not be spending the money required to get Ohlins though.

 

[RJ2112]

Someone mentioned in another thread that if you're a big guy then you should respring the bike, as it's already at its limits with just a larger rider. I'm pushing about 280 at 6'4" and if it's as important as indicated, I would like to have the bike resprung to suit my weight and possibly a pillion if possible.

I'm not sure where to start, is this doable on my own (I've installed an exhaust but that's about it) or should I bring it in to a mechanic? And if anyone can recommend a kit, I would appreciate it. Thanks!

The fork is easier to deal with than the rear. From a DIY aspect, you need to drop the fork tubes, open them up, tip out the old oil.... slide in the new, stiffer springs mount up the legs, and install fresh fork oil. Heavier weight fork oil will work better.

A number of vendors will be able to provide springs that are stiff enough to accommodate your size. There's look up tables to account for the mass of the rider, to set this up correctly. The idea is to have the full wheel travel available for road hazards, and have it set up so you are just beginning to compress the springs at each end to accomplish that.

In a perfect world, when you measure the amount you compress the springs in your 'typical' riding configuration, the suspension only compresses 1/4" or so from full extension.

The easiest way to check 'ride height' is to snug a zip tie onto the fork leg, just tight enough that it won't fall down the fork leg. With the fork leg fully extended (pull up on the bars so the wheel clears the ground and set it back down gently) push the zip tie to the dust seal on the lower leg. Measure from the zip tie to the lower triple clamp.

Then sit on the bike in your full gear, and have someone hold it in the vertical, so the suspension is carrying your full weight.

Get back off the bike, and measure the distance between the zip tie and the clamp. In the perfect world...... that change would be 1/4". Whatever that distance is, what remains of the full stroke of the fork is what you have to deal with bumps in the road. It's probable that with the OEM springs, you are going to find a difference in excess of 2". If it were 2, that would leave 2.5 to deal with bumps before the rim, and steering head bearings start to get whacked.

The springs in the fork have hollow tubes riding on top of them called spacers, which serve to apply some tension to the springs. Different lengths of spacer, will apply different amounts of force, which will in turn make the bike resist settling more.... pre-loading the springs. On a 'tuneable' fork, that's what the preload adjusts.

The rear is a more complicated deal. The rear shock is a straight forward simple system, exactly the same as a McPherson strut.... a shock absorber, surrounded by a spring, carried on the same assembly. Bolted to the chassis at the top, and the swingarm on the bottom.

It too, is a price point part. The spring is quite 'soft', and the damping rates are tailored to that soft spring. Replace the spring with a stiffer one, and it doesn't really have enough compression or rebound damping to control the action. Not only that, but the OEM shock is not designed to be rebuilt.

 

[Mancolt]

It too, is a price point part. The spring is quite 'soft', and the damping rates are tailored to that soft spring. Replace the spring with a stiffer one, and it doesn't really have enough compression or rebound damping to control the action. Not only that, but the OEM shock is not designed to be rebuilt.

Are you saying there's not much point in replacing the rear spring? If that's the case...damn. I take up so much of the rear travel just from sitting on the bike!

 

[RJ2112]

Are you saying there's not much point in replacing the rear spring? If that's the case...damn. I take up so much of the rear travel just from sitting on the bike!

I'm saying that if you want to have the suspension work the way it was intended to work, you should plan on giving it the full Monte. Save up the cash and buy the rear shock and spring that will support your use.

A stiffer spring will keep the back from 'bottoming out', but without addressing the damping, it's going to still bob and weave more than it should. I can't tell you that it's worthless...... that's where you are already at (or very nearly so). No disrespect intended. There's probably no bike sold OEM that is properly sprung for someone of your weight. A stiffer spring has got to be an improvement, I just know it's still going to leave a lot of room for improvement.

Firming up the back will make the steering much more predictable; especially if you do the fork at the same time. If the chassis doesn't rock and roll above the wheels, the rake and trail numbers won't be constantly changing.

I weigh around 200 lbs, and the fork for me was worse than the rear. Even on the hardest setting on the rear, it was still not worth a darn..... but the front felt so vague, it was worse. So much front end dive when you touch the front brakes, made it really hard to tell what the wheel was doing.

 

[FZ6-ZN]

Here is the cheapest option I’ve found thus far; I’m in the process of changing the spring rate on the R6 shock I fitted as the stock FZ6 spring I modified is a little to soft. I ordered an Eibach spring for $60 from eshocks.com: Springs: 2.25" I.D. - 7"

The ID of the $60 Eibach spring is the same as a $120 Racetech spring 2.25 inches. Both spring’s have a free length of 7 inches. There is a variety of spring rates to choose from. To complete the job you’ll need buy or fabricate two spring adaptor collars. Spring adaptor collars are available from racetech at $2.99 each

FZ6-ZN

 

[tuningfork]

The fork is easier to deal with than the rear. From a DIY aspect, you need to drop the fork tubes, open them up, tip out the old oil.... slide in the new, stiffer springs mount up the legs, and install fresh fork oil. Heavier weight fork oil will work better.

A number of vendors will be able to provide springs that are stiff enough to accommodate your size. There's look up tables to account for the mass of the rider, to set this up correctly. The idea is to have the full wheel travel available for road hazards, and have it set up so you are just beginning to compress the springs at each end to accomplish that.

In a perfect world, when you measure the amount you compress the springs in your 'typical' riding configuration, the suspension only compresses 1/4" or so from full extension.

The easiest way to check 'ride height' is to snug a zip tie onto the fork leg, just tight enough that it won't fall down the fork leg. With the fork leg fully extended (pull up on the bars so the wheel clears the ground and set it back down gently) push the zip tie to the dust seal on the lower leg. Measure from the zip tie to the lower triple clamp.

Then sit on the bike in your full gear, and have someone hold it in the vertical, so the suspension is carrying your full weight.

Get back off the bike, and measure the distance between the zip tie and the clamp. In the perfect world...... that change would be 1/4". Whatever that distance is, what remains of the full stroke of the fork is what you have to deal with bumps in the road. It's probable that with the OEM springs, you are going to find a difference in excess of 2". If it were 2, that would leave 2.5 to deal with bumps before the rim, and steering head bearings start to get whacked.

The springs in the fork have hollow tubes riding on top of them called spacers, which serve to apply some tension to the springs. Different lengths of spacer, will apply different amounts of force, which will in turn make the bike resist settling more.... pre-loading the springs. On a 'tuneable' fork, that's what the preload adjusts.

The rear is a more complicated deal. The rear shock is a straight forward simple system, exactly the same as a McPherson strut.... a shock absorber, surrounded by a spring, carried on the same assembly. Bolted to the chassis at the top, and the swingarm on the bottom.

It too, is a price point part. The spring is quite 'soft', and the damping rates are tailored to that soft spring. Replace the spring with a stiffer one, and it doesn't really have enough compression or rebound damping to control the action. Not only that, but the OEM shock is not designed to be rebuilt.

Static Sag (bike + rider) should be 25-33% of total travel....so the sag on our forks (with 5.1" of travel) would be in the 1.275"-1.683" range, not 1/4". Same applies to the rear suspension. I have read that the goal is to be operating in the middle third of the suspension travel...ie not topped out, and not bottomed out. When the combo of proper preload and spring rate is set, this should occur.

With only a 1/4" sag you will top out very easy which will give traction problems as the tire will un-weight from the road surface.

 

[RJ2112]

Static Sag (bike + rider) should be 25-33% of total travel....so the sag on our forks (with 5.1" of travel) would be in the 1.275"-1.683" range, not 1/4". Same applies to the rear suspension. I have read that the goal is to be operating in the middle third of the suspension travel...ie not topped out, and not bottomed out. When the combo of proper preload and spring rate is set, this should occur.

With only a 1/4" sag you will top out very easy which will give traction problems as the tire will un-weight from the road surface.

I guess we'll agree to disagree on that. I'd be very unhappy to lose over 1/3 of my suspension travel to static sag.

I just 'googled' for 'motorcycle suspension setup'.... which gave me a link to this:

http://www.sportrider.com/suspensio...spension_setup_guide/preload_and_damping.html

 

[kpaul]

Thanks all, for the replies. Very helpful.

I was under the impression that there's no adjustment possible, in the bike's stock form, but some are implying that this is possible? Or am I just misread? Thanks.

 

[RJ2112]

Thanks all, for the replies. Very helpful.

I was under the impression that there's no adjustment possible, in the bike's stock form, but some are implying that this is possible? Or am I just misread? Thanks.

The only easy adjustment OEM, is the rear shock preload. There's a tool in the kit to adjust the ramped collar on the back shock. The higher the number, the more tension on the spring. I rode with that set on 5, at 200 lbs. If you are as large or larger, I would suggest doing the same.

Beyond that...... you need to open up the fork, and replace the OEM springs with stiffer ones. And change the fork oil, and possibly add emulators. Springs and oil take no special tools.

The rear shock has to be removed from the bike, for any work beyond setting the preload on the spring.

• You could replace the spring, with a stiffer unit.
• You could potentially have the OEM shock worked on, which would involve someone opening it up, and replacing the OEM fork oil and valving. (the spring should be replaced, with one suited to your weight.
• You could replace the shock, and spring as a unit. Special order from Ohlins, Penske, and at least one other vendor can be tailored to your weight and use..... the fancy ones allow multiple adjustments after installation.

 

[tuningfork]

I guess we'll agree to disagree on that. I'd be very unhappy to lose over 1/3 of my suspension travel to static sag.

I just 'googled' for 'motorcycle suspension setup'.... which gave me a link to this:

Preload and Damping - Sport Rider Magazine

Good link, they are suggesting 1" ~ 1.2" of sag. I tend to think is a generic setting assuming a typical sport/supersport bike with around 4.5-5" of travel.

 

[tuningfork]

The only easy adjustment OEM, is the rear shock preload. There's a tool in the kit to adjust the ramped collar on the back shock. The higher the number, the more tension on the spring. I rode with that set on 5, at 200 lbs. If you are as large or larger, I would suggest doing the same.

Beyond that...... you need to open up the fork, and replace the OEM springs with stiffer ones. And change the fork oil, and possibly add emulators. Springs and oil take no special tools.

The rear shock has to be removed from the bike, for any work beyond setting the preload on the spring.

• You could replace the spring, with a stiffer unit.
• You could potentially have the OEM shock worked on, which would involve someone opening it up, and replacing the OEM fork oil and valving. (the spring should be replaced, with one suited to your weight.
• You could replace the shock, and spring as a unit. Special order from Ohlins, Penske, and at least one other vendor can be tailored to your weight and use..... the fancy ones allow multiple adjustments after installation.

It is possible to adjust the length of the spacers in the fork to fix the ride height using PVC tubing...assuming your weight is in the range for the stock springs (which are progressive wound, 0.8-kg/mm to 1.0 kg/mm depending on fork compression). But if you are a heavy rider or planning lots of two-up (or hittign the track) I'd agree that new springs will be a better solution. :thumbup:

 

[RJ2112]

It is possible to adjust the length of the spacers in the fork to fix the ride height using PVC tubing...assuming your weight is in the range for the stock springs (which are progressive wound, 0.8-kg/mm to 1.0 kg/mm depending on fork compression). But if you are a heavy rider or planning lots of two-up (or hittign the track) I'd agree that new springs will be a better solution. :thumbup:

Yeah reading that site, it's clear they are aiming for 20-35mm static sag. I ran that across a calculator and came out with an inch or so, rather than the 1/4" I guessed it at. I am perfectly okay with the stiffer setup..... topping out isn't an issue for me.

Both KPaul and Philosopherian are well over 200 lbs.... the ride height adjustment isn't going to cut it for them.

I personally really disliked the dual rate OEM springs, too. They never gave consistent performance for me.... noodling around on the 'soft' part of the spring sucks up too much of the fork's travel, and required very soft damping so it would be noticed. Made the front dive way, way too much in my use. I tried adding washers to add preload, before I did the fork and replaced the rear shock with an Ohlins.

Straight rate .9 Kg springs, modified valving, and 10 w oil completely transformed the fork.

The Ohlins, I had the spendy unit with ride height adjustment.... ran that 10 mm 'high' to quicken the steering, and loved how it all worked together. GP Suspension in Oregon City set the compression and rebound, as well as the ride height, and I couldn't be happier.

With the chassis consistent on the suspension, the steering worked much better, the bike ran corners on rails, and it was overall a much better experience. This is the fourth bike I have owned with OEM cr@p suspension.

It's likely to be the last I buy, with BS suspenders on it.

 

[tuningfork]

On my FZR600 a few years back I did the same type of stuff...racetech springs, emulators, heavier fork oil, fork preload adjusters from JEM MAchine, and a Fox Twin-clicker rear shock. BT-014 tires completed the transformation.

The stock fork springs were REALLY weak on thatbike..like 0.46 kg/mm-0.8kg/mm! Even with my rider weight of about 165lbs with gear, They bottomed out very easy on downhill braking, but it was comfy enough for day-long rides. The stock rear shock was wet noodle as well, the Fox setup really helped. The bike handled much better but was also less comfortable on the street for me.

By comparison, I'm pretty happy with the stock setup on the FZ6, But I'm after more of a touring ride these days. Even though the tech is similar, it is a lot firmer out of the box than my old bike. Plus the chassis feels very stable compared to the old steel deltabox frame. FWIW I'm at about 190 lbs with gear these days. I encounter enough crappy tarmac that I'll take the handling loss to have a cushier ride.

Although, I'd love to ride an R6 or something and see how that handles someday.:thumbup: