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  1. #1
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    Asymmetric wheel sizes affect handling?

    I am interested if anyone has knowledge of whether asymmetric size wheels affect handling, for better or worse, all other things equal.

    I am exploring converting my 29er to a 27.5 on the front wheel - I could get more travel without mucking up the geometry hardly at all. The front would be less gyroscopic and hence more flickable. The back would retain the advantages of the 29 with its rollover capability (where the most weight of the rider is).

    However, does the different diameter make handling 'funny'? I could see a smaller front meaning faster turn in, which would be good?

    I have looked on motorbike forums but the considerations there seem to be different.

    So, any advice/views much appreciated.

  2. #2
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    Re: Asymmetric wheel sizes affect handling?

    No personal experience, but what you should know is that when placing the 27, 5 front wheel, your axle will be lower to the ground, meaning you will change head angle and trail. Not by much, but these will have effect on handling. Probably your bike will feel a bit more twitchy

  3. #3
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    I think most who have tried different wheel sizes on the front vs back usually go with the larger diameter up front...

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  4. #4
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    Also, why do you think you will get any more travel?

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  5. #5
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    More travel : my bike currently has 110mm with 29" - the difference to 27.5" is 1.5" or 38mm. Half of that is 19mm, or 20mm approx.

    Therefore, if I put a 27.5" wheel in a 130mm fork on, it should be identical in ground to crown length terms, no change in the HA?

    However, I can see it would result in a very slightly longer wheelbase and quite significant smaller trail (see Motorcycle rake, trail and offset explained | bikearama motorcycle blog to visualise this). The reduced trail would make it much twitchier.

    I can't see any reason for going with a large front and small rear on a mtb - would be the worst of both worlds imho.... It seems they do this in dirtbikes because the smaller wheel at the back handles the power better and takes a fatter tyre, while the thin larger front wheel cuts through crud to the ground below for grip, while giving more gyroscopic stability and less tank slap.
    Last edited by marvin rouge; 04-27-2013 at 02:05 PM.

  6. #6
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    Motor bikes have engines, they twist the throttle to bring the back end around when they need it, if they had to provide the power themselves the rear would not be the bigger tyre. As far as doing a 69er with 26/650B in the back and 29er in the front loosing the advantages of the 29er When was the last time you worried about your rear wheel getting hung up on something as opposed to having the front get hung up??
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  7. #7
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    Quote Originally Posted by LyNx View Post
    When was the last time you worried about your rear wheel getting hung up on something as opposed to having the front get hung up??
    Probably last week. Front end is always easy to kick. But I do notice the back wheel slowing markedly on obstacles, which is why 29ers roll so much better imho.

    I always ride the line for the rear wheel, doesn't everybody? Who gives a rats what the front wheel bounces off?

  8. #8
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    Asymmetric wheel sizes affect handling?

    Marvin....what you are saying is not making much sense to me...good luck anyways.

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  9. #9
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    While I agree that proficient technical riders do, in fact, ride lines for their REAR wheel, I'm not understanding what benefit would be gained from going to a 650b wheel in FRONT.

    Once you factor in tire sizes, a 650b is much closer to 26 than 29; this will have significant handling impact in a negative sense. Also, I don't understand how this will increase front travel. An "xx" travel front fork gets "xx" travel. Reducing wheel size won't change that.

  10. #10
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    Re: Asymmetric wheel sizes affect handling?

    Trolling ??

  11. #11
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    Quote Originally Posted by Blatant View Post
    While I agree that proficient technical riders do, in fact, ride lines for their REAR wheel, I'm not understanding what benefit would be gained from going to a 650b wheel in FRONT.

    Once you factor in tire sizes, a 650b is much closer to 26 than 29; this will have significant handling impact in a negative sense. Also, I don't understand how this will increase front travel. An "xx" travel front fork gets "xx" travel. Reducing wheel size won't change that.
    He is changing forks...

  12. #12
    squish, squish in da fish
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    oh your setting up a drag bike, right? i get it, don't forget the wheelie bar

  13. #13
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    Oh dear.

    When I've given it a go, I'll report back.

  14. #14
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    I'm sure it will be a gem of a report

  15. #15
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    I experimented with a 69er conversion last year...made sure HTA was same, etc. Noticeable impact on handling...some good, but many negatives. I am not running it as a 69er any more.
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  16. #16
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    ^^^At last. To the bin then. Thanks

  17. #17
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    Damn! what a bunch of nonsense posts. The intelligence here is decreasing lately.

    I do see your point Marvin and I think you should try it really. I agree with most that it is better in certain conditions to run a bigger wheel up front. I also agree that running a bigger wheel in the back does have many advantages too. There is always going to be pros and cons to both but imo less cons with a bigger front. I personally find it easier (becasue of my upper body strength) to flick the front end of a bike around much easier and so usually don't need a lot of suspension in the front because of that. But when going down steep technical sections, the bigger wheel does help roll big obstacles. AND (a big AND) for me is that I hate brake dive and the resultant HA changes that occur when you have a lot of travel in the front. For me, that decreases precise handling. A lot of people like very short chainstays so having a smaller wheel is a major advantage for them. I am tall, so I like the added wheelbase the 29er rear wheel gives.

    A person's bike geometry preferences (like so many things) are so relaltive to many factors and cannot possibly be determined by asking people on a forum that have so much trouble looking outside of their own person preferences. I say you go for it. You obviously thought about it and I can relate to your reasoning. Let's face it, the bigger wheel does take away from a lot of front travel and if that is what you want, then that is what you should have.

    BTW, the difference in size between the 29er and 650b is 38mm. So to get the same ground to crown height, you would have to go with a 150mm travel fork. A 650b 130mm fork has about the same A-C length as a 29er 110mm fork, but then you have to make up for the 19mm in the difference in radius - from the center of the wheel to the ground.
    And don't forget about the extra sag.

  18. #18
    squish, squish in da fish
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    ^^^you must be more roadie than anything, mr prophet of jellystone, there there boo boo. i mean really how often do you see anyone riding like that? there is a reason n your not it

  19. #19
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    Quote Originally Posted by yogiprophet View Post
    Let's face it, the bigger wheel does take away from a lot of front travel
    Please xplain why ...

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  20. #20
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    Quote Originally Posted by yogiprophet View Post
    I do see your point Marvin and I think you should try it really.
    Thanks for the validation - sanity prevails.

    You make very good points about personal preferences.

    Very interested in your comment that a 650b 130mm fork would have the same A-C length as a 29 110mm fork - something I wasn't aware of. 150mm would be a lot of suspension, maybe more than I was looking for.

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