Sunday, December 30, 2018

Kuroshiro 6105 rims, long-term review.

I first laced these up in October of 2015.

They are 100mm wide internal, 105mm external.  550g/rim = very light.

90% of the miles they've seen have been snow of the incredibly soft variety.

The other 10% have been washes and sand dunes and some rock crawling.


I used DT Swiss SuperComp triple butted spokes, laced 2x, with DT Prolock alloy nips.  I find that with fatbike-width hubs the spoke gauge and lacing pattern matter very little, because so much of the wheel's stability is coming from the excessive center to flange distances.  Might as well go light.  More on that in a bit.


On normal doublewall rims the nipples are buried between the walls, and they never come in contact with the sealant or a tube.  On singlewall rims like these, the nips are right there, being bathed in sealant if tubeless, or poking into the tube if there is one.

I think it's important to cover the heads of the nips somehow.

Why?  Long term protection of the nipples from corrosion by sealant, and of the tube (should you ever need to use one) from being punctured by the nipples.  So in the pic above you're seeing blobs of Shoe Goo over top of the nipple heads.  Couldn't see a good reason to get more complicated than that.  YMMV.


This wheelset was built for a brand new chassis, and as such the first rides were spent more focused on getting my contact points in the right places, and marveling at the size and (slow!) speed of the tires.  Never really noticed anything about the wheels in any direction.


A few months later we'd managed a few deep snow alpine rides and a few local dirt/rock/ice rides.  The latter are emphatically not what this bike was designed for, and -- largely because these rims are so expensive and relatively fragile -- not the sort of place I like to take this bike.  I have other bikes for that.


After a ~month worth of soft snow, cold temp, high alpine rides, it became obvious that the Vee 2XL tires had massive float, but that the rubber compound was sub-optimal for subzero temps.  A few calls later and I'd not only learned that Vee made a cold-temp-specific compound, but I also had a few of those tires on the way.  Seen below, the 2XL's with creme-colored "PSC" cold-specific compound.  Much, much better.


I did a few springtime wash bashing rides using a Manitou Mastodon and (usually) with a set of B Fat wheels and tires on the bike.  Wash bashing is hard on bikes -- especially when there are pourovers or house-sized boulders that need to be clambered over or under -- and this bike is too rare and too precious to just beat senselessly like that.  I still ride washes but I typically do it on a stock Trek Farley with taller/skinnier B Fat wheels these days.  In essence I save this Meriwether for deep snow specific missions as it is so, so dialed for that purpose.


When we ride the alpine it usually means pressures of 1psi, usually less.  Basically just groveling along, almost riding on the rims.  Run more pressure, or narrower rims, or smaller tires, and you dig holes while remaining in place -- simple as that.  Anyone that doubts this is welcome to bring whatever bike they have and come join us sometime: We never tire of looking back to see their incredulous faces walking next to their inadequately floating bikes. And then we leave them with their thoughts.


I'm reluctant to say that any one part of this package is "the key" because without all of the attendant parts it simply wouldn't work.  Like, remove the crown race -- then what?

Pedantry aside, I get asked often which of the many attendant components make this bike work so well at it's intended purpose.  Is it the geometry?  The steering damper?  The enormous volume tires?  The gucci rims?


It's just never that simple.  


Below is a clip that shows a few seconds of an average winter ride in our backyard.


There is a clearly delineated and marginally packed trail.  There is no one else out, and the wind is drifting the trail in quickly.  I rode for another hour -- until I couldn't even make out where the trail had been -- then found an exit and got out while I could.



Because the snow we ride is so consistently soft, so devoid of moisture, with so little traffic compressing it before it gets buried again, and again, I think it's important to recognize that it's the sum of the parts of this package that make it work.

How do I know?  Last week I took my Trek Farley up to these same trails, shod with industry-standard rims and tires, and running low-as-you-could-go pressures.  The Farley is a great design, aimed at the bulk of the market whom ride trails with a lot less snow and a lot more traffic than what we get.  It is a universally loved bike -- I bought it because it is so good at so many things.

And on that day last week, with my trusty Farley by my side, I walked.  A lot.  While my wife (on her Meriwether) and Pete (on my Meriwether) pedaled along and conversed, somewhat oblivious to how soft the snow really was, and being careful to wait at intersections so that I could see which way they'd gone.



The Farley is -- just like every other box-stock fatbike -- adequate for an average range of conditions in an average range of places.  I love mine, and I use it when I go to those places, or when I ride fat in non-snow months.


In scenarios where maximum float is necessary I always reach for my Meriwether, shod with 2XL tires on these Kuroshiro rims.  Finally -- back to the rims.  The entirety of this post has been aimed at getting to where you the reader (and hopefully soft-snow-rider) could understand the conditions we have to work with when we ride snow.  And the pressures we have to ride, even with 5" tires on 105mm wide rims.

So?

So, I've never had to true or round or retension these wheels since built.  I check the tension on occasion as a preventative thing.

And, not once in the hundreds of hours and miles that I've ridden these tires have I been able to get them to burp when riding.  Think about the forces you can put on a 5" wide tire that's effectively running on the rim.  No burps, no seeps, no fluid or air loss whatsoever.

As unexciting as the above might seem, I consider that the highest form of flattery I can offer.  

These wheels?  I don't notice anything about them, except that they just keep going and going with effectively no air in the tires.


Future changes?  I'll probably unlace them at some point and re-lace using Berd spokes.  Knocking ~100g per wheel off might not be that noticeable in the grand scheme of things -- especially when it's loaded for a weeklong self-support in the sub-arctic.  But it's not going to hurt anything, either.

Don't hesitate with questions.

6 comments:

  1. Interesting post Mike. I like that short clip of your "average winter ride in our backyard". Hearing the wind and watching the snow blowing gives it entirely different perspective. Made me shiver just watching it.

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  2. Does your wife have the same wheel set up on her MW? Curious if she is able to ride that much further given same PSI in conditions so soft you are forced to walk.
    I'm guessing that while this is pretty much THE set up for uber soft snow, body weight is still going to be a limiting factor at some point.
    Rocky would have loved these.
    In soft snow, big dudes lose.

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  3. Ditto... I have had my Kuroshiro 6105's since 2015 as well. Mine are built up on Tune hubs with race spokes (1740g for the wheelset). My wheels are as true as the day they arrived and like you, They almost never see pressures over 2.5 psi, often 0.5 psi here in the dry, cold powder of the Rockies. I had a lot of problem with the valve and spokes leaking. I also have had several burps. I put on FattyStripper bands in Feb 2017 and haven't had to touch anything since. They hold their air all the way through the summer months while sitting in my basement waiting for their playground to come back.

    These wheels accelerate and corner spectacularly well. They are very stiff, yet I don't feel them loosing traction on higher speed, rough/icy corners. I'm a huge fan of Mauro's ENSO6105 and ENSO685 rims! They make me smile every time I throw a leg over them.

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  4. Hi Mike, I have no riding experience on these HMPE spokes, but from an engineering point of view thee dyneema spokes are not a good idea. Spokes are designed on stretch, not breakload. HMPE (dyneema) has a property called creep, which is slow elongation under load. all types of HMPE have this propertie (although DSM, the mother company of Dyneema markets it good/ differently). On top of the creep you will have construction stretch from the braided construction.
    Lastly, the modulus of steel is a lot higher then that of HMPE. I am not exactly sure which type of Dyneema is used for these spokes, but think a factor 1,8 to 3 lower. This means that you will need that multiple in cross section for the same stretch (breakload wise dyneema is much stronger). Please keep in mind that a braided construction will have at least 30% air in it, increasing the effective diameter even more. This leads to a large diameter spoke, with much more intitial stretch then a steel spoke. If the temp goes above 30C the creep will increase, resulting in loss of tension. All in all in think steel double butted spokes will result in a more stable wheel build then this (especially if you are above 85kg)
    my 2c. Constantijn13

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    1. I don't necessarily doubt your assertions. I also know, after having ridden Berd spokes for a few thousand miles already, that I'm not particularly concerned about your assertions. The Berd wheels ride fantastic, are light, and have proven durable thus far. Concerns about costs are valid, but that seems to be where the concerns end.

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