• 03-07-2015
    db9
    Any prevailing wisdom on wider rims? (upgrade)
    Maybe it's the riding bug setting in as my ski season winds down (well there is still a ways to go)..

    Currently running Stan's Arch (first gen for lack of a better description) on my 29er. Running 2.4 fr/2.25 rr tubeless.

    Wondering if I changed out the Arch's for say.. a set of Blunt SS (26mm inside vs 19mm inside for the Arch) will I notice anything in the way of an improvement? Not really sure what improvement I'd see really, the Blunts are lighter though. Just wasting money?

    Not a racer.. just climbing and general exploring...
  • 03-07-2015
    Circlip
    Is the assumption that you will still be using these same tires?
  • 03-07-2015
    db9
    Yes - the plan is to continue using same size maybe slightly larger at some point - but for the time being the same.
  • 03-07-2015
    BlackOut
    I enjoyed my old Mavic XM819 with an inner width of 19mm. I recently updated these to some Stan Flow EX's with an inner of 25.5mm and there is definitely more tire on the ground. Increased strength and increased tire footprint/profile were the big attractions for me. I have been known to climb trickly climbs because of this extra traction.

    I am using 26er's so probably more substantial with 29er.
  • 03-08-2015
    Circlip
    Quote:

    Originally Posted by db9 View Post
    Yes - the plan is to continue using same size maybe slightly larger at some point - but for the time being the same.

    It's generally accepted that the narrow XC pinner rims of yesteryear aren't your best option, but with explosion of wide and wider rims over the past few years there is also a growing body of experience and knowledge about what is too wide, which depends on a few factors.

    Here's a link to what might be considered the reference thread on this topic on MTBR, but it's a lot of reading at almost 700 posts, some of which are technical in nature and also some contradictory opinions. However, some of the folks contributing also have good knowledge on the subject at a professional level (e.g. work for tire companies, etc.) so there is definitely good information in there if you have the patience to check it out.

    http://forums.mtbr.com/wheels-tires/...pe-900712.html

    A couple of nuggets that I pulled from the thread which may help are;

    Now we've got a tire designer and a wheel manufacturer confirming the importance of "rim size to tire" relationship, as well as the shoulder lug orientation issue if your rim is too wide.

    In other words there is probably an optimal width for running a tire of a given size (remember that manufacturer's adherence to listed sizes may also vary), and furthermore that it ma not only be the size but also the arrangement of cornering tread blocks of a specific tire model, in terms of whether they get squared off on a wider rim such that their behaviour changes noticeably from what the design intended for what lean angle will get the best/worst use of the edge blocks. Also, this summary from one poster in the thread;

    On the good side:
    * Wide rims increase the air volume with the same size tire.
    * Wide rims support the tire better, allowing better tire support at lower air pressures and less burps.
    * Some find the lower tire pressure traction/handling quite compelling.
    * Other similar uses like offroad motorcycles have much lower tire to rim ratios, supporting the idea that low tire to rim ratios are a good thing.
    * the tire footprint gets wider and shorter (area unchanged and is directly related to load and air pressure).
    * Exactly what is wide seems unclear, but the Derby (external 40mm), Ibis 721 (external 41mm), and Nox Farlow 275 (external 35mm) seem commonly mentioned.

    However on the downside:
    * Wide rims are heavier (for the same design)
    * Lower air pressure and same ride height results in being more vulnerable to pinch flats and rim damage from small rocks and hard edges.
    * tire design is sensitive to rim size, pretty much all today popular tires are designed for non-wide rims.
    * Increased air volume means a more linear compression rate, easier to bottom out than a lower volume wheel setup.

  • 03-08-2015
    db9
    Thanks for the responses.. looks like some reading is in order.. thanks again. stay tuned