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  1. #1
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    Reputation: Jon Edwards's Avatar
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    Helius AM geometry Q's

    I'm gently looking for a new "big bike" to replace me '02 RFX which has seen 5 years of pretty serious abuse under me - gets used for a roughly 50/50 mix of rough trail riding and FR/DH stuff (Chicksands, Cwmcarn, Megavalanche), plus a 2 week Alpine DH holiday each year.

    So both the Helius AM and FR are of interest. I'm fairly light (140lb), but ride hard. The Turner is a hefty beast (37lb in XC guise, 39 in DH) and I'll admit I struggle to haul it about when knackered at the end of a 35mile trail ride. I've also genuinely never felt the need for more than 6" of travel at each end, no matter what the terrain - I'm no racer, more interested in riding smooth and with style. So that points me more towards the AM. 30lb XC, 33ish for FR/DH, perfect.

    But. The angles on paper, whilst perfect for ruftytufty XC (funny old world, it being an AM bike )look a little steep for DH. So my question is this:- Under full compression, how much space is there between the back tyre and the seat tube? Would it be possible to either run a shorter shock (Fox used to do a 190x57 DHX to custom order), or to make up a different front shock shuttle to knock maybe 1 of the HA and drop the BB a little? (Turner sorted me out with some 6Pack rockers, which knocked 1off the HA and .75" off the BB and I couldn't believe the difference it made, but for DH it could be slacker still)

    (As an aside, although, Nicolai give a BB "rise", could someone convert this into a "BB height" from the floor - assuming 2.3" ish tyres. Pure laziness prevents me dragging the RFX out of the cupboard and working it out myself )

    Whilst I'm pretty sure the AM is a fairly beefy frame, at what point will possible failure (and it does happen) turn into "sorry, but you should have bought a FR if you want to do that" territory? I knock out quite a few drops in the 6-8' territory, a few in 10' area and very, very occasionally a bit bigger. I've also been known to case the living cr@p out of the occasional jump. (for those who know it, the triple at Chicky has come very close to breaking me and the bike on numerous occasions. Truly horrendous bottom out )

    Anyway, thanks for any replies. I'm not signing on the dotted line anywhere yet - want to wait and see what the '09 RFX is like, before I commit to anything in either direction, but the AM is very high on the agenda...


  2. #2
    Nightriding rules SuperModerator
    Reputation: crisillo's Avatar
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    the "a few drops in the 6-8' territory, a few in 10' area " totally sounds like FR territory to me...

  3. #3
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    I should probably qualify the the "a few drops in the 6-8' territory, a few in 10' area by saying that this generally to a nice tranny. I've occasionally done the 6'ers on a 24lb XC hardtail with no problems - just have to be smooth and bend ze knees,

    There does seem to be a perception these days for saying that a 6" bike is a glorified XC bike. That's not what I'm after. I want a bike that I can climb 100% on, and ride 95% of DH trails at 90% of the speed of a DH bike.

    I want to be able to do stuff like this one day


    then stick my saddle up, change to XC wheels + spds and crack out a 6hour XC ride the next, without dying horribly on the climbs. In UK terms, it's rare that I come across XC riding that challenges a 6" bike - I'd actually be quite happy with less, but I don't have room for a trail FS and a DH bike, so I need one to do both.

    (it wasn't *that* long ago that a 6" bike was capable of winning world cups )

  4. #4
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    I'd agree with Crisillo. The FR might be the bike for you. I use mine for similar stuff although the drops are no more than 6-7ft at the moment. As my jumping got bigger I changed from 160mm forks to 180mm as I kept bottoming them out. The new FR at least gives you a choice of 160 or 180 forks as I believe the AM is not warranted for the bigger fork.
    I currently ride my FR on pretty much all trail types but it's good to know I can hit the big stuff without a second thought.

  5. #5
    wyrd bi ful rd
    Reputation: chinaman's Avatar
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    the diference in weight is only about 400-500g and so considering what you mentioned above ... you be better off getting an FR and just spec it with some light yet strong components ...

  6. #6
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    FR deinitely. It pedals much better than the RFX so even at 36lb it'll feel lighter

  7. #7
    steep fast and loose :)
    Reputation: The_Lecht_Rocks's Avatar
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    not much between them both jon - i've ridden both (yetiman's fr and my AM) and being realistic, the difference is primarily the option on the FR of running a longer fork.
    the AM has neater gussetry and shock mounts, but remains similar in geometry. the beauty is it's more trail orientated of course.
    the wheels are the bifggest likelihood in determining the rig's capability in this instance , not frame choice if 160mm is your limit anyway.
    i ride hardtails too, and aim for technique as opposed to blatting square edged hits. The AM is a lot of bike.
    note also that i ran a 6 pack on the CCDB prior to the AM too !
    pm me if you need more feedback - i'm tired and wine'd up tonight after a brilliant night ride.

  8. #8
    mtbr member
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    The basic issue I guess is whether it's worth spending the best part of 2k if it's not going to be significantly different. Dropping 2lb of weight is good. The FR with a coil is still going to be ~9.5lb frame weight which is exactly where I am at the moment. Other than the weight, and a slightly-too-short-for-xc top tube, I can't really fault the Turner, and its the weight I really want to get sorted, whilst still retaining the same capabilities. I'll admit to struggling with the concept that actually things don't seem to have moved on since 2002 - whilst 6" AM bikes are far more common (and lighter), they all seem to have got less capable, and what's the point of a 6" bike if you can't absolutely rag the arse off it over anything and everything you can find?

    Dipper - I've got a Pushed DHX with Ti coil at the mo, and it pedals pretty damn well, even with no propedal on. It's leg strength that determines what I can get up, not traction. It's just the sheer physical effort required to get it moving that gets me down.Once it's up to speed it's superb.

  9. #9
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    Reputation: Karve's Avatar
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    Whats the Turner frame weight and travel?

  10. #10
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    Rather than replace the RFX, why not just buy a DH bike?

    Regarding the geometry, why not just have Nicolai build you a custom frame with the geometry you want?

  11. #11
    steep fast and loose :)
    Reputation: The_Lecht_Rocks's Avatar
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    jon - the helius and the rfx cannot be compared. the lateral stiffness of the nicolai destroys the rfx and the pedalling action is phenomenal.
    my vote still goes to the AM though.

  12. #12
    from 0 - sideways 3.2 sec
    Reputation: derekr's Avatar
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    FR sounds like your frame!

  13. #13
    mtbr member
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    Karve - ~9.5lb and 6"

  14. #14
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    Reputation: derekr's Avatar
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    AM Spec

    This is my AM @ 31lbs (Air shock/fork) and @ 34lbs (Coil shock/fork), although VERY capable i think the FR frame would deffo be the choice for ya, Esp since you do alot of jumps/drops i believe the FR is alot more stable where as the AM is more of a Trail whippet which turns faster than the FR.
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  15. #15
    steep fast and loose :)
    Reputation: The_Lecht_Rocks's Avatar
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    thinking about your original post, and considering your rfx is 9.5lbs, the 400g difference between FR and AM is negligible and immediately taken care of using a Ti spring (assuming you'll use coil for the riding you're proposing).....
    the FR differs from the AM as per Derekr's post in that stability is equally strong for both the FR and AM, but steering response is noticeably reduced on the FR c/f the AM.
    i weigh in at 82kg's, and also ride light on kit, bending ze knees, and having ridden the 08/09 FR and the 09 AM, the AM is still my favourite 'all mountain' suspension bike. i must repeat that the difference between the nicolai and the turner is in execution. the nicolai is powerfully constructed, almost brash, with wide rear seatstays and a subsequent inherent stiffness that the Turner simply cannot match. there is no visible flex in the car park flex test apparent (stand on the stays and quantify deflection !!!).....
    also, the linkage plates on the nicolai are very short c/f the rfx linkages, and this i'd expect increases lateral rigidity dramatically.
    both the FR and the AM are great rigs on which to build, and looking at the 09 DW equipped RFX which looks overly complex and is a shift change from your 02 RFX, I chopped in my 06 6 Pack + CCDB and went for the AM. No regrets here.

  16. #16
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    Nice bike TLR. What size is yours? And what's the weight?

  17. #17
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    Reputation: derekr's Avatar
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    Wink AM vs FR

    This might be useful to compare the AM geometry to the FR.

    Both frames are medium so its easy to see the difference in the length of rear stays, and the shock rear mount position.

    Thanks to Richard at Gravity Sports for the pics of the Helius FR.
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