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  1. #1
    ....just cruisin through
    Reputation: dfrazm's Avatar
    Join Date
    Oct 2007

    Wolf Tooth 42T GC on Yelli Screamy (X-Post)

    Below is a X-Post that I thought might be informative (performed on a Large Yelli Screamy).

    Just got my Wolf Tooth Red 42T GC in last Thursday. Sram specific GC went on a Sram 1050 cassette (11-36) on a Canfield Yelli Screamy. I am running a regular Shimano 64BCD 28t "granny" chainring on the front. I have run this chainring, cassette, KMC X10SL chain, and a Sram X9 type II mid-cage derailleur for more than a year without a single dropped chain. The 28t "granny" does not have the ramps/teeth of a shifting middle or large ring, and the teeth are actually longer, so it pretty much works like a SS ring. The chainline on the Yelli is PERFECT with this ring in the 64 BCD position on a 2X (XT M785) crankset with one bottom bracket spacer on the drive side (as Shimano instructions say should be done). Perfect 1X10 shifting and no dropped chains in over a year (riding in AZ chunk).

    I was nervous about the GC with the Yelli's chainstays being so short. I mounted it per directions, but I left out the 15t cog, as I always use the 17t and 19t. I ordered a new KMC X10SL chain, as I new I would need a longer chain and these cannot be lengthened as they have mushroomed pins, and the pin mushroom is destroyed when you push a pin out. I could have used another quick-link, but I did not want two on a chain.

    I measured the chain using the large chainring (my only chainring, 28T), around the GC, bypass the derailler, and added two links. Cut (pushed pin) the chain to my measured length and installed it in the derailler. Adjusted "B" screw so that there was no rubbing between 36T and GC. I did not need the longer screw included with the GC. In fact, I still had 3mm of screw showing with the correct adjustment. I went for a driveway test and adjusted trim on the derailler. Shifting was marginal (at best). I was quite dissapointed, so I started the typical break-down of potential problems.

    I started with the derailler hanger allignment. Made a small tweek using the 5mm allen key in the derailler mounting hole on the hanger and eyeballed the derailler allignment. Looked good.

    I then looked at chain tension. My derailler was almost at full tension with the 28T X 42T (GC) combo. The way the Sram (maybe Shimano too) deraillers are set-up, the upper cage pulley is offset, so that the farther the cage is pulled (larger cogs), the further it is pulled away from the cog. Although it seemed to me that I would want the shortest chain possible to take advantage of this design (cage pulled towards the crankset as far as possible) I re-visited proper chain length. I went the opposite way this time. I put the derailler in the 11T position and added links using two quick-links until the chain still had tension on the smallest cog (11T) and did not rub on itself where it wrapped through the cage. I made sure the chain below the bottom pulley heading to the chainring did not rub on chain below the top pulley, as the two pulleys are nearly horizontal to each other in the highest (smallest) cog. I then shifted to the 42T GC. The derailler was less into it's total swing, as I added three links. I did the driveway test and surprisingly shifting was better, but not where it was before the GC installation. More frustration.

    I then decided that with a new chain maybe I had wear in my drivetrain and the new chain wasn't matching up with old cassette. I did not want to buy a new cassette unless completely necessary. I then decided that I would try to install some new jockey pulleys on the derailler. I picked up some $15 alloy pulleys from the LBS, installed, and ......PERFECT SHIFTING!!!

    I ordered a new KMC X10SL chain as I did not want a chain with two quick links in it. Installed yesterday and I cannot say that I now notice any shifting difference between stock Sram 11-36 and now Sram/Wolf Tooth 11-42. Here are the key points I found:

    1) Install a new chain (as most 10spd chains have mushroomed pins and cannot be lengthened by putting a pin back through them). Make sure that it is as long a possible in the highest gear (smallest cog), but that it will still have tension and does not rub on itself.
    2) Adjust "B" screw tension so that there is no rubbing in shifts between 36T and 42T. Turn screw out until there is just a little rubbing from 36T to 42T, and then screw it in (more tension) half a turn.
    3) I removed the 15T and shifting is perfect up and down across all cogs, even the 13T to 17T.
    4) The key to my final shifting issue was the derailler jockey pulleys. Once I installed new allow pulleys (these) everything is PERFECT.
    5) NOTE: Adding B screw tension lengthens the drivetrain, effectively shortening your chain. Make sure you account for this in measuring your chain before shortening!!!

    Hope this helps...


    General drivetrain

    Another general drivetrain

    Chain on 11T

    Chain gap on 11T

    Chain on 11T

    Chain on GC 42T

    Chain on GC 42T backside

    Derailler position on GC 42T

    Alloy jockey pulley
    Last edited by dfrazm; 03-09-2014 at 10:27 AM. Reason: Key chain length info added/added pics
    Here are just a few of the key ingredients: dynamite, pole vaulting, laughing gas, choppers.....

  2. #2
    mtbr member
    Join Date
    May 2004

    Wolf Tooth 42T GC on Yelli Screamy (X-Post)

    Love it, will be doing this soon. What crankset are you using?

  3. #3
    mtbr member
    Join Date
    Feb 2009
    So wait a minute, you can go 28:42?!?!?!

    Where do you ride, Mount Everest?!?!

    I have to admit, even though I just don't "get" the trend of such short gearing, your bike does look freaking sweet.

  4. #4
    mtbr member
    Join Date
    Aug 2012
    I put the OneUp 42 tooth cog on my Yelli it it works great. 32 tooth raceface NW ring, RaceFace Turbine crank. Shimano M770 XT cassette. XT Shadow Plus medium cage Der.
    "You can't drink all day if you don't start in the morning." ShakyPuddin

  5. #5
    mtbr member
    Join Date
    Aug 2011
    My red 42 cog on the way, I just sold my Yelli. It had a lefty carbon fork on it also had Hadley rear 10mm axle like yours. Fun bike, Nice !! I have Sram XX1 crank with 30 tooth ring with XTR 11x36 cassette. I will need a new derail. since I have the ZEE short cage now, don't think it will work. Probably get Xt shadow plus medium cage like Swildnm.

    Also in the process of getting XO1 drivetrain, so I'll be able to compare the two. Very wet on the East Coast now so I will save the new 11speed after the slop dries up. Can't wait to try the Woof tooth !! Thanks for the great info !!

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