2 by 11-40 vs 11-42
08-19-21, 11:03 AM
#1
Junior Member
Thread Starter
Join Date: Jan 2008
Location: Utah
Posts: 103
Bikes: CAAD10 105
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
Likes: 0
Liked 3 Times
in
2 Posts
2 by 11-40 vs 11-42
I'm replacing the rear cassette on my boke. I have Deore XT components from 2016. Up front I have 26 / 36 chain rings. In the back I currently have 11-40 cassette. Will I have a problem if I install 11-42? Will I get a significant difference in climbing ability? I'm really only considering the 42 because that is what I see in stock as I search around - the 11-40 appears to be sold out.
08-19-21, 11:42 AM
#2
Advanced Slacker
Join Date: Feb 2017
Posts: 6,210
Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2762 Post(s)
Liked 2,537 Times
in
1,433 Posts
I'm replacing the rear cassette on my boke. I have Deore XT components from 2016. Up front I have 26 / 36 chain rings. In the back I currently have 11-40 cassette. Will I have a problem if I install 11-42? Will I get a significant difference in climbing ability? I'm really only considering the 42 because that is what I see in stock as I search around - the 11-40 appears to be sold out.
40 to a 42 cog is only going to be a little easier. About a half a gear (or a little less) easier.
08-19-21, 12:12 PM
#4
Senior Member
Join Date: Oct 2013
Location: Highlands Ranch, CO
Posts: 1,221
Bikes: '13 Diamondback Hybrid Commuter, '17 Spec Roubaix Di2, '17 Spec Camber 29'er, '19 CDale Topstone Gravel
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 590 Post(s)
Liked 445 Times
in
260 Posts
42 is the answer
08-19-21, 07:35 PM
#5
Senior Member
Join Date: Mar 2015
Location: Martinsburg WV Area
Posts: 1,704
Bikes: State 4130 Custom, Giant Trance 29
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 422 Post(s)
Liked 182 Times
in
123 Posts
Won't deny 42 as the answer, but if interested, did find a 40 tooth here that they are stating is in stock:
BackCountry Shimano XT 11-40 11 speed
Amazon also has a Shimano XT 11-40 avail:
https://www.amazon.com/SHIMANO-CS-M8...-18&th=1&psc=1
BackCountry Shimano XT 11-40 11 speed
Amazon also has a Shimano XT 11-40 avail:
https://www.amazon.com/SHIMANO-CS-M8...-18&th=1&psc=1
08-19-21, 09:17 PM
#6
Advanced Slacker
Join Date: Feb 2017
Posts: 6,210
Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2762 Post(s)
Liked 2,537 Times
in
1,433 Posts
You have an XT RD-M800. The question is whether it is an SGS (long cage) or GS (medium cage).
If it is the SGS, you can definitely run the 11-42 if you like.
If it is the GS, then you are probably OK, but you might come up just a hair short on the chain wrap capacity, and lose the small/small combo. In my experience this is no big deal, just don't use it (you should not be use it anyway)
In either of the above cases (but especially the GS), you need to be sure you are using a chain sized to accommodate the big-big combo. This may mean a new chain, as the current one you have is sized for a 40t large cog, not a 42t.
If it is the SGS, you can definitely run the 11-42 if you like.
If it is the GS, then you are probably OK, but you might come up just a hair short on the chain wrap capacity, and lose the small/small combo. In my experience this is no big deal, just don't use it (you should not be use it anyway)
In either of the above cases (but especially the GS), you need to be sure you are using a chain sized to accommodate the big-big combo. This may mean a new chain, as the current one you have is sized for a 40t large cog, not a 42t.
08-20-21, 12:23 PM
#8
Advanced Slacker
Join Date: Feb 2017
Posts: 6,210
Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2762 Post(s)
Liked 2,537 Times
in
1,433 Posts
08-20-21, 12:49 PM
#9
Senior Member
Join Date: Jun 2015
Location: North Central Wisconsin
Posts: 4,622
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 2975 Post(s)
Liked 1,180 Times
in
770 Posts
Just a good guess because OP indicated he has a 2x system. Long cage includes a 3x system as you see in the specs here...
https://bike.shimano.com/en-EU/produ...M8000-SGS.html
I recently upgraded the drive train on my hardtail back in June. Went with the XT GS deraillaiur. 30T front chain ring and 11-46 cassette. It used to have a 42 cassette.
https://bike.shimano.com/en-EU/produ...M8000-SGS.html
I recently upgraded the drive train on my hardtail back in June. Went with the XT GS deraillaiur. 30T front chain ring and 11-46 cassette. It used to have a 42 cassette.
Last edited by prj71; 08-20-21 at 12:56 PM.
08-20-21, 03:37 PM
#10
Junior Member
Thread Starter
Join Date: Jan 2008
Location: Utah
Posts: 103
Bikes: CAAD10 105
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
Likes: 0
Liked 3 Times
in
2 Posts
for the medium cage (per the link)
It does say :Low sprocket_Max. 42T(2x11-speed), 46T(1x11-speed) Low sprocket_Min. 40T
I see the 40 is available now - it wasn't before. But from what I see on that link is that 42 should work fine right? you said I might have cross chain slack issues - but the website wouldn't say it's capable there right?
Total capacity =39 T. So if I put the 42 I would be over capacity (36 - 26) + (42 - 11) = 41. With the 40T I am right at the capacity of 39. I think that answers my question.
Thank you all!
Last edited by NyoGoat; 08-20-21 at 03:43 PM.
08-20-21, 03:48 PM
#11
Junior Member
Thread Starter
Join Date: Jan 2008
Location: Utah
Posts: 103
Bikes: CAAD10 105
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 38 Post(s)
Likes: 0
Liked 3 Times
in
2 Posts
I'm still not sure if I have the Medium or Long cage derailer. How can I tell? I did measure the long arm on it at 4.5 inches center pulley to center of pully
08-20-21, 09:41 PM
#12
Advanced Slacker
Join Date: Feb 2017
Posts: 6,210
Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2762 Post(s)
Liked 2,537 Times
in
1,433 Posts
for the medium cage (per the link)
It does say :Low sprocket_Max. 42T(2x11-speed), 46T(1x11-speed) Low sprocket_Min. 40T
I see the 40 is available now - it wasn't before. But from what I see on that link is that 42 should work fine right? you said I might have cross chain slack issues - but the website wouldn't say it's capable there right?
Total capacity =39 T. So if I put the 42 I would be over capacity (36 - 26) + (42 - 11) = 41. With the 40T I am right at the capacity of 39. I think that answers my question.
Thank you all!
It does say :Low sprocket_Max. 42T(2x11-speed), 46T(1x11-speed) Low sprocket_Min. 40T
I see the 40 is available now - it wasn't before. But from what I see on that link is that 42 should work fine right? you said I might have cross chain slack issues - but the website wouldn't say it's capable there right?
Total capacity =39 T. So if I put the 42 I would be over capacity (36 - 26) + (42 - 11) = 41. With the 40T I am right at the capacity of 39. I think that answers my question.
Thank you all!
08-21-21, 12:08 AM
#13
Senior Member
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,805
Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1943 Post(s)
Liked 2,164 Times
in
1,323 Posts
I wouldn’t sweat 2t on the capacity. Generally Shimano is conservative enough that it will work.
Plus, can you even run the 26/11 without the chain clipping the outer 36t chainring?
John
Plus, can you even run the 26/11 without the chain clipping the outer 36t chainring?
John
08-21-21, 11:55 AM
#14
Advanced Slacker
Join Date: Feb 2017
Posts: 6,210
Bikes: Soma Fog Cutter, Surly Wednesday, Canfielld Tilt
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 2762 Post(s)
Liked 2,537 Times
in
1,433 Posts
