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Baileyrock

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Just to keep the thread alive... Last year on my 4th gen, I revalved my forks with Racetech gold compression and rebound and the suggested (on Racetech site) .95 front springs. I also upgraded to the 929 rear shock. Found out the spring was too soft when I couldn't get a decent sag with rider. At the time I weighed about 185lb.

Over the winter, I have lost about 40lbs and am now down to a much healthier 145lb (I'm 5"7). I am going to get Jamie D. to change my rear spring to a harder rate, probably 19kgs to balance out the bike. I am just wondering if the whole thing is going to be too stiffly sprung for my now trimmer weight. Maybe I should just carry a bunch of water in my saddle bags? smile.gif

Honestly, I'd rather not have to disassemble the forks again, change springs, re-valve to match, etc. I want the easy button... I just don't know if there is one. Any opinions?

I mostly commute, but tend to ride fairly aggressively.

Have you check free & Rider sag on your bike since dropping to 145 lbs?

I would venture to guess that at 145 the front is too stiff now and the stock 929 shock wouldn't be to far off(check #'s).

I would just drop in some .85 in the front and see how the valving feels. Measure the stock 929's free & rider sag and go from there, I would think a 17 kg rear max. If you plan to remain at 145 you won't want the .95's at all IMO & and making the entire bike Too Stiff for balance is not a good approach IMO.

BR

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MadFrog if you did your fork valving yourself you may have noticed that RaceTech's compression valving recommendations covers a few different spring rates based on the style of riding. The rebound valving is usually set to the spring but as Kevin stated above just throw in a set of less stiff springs and see how it feels. I'm not sure what oil weight your currently using but you could always thin it out a bit if the ride isn't what you want and you really don't want to take it apart again. I'm running .95kg and I am 220lbs, they are perfect for me.

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Just to keep the thread alive... Last year on my 4th gen, I revalved my forks with Racetech gold compression and rebound and the suggested (on Racetech site) .95 front springs. I also upgraded to the 929 rear shock. Found out the spring was too soft when I couldn't get a decent sag with rider. At the time I weighed about 185lb.

Over the winter, I have lost about 40lbs and am now down to a much healthier 145lb (I'm 5"7). I am going to get Jamie D. to change my rear spring to a harder rate, probably 19kgs to balance out the bike. I am just wondering if the whole thing is going to be too stiffly sprung for my now trimmer weight. Maybe I should just carry a bunch of water in my saddle bags? smile.gif

Honestly, I'd rather not have to disassemble the forks again, change springs, re-valve to match, etc. I want the easy button... I just don't know if there is one. Any opinions?

I mostly commute, but tend to ride fairly aggressively.

Have you check free & Rider sag on your bike since dropping to 145 lbs?

I would venture to guess that at 145 the front is too stiff now and the stock 929 shock wouldn't be to far off(check #'s).

I would just drop in some .85 in the front and see how the valving feels. Measure the stock 929's free & rider sag and go from there, I would think a 17 kg rear max. If you plan to remain at 145 you won't want the .95's at all IMO & and making the entire bike Too Stiff for balance is not a good approach IMO.

BR

Thanks for the advice and quick response. I am not sure what my future weight will be. Ideally, I'd get back up to 155, putting on about 10lb of mostly muscle.

I guess it is going to come to a compromise. If I assume that my weight will be around 155 +/- 10 lbs, what's a good spring rate to use front/back? I'm at 145, without any clothes on, so about 150 fully dressed. Add another 10-15lb for riding gear + helmet, then my saddle bags with my lunch, rain suit and gym bag - that's another 10-20 lbs maybe?

So now, we're up to 170-190 lbs worth of fully outfitted rider and payload.

Arumph! I guess I need to weigh all my gear (and various combinations of shoes, boots, synthetic, leather) and my usual "luggage" to get a more accurate typical payload weight. I'm starting to feel for factory bike suspension designers...

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  • 2 weeks later...
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Recently installed a Daugherty rebuilt shock (a stock 5th gen shock with a 1050#/in spring and gold valving), and I must say that I am very happy with the results. I had my front-end race teched a while back (.90 springs and gold valves) and the back-end was lacking. After a 200 mile ride today, my back has been transformed. It keeps the line well, and I felt confident all day. When I set up the rear suspension sag, I got a rider sag of 31mm and a free sag of 9mm with three turns of the preload adjuster (from all the way out) with 3/4 full tank of gas. I may lower the preload to see how it feels, but for now, I'm pleased. By the way, I weigh 185 lbs., but when I ordered the shock to be rebuilt by Jamie, I weighed 173-ish. Based on the desired sag numbers, I'm thinking that a 1050#/in spring is good for weights between 170-190 lbs. +/- 5 lbs.

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Recently installed a Daugherty rebuilt shock (a stock 5th gen shock with a 1050#/in spring and gold valving), and I must say that I am very happy with the results. I had my front-end race teched a while back (.90 springs and gold valves) and the back-end was lacking. After a 200 mile ride today, my back has been transformed. It keeps the line well, and I felt confident all day. When I set up the rear suspension sag, I got a rider sag of 31mm and a free sag of 9mm with three turns of the preload adjuster (from all the way out) with 3/4 full tank of gas. I may lower the preload to see how it feels, but for now, I'm pleased. By the way, I weigh 185 lbs., but when I ordered the shock to be rebuilt by Jamie, I weighed 173-ish. Based on the desired sag numbers, I'm thinking that a 1050#/in spring is good for weights between 170-190 lbs. +/- 5 lbs.

Sounds good! :fing02:

I just installed a Penske on my street Vtec with a 1150 lb spring. With 10mm of pre-load I got 32-33mm Rider sag(in gear) with 9.5mm of free sag, pretty happy with those numbers and I weigh 185-190 at the moment!

Finally changed my fork fluid after 40k miles! :blink:

Now I just need to got out on it and work of rear shock settings. :wheel:

My Ohlins has the a 1050 lb spring and I think I got 10/32mm on it?

BR

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Recently installed a Daugherty rebuilt shock (a stock 5th gen shock with a 1050#/in spring and gold valving), and I must say that I am very happy with the results. I had my front-end race teched a while back (.90 springs and gold valves) and the back-end was lacking. After a 200 mile ride today, my back has been transformed. It keeps the line well, and I felt confident all day. When I set up the rear suspension sag, I got a rider sag of 31mm and a free sag of 9mm with three turns of the preload adjuster (from all the way out) with 3/4 full tank of gas. I may lower the preload to see how it feels, but for now, I'm pleased. By the way, I weigh 185 lbs., but when I ordered the shock to be rebuilt by Jamie, I weighed 173-ish. Based on the desired sag numbers, I'm thinking that a 1050#/in spring is good for weights between 170-190 lbs. +/- 5 lbs.

Sounds good! :fing02:

I just installed a Penske on my street Vtec with a 1150 lb spring. With 10mm of pre-load I got 32-33mm Rider sag(in gear) with 9.5mm of free sag, pretty happy with those numbers and I weigh 185-190 at the moment!

Finally changed my fork fluid after 40k miles! :blink:

Now I just need to got out on it and work of rear shock settings. :wheel:

My Ohlins has the a 1050 lb spring and I think I got 10/32mm on it?

BR

.90/1050 for 185-190 sounds bang on.

oh I so need to put my 1200# in.... just don't wanna take it apart again. sad.gif I think I'll loose 15 lbs, may be easier.

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.90/1050 for 185-190 sounds bang on.

oh I so need to put my 1200# in.... just don't wanna take it apart again. sad.gif I think I'll loose 15 lbs, may be easier.

Jason,

Don't worry about it, just ride the thing as you are SO close to perfect as is.

We just wanted to see what that small change would do. I just went 100 lbs stiffer and don't see much of a change except maybe gaining some free sag, but I'll have to do a two person re-check of the Ohlins w/1050 lb spring. :blink:

I think I'm .925 or .950 w/1150 lb rear now on the street Vtec and .950/1050 on the track Vtec.

BR

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How come when I pull a stoppie, so all the weight is on the fork, it doesn't bottom out? The combined weight of me and the VFR is 350kg, say the front springs are 0.9 (stock is 0.63) then I need 194mm-16mm(preload) of travel or 350/(136*2) (120mm fork travel +16mm preload * 2 parallel springs)) = 1.3kg/mm springs. What role does the air chamber play here? Seems to me it is very significant and I do not see the need to have full range of springs in very small increments.

Anyone that can share some insight on this?

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BR and VFRD folk... I just went back to 10W fork oil after trying 15W (a friend supposedly in the know recommended this but it is much worse, too harsh, confirming your spring vs valving comment)...

I knwo the OEM front and rear srpings ar too soft for me... 90 kg naked, always carry heavy tankbag and just bought OEM sidebags... I don't have the time to do the revalving up front with those gold valves... having to drill and such... So I'm wondering if I could opt for a compromise... if revalving is essential when incrementing front spring tension... Maybe I could work within the OEM valves' functional range and up the spring tension half way... OEMs are what? 0.75 kg?? So instead of going up to 0.95 maybe 0.85 would work???

I was considering sending the OEM shock off for respringin and revalving... it's fairly economical at 250€... unless I can find a decent 929 shock and have that resprung and revalved... that would be a gain in adjustability right? I believe it has compression adjustment, which the VFR shock doesn't have???

I ended up being obliged to change the fork seals after running up onto the piano at a track-day and they have these massive shudder-bumps to stop the trucks and cars that race at the track from cutting corners... (very dangerous for motorbikes. insert mad-devil icon) so I took advantage of the fact and went back to OEM spec fork oil.

So when are you thinking of getting back on the bike?? you surely have time to fine tune your babies to the nth degree.

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What role does the air chamber play here?

The air works as a secondary spring, it will effect the full range of travel some, but has the biggest effect on the last portion of travel and can be used to help prevent bottoming. It is a tuning tool and all you need to do is +/- cc's of oil level. :blink:

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How come when I pull a stoppie, so all the weight is on the fork, it doesn't bottom out? The combined weight of me and the VFR is 350kg, say the front springs are 0.9 (stock is 0.63)then I need 194mm-16mm(preload) of travel or 350/(136*2) (fork travel +16mm preload * 2 parallel springs)) = 1.3kg/mm springs. What role does the air chamber play here?

I've been led to believe that the air chamber has everything to do with that final compression phase of the fork... but I'm just repeating what I've gleaned from fairly trustworthy sources... I actually had the oil level in my VTEC forks filled to 95 mm from the tube tops instead of the 100mm OEM spec... apparently this gives the forks a little stiffer action in that last part of their compression under heavy braking etc...

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I can see it acts as a progressive spring. Only I hadn't given it any thought before and to me it seems it plays a very important role, not only in the final stroke of the suspension travel, yet I see it hardly being discussed in topics like this. I have progressive aftermarket springs suited for my weight (230lbs) and riding style (relaxed) and for the first two thirds of suspension travel the rate is 0.67 (rear is 21kg/mm) so it is pretty close to stock but the instructions that came with it mentioned to set the air chamber to 170mm instead of the stock 178mm. The new springs take up 60% more volume than the stock springs so in all the air chamber has decreased considerably. The last one third of suspension travel the spring has a rate of 1.1kg/mm still far off from the average of 1.3kg/mm.

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How come when I pull a stoppie, so all the weight is on the fork, it doesn't bottom out? The combined weight of me and the VFR is 350kg, say the front springs are 0.9 (stock is 0.63) then I need 194mm-16mm(preload) of travel or 350/(136*2) (120mm fork travel +16mm preload * 2 parallel springs)) = 1.3kg/mm springs. What role does the air chamber play here? Seems to me it is very significant and I do not see the need to have full range of springs in very small increments.

Anyone that can share some insight on this?

Your actual weight on the forks when you do a stoppie is dependent on the angle of your stoppie and the inertia that you built up prior to your stoppie as well as a bunch of other dynamic factors. It can't be calculated that easy in my opinion.

Your air chamber upon your fork compression compresses, just like in hydraulics. If you have enough air to compress to a higher level, the force of the air on the surface area of your oil in your shock combined with the spring pressure can easily overcome the minor weight of you and bike. The less air the less it will compress upon fork compression the less it will fight back. The more air the more it will compress and the more it will fight back upon compression.

This thread to me has been mostly about the "balance" of a bike more so than tuning per se, but being such an awesome thread it may be a good idea to talk about the air a little bit.

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Your actual weight on the forks when you do a stoppie is dependent on the angle of your stoppie...

I realise it's more complex with the forks not being vertical. Decellerating with the rear just of the ground adds even more load on the front than just the weight of the bike and rider.

The less air the less it will compress upon fork compression the less it will fight back. The more air the more it will compress and the more it will fight back upon compression.

It's just the opposite. The smaller the initial air chamber the higher the progressive rate of the air spring will be.

This thread to me has been mostly about the "balance" of a bike more so than tuning per se, but being such an awesome thread it may be a good idea to talk about the air a little bit.

That is why I brought this up. How can you talk about balance if you only focus on coil springs and more or less ignore the air spring? Swapping fork springs means altering the air spring too as every coil spring takes up a different volume. Like I said, the new rear spring on my 3rd gen is now 21kg instead of the 16kg stock yet the rate of the front springs has decreased from 0.69 to 0.67 but they have to be installed with a little more preload (+4mm) and a smaller air chaimber. With the lower rate springs and smaller air chamber I was now able to get correct sag numbers that I could not with the stiffer stock fork springs, stock air chamber and the preload adjuster maxed out (The new springs have more preload because they are 10mm longer than stock so I could back out the preload adjuster by 6mm).

Hopefully Jamie Dougherty will share some of his wisdom, not that I don't value your wisdom on this matter :pinocchio:, but in another post he mentioned using a 120mm air chaimber in 3rd gen forks instead of the stock 178mm and it would be interesting to know how/why he decided on reducing the air chamber by that large(?) amount.

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You are correct, I totally got that backwards, the force will increase a lot quicker with less air. I still don't think the air does anything other than controlling the bottoming of the forks though. The air needs to be compressed for it to do anything past the springs and valving that are already in there. I think it has very little to do with the "balance" of the bike but is a great tool for tuning the bottom of your fork travel and brake feel.

edit: added "and valving".

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  • 1 year later...

history: my 04 had 1.0 and 18.34kg 3-way . I asked Phil work the forks for aggresive street with 220lbs. pilot.

had to pre-load the rear way too much for correct rider sag which of course topped out the shock and the front worked better the harder I rode I could really feel the small expansion joint on the highway.

the 08 has carbon fiber exhaust (hard bags for trips only) and I'm 210lbs. w/o gear

I kept the 3-way off the 04 that I intend to pair with a 20.3-21.4 spring

I ordered 1.0 springs again thinking I would have the forks shimed again.

will thinner fork oil and valve re-work take care of the harsh intial feel?

what about valves, are they really needed?

Edited by 04asphalt
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I was going to ask what wt oil you're using , I'm running 5 wt. (and it varies with brand o/oil).

Note: I'm not speaking from my own knowledge, it was worked out for me.

I have a sonic 1.0 with 5wt......... I'm 250 .... and carry 5lb t-bag(always) ....and 15 lb tail bag(always).

My frt is granked almost all the way...... works great release the brake and it comes back up and stays there except for a slight settle (but no po-go).....(not that I normally release the brake that way while riding, I smoothly release it).

Anyway oil can be a big factor.

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history: my 04 had 1.0 and 18.34kg 3-way . I asked Phil work the forks for aggresive street with 220lbs. pilot.

had to pre-load the rear way too much for correct rider sag which of course topped out the shock and the front worked better the harder I rode I could really feel the small expansion joint on the highway.

the 08 has carbon fiber exhaust (hard bags for trips only) and I'm 210lbs. w/o gear

I kept the 3-way off the 04 that I intend to pair with a 20.3-21.4 spring

I ordered 1.0 springs again thinking I would have the forks shimed again.

will thinner fork oil and valve re-work take care of the harsh intial feel?

what about valves, are they really needed?

I think most of the harshness you felt with your old bike was from the TOO Stiff fork springs compared to the too Soft rear spring for your weight.

Like this thread I started, I was very disapointed in my bike after have the forks revalved/resprung and installing a Ohlins on the rear but only with a stock 850 lb spring on it. It felt good when I slammed on the brakes because of less fork dive, but felt crappy the rest of the time until I installed the stiffer 19kg spring.

BTW I now run a 20kg rear spring w/.95kg fork springs and it feels great.

I suggest a 21kg rear if you plan to stay with the 1.0 fronts. :tour:

BR

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Guest Gamecock94

I will hopefully be taking my bike to Traxxion Dynamic which happens to be just 5 miles from house. They did my previous bike, a 2001 FZ1, and it was night/day from the before and after. I have a guy I know that works there I met through the FZ1 board and could really give me the best recommendations. I wish I could afford their AK20 cartridges for the front, but like will just go with a revalve, stiffer springs, new oil and bushings. On the back I'll go probably with the Penske double clicker with the remote resevouir (not sure if the piggyback style will fit). Likely this would run in the $1200-1500 range. That's about 35% of what I paid for the bike! However, if you plan to keep your bike for years and ride it regularly I feel it justified.

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I will hopefully be taking my bike to Traxxion Dynamic which happens to be just 5 miles from house.

Sounds great, plz let us know and be sure to ask them what spring rates they install. Hopefully TD in house won't just set-up the bike off some faulty VFR spring rate calculator like 90% of the other suspension shops seem to use! :ph34r:

BR

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  • 3 months later...

I own an RC46C/A6 (VTEC 06 ABS). I'm about to upgrade my suspension (both front and rear). I will replace the fork springs with ones from RaceTech and also install the Gold Valve kits (for compression and rebound). At the rear I will replace the stock shock with a HO605 from ohlins (external reservoir, hydraulic preload, compression and rebound damping adjustable).

I ride on the street (often at quite a spirited pace). Most of the times I ride without luggage, but I also do a couple of week-long trips each year with side cases and a tail-pack. Most of the riding I do is on twisty back-roads, where the pavement is at some sections very good, and elsewhere far from perfect (bumpy, cracked, and / or slippery). I weight approx 100kg (220lbs).

What spring-rates would you recommend? Having read this thread I'm leaning towards either .95kg/mm or 1.0kg/mm front, and 19.3kg/mm or 20.3kg/mm rear? The HO605 shock comes from ohlins with a standard 17.3kg/mm spring; I guess this is totally inadequate (or am I wrong)?

Edited by npat
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I weight approx 100kg (220lbs).

What spring-rates would you recommend? Having read this thread I'm leaning towards either .95kg/mm or 1.0kg/mm front, and 19.3kg/mm or 20.3kg/mm rear? The HO605 shock comes from ohlins with a standard 17.3kg/mm spring; I guess this is totally inadequate (or am I wrong)?

I would do a 20/21kg rear on the front how about .975kg (one .95 & one 1.0) . Ohlins should install whatever spring you want at no extra charge.

BR

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I would do a 20/21kg rear on the front how about .975kg (one .95 & one 1.0) . Ohlins should install whatever spring you want at no extra charge.

BR

Thank you for your answer.

I'm a little hesitant to use so stiff a rear shock, since roads around here are often quite rough. I guess I'll stick to 0.95 front and 19.3 rear, and maybe play with a rider-sag a bit more than 3.5 (if I can't get a decent static-sag). Does this sound reasonable?

Also: Other than from RaceTech, do you know where I could find fork-springs at this rate? Do you know if Ohlins or WP have such fork-springs (suitable for the VFR)? I'm trying to locate a supplier that has good representation somewhere in the EU (or even-better locally, I live in Athens / Greece).

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I would do a 20/21kg rear on the front how about .975kg (one .95 & one 1.0) . Ohlins should install whatever spring you want at no extra charge.

BR

Thank you for your answer.

I'm a little hesitant to use so stiff a rear shock, since roads around here are often quite rough. I guess I'll stick to 0.95 front and 19.3 rear, and maybe play with a rider-sag a bit more than 3.5 (if I can't get a decent static-sag). Does this sound reasonable?

Also: Other than from RaceTech, do you know where I could find fork-springs at this rate? Do you know if Ohlins or WP have such fork-springs (suitable for the VFR)? I'm trying to locate a supplier that has good representation somewhere in the EU (or even-better locally, I live in Athens / Greece).

comp/rebound will impact things more than anything with your bumps. the rate is necessary for your weight and to get proper sag geometry for handling. do what you will, but my suggestion is at least the 20kg spring.

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comp/rebound will impact things more than anything with your bumps. the rate is necessary for your weight and to get proper sag geometry for handling. do what you will, but my suggestion is at least the 20kg spring.

Thanks! So a 20.3kg/mm shock-spring, and 1.0kg/mm fork-springs, or 0.95kg/mm fork-springs?

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