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K-Edge -vs- Wolf Tooth

Old 08-10-17, 01:04 PM
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K-Edge -vs- Wolf Tooth

I'm assuming that K-Edge and Wolf Tooth are trying to accomplish the same purpose: to increase gear range using standard derailleurs (correct?).

We have a K-Edge on a Shimano Di2 Ultegra rear derailleur. Our lowest smallest gear combination is 34t front x 11t rear. Our largest combo is 52t front x 36t rear. Though we never intentionally run these combos, it is important to be able to engage it without any bad consequences. The K-Edge does this by simply increasing the length of the rear derailleur arm in order to take up the slack when in the small-small combo.

I'm nut sure I understand how the Wolf Tooth works. I know that it repositions the whole rear derailleur.

Does anyone know what the advantages/disadvantages are of each? Which one allows for the greatest range (>5:1)? Which one allows for smoother operation?

Thanks
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Old 08-10-17, 01:18 PM
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K-Edge is a manufacturer, not a product.
Can you tell us which of their products you are talking about?

The Wolf Tooth Goatlink/Roadlink just move the RD's pivot point aft and below the mounting bolt.
If you look at any Shimano RD with "Shadow" in the name, you will see they have this feature builtin.
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Old 08-10-17, 02:04 PM
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Searching I found that it is a K-Edge Long Cage Derailleur cage.
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Old 08-10-17, 02:07 PM
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it's the K Edge derailleur cage mod for Di2 derailleurs.


We have one on a Dura Ace Di2 derailleur.


The K Edge Mod does 2 things: 1) it's a longer cage so it increases chain wrap, and 2) it moves the top pulley farther back to allow use with a larger big cog.


The Wolf Tooth, to my understanding just repositions the pulley. So it increases the maximums size cog you can use, but I don't think it has much, if any effect on how much chain it can wrap.


Many people on here have reported successfully running a 40 tooth rear cog with the K Edge conversion.


It may be that you your Ultegra derailleur, if you have the GS cage already has enough chain wrap to run a bigger rear cog, and you only need the Wolf tooth for the pulley positioning.


With the greater capacity of the current Ultegra Di2 RD, compared to the original Dura Ace, not sure there's as much need for the K edge conversion these days.
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Old 08-10-17, 02:16 PM
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I should say the above comments are relative to the Wolf tooth road link.


Wolf tooth also makes a Wolf cage, which appears to be similar to a K Edge.


If you're just going to a 36 cog, I'd try and see if the Ultegra will shift that acceptably with just adjusting the B screw.


If that doesn't work, I'd try the RoadLink first because its cheaper.
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Old 08-10-17, 02:17 PM
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Interesting.
I didn't find it on their website, so it must be a discontinued item.
(I know they also recently dropped the Dirt3 chain catcher which I love.)

If you put on a cassette with a larger cog, the Goatlink/Roadlink will give you more clearance to keep the upper pulley from hitting the large cog. The longer RD cage will not. An extra long B-screw is another workaround for this situation.

On the other hand, if you replace the small chainring with a smaller one, (or replace the large ring with a larger one), you will need more chainwrap which the longer RD cage will give you. The Goatlink/Roadlink won't help here.
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Old 08-10-17, 03:51 PM
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One point about specifying (or not) the exact RD model you have as a starting point.

Ultegra 10spd RD (6700/6770) has a smaller 28t max cog size capacity than the 32t max cog 11spd RD (6800/6870) even though both are designated as SS/GS lengths (length is for chain slack uptake, not cog capacity). The diffs in cog size capacity are due to the top pulleys being in slightly different positions.

In either case a problem can arise when you move the top pulley backward (by b-screw or otherwise repositioning the RD backward). Doing so reduces the chainwrap around the cogs, and can cause the chain to skip on the largest cog under high chain loads. This issue can usually be solved by adding a couple more chain links, and ignoring a little excess chain sag when in the small/small gears (should never ride in this crosschain mode anyway, so it is a mute point).

Lastly, if going the b-screw route and you find you need just a bit more length or that the screw tip starts to miss the dropout stopper, flip the screw around to the inside and let the screw head rest against the dropout stopper.
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Old 08-11-17, 08:47 AM
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Our bike was built with the K-Edge arm and Ultegra Di2 derailleur. I never tried it with the standard arm. We are running a wider range than normal so I don't know if the standard arm would work. As with most things, I assume that the longer arm has advantages & disadvantages. I'd guess that a disadvantage might be that the response might be more sluggish & less precise (?).
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Old 08-11-17, 09:00 AM
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Originally Posted by oldacura View Post
Our bike was built with the K-Edge arm and Ultegra Di2 derailleur. I never tried it with the standard arm. We are running a wider range than normal so I don't know if the standard arm would work. As with most things, I assume that the longer arm has advantages & disadvantages. I'd guess that a disadvantage might be that the response might be more sluggish & less precise (?).
Think about it: Only the upper pulley is involved in making the shift.
There is no reason a longer arm would make a shift sluggish.
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Old 08-11-17, 09:21 AM
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I guess that I'm thinking that the force is provided by the motor and the action is at the height of the parallelogram. The longer arm (along with additional chain links) might act like a pendulum lagging behind the motion of the top pulley. Maybe this is a negligible effect.

Our bike was built with a triple crank with the big ring attached to the inboard face of the spider and the small ring attached to the smaller bolt circle. This is what allows us to go from a high of 52t x 11t to a low of 34t x 36t. I did buy (but not install) a 11t x 40t cassette. I was thinking that if I used the wider range cassette and replace the 34t ring with a 36t ring we could avoid the huge jump from the 52t big ring to the 34t small ring. However, I don't know if I can find a 36t small ring that would bolt up to the bolt circle on our crank spider (72mm I think).
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Old 08-11-17, 01:36 PM
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Originally Posted by oldacura View Post
I guess that I'm thinking that the force is provided by the motor and the action is at the height of the parallelogram. The longer arm (along with additional chain links) might act like a pendulum lagging behind the motion of the top pulley. Maybe this is a negligible effect.

Our bike was built with a triple crank with the big ring attached to the inboard face of the spider and the small ring attached to the smaller bolt circle. This is what allows us to go from a high of 52t x 11t to a low of 34t x 36t. I did buy (but not install) a 11t x 40t cassette. I was thinking that if I used the wider range cassette and replace the 34t ring with a 36t ring we could avoid the huge jump from the 52t big ring to the 34t small ring. However, I don't know if I can find a 36t small ring that would bolt up to the bolt circle on our crank spider (72mm I think).
Stronglight Type S 7075-T6 Shimano 74 mm 9/10 Inside Position Chainring - Silver
https://www.xxcycle.com/stronglight-...silver,,en.php
36t is < $15 + shipping.

FWIW, when we ran 48/30 front rings (and after I had sorted out the best mfr/model - Stronglight) shifting was great, and that was with a 18t gap between rings.

Not sure why your 16t gap is not great, but perhaps you should look at rotating the inner ring by one arm position at a time and test. Sometimes the ring teeth will line up better to let the chain properly engage the big ring shift pins (on shift up to the big ring). If your problem is shifting down to the granny, that issue is most likely just a tuning problem.
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Old 08-11-17, 02:52 PM
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Thanks for the link. I've not heard of XXCycle. Are they US (or UK)? If not US it seems like shipping would be long & expensive. I assume that the standard small ring BCD is 74mm (not the 72mm I stated above).

I'll have to look at our setup this weekend. I recall that our chainring setup is as stated above but I need to verify.

Actually, shifting up & down in the front is fine - its just that the drop from bike to small in front is huge and I was trying to reduce the jump in front to a more incremental step in the rear. On my single bike I can pretty easily pedal up to about 18 mph on the small ring (39t). On our tandem, we pretty much run out of cadence about 15 mph on the small ring (34t).
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Old 08-11-17, 03:13 PM
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Our Dura Ace Di2 with k edge shifts fantastically, I can't imagine the short cage RD shifts noticeably better.

I think the primary disadvantages of the longer cage are 1) a little weight (although I haven't weighed the difference; 2) aesthetics (it looks less racy), and the 3) the biggest disad, the cost.
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Old 08-11-17, 06:03 PM
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Originally Posted by merlinextraligh View Post
it's the K Edge derailleur cage mod for Di2 derailleurs.


We have one on a Dura Ace Di2 derailleur.


The K Edge Mod does 2 things: 1) it's a longer cage so it increases chain wrap, and 2) it moves the top pulley farther back to allow use with a larger big cog.


The Wolf Tooth, to my understanding just repositions the pulley. So it increases the maximums size cog you can use, but I don't think it has much, if any effect on how much chain it can wrap.


Many people on here have reported successfully running a 40 tooth rear cog with the K Edge conversion.


It may be that you your Ultegra derailleur, if you have the GS cage already has enough chain wrap to run a bigger rear cog, and you only need the Wolf tooth for the pulley positioning.


With the greater capacity of the current Ultegra Di2 RD, compared to the original Dura Ace, not sure there's as much need for the K edge conversion these days.
I would add one more thing included in the K-Edge mod. The hanger spring is re-positioned to provide a little more tension.
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Old 08-11-17, 07:35 PM
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I'm using DA Di2 with the Road Link. I've replaced the cage with a GS cage from a like model Ultegra. I also re-positioned the cage spring to give it a little more tension. I'm running 34-50 with 11-36 and it works great. I don't use the 50-36 because it is noisy, but it will work in the event I select it.
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Old 08-11-17, 09:52 PM
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Our new tandem came with Ultegra GS RD as well as a Wolf Tooth Roadlink. Front gearing is 50/34 and rear is 11-40. I was concerned with the GS RD not having enough chain wrap capacity. To my surprise it did and I have no issues with the extreme cross chain combinations. The new Ultegra is supposed to have even higher chain wrap capacity but I think the largest gear is still limited to a 34.
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Old 09-27-17, 01:02 PM
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Originally Posted by pdlpsher View Post
Our new tandem came with Ultegra GS RD as well as a Wolf Tooth Roadlink. Front gearing is 50/34 and rear is 11-40. I was concerned with the GS RD not having enough chain wrap capacity. To my surprise it did and I have no issues with the extreme cross chain combinations. The new Ultegra is supposed to have even higher chain wrap capacity but I think the largest gear is still limited to a 34.
Do you have an idea if you could run a 42t cassette with your set-up? I'd like to interchange my light MTB wheels with my gravel bike if possible. I have a roadlink on order.
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Old 09-27-17, 04:24 PM
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The K edge cage is not only longer but also repositions the top pully down and back. We have used the k-edge very successfully with 11-40 and I think it would do 11-42 with just a little more b screw. You have to actually call K-edge to order one as originally they would only sell to dealers. Joe Savoloa who runs the company (Kristen Armstrong 's husband) is very responsive to inquiries. With the new rear Gs derailleurs a road link will basically accomplish this. When we travel I carry our original cage and a road link as a spare. Never had to use it but it is cheap insurance on a trip.
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Old 09-27-17, 06:47 PM
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The rollout for the new Ultegra 8000 series has been a bit slow, but it is beginning to appear online.
A study of the RD shows Shimano has adopted the ATB RD design by separating the RD mount
screw from the pivot point, unlike all prior road RD where the mount and pivot are the same
location. In the R 8050/8070 the pivot is behind and slightly lower than the mount allowing
clearance for a larger cassette. The GS is rated at 34t but judging from the 36t performance
by both 6870-GS and Wifli Etap RD it is likely the 8050/8070 will clear 36 and probably 40t
cassettes with B screw manipulations. The wolftooth device drops the RD down vertically
with no rear offset but is an inexpensive adapter to allow larger cassettes.

It is unclear whether the 8000 series derailleurs are compatible with 6870 brifters at present
however, and their availability is sparse as yet, with the disc variant real soon now. SS 8000
mechanical groupsets are on some sites in the $1400 or so range.

pix: http://bike.shimano.com/content/sac-...trys-wide.html
Scroll down for RD

Youtube of 11-40 and R8000 GS RD from early August:
Note horizontal dropout, probably better with modern vertical dropouts.

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Old 09-28-17, 12:18 PM
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^^^ for clarification, do note the new Ultegra group is called R8000. The new mount borrowed from the mtb area is what they call the "Shadow" design.

I can't recall if the current 11spd mtb m8000 and road derailleurs share the same cable pull ratios. If so, then opting for a XT or XTR RD could provide even better capacities. I have a long cage SGS XT M8000 RD on our mtb tandem but no road shifters to test with. Can some here verify this?

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