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  1. #1
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    Big suspension v big tyres.

    So....

    I'm running 165/180mm travel 27.5" 2.30 dhf 2 minions.

    My buddy rides 150mm 29er with some big chunky magic Mary's.

    We did the bike swap today and the comparison was interesting.

    My bike pedalled better than than my buddies 29er. But both bikes rode over the roots about the same. It got me thinking that bigger suspension and smaller tyres is a better overall combo than less travel more wheel/tire for overall aggressive all mountain riding.

    Discuss!

  2. #2
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    Well you can control your suspension, but you can't control your tire.

  3. #3
    RAKC Industries
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    There's A LOT more to things than that.

    29ers dont spin up as easily. Gearing, suspension design etc all play a part in how a bike pedals. I doubt all those details match between the bikes.

    Not sure why you say his tires are bigger beyond being 29 instead of 27.5. But he has big heavy knobby tires and yours are simply smaller thus lighter weight/smaller diameter. No more tire to "control" just the increased diameter to deal with. And your also comparing magic Mary's to your tires. There's a lot of differences right there. If you guys had same tires and same bikes (just one if 27.5 and one in 29 version) for every detail including final gear inches that gap in how it feels would close up. The 27.5 you'd notice slightly faster input response and handle tight corners slighy better possibly.

    In your case it's a mix of the details and what your used to riding. I'm someone who left 29s for 27.5 for my trail bike. And wish I had done it sooner.

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  4. #4
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    It is complicated, and there's a lot of room for subjective opinion and preferences, including what is meant by "better". Better can be something relatively simple and quantitative, like speed over a given course by a particular rider, or more nebulous, like how it feels riding that course. A bike might "feel" better and faster despite actually being slower, and vice versa.
    Do the math.

  5. #5
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    It depends on the track I think. When grip is a major determining factor then tyres will play a bigger part. If it's hero dirt with rough sections and high g corners then smaller tyres and big squish will prevail.

    I know for me, where I ride, big tyres are king. That's why I ride 2.8 front and a big 2.5 (measures 2.6) rear.

  6. #6
    Elitest thrill junkie
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    I find that there's a "happy medium" if you want to go fast and rip up and down the trail. There might be people leaning a particular way within this area, but when you move far outside of it, things get slower and the benefits decrease for many people. Go back in time to when we were experimenting with 3.0 tires in downhill. That didn't last. 3.0 tires weren't the fastest and best way to get down a mountain.

    I DHed a 29er Enduro bike a few seasons. With adequate DH tires (minion 2.5) the roll-over was great, but making medium turns at high speed was painful, because you had to slow down some or the gyroscopic stability would simply make the bike skid towards the outside of the turn, off the trail if you were going fast enough, whereas a bike with smaller wheels (mass much closer to the axle) was able to maintain the line at a higher speed. Tight stuff was no problem, that geometry problem with 29ers was fixed a little while back on many bikes, but you can't fix this wheel/tire problem.

    Then there's big tires on rigid bikes, which limits how fast you can go because it becomes undamped suspension, you simply get bounced/pounded into oblivion. Sometimes these and especially fat-bikes are good for people who go slow and are new to the sport. The inspire confidence, etc., but riding my fatbike in winter is nothing like doing the same in summer. A lot of "what makes it work" doesn't exist in the summer time (snow and the generally lower pressures in the winter absorb a lot of impact energy).

    I notice with my 29er race-FS bike I can make it over roots and nasty tech sections easier than my 27.5 that has 60mm more travel. Part of it is geometry, but part of it is the bigger wheels. Tires are normal 2.2ish size on that bike. Going downhill the 29er has decent roll-over, but neither the geometry, the stability or the travel to deal with big chunky riding. I am going to put some slightly bigger tires on it this year with an extra wheelset, around 2.3, for more "trail" orientated riding, but I know from past experience that going "too big" will just slow me down.

    There are still reasons to go with wheel/tire combos outside of these ranges, but that's where it drops off significantly as far as being "for everyone". Looking at racing, you can see what tends to work best for both XC, DH and Enduro racing. Despite what some may think, modern big XC races are technical and chunky in most Western US races and the riders usually ride DH faster than intermediate "DH" riders, not that you need to replicate their setups, but then looking DH setups it would be somewhat logical to think that your setup would fall somewhere in the middle.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  7. #7
    mtbr member
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    Quote Originally Posted by Jayem View Post
    I find that there's a "happy medium" if you want to go fast and rip up and down the trail. There might be people leaning a particular way within this area, but when you move far outside of it, things get slower and the benefits decrease for many people. Go back in time to when we were experimenting with 3.0 tires in downhill. That didn't last. 3.0 tires weren't the fastest and best way to get down a mountain.

    I DHed a 29er Enduro bike a few seasons. With adequate DH tires (minion 2.5) the roll-over was great, but making medium turns at high speed was painful, because you had to slow down some or the gyroscopic stability would simply make the bike skid towards the outside of the turn, off the trail if you were going fast enough, whereas a bike with smaller wheels (mass much closer to the axle) was able to maintain the line at a higher speed. Tight stuff was no problem, that geometry problem with 29ers was fixed a little while back on many bikes, but you can't fix this wheel/tire problem.

    Then there's big tires on rigid bikes, which limits how fast you can go because it becomes undamped suspension, you simply get bounced/pounded into oblivion. Sometimes these and especially fat-bikes are good for people who go slow and are new to the sport. The inspire confidence, etc., but riding my fatbike in winter is nothing like doing the same in summer. A lot of "what makes it work" doesn't exist in the summer time (snow and the generally lower pressures in the winter absorb a lot of impact energy).

    I notice with my 29er race-FS bike I can make it over roots and nasty tech sections easier than my 27.5 that has 60mm more travel. Part of it is geometry, but part of it is the bigger wheels. Tires are normal 2.2ish size on that bike. Going downhill the 29er has decent roll-over, but neither the geometry, the stability or the travel to deal with big chunky riding. I am going to put some slightly bigger tires on it this year with an extra wheelset, around 2.3, for more "trail" orientated riding, but I know from past experience that going "too big" will just slow me down.

    There are still reasons to go with wheel/tire combos outside of these ranges, but that's where it drops off significantly as far as being "for everyone". Looking at racing, you can see what tends to work best for both XC, DH and Enduro racing. Despite what some may think, modern big XC races are technical and chunky in most Western US races and the riders usually ride DH faster than intermediate "DH" riders, not that you need to replicate their setups, but then looking DH setups it would be somewhat logical to think that your setup would fall somewhere in the middle.
    Good insites man. I tend to agree with you.

  8. #8
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    Quote Originally Posted by Lone Rager View Post
    It is complicated, and there's a lot of room for subjective opinion and preferences, including what is meant by "better". Better can be something relatively simple and quantitative, like speed over a given course by a particular rider, or more nebulous, like how it feels riding that course. A bike might "feel" better and faster despite actually being slower, and vice versa.
    In my instance the 29er with the big magic mary's had more roling resistance. It was harder to pedal and took more energy to go the same speed. Jumping back on my bike it was noticably easier to pedal the same terrain.

    But both bikes rolled over roots about the same. Mine using plusher suspension and the 29er bike wheels and tires. For me it was interesting comparison.

  9. #9
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    tire pressure is --everything-- with big tires.

    experimenting with pressures front and back. there is an absolute sweet spot where things really fall in place and you can simply rip.

    outside the sweet pressure zone, is riding like in mud, or getting your bones rattled.
    "Put your seatbelt back on or get out and sit in the middle of that circle of death." - Johnny Scoot

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