Blog

HOW TO SET UP FRONT FORKS

Tarmac Japan

Tarmac Japan

Here’s a quick guide on how to measure your bikes front fork sag. I hope this is useful for y’all. For a review on the E-Bay, Amazon, AliExpress adjusters I used, see here: Click Here

Step 1: Extend the fork completely and measure from the two set points. This time I literally lifted the front wheel completely off the ground using the “Ye Olde Sidestand Swivel Trick”. On my bike I have fork gaiters fitted so it’s not possible to measure from the dust seal as is pretty much the standard way to do it. On my bike I put some masking tape in two positions as seen in this picture.

One piece of tape on the lower triple, and one on my actual fork gaiter

This measurement is what we will call L1.

Spot the deliberate mistake? Comment if you can see what I’m doing wrong in this picture

Step 2: Take the bike off the sidestand, and sit in your riding position. Ideally you should be wearing all the usual gear you wear. Jacket, boots, helmet etc. I’m not trying to set up my bike for MotoGP, so this time I was just wearing my work clothes. With all my riding gear on, I probably weigh an extra 10KG. Get an assistant to balance the bike from the rear or like I did, balance against a wall etc. (very lightly, so as to not upset the weight balance) then PUSH DOWN on the front end and let it extend very slowly.

Where it stops, measure the distance between your markers again. Don’t bounce the bike.
This measurement is L2.

Step 3: LIFT UP on the front end and let it drop very slowly. Where it stops, measure again. Don’t bounce. This measurement is L3.

L2 and L3 are different due to stiction or drag in the seals and bushings.

Step 4: Just as with the front, halfway between L2 and L3 is where the sag would be with no drag or stiction. Therefore L2 and L3 must be averaged and subtracted from L1 to calculate true spring sag: static spring sag = L1 – [l2 + l3) / 2].

Measurements from another time I did this to a friends MT-07. My bike is obviously an MT-07/FZ-07 but this method is the same on nearly all makes and models of bikes.

Step 5: Now adjust your newly fitted preload adjusters and do all the above measurements again until you get your desired numbers. I was looking for the magic 30mm…

These adjusters have notched markings, so it’s easy to do it without using exact measurements. Just count the markings!

FINAL NOTES

Street bikes run between 25 and 33 percent of their total travel, which equates to 30 to 35mm. Roadrace bikes usually run between 25 and 30mm.

This method of checking sag and taking stiction into account also allows you to check the drag of the linkage and seals. It follows that the greater the difference between the measurements (pushing down and pulling up), the worse the stiction. A good linkage (rear sag) has less than 3mm (0.12″) difference, and a bad one has more than 10mm (0.39″). Good forks have less than 15mm difference.

Your personal sag and front-to-rear sag bias will depend on chassis geometry, track or road conditions, tyre selection and rider weight and riding preference.

Using different sag front and rear will have huge effect on steering characteristics. More sag on the front or less sag on the rear will make the bike turn more slowly. Increasing sag will also decrease bottoming resistance, though spring rate has a bigger effect than sag. Racers often use less sag to keep the bike clearance, and since roadraces work greater than we see on the street, they require a stiffer setup. Of course, setting spring sag is only first step of dialing in your suspension, so stay tuned for future articles on spring rates and damping.

Tags: , , , , , , , , , , , ,

51 Comments

  1. I’m really loving the theme/design of your web site.

    Do you ever run into any web browser compatibility issues?
    A couple of my blog visitors have complained about my site
    not working correctly in Explorer but looks great
    in Firefox. Do you have any ideas to help fix this issue?

  2. Howdy I am so glad I found your blog, I really found you by accident,
    while I was researching on Askjeeve for something else, Anyhow I am here now and would just
    like to say thanks for a tremendous post and a all round exciting blog (I also love the theme/design), I don’t have time to read it all
    at the minute but I have saved it and also added your
    RSS feeds, so when I have time I will be back to read much more, Please do
    keep up the fantastic work.

  3. Does your site have a contact page? I’m having problems
    locating it but, I’d like to shoot you an email. I’ve got some
    suggestions for your blog you might be interested in hearing.
    Either way, great blog and I look forward to seeing it grow over time.

  4. Thanks a bunch for sharing this with all of us you really know what you are speaking approximately!
    Bookmarked. Please additionally consult with my website =).

    We may have a hyperlink alternate agreement between us

  5. A person necessarily lend a hand to make severely posts I’d state.
    That is the very first time I frequented your web page and to
    this point? I amazed with the analysis you made to create this actual publish amazing.
    Fantastic job!

  6. scoliosis
    You really make it seem so easy with your presentation however I
    find this matter to be actually one thing that I feel I might never understand.
    It seems too complex and very extensive for me.
    I am taking a look forward to your next publish, I’ll attempt to get the cling of it!
    scoliosis

  7. scoliosis
    What’s Going down i am new to this, I stumbled upon this I have discovered It absolutely helpful and it has helped me out loads.
    I’m hoping to contribute & aid different customers like its aided me.

    Good job. scoliosis

  8. scoliosis
    Awesome website you have here but I was wondering if you
    knew of any community forums that cover the same topics talked about here?

    I’d really like to be a part of group where I can get feed-back from
    other knowledgeable people that share the same interest.
    If you have any suggestions, please let me know.
    Appreciate it! scoliosis

  9. I do not even know how I ended up right here, however I assumed
    this post was good. I do not recognize who you might be but certainly you are going to a famous blogger should
    you are not already. Cheers!

  10. Write more, thats all I have to say. Literally, it seems as though you relied on the video
    to make your point. You obviously know what youre talking about,
    why waste your intelligence on just posting videos to your site
    when you could be giving us something enlightening to read?

  11. Its like you learn my mind! You appear to grasp a lot approximately this, such as
    you wrote the ebook in it or something. I think that
    you simply can do with some p.c. to pressure the message house a bit, but other
    than that, that is wonderful blog. An excellent read.
    I’ll certainly be back.

  12. We stumbled over here coming from a different web page and thought I might
    as well check things out. I like what I see so now i’m following you.

    Look forward to going over your web page yet again.

  13. First off I want to say superb blog! I had a quick question which I’d like to ask if you do not mind.
    I was curious to find out how you center yourself
    and clear your mind before writing. I’ve had trouble clearing my mind in getting my
    thoughts out. I truly do enjoy writing but it just seems like the first
    10 to 15 minutes are generally lost just trying to figure out how to
    begin. Any recommendations or hints? Thank you!

  14. Thank you for some other informative blog. Where
    else could I get that kind of information written in such an ideal method?
    I’ve a challenge that I’m simply now operating on, and I have been on the look out for such information.

  15. you’re really a just right webmaster. The website loading speed
    is amazing. It seems that you’re doing any unique trick.

    Also, The contents are masterwork. you have performed a wonderful
    process in this matter!

  16. Does your site have a contact page? I’m having trouble locating it but, I’d like to
    shoot you an email. I’ve got some ideas for your blog you
    might be interested in hearing. Either way, great blog and
    I look forward to seeing it grow over time.

  17. Unquestionably believe that which you stated. Your favorite reason seemed to be on the net
    the easiest factor to have in mind of. I say to you,
    I certainly get irked at the same time as people think about concerns that they
    plainly don’t know about. You managed to hit the nail upon the highest and defined out the entire thing without having side
    effect , other people could take a signal. Will probably be back to get more.
    Thank you

  18. Hi there, just became alert to your blog through Google, and found that
    it’s really informative. I’m going to watch out for brussels.
    I’ll appreciate if you continue this in future.
    Numerous people will be benefited from your writing.
    Cheers!

  19. I’m really enjoying the design and layout of your site.
    It’s a very easy on the eyes which makes it much more enjoyable
    for me to come here and visit more often. Did
    you hire out a developer to create your theme? Fantastic work!

  20. Howdy! I know this is kinda off topic however , I’d figured I’d ask.
    Would you be interested in exchanging links or
    maybe guest writing a blog article or vice-versa?
    My blog covers a lot of the same subjects as yours and I feel we
    could greatly benefit from each other. If you’re interested feel free to shoot me an e-mail.
    I look forward to hearing from you! Superb blog by the way!
    scoliosis surgery https://0401mm.tumblr.com/ scoliosis surgery

Leave a Comment