How much should a front fork move?

sparkov
sparkov Posts: 10
edited April 2009 in MTB beginners
I have recently bought a new bike with a 100mm RockShox Dart 2 fork. No matter how I ride, the fork never compresses more than 40mm. It doesn't seem to cushion the blows as much as I expect it should. Is it normal for a fork to move less than 50% of it's available travel?

Comments

  • nicklouse
    nicklouse Posts: 50,675
    well it should move through all its travel. and when in the attck position you should have about 20% sag.

    if sounds like the fork needs setting up for you by the supplying shop.

    it should be a coil sprung fork with a preload adjuster. wind the preload off and see if that is better.

    manuals can be found here http://www.sram.com/en/rockshox/crosscountry/dart/#tab2
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • sparkov
    sparkov Posts: 10
    I've read through the manuals but they don't give any information about how the fork should move during use - only when stopped. The preload is as loose as it'll go which is why I'm concerned about it.
  • The Northern Monkey
    The Northern Monkey Posts: 19,174
    are you saying that if your stationary you can compress the fork, but when riding it only uses 50% travel?
    Santa Cruz Butcher
  • supersonic
    supersonic Posts: 82,708
    As above: are you hitting big enough bumps to use all the travel?
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  • Dirtydog11
    Dirtydog11 Posts: 1,621
    How much sag have you got ?? You may need a softer spring.
    Kinesis Maxlight XC

    Orange 5 AM Custom
  • sparkov
    sparkov Posts: 10
    I think the sag is only about 10-15mm but I'll check properly this evening.

    Even when stopped and throwing all my weight down on the handle bars the most I've been able to get the fork to move is 40mm - not once has it compressed more than that.
  • whyamihere
    whyamihere Posts: 7,714
    sparkov wrote:
    I think the sag is only about 10-15mm but I'll check properly this evening.

    Even when stopped and throwing all my weight down on the handle bars the most I've been able to get the fork to move is 40mm - not once has it compressed more than that.
    Sounds about right. Put a small zip tie onto one of the stanchions. This will be moved up as you're riding, and will stay wherever it's pushed to. Then you should be able to see how much travel is used while actually riding.
  • xtreem
    xtreem Posts: 2,965
    I have a Dart 2 and i can compress it up to 70-80mm with just using my arms and legs.
    The fork goes above 90mm when I hit a big jump. And I get 3-5mm of sag. :lol:

    So you should be able to compress the fork to 90mm if you get 10-15mm of sag.
    NS Bikes Eccentric Alu custom - 2016
  • sparkov
    sparkov Posts: 10
    I get about 15mm of sag, which leaves me with only 25mm of travel when I'm riding. I had the bike down some singletrack today and it's still not moved past the 40mm mark. There's maybe a problem with the lockout - I'll take it back to the shop tomorrow.

    Cheers for the feedback.
  • Sheppy
    Sheppy Posts: 140
    I have a GF Marlin with a Dart 2. When I first got it I would say I was getting similar travel to what you describe. However, I would say over time it started to increase in travel, I noticed the increase after about 3 months then about 6 months on it was at full travel. It's a long time to wait though :(
  • Rockhopper
    Rockhopper Posts: 503
    How heavy are you?
  • sparkov
    sparkov Posts: 10
    About 15.5 stone so I really shouldn't have any trouble compressing the fork!
  • Dirtydog11
    Dirtydog11 Posts: 1,621
    sparkov wrote:
    About 15.5 stone so I really shouldn't have any trouble compressing the fork!

    I'm 13.5 stone and have no problem compressing my Dart 3's on my old Saracen. One thing I would say though is that the small bump sensitivity is pretty poor it takes quite a big hit to get them moving.

    Prise the dust seals back (just a little) with a blunt instrument (a spoon handle will works fine) and apply a some silicon lube. I've used finishline wet lube and it seems to work well I'm just not sure how it would effect the seals over time.

    If your still having problems then I would take them to your LBS and get them to have a look. It could be a problem with the oil volumes.

    Kinesis Maxlight XC

    Orange 5 AM Custom
  • sparkov
    sparkov Posts: 10
    I took my bike back to the shop today and the guy immediately noticed that the fork wasn't working like it should. It's getting sent away for repair so hopefully I'll notice a huge difference when I get it back.

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