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Mukluk + Knard + Lefty: A Cautionary Tale

7K views 19 replies 10 participants last post by  vikb 
#1 ·
I got a Mukluk last fall and was blown away at how fun and versatile it was. I was so impressed I sold my FS29 and started scheming the ultimate summer build for my Mukluk: 29+ and a Lefty
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The back half of the project is fantastic. The West Hill Shop in Putney VT set me up with a Rabbit Hole + Hope FatSno wheel. Clearance is tight in the forward-most position, but might be OK for dry conditions. There is plenty of room for singlespeed chain tensioning.

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The front half is what's giving me fits. I read about the folks using a Lefty wheel with Flow rims with no problems, so I figured I'd try to push the envelope using a Salsa Gordo 35mm rim. ProWheelBuilder.com still has them in stock, so I had them build up a wheel for me. They are excellent to deal with, do great work and are a remarkable bargain considering the quality of work and excellent customer service.

Using a 2012 alloy Lefty (with the awesome Project 321 conversion), the Knard rubs VERY hard with left hand turns and any compression of the suspension.
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It's clear to see that the mold-release nubbies are giving Lefty butterfly kisses. The barrel flares as it goes up toward the lower clamp, making the tire rub progressively more and more. If the leg were a perfect cylinder of the smaller diameter, it would work.

I borrowed a wheel with a narrower rim to see if that would help. It did, but it still rubs with left hand turns at the end of travel.
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Stuffing the Knard onto a 25mm rim looks wrong, although it doesn't really mess with the profile as much as I thought it would.
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The Gordo still looks a little anemic compared to the Rabbit Hole, but much healthier than the 25mm Sun Inferno.
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So, now the calculus begins:
1. abandon my suspended 29+ dream, stop throwing time and money at a non-problem and build it back up as a proper fat bike (selling my new stuff at a loss)

2. find a fork that works, potentially throwing even more time and money at a non-problem

3. mess with the wheel, re-dishing it off center enough not to rub - I'm not too psyched about doing this, but I'm willing to try if someone can offer first hand success stories

So, based on my experience, 2012 alloy Lefty shocks + 29x3 Knard will rub when the suspension is compressed, more so when turning left. The wider the rim, the worse it will be.
 
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#2 ·
Drop mendoncyclesmith a line, he is a lefty guru will tell you where you going wrong.... I rode a guys Fatback + Lefty with Full Fat front a couple of weeks ago, a 3.0 knard should be no problem.... might be the type of lefty as his was not the PBR one like yours!

But lefty + fatbike = awesome!!

edit: here you go - http://forums.mtbr.com/fat-bikes/lefty-models-854216.html sounds like you need to build the front wheel with a 17.5mm offset! :thumbsup:
 
#3 ·
Thanks. I have talked with Craig already. My goal was to use a standard Lefty, since they are so inexpensive and abundant, especially since the 2013 re-design people don't seem to want their old shocks. I thought it was possible without the 321 fat bike clamps, and it may be, but it's certainly not a slam dunk.
 
#10 ·
So, big update and very good news to anyone who wants to try this at home!

My 7 year old dragged me out of the shop to ride around the house with him. Up to that point I was trying hard not to get my tires, wheels, etc. dirty so I could get max value re-selling. Bad move. In the real world the tire barely rubs at all.

I just got back from a 3 hour ride:
 

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#11 ·
For anyone interested:
We had 1.5 inches rain in the past 24 hours and after a 3 hour ride on tight VT singletrack there was no build up of gunk at the chainstay bridge. I may play around with rear wheel position, mostly because I can, but also because the handling was different from what I am accustomed to with the stock RHD/Nate wheels.

The head angle feels a little slack, which could be due to my use of a EC56 headset lower instead of the ZS44, which raises up the front end and slackens angles about 1 degree. I'll ride it a few more times and if it still feels like it's flopping over I'll get the 1.125 inch 321 Lefty adapter to see if it improves handling.

As so many other people have posted, the Knard is NOT at its best in the wet. Dry roots and rocks were fine, especially once I got the tire pressure back down. I started out at 15psi and had 2 scary crashes (no way they would have happened with my fat tires) then let out to 9.5psi rear and 11psi front. Much better.

The front tire only rubbed on the shock when I had the wheel turned at a sharp angle at very low speed. One time in a big sweeping turn the Knards let loose (too wet for them) and I skidded sideways hard. The tire buzzed for a brief moment. The test riding I did in my shop was all very trials / track stand kind of thing and exactly what makes things rub together. This barely happened at all while riding, and when it did it was minor.

The jury is out as to whether I'll stick with this or get a Mendon Cycle Smith fat bike converted shock and wheel. This is a small bike, and it's flat out awesome with the fat bike tires. Time and tweaking will tell if the same can be said of the Knard / Lefty version.
 
#14 ·
Thank you for all the helpful replies. Done and done. I used some aluminum tape to cover the shock. I finally got a Cannondale truing stand adapter and moved the wheel to the drive side 1-2mm. I can ride no handed without any problem and sighting down the steer tube it appears to be dead center.
 
#16 ·
Yes, all pics are with Alternators all the way forward. I had no problems at all with clearance riding loamy singletrack hours immediately after 1.5" of rain. It would probably be an issue in anything that really packs up the tires.

I played around with set up today and it seems to ride a lot better with the rear wheel farther back. My typical fat bike setup with Nate / HRD is rear wheel all the way forward and a 100mm stem (this is a size Small frame). This same position with the Knards and Lefty felt weird to me yesterday, so I moved the rear wheel all the way back, slid the saddle back 1cm and swapped to a 90mm stem. I liked the way it rode a LOT better. I believe it plays to the strengths of the suspension.

My initial impression is that in a perfect world I'd have one Mukluk set up rigid with Nates and a second Mukluk permanently set up with Lefty and Knards. I can't see going back to a full suspension bike unless I took up racing, and maybe not even then.
 
#18 ·
Will work fine if you slightly dish

" mess with the wheel, re-dishing it off center enough not to rub"
This is necessary and works fine. I have two lefty wheels with knard tires; one is a Blunt 35 and the other is a Rabbit Hole rim. Just needed to be moved a little for my 2012 carbon lefty. I probably have 2,200 miles on this setup and used it at DK last week.
 
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