Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Shimano triple chainring on double chainring same BCD?

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Shimano triple chainring on double chainring same BCD?

Old 11-29-22, 07:48 PM
  #1  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Shimano triple chainring on double chainring same BCD?

Can I put this chainring on meant for tripple that has the same 96mm BCD as the double crankset
Shimano Deore M6000 40T Chainring - 10 Speed, BCD 96mm, for 40-30-22T Set
https://bike.shimano.com/en-US/produ...Y1WC98020.html
https://www.modernbike.com/product-2...kaAsqUEALw_wcB


On this 2x mtb crankset?
DEORE_M6000_m FC-M6000-2 BCD 96/64
https://bike.shimano.com/en-US/produ...C-M6000-2.html

or is there something preventing this ( bolt pattern, cutout , notches, 3mm offset to one side etc..... )
sean.hwy is offline  
Old 11-29-22, 11:32 PM
  #2  
maddog34
Senior Member
 
maddog34's Avatar
 
Join Date: Jul 2015
Location: NW Oregon
Posts: 1,532

Bikes: !982 Trek 930R Custom, Diamondback ascent with SERIOUS updates, Fuji Team Pro CF and a '09 Comencal Meta 5.5

Mentioned: 12 Post(s)
Tagged: 1 Thread(s)
Quoted: 625 Post(s)
Liked 62 Times in 50 Posts
well... i'd give it a try... have you Tried it yet? What's the small chainring's tooth count?

step away from the keyboard, grab a 5mm allen, and go for it.
maddog34 is offline  
Old 11-29-22, 11:45 PM
  #3  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
I own a praxis 2x. the smallest I can get is 32 that's why I was looking into a MTB crankset.
https://praxiscycles.com/product/zayante-carbon/

Before I buy the shimano mtb crankset I want to make sure this would work. You can get 28, 26, 24 for the inner ring and they are cheap.
sean.hwy is offline  
Old 11-30-22, 01:06 AM
  #4  
anga
Full Member
 
Join Date: Aug 2013
Posts: 352
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked 21 Times in 18 Posts
That Shimano crankset comes as a triple.

https://bike.shimano.com/en-US/produ...C-M6000-3.html
anga is offline  
Old 11-30-22, 01:45 AM
  #5  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Originally Posted by anga View Post
That Shimano crankset comes as a triple.

https://bike.shimano.com/en-US/produ...C-M6000-3.html

it also comes as a 2x.
sean.hwy is offline  
Old 11-30-22, 03:18 AM
  #6  
anga
Full Member
 
Join Date: Aug 2013
Posts: 352
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
Liked 21 Times in 18 Posts
Originally Posted by sean.hwy View Post
it also comes as a 2x.
Of course it does. I should've explained.
They are priced closely.
Why not buy the triple and remove/not use the small chainring and save the cost of buying the 40T chainring?
Perhaps there are other reasons.
anga is offline  
Old 11-30-22, 02:09 PM
  #7  
noobinsf 
Senior Member
 
noobinsf's Avatar
 
Join Date: Sep 2005
Location: Oakland, CA
Posts: 3,240

Bikes: '82 Univega Competizione, '72 Motobecane Grand Record, '83 Mercian KOM Touring, '85 Univega Alpina Uno, '76 Eisentraut Limited

Mentioned: 56 Post(s)
Tagged: 0 Thread(s)
Quoted: 1071 Post(s)
Liked 1,136 Times in 673 Posts
But to answer your question, it should work, barring any spacing issues or ramping between chainrings. The 96mm bcd of the outer ring is the same between the two cranks.

Shimano stuff is so product specific these days that I have no idea if it will actually work, because typically the ramps are aligned to allow specific jumps, and the triple vs. double crank may use different bolt spacers. Unless someone else has tried it and documented it somewhere, or unless Shimano has noted cross-compatibility, there's only one way to find out.
noobinsf is online now  
Likes For noobinsf:
Old 11-30-22, 05:23 PM
  #8  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Originally Posted by noobinsf View Post
Unless someone else has tried it and documented it somewhere, or unless Shimano has noted cross-compatibility, there's only one way to find out.
Yeah I figured someone must have tried this at one time.

I have also been looking at old ( 2009 ish ) 2x MTB cranksets. Some of those come with 104 bcd / 64 bcd. With that bolt spacing I can get a 40T and 28T which would be nice for my gravel bike.
I would prefer to buy a new crankset instead of something that's 10+ years old if I can help it.
sean.hwy is offline  
Old 11-30-22, 07:22 PM
  #9  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,445

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: 1815 Post(s)
Liked 1,956 Times in 1,200 Posts
My initial thought would be yes, but if you look at the Tech Doc I don't think so.

The mounting surface for the triple is different than the double. You would have to buy the parts and see if the spacing between the chianrings would work. There are also ramp and pin considerations, but generally a shift is possible even if it not at the highest level.

https://si.shimano.com/en/pdfs/ev/FC...M6000-4187.pdf

John
70sSanO is offline  
Likes For 70sSanO:
Old 11-30-22, 07:46 PM
  #10  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Originally Posted by 70sSanO View Post
My initial thought would be yes, but if you look at the Tech Doc I don't think so.

The mounting surface for the triple is different than the double. You would have to buy the parts and see if the spacing between the chianrings would work. There are also ramp and pin considerations, but generally a shift is possible even if it not at the highest level.

https://si.shimano.com/en/pdfs/ev/FC...M6000-4187.pdf

John
Thanks for figuring that out.

I guess back to looking at 2010 MTB double cranksets.
sean.hwy is offline  
Old 11-30-22, 08:08 PM
  #11  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,445

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: 1815 Post(s)
Liked 1,956 Times in 1,200 Posts
Originally Posted by sean.hwy View Post
Thanks for figuring that out.

I guess back to looking at 2010 MTB double cranksets.
If you can live with a 38t instead of a 40t, you can buy a 38/28 2x and swap the 28t for a 26t or 24t if you need to.

John
70sSanO is offline  
Old 11-30-22, 09:11 PM
  #12  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Originally Posted by 70sSanO View Post
If you can live with a 38t instead of a 40t, you can buy a 38/28 2x and swap the 28t for a 26t or 24t if you need to.

John
I lived with a 40T 1x for a little while. I don't think I want to go any lower for dual purpose bike that sees road a lot with road tires.

I am thinking about one of these. I am not sure how good they are. Going to try and find a shimano crank if possible.

These both have the 104 BCD for the outer ring. I don't 'think' there's anything special (notches, offsets, pins, funky bolt pattern ) about there outside ring.

FSA K-Force Light ATB MTB Crankset 170mm 24/38t Double 4 Bolt

https://www.ebay.com/itm/19477171067...Cclp%3A2047675


SRAM X9 BB30 Crankset42/28T BB30
https://www.ebay.com/itm/27537296764...Bk9SR7rUj7iZYQ
sean.hwy is offline  
Old 12-01-22, 12:53 PM
  #13  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,445

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: 1815 Post(s)
Liked 1,956 Times in 1,200 Posts
You are kind of in no man's land. Any mtb 2x will probably be an issue if you want to swap the outer 2x ring with an outer 3x ring.

The SRAM X9 would probably work since it is a 42t and it is possible to get a 26t, but there are some issues. The BCD is 120/80 not 104/64. It looks like 120/80 is used on the 42t and 39t cranks and the 104/64 is used on smaller chainring offerings. I'm not sure anyone else uses that BCD so when replacement rings are gone, they are gone.

I'm not up to speed on the BB30 and the threaded work arounds, but that is a consideration.

If I were to go back to a 10+ year old mtb 2x, I'd probably look at an M785 or M985. As far as an FD, I would guess that an FD that will work with a 38t could be squeezed to go to 40t or 42t.

John
70sSanO is offline  
Likes For 70sSanO:
Old 12-01-22, 03:39 PM
  #14  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Originally Posted by 70sSanO View Post
You are kind of in no man's land. Any mtb 2x will probably be an issue if you want to swap the outer 2x ring with an outer 3x ring.

The SRAM X9 would probably work since it is a 42t and it is possible to get a 26t, but there are some issues. The BCD is 120/80 not 104/64. It looks like 120/80 is used on the 42t and 39t cranks and the 104/64 is used on smaller chainring offerings. I'm not sure anyone else uses that BCD so when replacement rings are gone, they are gone.

I'm not up to speed on the BB30 and the threaded work arounds, but that is a consideration.

If I were to go back to a 10+ year old mtb 2x, I'd probably look at an M785 or M985. As far as an FD, I would guess that an FD that will work with a 38t could be squeezed to go to 40t or 42t.

John
I was looking at M785 just the other day. I the M985 uses a proprietary big ring for some reason.

the older fsa is BCD: 104/64mm. I am thinking the Shimano M785 might be more trouble in the long run even if it's about 200 grams more though.


$295
FSA K-Force Light ATB MTB Crankset 170mm 24/38t Double 4 Bolt
Length: 170 mm
BB30 Spindle
BCD: 104/64mm
Weight: 560 grams
https://www.ebay.com/itm/19477171067...Cclp%3A2047675
sean.hwy is offline  
Old 12-01-22, 04:53 PM
  #15  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,445

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: 1815 Post(s)
Liked 1,956 Times in 1,200 Posts
Originally Posted by sean.hwy View Post
I was looking at M785 just the other day. I the M985 uses a proprietary big ring for some reason.

the older fsa is BCD: 104/64mm. I am thinking the Shimano M785 might be more trouble in the long run even if it's about 200 grams more though.


$295
FSA K-Force Light ATB MTB Crankset 170mm 24/38t Double 4 Bolt
Length: 170 mm
BB30 Spindle
BCD: 104/64mm
Weight: 560 grams
https://www.ebay.com/itm/19477171067...Cclp%3A2047675
The outer ring is still a 38t.

What 2x outer ring, or possibly a 3x middle ring, do you plan to use to get to 40t/42t?

John
70sSanO is offline  
Old 12-01-22, 05:22 PM
  #16  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
104 bcd is common, I can get 40T + chain ring. It's difficult to find 40T + on the 96 BCD and next to impossible on the modern direct mount 2x MTB cranks.

https://www.amazon.com/DECKAS-Chainr...934&th=1&psc=1

https://www.amazon.com/Truvativ-Chai.../dp/B004SHE5WK

https://www.ebay.com/itm/22428986919...Bk9SR4j03_-ZYQ

I think I am going to skip the FSA crankset though after watching Hambini video.

In this video I marry a Time Scylon with an FSA crank. The Scylon is one of the best bikes I've come across, it is well made and the fit and tolerances are excellent.

The FSA Crank has some of the worst machining I've ever seen.
sean.hwy is offline  
Old 12-01-22, 05:43 PM
  #17  
70sSanO
Senior Member
 
70sSanO's Avatar
 
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,445

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: 1815 Post(s)
Liked 1,956 Times in 1,200 Posts
Originally Posted by sean.hwy View Post
104 bcd is common, I can get 40T + chain ring. It's difficult to find 40T + on the 96 BCD and next to impossible on the modern direct mount 2x MTB cranks.

https://www.amazon.com/DECKAS-Chainr...934&th=1&psc=1

https://www.amazon.com/Truvativ-Chai.../dp/B004SHE5WK

https://www.ebay.com/itm/22428986919...Bk9SR4j03_-ZYQ

I think I am going to skip the FSA crankset though after watching Hambini video.

https://www.youtube.com/watch?v=nwiVlLfqG1M
The SRAM is the only one I would consider since it is for a 2x10 and 104mm BCD is not a road size.

The Deckas is a narrow-wide.

Have no idea if the steel Truative will work. Generally steel is usually lower end and I would guess for a triple, but didn't look into it.

John
70sSanO is offline  
Likes For 70sSanO:
Old 12-04-22, 01:46 PM
  #18  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
Originally Posted by 70sSanO View Post

If I were to go back to a 10+ year old mtb 2x, I'd probably look at an M785 or M985. As far as an FD, I would guess that an FD that will work with a 38t could be squeezed to go to 40t or 42t.

John
I purchased an M785 170mm the other day with a 40-28T chainring from Japan. Should get it here in a few weeks. Hopefully it works out well.


this might be usefull for anyone else that might come accross this thread that is looking for a wide range 2x crankset.

Path Less Pedaled
My Favorite Crankset That No One Knows About

Best Modern Alternative Cranks!

Nerd Crank Database
https://docs.google.com/spreadsheets...duk/edit#gid=0

sean.hwy is offline  
Old 12-04-22, 02:38 PM
  #19  
base2 
Doesn't brain good.
 
base2's Avatar
 
Join Date: Jun 2015
Location: Pacific Northwest
Posts: 2,389

Bikes: 5 good ones, and the occasional project.

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 1317 Post(s)
Liked 1,033 Times in 597 Posts
Originally Posted by sean.hwy View Post
I purchased an M785 170mm the other day with a 40-28T chainring from Japan. Should get it here in a few weeks. Hopefully it works out well.
I bought the same crankset as you. For better top end, I swapped out the 40 for a 44 from a triple crankset. From what I remember, I think it was from a M785 triple so it should've been an easy bingo-banging swap.

It wasn't. For brevity, the engineering of the rings for a double are a package. The engineering of the rings for the triple is a package deal too. A triple outer is designed to fall on a triple middle. Mating it to a double inner leaves a gap large enough the chain will fall between the rings, skate & jam.

The solution for shifting perfection was a Wheels Manufacturing 1.2mm spacer between the outer ring and the crank spider to move the ring inboard to eliminate the gap.

Chainring spacer by Richard Mozzarella, on Flickr

The result was 19-109 gear inches with an XT 11-40 cassette.
__________________
I shouldn't have to "make myself more visible;" Drivers should just stop running people over.

Car dependency is a tax.
base2 is offline  
Likes For base2:
Old 12-04-22, 03:12 PM
  #20  
sean.hwy
Senior Member
Thread Starter
 
sean.hwy's Avatar
 
Join Date: Jan 2020
Location: San Jose
Posts: 880

Bikes: Blur / Ibis Hakka MX

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Liked 226 Times in 165 Posts
that's good to know, thanks.

How did you like the 28T? :-)

My current setup is front 32T with back 36T for the road wheel set and front 32T with back 40T for the gravel wheel set.

Do you sprint much or pedal down hill a lot? I had 1x 40T on the front for a little while there was only one hill I spun out on because it was just a slight down grade, arrow straight and smooth. Most hills between the turns, cars, ruts I tend to just coast or even use my brakes. I don't tend to not go much faster than 30 mph downhill unless the conditions are really good.

front 40T / back 11T should be good for 23 mph to 29 mph which is plenty for me.

https://www.bikecalc.com/speed_at_cadence
sean.hwy is offline  
Old 12-04-22, 05:23 PM
  #21  
base2 
Doesn't brain good.
 
base2's Avatar
 
Join Date: Jun 2015
Location: Pacific Northwest
Posts: 2,389

Bikes: 5 good ones, and the occasional project.

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 1317 Post(s)
Liked 1,033 Times in 597 Posts
Originally Posted by sean.hwy View Post
that's good to know, thanks.

How did you like the 28T? :-)
For unladen smooth road use. I found that with the riding I did, I mostly stayed in the 44 & I was mostly in cog 10 through about 5 or 6 on the small end of the cassette. Position 11, the 11 tooth wasn't used very often but it was very nice to have. I didn't really use the 28 all that much.

Now for fully loaded panniers or gravel riding the situation was well reversed. The availability of the 28,40 combination was nearly ideal. The whole cassette was used for the duration.

I have found that for non-paved surfaces anything lower than about 15 gear inches, it's hard to pedal fast enough to stay upright. The balance between traction, strength & speed becomes unworkable for me.

So, 19-ish gear inches afforded by the 28 tooth ring (for me) is about the bottom of the useable range anyway. Enough purchase per pedal stroke to maintain balance, a low enough cadence to stand & jockey weight around for traction, & enough strength to keep the whole situation moving forward. In short, anything steeper/looser & I'd be walking anyway.

FWIW: A 0.7:1 drive ratio is wicked low. If you have individual cogs like with Shimano 11 speed cassettes, the torque can bite aluminum freehub bodies pretty hard. It would be best to stick with steel or titanium in that case. Otherwise, pinned/riveted cassettes or monoblock designs like XD start becoming good ideas.

Last edited by base2; 12-04-22 at 05:38 PM.
base2 is offline  
Likes For base2:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information -

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.