Understanding my Forks- Mtbr.com
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  1. #1
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    Understanding my Forks

    I have the following forks, and some newbie questions.

    Suntour XCM HLO; Coil; 100 STR; Lockout; 46mm fork offset

    An I correct in assuming these do not require air ? The anatomical diagram below suggests that it is instead a physical spring.

    The knob on the top right to my sitting position seems self-explanatory, in that it adjusts the travel distance from fully open to fully locked.

    The knob on the top left is marked 'preload'. What does this do ? I've made some adjustments and can't notice it doing anything. And stupidly, I forgot the original position, so I don't know what I've adjusted it to ! I gave seen a few videos where there is a setting that allows changing the time it takes to return to resting position, so I'm wondering if this is the control for it.

    Apart from some occasional grease applied to the outside, is there any other regular maintenance required, apart from maybe an annual tear-down to check the seals etc?


    ‚Äč



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  2. #2
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    No your fork does not take air.

    The preload adjustment sets the ride height when you are seated on the bike. If your super light weight it wonít do much at all.

  3. #3
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    That 'fork' is for bike paths and smooth trails with no possibility of rebuilds.
    It has a spring that is compressed with the knob.
    Inside are plastic bushings that can wear quickly if the 'fork' is used on technical fun terrain. Mt bike forks have metal bushings inside.
    It also weighs 6.5 lbs. instead of 4 lbs. You'll notice that when climbing as you try to get over logs or rocks.
    No rebound adjustment.
    The primary function is to make a bike look like a capably equipped offroad bike.

    Suntour took enough flak on this to offer an upgrade program for riders who want actual performance.
    https://www.srsuntour.us/pages/upgrade-program
    A Raidon with the grease changed to oil is a good maintenance free fork.

  4. #4
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    Quote Originally Posted by NorCal_In_AZ View Post
    No your fork does not take air.

    The preload adjustment sets the ride height when you are seated on the bike. If your super light weight it wonít do much at all.
    Right, thanks. I was not on the bike when fooling with the preload, just pushing down on the bars with my hands. That's probably why I didn't notice anything.

    I weigh in at around 210lb/95kg and am approx 6ft2in/188cm in height. Running an XL hardtail frame on 29" rims

  5. #5
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    Some great info, thanks. It's an entry level MTB so I am half-expecting some of the gear to be at the lower end. But when weighing up the choice of either paying almost $1k to get out and start riding, or waiting months, years even, to get something higher spec'd, I decided on the former. I guess I'll look at upgrade options as my riding style & equipment failure progresses over time.

    Are you suggesting that with 'no rebuilds' that when the plastic bushings go, that it, they're at the end of their life ? That's a bit crap.

  6. #6
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    Not really. Because they go when the fork is used outside its intended performance capabilities. So a rebuild wouldn't get you anything other then another failure.
    The crap is the lack of this info when your sales guy let you buy the model.
    CRC gets stock periodically of bikes with usable forks at around 1.1k.
    https://www.chainreactioncycles.com/.../rp-prod183330
    Also has Boost hubs wide rim wheels and space for 2.5 tires. Decent slack geo.

  7. #7
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    Quote Originally Posted by eb1888 View Post
    Not really. Because they go when the fork is used outside its intended performance capabilities. So a rebuild wouldn't get you anything other then another failure.
    Well, rebuilding after a failure would provide me with something else... mechanical experience and a greater understanding of forks

  8. #8
    RAKC
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    If the bushings fail you arent rebuilding those yourself anyway.

    When you start adding the money spent in upgrading your going to regret not buying a better bike up front.

    Sent from my SM-N975U using Tapatalk

  9. #9
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    Quote Originally Posted by tigris99 View Post
    If the bushings fail you arent rebuilding those yourself anyway.

    When you start adding the money spent in upgrading your going to regret not buying a better bike up front.
    Ouch ! I'm not sure I'll have any regrets, when the difference is between buying the bike I have vs. holding out to spend more on a better spec'd bike means the difference between getting out an riding now, or not riding for a few more months (or maybe never).

    Bear in mind that I haven't rode for decades, so I won't be going straight to intense technical trails, or whatever the more rugged tracks are referred to.

    I dare not mention the new beast's brake and gear system, or I'll hear how crap they are too !

  10. #10
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    In reality if all your ridding is gravel roads and light trails, that fork will get you out and riding. No that fork isnít for serious off road use, which is what most people talking against are doing.

    Get out on some gravel roads and get your fitness up. Try and get up to 10-12 miles in a hour. Once you get there if you want to get more serious then we can talk about upgrades.

  11. #11
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    Quote Originally Posted by NorCal_In_AZ View Post
    Get out on some gravel roads and get your fitness up. Try and get up to 10-12 miles in a hour.
    Yes, for sure, great advice. A 5km ride kills me right now. But Strava segments clocks me at a max. of 22km speed on dead-flat bitumen with no downhill run-ins. I'm on the highest (or lowest?) gear for that section.

    Quote Originally Posted by NorCal_In_AZ View Post
    if you want to get more serious then we can talk about upgrades.
    I certainly don't wish to sound ungrateful to the experienced members, because every comment in this thread has provided some incredible value to me, in some way or the other. But I didn't start this thread to talk about upgrades right now. I won't be rushing out to change the forks on a brand new bike.

    In that the general vibe is that 'failure is inevitable' with the stock Suntours, it will be interesting to see how many kilometres under various conditions will be clocked before they fail. As I progress to more rugged terrain, I should keep in mind that new forks might need to be budgeted for.

    I'm a little surprised that they can't be serviced though. That does kind of suck.

  12. #12
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    well, that was a conversation killer !

  13. #13
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    My raidon was $130 shipped brand new. Dont worry about the fork for now. I bought a $500 marlin 5 and its heavily upgraded. It would have cost me twice as much to just buy this much bike up front, not only do I have no regrets, I saved a considerable amount of cash.

    The preload changes the initial spring rate. More preload makes the spring a little firmer right at the start of the travel. On that fork it doesnt actually work all that great, so you not feeling a big difference isn';t abnormal. Wind it all the way out and see how it feels, then add more and see how it feels. You wont break it or anything.

    You can probably pop the lowers off now and add oil instead of grease. Suntour likes grease, and it doesnt work well and causes wear.

    People sometimes like to crap on upgrading lower end bikes... then they go out and spend thousands on a bike, and change out the fork and wheels anyway. I have a high end bike and a low end bike, and no regrets on upgrading either of them. Dont mind the "you should have bought a nicer bike" people, their fork probably sucks too.

  14. #14
    EAT MORE GRIME
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    people can kick arse on trails on rigid bikes

    though your fork is entry level,
    there is zero reason you cannot
    also kick ass on any trail using it

    but there are better performing forks

    have fun rippin
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

  15. #15
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    Quote Originally Posted by NorCal_In_AZ View Post
    In reality if all your ridding is gravel roads and light trails, that fork will get you out and riding. No that fork isnít for serious off road use, which is what most people talking against are doing.

    Get out on some gravel roads and get your fitness up. Try and get up to 10-12 miles in a hour. Once you get there if you want to get more serious then we can talk about upgrades.
    This.
    Quote Originally Posted by Mr Pig View Post
    Avid is spelled wrong, there should be an 'O' in there.

  16. #16
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    Quote Originally Posted by 127.0.0.1 View Post
    people can kick arse on trails on rigid bikes

    though your fork is entry level,
    there is zero reason you cannot
    also kick ass on any trail using it

    but there are better performing forks

    have fun rippin
    This too.*




    *unless the fork falls apart, not sure how likely that is though.
    Quote Originally Posted by Mr Pig View Post
    Avid is spelled wrong, there should be an 'O' in there.

  17. #17
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    Quote Originally Posted by 127.0.0.1 View Post
    people can kick arse on trails on rigid bikes...
    and, people get their arse kicked on trails by rigid bikes.
    What, me worry?

  18. #18
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    Quote Originally Posted by Jay719 View Post
    Yes, for sure, great advice. A 5km ride kills me right now. But Strava segments clocks me at a max. of 22km speed on dead-flat bitumen with no downhill run-ins. I'm on the highest (or lowest?) gear for that section.

    I certainly don't wish to sound ungrateful to the experienced members, because every comment in this thread has provided some incredible value to me, in some way or the other. But I didn't start this thread to talk about upgrades right now. I won't be rushing out to change the forks on a brand new bike.

    In that the general vibe is that 'failure is inevitable' with the stock Suntours, it will be interesting to see how many kilometres under various conditions will be clocked before they fail. As I progress to more rugged terrain, I should keep in mind that new forks might need to be budgeted for.

    I'm a little surprised that they can't be serviced though. That does kind of suck.
    The problem with a lot of the super low end gear is that it's more or less designed to be disposable. There actually is some degree of service that you can perform for that fork. Suntour sells parts for it.

    https://www.srsuntour.us/collections/xcm-service-parts

    The problem is that certain things (like the bushings) are not DIY jobs and require a pro with special tools to even consider (this is true for any fork). with the low cost of these entry level forks, the repair costs rapidly exceed the costs of buying a new (better) one. some things can be done as DIY jobs (and quite cheaply, too), but a whole lot of beginner riders are totally unwilling/unable to do that kind of work, so they don't. and when they learn how much it costs to service their fork when paying someone else for labor, they balk at it and refuse to perform the service completely. even for more expensive suspension. It's one of those costs that doesn't change much from the low end to the high end because even though the parts are fairly cheap, it takes roughly the same amount of time to complete the job.

    The "failure is inevitable" statement with these low end forks is really only partly true. They have a LOT of plastic parts. That means they wear out faster, and they can't take use as hard as more robust parts, so they'll fail faster. IF you perform frequent service on them and replace what you can sooner rather than later, you can make them last longer. But, again, with that more frequent service, you run into service costing more than a new (better) fork before too long. If you keep use at low intensities, within the design parameters of the fork, then it can last awhile if taken care of.

  19. #19
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    There is another option ,if/when that fork is worn out. And cheaper ,a rigid fork . Lighter also.

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