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  1. #1
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    Mixing Tire Sizes

    Rare post for me. Am more of a lurker soaking up all of the good info on here. My main sport is tennis but have found I really like riding mountain bikes and have jumped all in on fat bikes. I have 3 now. So much fun even though I'm pushing 65 now. Any way....to my question....I have a bike that has a pair of the 27.5 Barbegazis on it. On another bike I have a pair of the 26 inch Barbegazis on it. I am considering switching front tires between the two. If I could, I would switch the rears too but they are not compatible. What would be the pros and cons of running the shorter tire (1 inch diff) in front? And visa versa with the taller one in front?

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    I am going to assume that these are trek farley bikes. The only sorta good way of knowing is trying it yourself. I can imagine that putting a larger wheel on the front will make the bike feel slacker, Just like a longer fork. I see nothing but bad things coming from the inverse of this (flipping otb, steep head angle, etc.) I look forward to seeing your results if you actually do this!

    -Ben

  3. #3
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    Everyone acts like any increase in head angle will cause you to instantly burst into flames.
    Switch it up. You probably won't even notice.

  4. #4
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    Quote Originally Posted by KTMNealio View Post
    Everyone acts like any increase in head angle will cause you to instantly burst into flames.
    Switch it up. You probably won't even notice.

    Any increase in head angle will cause you to instantly descend slower and go over the handlebars more often.

  5. #5
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    If you put the small one in front you'll always be going downhill so you'll be faster.

    Physics.

  6. #6
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    Quote Originally Posted by Volsung View Post
    If you put the small one in front you'll always be going downhill so you'll be faster.

    Physics.
    lol.......in that case, I'll put a 16" wheel up front

  7. #7
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    Mixing Tire Sizes

    Quote Originally Posted by Benskoning View Post
    I am going to assume that these are trek farley bikes. The only sorta good way of knowing is trying it yourself. I can imagine that putting a larger wheel on the front will make the bike feel slacker, Just like a longer fork. I see nothing but bad things coming from the inverse of this (flipping otb, steep head angle, etc.) I look forward to seeing your results if you actually do this!

    -Ben
    Well, surprisingly, I prefer the smaller tire up front. Seems to corner and climb better. No problem going down the steeps.....I get back behind the seat.
    Last edited by burtjason; 05-19-2017 at 04:16 PM. Reason: Used the word "descend" instead of "climb"

  8. #8
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    At least on sand, I find a larger front tire decreases understeer, and I more easily recover when the rear begins to step out before the front.

  9. #9
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    Quote Originally Posted by burtjason View Post
    Well, surprisingly, I prefer the smaller tire up front. Seems to corner and climb better. No problem going down the steeps.....I get back behind the seat.
    Better climbing ability is certainly a positive outcome of a steeper head angle. I suppose bikes could benefit from a smaller front wheel if their geometry is more relaxed than a trail requires.

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    I've heard that but never experienced it. How do bikes go uphill faster by steepening the head geometry ? I've also never noticed a smaller tire holding better in a corner than a bigger tire. The opposite is usually true.

  11. #11
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    Quote Originally Posted by endo_alley View Post
    I've heard that but never experienced it. How do bikes go uphill faster by steepening the head geometry ? I've also never noticed a smaller tire holding better in a corner than a bigger tire. The opposite is usually true.
    I didn't go uphill faster....but I did make a climb that I haven't made yet. It's steep and hard not to wheelie or spin. I don't know....maybe I just had a good day. And you're right about cornering with a bigger tire and it surprised me that I felt more nimble around a fast corner. I can't explain that. I should add that I recently added a Lauf which jacked the front end up a sixth of an inch whereas the inch larger tire brought it down a half an inch. So the difference is only a third of an inch lower than stock. The stock HTA is 69 degrees. I thought I wouldn't even notice the diff at all....but I did. Go figure.

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    Quote Originally Posted by endo_alley View Post
    I've heard that but never experienced it. How do bikes go uphill faster by steepening the head geometry ? I've also never noticed a smaller tire holding better in a corner than a bigger tire. The opposite is usually true.
    First off, Perfect name for this conversation! Secondly, I can confirm first hand about a steeper head angle making a bike climb better. I was in a recent 6hr fat bike race last summer and hit a tree dead on in my final lap. This bent my headtube and downtube back enough that my front tire was only a few mm away from rubbing on the down tube. I decided to finish the lap and kept on riding the bike. While the downhill performance was extremely reduced, As soon as a twisting climb started I was going strait up it better than ever before. My best guess for why this happened is the shortening of the wheelbase. This moved my weight farther over the front wheel while allowing the back tire to still grip.

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    Hmm. I can see how a steeper seat tube angle will put more weight forward. And a slightly longer stem. But a steep head tube angle makes for a very unstable bike. On very steep rutted single track climbing, the unstable front end tends to steer uncontrollably. For example, if you are trying to climb on the crown between two tire ruts on a steep eroded double track, a steep head angle will want to pitch you into the rut. On steep climbs, one must stand over the pedals to maximize pedaling power. Which is weighted forward of the seat. But one must also try to get enough weight over the back tire to keep it from losing grip. Which usually means awkwardly applying some weight to the front tip of the seat. Head tube angle does not come into play.

  14. #14
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    Quote Originally Posted by endo_alley View Post
    Head tube angle does not come into play.
    I would have to disagree. When reducing the head angle the wheel base is shortened allowing your weight to be proportionally more even compared to a longer/slacker bike. I am not saying that this wont completely screw up the bikes handling and any other scenario, just that this makes steep twisting climbs easier. I am not sure where you are from or what trails you ride, but local to me are some incredibly steep tight switchbacks that are almost impossible to clear if not done perfectly. (not trying to take anything out of context with your quote, just focusing on one part)

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    I am in western Colorado. And on some of the trails, if you ride squirrely, you are in the rut. Little by little we are repairing old trails where the Forest Service allows us to. But in many out of the way trails, the climbs can be very technical. And a squirrely uncontrollable front end makes things all that much harder.

  16. #16
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    Mixing Tire Sizes

    I remember when Rock Shox first came out. We were all riding rigid on 1.95 inch tires. Average head angle was about 71 degrees. When I got my first Rock Shox, it jacked the front end up a bit. Going downhill or over rough stuff was great, however I couldn't tackle my local steeper climbs anymore. The front end would wander and want to wheelie on the steep stuff. Rigid forks are suspension corrected nowadays so no worries. I guess the thing that surprises me the most is that lowering the front a third to a half an inch would even be noticeable at all. The bike feels perfect to me know. I may do the same to my other fattie. The bigger Barbegazi on the back.
    Last edited by burtjason; 05-20-2017 at 10:07 AM. Reason: mis-spell

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