Alright, for posterity, here's the saga of the Mukluk.
Yesterday I put a new drivetrain on the fat bike. The chain was way past due and everything with teeth on the verge of sucking it up. It should be ready for a new year of camping adventure after some more tinkering.
I'm pretty excited about it. I discovered that the rear derailleur's guide pulley was cracked completely through. I probably didn't say anything about it, but I was getting a persistent quiet clack out of the rear of the bike, and I thought it was the freehub, but now I think it was the derailleur pulley.
Today I plan on putting a dropper post on the fat bike. That will make it more fun to ride.
I made the bike a custom 1x9 drive. Now I can put the dropper lever on the left. I ditched the Grip Shift stuff which worked great actually, because the shifter grips were all munched up and replacements were expensive if I could find any.
To make the fat bike 1x system I used the derailleur from my wife's bike which I replaced last week with a new one. The old XT one was hacked using an aftermarket Goat Link hanger extender. I used the donor mechanism with part of a slightly used 11-46 cassette that came from my Specialized (I'm using a 28t x 11-42 cassette on the Stump Jumper now).
The aluminum fat bike, an original 2012 Salsa Mukluk 3, came with a design flaw. The chain rubbed the rear tire slightly in the two low gears (which are the most important). This feature increased drag going uphill. It was perhaps negligible, but when I knew it and I'm tired it bothered me. The reason for this was that the spec bottom bracket spindle was just a little to narrow. It is a good bottom bracket, a Truvativ Howizter which has quad bearings, and plenty of life left I think. The spindle is the widest (148mm) they made.
The option of getting a narrower rim rear wheel made exists. Not doing that. The existing wheel could be re-dished slightly. This is a future possibility. They say the small movement is virtually undetectable. I know that many wheels are on purpose asymmetrically built, and don't suffer weakness. Just two or three millimeters would be wonderful.
I created different solution by relocating the chainring drive and shrinking the cassette simultaneously!
I found in my spare parts a 32t 94bcd chainring that I bought for another bike a long time ago that I forgot about. It's a high quality aluminum SRAM narrow wide type made for 1x. It won't work with a front derailleur because the teeth are extra tall, and also the teeth alternate between narrow and wide, both features combine to keep the chain on the ring.
[The narrow/wide feature, on all production 1x bikes, is essentially that a chain has alternating narrow gaps and wider gaps into which the narrow/wide chainring teeth mesh. It is proven that this profile in combination with a rear derailleur clutch keeps the chain on in most cases. (Oh, BTW, there are aftermarket narrow/wide derailleur pulleys which allegedly improve performance now). * This lame explanation of mine includes extraneous information and BS.]
With more than you need or want to know, I shall continue. I did all of this stuff by intuition mostly, maybe.
The crankset on the Mukluk had a big plastic bash-guard. I took it off. It was heavy! There was a 38/24 x 11-34 on the back. Funny, I thought it was a 36t cassette the whole time, but I was wrong.
The new 32 ring was installed with 2mm spacers towards the inside. This would help the chainline not rub the tire.
The interesting part is that I used part of the 11 speed cassette to make a 9 speed cassette. This 9 speed cassette is narrower because the gaps between 11 speed cogs are smaller than 9s. I put two 2mm spacer (yes, we've got a lot of junk here, and these are found between sprockets in cheaper old 9spd cassettes, but I found a nice 4mm aluminum one later); I put 4mm of space between the cassette and the spokes. This made the chain clear the tire in low gear.
The Sunrace 11 spd 11-46 rear cassette model I have consists of two red aluminum spiders, 4 big sprockets, and 3 middle sprockets respectively, plus the 4 remaining go on separately with the two smallest on one piece, plus a lockring. I used the two spiders to make 7 of the sprockets.
The plan was to use two 9 speed sprockets for the small sprockets. I fiddled around.
Okay, so now you might be wondering, how in the world do I expect this to work? Exactly.
The shifter I have is a brand new 9 speed SRAM X5 trigger. It's probably on par with LX. Something I got a long time ago for the Mukluk for cheap.
Being curious about all this stuff we know that 9 and 11 speed aren't compatible.
I did glean that 11 speed rear derailleurs have a different actuation ratio that 9 speed. They don't mix.
However while 9 and 11 speed shifters do pull different amounts of cable per click, the difference is not huge.
My kludge is that the inherent designed flexibility of the rear derailleur makes up for the variance.
At first I tried using the 11t sprocket and like a 14t. The smallest sprocket on the 11 speed is like 24t. The jump was too big, and I didn't think it would work well enough.
The breakthrough was some part I bought two of seemingly a couple of decades ago. It's called a two sprocket Titanium Shimano 17-20 Umeya spider. It was a hop-up part to lighten 9 speed cassettes with. I never used them. I got them on clearance at Jenson USA. They'd make great pedants if it weren't for the fact that they are sharp and dangerous. These are nicely machined titanium sprockets rivetted onto an aluminum spider.
The final cassette is 9 speed 17-46. I used the Sunrace lockring which has a few extra threads deep on it that the SRAM and Shimano ones, and I put some blue locktite on it.
The result of testing is that it actually shifts pretty good, and stays in each gear.
The cassette looks excellent. The range is not very wide though. The high gear is 32x17. This isn't that bad though since I'm not trying to race and this is really dedicated to off-road pursuits. The low gear isn't as low as I want though. 32x46 for example is not as low as commonly found 30x46 or the 32x50. But most of the time, the gear range is excellent for mountain biking.
Luckily a solution was right at hand. In parts I found a nice new aluminum 24t 64 bcd chainring. I put that on the crankset granny position with 2mm spacers to keep the chain clear of the big ring. Now the Mulkuk has the option of a low range which can be accessed by releasing the derailleur clutch, moving the chain by hand, and resetting the clutch. Voila! Super-low gears. It rubs the tire in the two lowest gears again, but the 3rd sprocket is still a lower gear, and it will run fine with the tire rub if need be. If I can find 1mm chainring spacers I might be able to have less rub too.
Yeah, so by going 1x I moved the single chainring inboard, and moved the cassette outboard, making a good chainline, but the low range is now in the same predicament as the original granny gear was.
Of course I am using an 11 speed chain, and used the last new one I could find in the garage, the cheapest SRAM, which is of course perfectly fine.
Originally I was going to make the Mukluk another 2x9 drivetrain. I have two new nice 9 speed cassettes, and no 9 speed bikes anymore. The whole conversion to 11 speed was realized when I saw the cracked guide pulley on the X7 rear derailleur. I fixed the pulley, as I have spares for the tandem (which twice cracked guide pulleys). Also the Mukluk had a custom Problem Solvers front derailleur hanger, and I didn't like the look of the SRAM X-5 front derailleur, which worked well enough though. In the junk I found a new XT front derailleur that fit perfectly! We have three nice left shifters here too. So altogether we have a complete 9 speed drivetrain ready to go (old cranks, decent bottom brackets, and various chainrings too).
And so there you have it so far.
Now when you hear my gears make strange sounds next year, you'll know why.
Today I added an old but little used 27.2 Gravity Dropper post.