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  1. #1
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    Need a better stem / setup for descending

    Hey guys...

    First off, thank you to the forum posters for getting me interested in the Mojo HD 140 - I was 80% of the way to buying another Stumpjumper before I came on here, but instead I picked up my Mojo last weekend. Yody, your reviews and comparisons (160 / 140 / SL-R) are stellar and full of useable information I needed to make a good choice.

    Overall I am thrilled with this ride, it climbs better than I had hoped (I don't miss the Brain at all) and pedals great at 150mm, which was another concern I had. My only complaint is the bike is sketchy on the steeps, which I know isn't right.

    I think the culprit is the 110mm stem. I'm 6'4" with long arms, so I told the LBS that I was cramped in the cockpit of my size L Stumpy FSR, and got an XL Mojo and also went long with the stem as per their reco - the LBS said we could swap it out later if it didn't feel right. Now my reach feels longer (much longer than my old bike), but it feels like I can't get into a wheelie / manual without way more pulling back. And I landed really nose heavy on a couple of 3' - 4' drops that I can ride like butter on my old bike, and felt like I couldn't shift back as well on some rock rolls and steep pitches. I'm guessing this is a combination of a longer TT, super long stem, and maybe more sag / travel in the fork (the fork feels awesome in general).

    I was riding a 105mm stem on the Stumpjumper, according to the Spec website, so not sure why this 110mm would feel so different. Would going down to 90mm make a big difference while still letting me stretch out a bit? Should I go shorter? I'm not an expert at bike geometry but many of you guys seem to know this stuff cold, so I'm looking for some direction. Thanks!

  2. #2
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    Stem is way too long. I would suggest that you try a 70mm and wider bars to compensate for your long arms. Experiment to see what works best. Most DH riders use 50mm stem with 31" bars.

  3. #3
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    Quote Originally Posted by Cable0guy View Post
    Stem is way too long. I would suggest that you try a 70mm and wider bars to compensate for your long arms. Experiment to see what works best. Most DH riders use 50mm stem with 31" bars.
    This^^
    70mm stem and 720mm+ wide bars. I have RaceFace SIXC bars @ 725mm and really like them. Though at 6'4" you may like even wider ones.
    Those who know, ride a Mojo AND a Mojo HD.
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    Ok, whatever, cold water on my bike boner right there.

  4. #4
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    Longer top tube/ shorter stem is the way to go. I would think the XL should be perfect. As stated above, I think the long stem is to blame. It restricts your movements. It seems a lot of shops fit people with roads bikes in mind. The wider bar is also a great idea IMO. More stability for taller guys, and lets you use a shorter stem for easier weight shifting.

  5. #5
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    6"2 myself and ride an XL with a 50mm stem and 750mm bars. Your first ride will feel weird but give it a couple rides and you will wonder how you rode with a long stem and narrow bars.

  6. #6
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    Have you measured your old bike seat post to handle bar and then compared it to the HD? That would give you idea of where you were before.

    I'm 6'1" and run an XL with a 40mm 0 Deg. stem with 30" bar.

    What I noticed was with my seat fully extended I had too much weight on my hands so I went with a 3" riser bar and now I feel I have more weight on the seat and I'm comfortable.

    What type of handle bar are you running?
    Last edited by mbikerguy; 06-13-2012 at 08:34 PM.

  7. #7
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    I am 6'4.5 and have spent the last 2 years swapping stems and bars trying to get the best fit with the shortest possible stem on my hd160. I finally gave up on an 80mm stem and went back to a 0 degree 90 mm stem with 780mm boobars. This combo feels really good and my back does not hurt by the end of my ride but I am definitely in more control on the downhills with an 80mm stem. I would like to run a 70 mm stem but I am just too tall for the smallish XL HD frame. I wonder if there is any chance that Ibis will produce an XXL HD with a 20mm longer top tube than the current XL? This would be equivalent to other manufactures all mountain XL frames. Maybe I'll start a new thread to see if there is interest for an XXL HD.

  8. #8
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    Thanks for the feedback guys.

    I measured up the bikes and confirmed the measurements with the owner's manuals:

    Stumpy FSR: Horizontal TT = 612mm + 105mm stem, total = 717mm
    Ibis Mojo HD: Horizontal TT = 622mm + 110mm stem, total = 732mm

    So the Ibis has about 15mm more reach than my old Stumpjumper. The Stumpjumper (so far) is way more confidence inspiring on downhills, which I know is backwards, but there it is.

    The handlebar is the stock bar from Ibis: EC70 XC Carbon Fiber Lo-rise 685mm wide. The bar feels a lot wider (40mm wider than my old bars) but has less rise.

    Mbikerguy, I think I have the same issue you used to; my hands always hurt after a ride. I sit with my seat up high too. I will look into a bar with more rise.

    I think I am going to ask the shop to throw on a 90mm stem. I would love to go 80mm or 70mm, but I know that will be too short and feel cramped. Would getting a 90mm stem with some rise in the stem itself mean that I don't need to replace the bars?

  9. #9
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    Trust me (and the others on this thread): defInitely get wider bars too! It's not about fit, but rather about control for rough terrain and cornering. Going to a wider bar (and an appropriately shorter stem to dial in fit, since a wider bar has the effect of increasing reach) has transformed my riding, no joke. It's essential for effective counter steering. Just try riding down the block with your hands on the bars right near the stem, roadie aero-style, & how unstable that feels. Widening has the opposite effect, and particularly at your height I would say is only limited by how much narrow single track through the trees you have where you live.

    Your LBS should be able to swap in a cheap alloy bar for you to try out, and then you can upgrade to a carbon version once you find a fit you're happy with. I recommend starting with 720-725mm at least.
    On heavy rotation: White Lung: Deep Fantasy

  10. #10
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    You might want to consider sliding the seat back on the rails, or even getting a setback post, along with a shorter (70mm) stem. That way you can maintain the reach you are accustomed to, while shifting the whole cockpit rearward on the bike. In my experience, this leads to better descending performance.

    Wider bars take some getting used to, and could even be one of the reasons that the HD isn't as confidence inspiring as your old bike right away. I run 711mm bars on my HD and love them. On a ride last weekend, I hit a deep rocky rut at an odd angle with the front wheel, throwing the wheel sideways and damn near wrenching the bars out of my grip. I wonder if I had the lower leverage of narrow 650mm bars if I would have been able to hold on.

  11. #11
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    Quote Originally Posted by switch1213 View Post
    Stumpy FSR: Horizontal TT = 612mm + 105mm stem, total = 717mm
    Ibis Mojo HD: Horizontal TT = 622mm + 110mm stem, total = 732mm

    So the Ibis has about 15mm more reach than my old Stumpjumper. The Stumpjumper (so far) is way more confidence inspiring on downhills, which I know is backwards, but there it is.

    The handlebar is the stock bar from Ibis: EC70 XC Carbon Fiber Lo-rise 685mm wide. The bar feels a lot wider (40mm wider than my old bars) but has less rise.
    Yes, the first try would be the 90mm stem to regain about the same reach as you were previously comfortable descending.

    Then to gain more descending control and confidence, go with wider bars and shorter stem. More or less, about 3 times wider bars as the stem becomes shorter to maintain the same reach.

    And a shortened reach helps further. And requires bending your arms more to get weight on the front wheel for fast cornering, improving control and feel.

    The handle bar height two inches lower than full seat height is usually about right for all around gradual descending, level, and climbing.

    A remote dropper seat post is a major convenience to lower the seat for steeper descending and very rocky rooty level with short climbs.

  12. #12
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    Quote Originally Posted by switch1213 View Post
    Thanks for the feedback guys.

    I measured up the bikes and confirmed the measurements with the owner's manuals:

    Stumpy FSR: Horizontal TT = 612mm + 105mm stem, total = 717mm
    Ibis Mojo HD: Horizontal TT = 622mm + 110mm stem, total = 732mm

    So the Ibis has about 15mm more reach than my old Stumpjumper. The Stumpjumper (so far) is way more confidence inspiring on downhills, which I know is backwards, but there it is.

    The handlebar is the stock bar from Ibis: EC70 XC Carbon Fiber Lo-rise 685mm wide. The bar feels a lot wider (40mm wider than my old bars) but has less rise.

    Mbikerguy, I think I have the same issue you used to; my hands always hurt after a ride. I sit with my seat up high too. I will look into a bar with more rise.

    I think I am going to ask the shop to throw on a 90mm stem. I would love to go 80mm or 70mm, but I know that will be too short and feel cramped. Would getting a 90mm stem with some rise in the stem itself mean that I don't need to replace the bars?
    I think the Mojo HD sits higher in its travel than the stumpy and that could be the reason you are more comfortable DH with the Stumpy.
    I would try sitting on both and measuring your seat height to compare them when the suspension is compressed.

    Also I would measure the handle bar height vs seat height on your bikes and see if there is a big difference between the two.

  13. #13
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    Big guys need longer stems and wider bars than small guys. Your long arms mean you'll be more comfortable with a longer reach.

    That being said, try the wide bars on that stem first before going out and buying a new stem. Wider bars make much more of a difference than stem length when descending IMO.

  14. #14
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    Quote Originally Posted by mbikerguy View Post
    I think the Mojo HD sits higher in its travel than the stumpy and that could be the reason you are more comfortable DH with the Stumpy.
    I would try sitting on both and measuring your seat height to compare them when the suspension is compressed.....
    Yes check your sag. The HD likes deep rear sag.

    The HD rides relatively high in travel only while climbing, compared to most other bikes. When coasting and downhill, like any other bike, it's all about sag and spring rate.

    The HD likes deeper sag than many longer travel trail bikes, since it does not squat to sag deeper while climbing, having over 100% anti-squat geometry in the middle and granny rings with the big cogs.

    Downhill rear sag rises from the weight shift forward, unweighting the rear spring, so use 5 to 10% deeper sag than the FSR for better descending and without loosing the better climbing efficiencies of the DW-Link.

    IMO, 30% static sag at the shallowest for trail uses, unless maybe XC racing it and standing to pedal and accelerate a lot, then 25%, sacrificing more optimum descending.

    It pedals and climbs pretty well with up to 40% sag as long as your fit is adjusted, and an adjustable drop height fork for climbing helps when using deeper than about 33% rear sag.

    Personally, I use 25% fork sag, with 33% rear sag for trail riding with much climbing, deeper rear sag for DH shuttle and DH park. And an on-the-fly adjustable height fork and remote drop seat post, 750mm bars, 70mm stem, I'm 6'0 on a Large size HD.

  15. #15
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    Guys, thanks for the tips.

    For anyone following along with a similar issue, I swapped for a 90mm stem, and the 20mm less made an immediate difference. I am also noticing myself riding with my hands out to the ends of the bars, so I may go wider, but the trails here have some tight squeezes and I am already barely scraping by. Next up is messing with the suspension, but it feels so good I'm hard pressed to find anything to fix!

  16. #16
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    Quote Originally Posted by switch1213 View Post
    I am also noticing myself riding with my hands out to the ends of the bars
    Where else should your hands be?.

    I run 760 so if you are 6'4 I can imagine you could go 780 even.

  17. #17
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    ^^ LOL, fair enough question... I mean my pinky finger actually wants to overhang the ends of the bar. I'm going to try something wider in aluminum per the recommendations above, hopefully that will sort me out.

  18. #18
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    One point to think about is bar height.

    When seated normally most people's shoulder to hands angle is about 45 degrees. So if you shorten your stem by, say, 30mm, and lower your bars by the same amount, your general riding (and climbing) position remains basically the same.

    The wide bars add great stability even when climbing, and once you get off the saddle to descend, the shorter stem makes for more relaxed arms ( not as stretched out) and the lower bars aid cornering.

    I have pretty broad shoulders, but I ride mostly on narrow trails around Wellington, NZ, ( think many trees and embankments very close by ) so I am happy with 740mm/29.1 bars, about 40mm/ 1.5" lower than my saddle, bolted to a 60mm stem.

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