How do I convert 2x Di2 to 1x?

Especially for light weight issues concerning cyclocross / touring bikes & parts.

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GonaSovereign
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by GonaSovereign

I love my Di2, but also like a 1x for cross. Has anyone modified an existing 6870 2x Di2 setup for 1x? Is it as simple as swapping the rear derailleur for an XT or XTR, removing the front der, and installing a narrow-wide ring? Or does it also take a software update? Please share your experience!

motorapido
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Joined: Fri Jul 30, 2010 7:08 pm

by motorapido

What you've said is pretty much it,

Swap the mech's and chainring and your good to go,
The only think you may want to do is re configure your shift levers, to say, both on right hand upshift, both on left hand down shift.

it makes it simpler in the heat of a race offroad.

by Weenie


mrlobber
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by mrlobber

Hydraulic 6870 here, just converted to 1x. Yes, remove the FD (and the corresponding EW-SD50 wire - saves a gram or two :D :D), mount an appropriate ring on the crankset, and that's basically it. XTR rear would be nice, but so far for commuting & city I'm perfectly ok with the 6870 RD. Not even running a true narrow-wide ring on the front, but custom made steel oval ring with long teeth.

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GonaSovereign
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Location: New Zero Kanada 43° 40' 0" N, 79° 25' 0" W

by GonaSovereign

Nice. I've got a Wolftooth ring kicking around and ordered up an XT rear der. Hopefully I'll be 1x by next weekend.

weastman
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Joined: Sat Apr 16, 2016 3:06 pm

by weastman

Interested in this also, would be great to hear how you get on/ see some pics.

njyeti
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Joined: Thu Dec 03, 2015 4:14 am

by njyeti

I'm running DA 9070 rear derailleur w/ 11-28 spread and a CX1 narrow wide ring from Rotor. I haven't had any issues with chain drop- and I've done about 20 races on this set up.

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GonaSovereign
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by GonaSovereign

Closing the loop. I made the mod and it works perfectly. After buying the XT rear derailleur, I was surprised to find that the Ultegra works perfectly in 1X set up. Just take off the front der and go!

I did end up installing the XT, as it's clutched and also sits much farther inboard....you can barely see it from above.
ImageUntitled by Geoffrey Morgan, on Flickr


I added the full bike shot just to prove that there actually is a derailleur there:
ImageUntitled by Geoffrey Morgan, on Flickr

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wheelsONfire
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by wheelsONfire

I see the WF offset/ chainline is 47.5mm, which probably helps getting an optimal chainline
Using standard Shimano 2*11 crankset at 43.5mm is not.
A pity Shimano doesn't care to make a true gravel/ cx Di2 Ultegra groupset (2*11).
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Lelandjt
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by Lelandjt

If I was going 1x road/CX I'd get a Sram or Easton crank for the direct mount ring with proper chainline. In the MTB world we've learned that having that chainring inboard helps shifting and reduces wear SO MUCH in those big 1st and 2nd cogs, to the point that we often set the ring farther inboard than intended (using a non-boost ring on a boost bike or other such mods). Even though you'd think you want the ring lined up with the middle of the cassette so chainline is the same in 1st and 11th, in practice chainline seems to matter more in the big cogs.

I think the narrow/wide rings for double cranks mentioned above are offset to bring them inboard but pay attention to chainline during setuo and use spacers if necessary.

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wheelsONfire
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by wheelsONfire

Lelandjt, all interesting. However measuring chainline using 12*142 rear drop/ cassette spacing it is obvious it is off.
My chain jumps at small chainring at what seems to be around 1-3 o'clock.
The big three, Shimano, Sram and Campa does not oversee this.
Sram made 1*11 which i personally suspect is because they have seen the issue.
With 1*11 it's not, especially with a clutch RD.
Shimano have ignored this and constantly hinders users from mixing mtb and road groupsets.
Campa is not known to be used for cx/ gravel. Even so, Campa now released H11 crankset for disc brake road bikes.
This crankset have a wider chainline.
The 1*11 WT chainring is offering an outboard chainline. Like riding on large on a 2*11.

My last attempt to solve this is Easton EC90SL crankarms+axle, a custom CNC spider from Kent Eriksen and chainring combo 44/34 from Wickwerks.
My FD holder is lowered with an adapter, for FD to be positioned for 44 or 46T large chainring.
I also modified the FD cage to be lower in height, to position itself better for 44 or 46 large chainring.
It also comes down deeper, so it moves the small chainring better than a standard FD.

With the new crank+spider, i should get a chainline of 46-47mm.
This is probably the only avaible solution right now.
Rotor Aldu 3D+ is made to used either an axle allowing 43.5mm chainline for rim brake bakes (130mm rear drop out and normal cassette spacing)
Or, you buy the longer axle and get 46mm chainline for disc brake bikes with 12*142 rear drop out.
But Aldhu still will not be available with smaller chainrings.
Perhaps it'll come in due time.

Look at FSA SLK or K-Force Adventure cranks. They offer 48/32 or 46/30 chainrings, but chainline is still to small at only 44.5mm.

So, i believe 1*11 is partly made because you run less risk of chainsuck or chain jumping.
No road groupset is really designed for a more outboard chainline, but i guess they should be, if designed to be optimized for 2*11 gravel.
Especially the FD and the cranksets chainline.

Thing is, both cx and gravel is a niche market so Shimano probably don't invest money into this.
But i am dead sure they know very well that people try to solve this.
But there is no big money involved like with road bikes or mtbs.
I mean, look at road bikes, people always want to ride what the pro team riders use.

Where is this talking cx/ gravel? Ofcourse they boost 1*11.
But i ask, how can this be a progress?
You'd want a more linear ratio when shifting and less friction.
This is progress. Not a more crude ratio and skipping an FD.

For me, this is marketing hype. Sure, it's great that people can chose to use it.
But 11 gear, in the 90is we had what, 27, then 22. Now progress is using 11?

Who spins out a 50/34 using either 700*38-40 or even worse, 650*45-52mm?
You'd want smaller chainrings if you run 2*11.
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Ax Lightness Vial EVO D
Paduano Racing Fidia
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justaute
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Location: UT/TX/PA, USA

by justaute

wof...FWIW, Easton told me it's testing sub-compact chainrings (e.g. 48/46/32/30). Probably 1Q 2018.


wheelsONfire wrote:Lelandjt, all interesting. However measuring chainline using 12*142 rear drop/ cassette spacing it is obvious it is off.
My chain jumps at small chainring at what seems to be around 1-3 o'clock.
The big three, Shimano, Sram and Campa does not oversee this.
Sram made 1*11 which i personally suspect is because they have seen the issue.
With 1*11 it's not, especially with a clutch RD.
Shimano have ignored this and constantly hinders users from mixing mtb and road groupsets.
Campa is not known to be used for cx/ gravel. Even so, Campa now released H11 crankset for disc brake road bikes.
This crankset have a wider chainline.
The 1*11 WT chainring is offering an outboard chainline. Like riding on large on a 2*11.

My last attempt to solve this is Easton EC90SL crankarms+axle, a custom CNC spider from Kent Eriksen and chainring combo 44/34 from Wickwerks.
My FD holder is lowered with an adapter, for FD to be positioned for 44 or 46T large chainring.
I also modified the FD cage to be lower in height, to position itself better for 44 or 46 large chainring.
It also comes down deeper, so it moves the small chainring better than a standard FD.

With the new crank+spider, i should get a chainline of 46-47mm.
This is probably the only avaible solution right now.
Rotor Aldu 3D+ is made to used either an axle allowing 43.5mm chainline for rim brake bakes (130mm rear drop out and normal cassette spacing)
Or, you buy the longer axle and get 46mm chainline for disc brake bikes with 12*142 rear drop out.
But Aldhu still will not be available with smaller chainrings.
Perhaps it'll come in due time.

Look at FSA SLK or K-Force Adventure cranks. They offer 48/32 or 46/30 chainrings, but chainline is still to small at only 44.5mm.

So, i believe 1*11 is partly made because you run less risk of chainsuck or chain jumping.
No road groupset is really designed for a more outboard chainline, but i guess they should be, if designed to be optimized for 2*11 gravel.
Especially the FD and the cranksets chainline.

Thing is, both cx and gravel is a niche market so Shimano probably don't invest money into this.
But i am dead sure they know very well that people try to solve this.
But there is no big money involved like with road bikes or mtbs.
I mean, look at road bikes, people always want to ride what the pro team riders use.

Where is this talking cx/ gravel? Ofcourse they boost 1*11.
But i ask, how can this be a progress?
You'd want a more linear ratio when shifting and less friction.
This is progress. Not a more crude ratio and skipping an FD.

For me, this is marketing hype. Sure, it's great that people can chose to use it.
But 11 gear, in the 90is we had what, 27, then 22. Now progress is using 11?

Who spins out a 50/34 using either 700*38-40 or even worse, 650*45-52mm?
You'd want smaller chainrings if you run 2*11.

rma
Posts: 165
Joined: Mon Apr 21, 2014 9:17 pm
Location: Belo Horizonte, Brazil

by rma

How do I change a 2x crankset to 1x? I have a P2M type S spider and I'm interested in running 1x on my cyclocross but keeping the current crank and power meter.

Thanks

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GonaSovereign
Posts: 541
Joined: Thu Nov 24, 2005 2:34 pm
Location: New Zero Kanada 43° 40' 0" N, 79° 25' 0" W

by GonaSovereign

rma wrote:How do I change a 2x crankset to 1x? I have a P2M type S spider and I'm interested in running 1x on my cyclocross but keeping the current crank and power meter.

Thanks


Get a Wolftooth chainring, which places the teeth slightly inboard. They offer rings that will fit on the P2M Type S (except maybe the Campagnolo four-arm...I don't know about that one.)
https://www.wolftoothcomponents.com/collections/chainrings

by Weenie


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