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First Components Cassette Expander Cog
(12)

First Components Cassette Expander Cog

Item #: CS201Z00
USD$32.99 SAVE 53% USD$69.99 msrp
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First Components Cassette Expander Cog

First Components 10 Speed Cassette Expander Cog

Go Big!

For those of us running 1x10 setups and looking for a wider gear range out of our cassettes, First Components throws another option into the ring. This cassette expander cog will turn your Shimano 11-36 XT or XTR cassette into an 11-42 allowing for a much lower climbing gear. This is accomplished by removing the 15T and 17t cog in your cassette, installing the expander cog and the 16T where your 15T and 17T came off. First Components kindly include a longer B-limit screw to allow your derailleur clearance to enter the 42T cog. Note: A longer chain will most likely be needed post installation. Go big and KEEP PEDALING!

Features

  • Material: Anodized AL7075 (42T), Stamped Chromoly (16T)
  • Teeth: 42T (+16T)
  • Compatible with Shimano XT M771 or XTR M980 11-36T cassettes Only (will not work with SLX or Deore Cassettes)
  • Weight: 96g (42T) +23g(16T)
  • Includes longer B-limit screw.
2.6 / 5.0
12 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Stars
1
3
3
0
5
Not the best, but it gets the job done for the price.
Took a little tinkering to get it to work, but once I got it set up it works fine. I installed on an XT 10 speed hub (M785 I think?), and it required washer behind the large cog. Without the washer it digs into the hub/spokes when you tighten the locking and then free hub won't spin, well... freely. I used a Shimano 10spd cassette washer (1mm I think). It worked, but it pushed the 11t cog a little higher off the free hub body than I would have liked. I think a .5mm cassette space would be the best, but I used what I had lying around. Three stars just cause of the extra time that went into making this part work. It was still a good deal, so it was worth the time spent, but I think it should either be machined properly to begin with, or they should provide the washer with the product.
August 11, 2017
Purchased
6 months ago
Location:
Traverse City, MI
Couldn't make it work.
Great quality. I couldn't get this to work with my ten-speed cassette. The width of the cog prevented me from being able to thread the lock ring on the rear cassette even after removing the necessary cog. So I'm making due with a bike that is geared a little high.
August 2, 2017
Purchased
11 months ago
Location:
Maple Valley, Washington
Absolute garbage
U took a chance on this and what a mistake. Paired to a new chain, cassette and chainring it skipped so bad it was unusable. Spend the extra $20 and get a wolf tooth or on one.
September 4, 2016
Location:
michigan
Great addition to a 1x10.
Set up was easy. Shifting smooth so far.
September 18, 2016
Location:
Bend, OR
Great innovation
Happy to change to 1x10 not so expensive
September 23, 2016
Location:
MIAMI
Works well, but must use a 1mm cassette spacer
I got this to work nicely with shimamo xt shadow +
But only after putting a 1mm spacer between this cog and the one next to it.
Cheaper than oneup which I could not get to work well.
September 28, 2016
Location:
SoCal
This didn't work
Would have been nice if they included a washer to keep the big cog from hitting the spokes, could barely tighten the cassette before it would rub, good idea but First Components didn't cover all the bases, I have an XT 10 sp cassette a Shimano 10 sp Hub, this should fit right?
September 12, 2017
Location:
SoCal
First component exspader cog
This cog only will fit certain hubs it will touch the spokes on many wheels and if you add a spacer then all the other cogs
Won't fit so know your type hub and spacing before you order this .
January 11, 2017
Purchased
10 months ago
Location:
Midwest
Does not fit my Mavic hub. Chainring is recessed on hub side and shouldered on cassette side.
July 24, 2017
Purchased
2 months ago
Location:
Tahoe
great value
was fast
October 27, 2016
Location:
MIAMI

Q & A

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Browse 1 question Browse 1 question and 1 answer
I've been unable to mount the product, using no spacer the expander cog hits the spokes when tightened and with the spacer from the xt cassette you cannot get the lock ring on. Am I missing something? I'm going to track down a tiny spacer and see if it works but so far I am extremely unimpressed.
Ondras on Aug 31, 2016
BEST ANSWER: You need a spacer to make it work. The spacer prevents cassette from rubbing. I took mine off and ordered the wolftooth components expander cog instead i am impressed with wolf tooths drop stop chainring so id rather have matching rear.
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Free Shipping Offer

Get free Standard Shipping with your $50 purchase today! Just choose Standard Shipping during checkout.

Please note this offer is only available to physical shipping addresses in the 48 continental United States (no PO Boxes), and oversize charges still apply on some heavy/large items.