Front fork spacer lenght

[Claude]

As suggested in the Dave Moss video, I intend to sorthen the front fork spacers of my newly acquired 2017 FZ07.

However, before doing so, I would like to know what's the stock lenght of those spacers? I just want to be sure that the previous owner did not already make this mod which would end up with too short parts if I cut them a second time. I tried to search for the information but I failed.

Many thanks!

[ElGonzales]

It's 150 mm  
The upper one is already shortened.

[Claude]

150 mm. Great!! Thanks a lot for the information!!

[M. Hausknecht]

I suggest you check your front and rear suspension sag before making any changes. I have subscribed to Dave Moss, and learned some stuff, but his "one size fits all" suggestions leave me cold. Additionally, he is really big on unladen sag (some sag in the suspension without a rider), but to me, the sag when there is no rider is irrelevant. Its a datum with no real world application. I say this stuff as someone who only races these days, and has raced bikes with some success off and on since the early '90s. So, check your sag and see if you need more in the front end, that would justify less preload before cutting your spacers.   

[Claude]

10 minutes ago, M. Hausknecht said:

I suggest you check your front and rear suspension sag before making any changes. I have subscribed to Dave Moss, and learned some stuff, but his "one size fits all" suggestions leave me cold. Additionally, he is really big on unladen sag (some sag in the suspension without a rider), but to me, the sag when there is no rider is irrelevant. Its a datum with no real world application. I say this stuff as someone who only races these days, and has raced bikes with some success off and on since the early '90s. So, check your sag and see if you need more in the front end, that would justify less preload before cutting your spacers.   

Interesting. What's the suggested FR & RR sag on a 2017 FZ07?

[ElGonzales]

I think it makes sense if you are a lightweight rider (like me). With shortened spacers my negative sag (with rider) is now circa 38 mm.
I was to lazy to try this modification and sceptical, but when I measured I noticed my rider sag  was like 15-20% of 130 mm

Edited January 30, 2023 by ElGonzales

[Claude]

ElGonzales, do you know what's the outer diameter of the fork spacers? I intend to source some pvc piping but need to know what OD to look for.

I'm a bit less than 200 lbs so not a lightweight. So, checking sag as M.Hausknecht suggested, is surely a good idea before taking the fork apart.

[ElGonzales]

The outer diameter of the spacers is 34 mm. 
 

[M. Hausknecht]

13 hours ago, Claude said:

Interesting. What's the suggested FR & RR sag on a 2017 FZ07?

Both front and rear suspension have 5.1" of travel (130mm). The difference between topped-out and the suspension travel used up when you sit on the bike, in all your gear, in your regular riding position, is the laden sag. Because you want to spend most of your time riding in the middle half of travel, a good rule of thumb is that your laden sag should be 1/4 of the total, or for the 07, about 1 3/8" (32.5mm).

There is room for personal taste here. I prefer a little firmer feel, so my sag front and rear is about an inch or even less on a  smooth track. If you like a cushier ride, you could go to 1.75"  and as long as you don't bottom out the suspension, especially the front, you'll be fine.  As a bigger guy, you've probably already got more than 1 3/8" sag in the front. Because the rear shock is adjustable for preload, if you have it cranked up a bit you already could be within the acceptable range. If you need more fork preload, PVC pipe cuts easily and works well as a spacer, and you can make up a few different sets and pick your favorite.

The other piece of Dave Moss's 07 "mod" is replacing the fork oil with something a bit thicker, so there is more damping (compression and rebound).  This element, especially for a 200lb rider, is a good idea. You'll feel like you have more control with the front better "planted".  

[Claude]

3 hours ago, M. Hausknecht said:

Both front and rear suspension have 5.1" of travel (130mm). The difference between topped-out and the suspension travel used up when you sit on the bike, in all your gear, in your regular riding position, is the laden sag. Because you want to spend most of your time riding in the middle half of travel, a good rule of thumb is that your laden sag should be 1/4 of the total, or for the 07, about 1 3/8" (32.5mm).

There is room for personal taste here. I prefer a little firmer feel, so my sag front and rear is about an inch or even less on a  smooth track. If you like a cushier ride, you could go to 1.75"  and as long as you don't bottom out the suspension, especially the front, you'll be fine.  As a bigger guy, you've probably already got more than 1 3/8" sag in the front. Because the rear shock is adjustable for preload, if you have it cranked up a bit you already could be within the acceptable range. If you need more fork preload, PVC pipe cuts easily and works well as a spacer, and you can make up a few different sets and pick your favorite.

The other piece of Dave Moss's 07 "mod" is replacing the fork oil with something a bit thicker, so there is more damping (compression and rebound).  This element, especially for a 200lb rider, is a good idea. You'll feel like you have more control with the front better "planted".  

Wow! Many thanks for such important information!! Great info!

[Claude]

3 hours ago, ElGonzales said:

The outer diameter of the spacers is 34 mm. 
 

The smallest PVC pipe I found this morning was 44 mm OD. Will have to source elsewhere...

[Claude]

As a follow-up, I followed sag measurements instructions posted by M. Hausknecht (thanks again BTW!!!).

With stock fork spacers front sag is 35 mm (without riding gear). This is about the correct amount to have so I left the spacers as is. I’m quite surprised as previous readings made me believe the front end was oversprung and I was convinced I would need to shorten the spacers. I’m not a lightweight at 200 lbs but I’m not a real heavyweight either.

Rear sag was 40 mm with two (stiffer) adjustment notches remaining on the shock. I simply turned it to the next stiffer one. I will measure the new sag soon but it should be pretty close to OK.

NB: I did found 34 mm OD PVC pipe but won’t need it...

********************  EDIT  ***

Oops! Forgot to say that I changed the fork oil though; I poured 20W in the tubes.

Edited March 30, 2023 by Claude

[Pursuvant]

On 1/30/2023 at 4:39 PM, M. Hausknecht said:

I suggest you check your front and rear suspension sag before making any changes. I have subscribed to Dave Moss... his "one size fits all" suggestions leave me cold. Additionally, he is really big on unladen sag (some sag in the suspension without a rider), but to me, the sag when there is no rider is irrelevant....

 

Practical, valuable applied advice M.H.