Shimano R9150 RD - Why so few direct mount hangers?

Discuss light weight issues concerning road bikes & parts.
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Calnago
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by Calnago

Good eye @Turbokoo... and I thought exactly the same thing. Except... that's not where the hangup occurs. In all cases that I've seen where rear wheel removal is difficult, it's at the point below the hanger where you're trying to clear the upper pulley and the cog/chain. The derailleur just stops and physically can't move back any farther. This is the stopping point regardless of which hanger you use. And it's not the hanger that's getting in the way. It's the upper pulley, and since the derailleur should be in the same spot in space regardless of the hanger used, so is the upper pulley. So, the solutions thus far have been discussed earlier in the thread. Grinding some of the B-link away... I don't like this solution because I physically wrestled with the derailleur with not chain attached and I think the reason for those stops are simply that pulling the cage back farther than that puts such huge stress on the pulley cage that I don't think it would last very long.
The other solution, and the one that Team SKY is clearly using... is to just ignore where the derailleur would normally rest on the regular derailleur hanger stop and, against Shimano's instructions, rotate the B-link away from the stop so that it is horizontal to the ground, essentially placing it a bit further back in space. I describe that in this thread as well. And in fact, for this bike, which is small and the wheel is in fact a pain in the ass to remove... that's all the change that is needed. Doesn't look like it'd be much, but it doesn't have to be... it's enough. Trouble with that is you're relying solely on the torque of the mounting bolt to hold that derailleur in place, without the support of the hook on the derailleur hanger. In any case... the shifting is unquestionably superb, and all that chain wrap not only provides for better shifting, but by having more teeth engaged it also has to increase the longevity of the cassette as the driving force is distributed over a greater area at any given time. The cost for all this technological goodness... Rear wheel removal is more annoying for sure for almost all bikes, and extremely frustrating for some. Meh... I can live with that. But at least now I know why.

@Pdlpsher1's bike, has other issues related to optimizing his shifting, but these are all due to where his derailleur is in space, a possible incorrect chainlength, and possible adjustment factors, etc. Granted, his current hanger is spec'd for mountain bikes, but I think that difference alone is not going to resolve the biggest issue which is where, exactly in space, the derailleur ends up being positioned. His scenario, with 425mm chainstays and a frame/hanger arrangement which places the derailleur, in my opinion, way too far back and elevated from the Shimano spec, creates a situation where rear wheel removal is the least of his worries. I'm sure that rear wheel just drops right out. In fact I even said it looks like he could just pull it at a slight rearward and it would still come out, given how the dropout angle looks.
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BdaGhisallo
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by BdaGhisallo

I spotted this over on CN. Looks like Bianchi went a different way than BMC, opting to go for a solid and chunky DM hanger.
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Bianchi DM hanger Groenewegen.jpg

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zank
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by zank

The difference between road DM and mtb DM is the road DM is 0.65 mm further rearward and 3.79 mm lower.

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Calnago
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by Calnago

@bdghisallo: That Bianchi hanger does look solid, and to the extent the ultimate connection from derailleur to frame doesn’t move or bend that’s a plus. When the B-Link first came out with the derailleur I questioned how much more leverage it would put on a regular hanger. And if that hanger was already on the soft side, then that could not bode well for shifting. Someone argued that it did not add any extra leverage from a physics standpoint but I couldn’t quite grasp that concept. The BMC hanger, when looked at from a dead on side profile looks super thin, but it’s structure when looked at from above is very thick and when considered from a 3d perspective it doesn’t look very susceptible to bending or twisting either. I’m presuming Bianchi is offering two hanger choices for this frame then, the hanger you showed as the option for the new Shimano derailleur and a different hanger for Campy or SRAM?

@Zank, thanks for those specs on the differences as to location of the road vs mtn hanger. And there’s one more in the angle of the hook coming off the bottom of the hanger, correct? That angle is different by 10 degrees which would also add a bit to both those numbers you presented as the derailleur, once mounted against the Road stop, allows the road version to rotate a little more forward than the stop on the mtn version would allow. Not sure it makes much difference but as I showed earlier in an example using a Campy derailleur, it was enough of a difference for Pilo Mfg to change their design when I presented it to them.
Last edited by Calnago on Sat Feb 10, 2018 2:21 pm, edited 1 time in total.
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zank
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by zank

Yes, you are correct. 35.5 degrees for road vs 22.5 degrees for mountain. Both are plus minus 2.5 degrees.

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Calnago
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by Calnago

Hmm, so I was assuming it was the other way around... with the bigger angle being for the mtn hanger. That changes what I just said then about the angle bringing the road position of the derailleur even more forward. It actually would make it stop more rearward than it would of attached to the mtn hanger, all else being equal.

[edit]: ignore that last paragraph I just wrote. I was visualizing the Campy hanger spec diagram which measures that angle from the opposite side. Just had a look at the Shimano spec again and yes, the difference will have the effect I described in my previous post.
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rpowell
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by rpowell

it really looks like if you changed the derailleur hanger side of the b-link from a fixed attachment to a pivot with some type of clutch then you could easily swing it out of the way when the clutch was activated but otherwise it would remain fixed. that would let you keep your short stays and snappy handling.
maybe im missing something in the geometry but it looks like you just need one mor pivot to get the pulley farther back.

sun
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by sun

Looks like some manufacturers are testing these out at Paris Roubaix.

https://www.instagram.com/p/BhUrN2fBclK ... =bikeradar

Geraint Thomas' bike Image

BdaGhisallo
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by BdaGhisallo

sun wrote:
Mon Apr 09, 2018 4:45 am
Looks like some manufacturers are testing these out at Paris Roubaix.

https://www.instagram.com/p/BhUrN2fBclK ... =bikeradar

Geraint Thomas' bike Image
Sky have been using those on their Pinarellos for a month or two now. Froome was running one in one of the early races he did this year.

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Calnago
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by Calnago

I'm not surprised that SKY is using a new hanger. As they were one of the ones that were "modifying" the position of the B-Link to better work with their bikes as far as rear wheel removal goes last year, going against Shimanos guidleines. So, I would suspect that this hanger might even put things even a bit further back than Shimano's specs for their DM hanger. The modification they used is shown somewhere in this thread, and another thread on the forum, and I've tried it out. It works when all you need is a smidge more setback in order to get the rear wheel out easier.

And now that the new Campy 12sp stuff is incorporating an offset hanger position as well, I'm curious as to how it will work, hopefully better than the shimano implementation as far as rear wheel removal goes. Keep in mind that easier rear wheel removal was never achieved with the Shimano DM hanger, at least for road bikes, and in fact made things downright annoying in some cases. But the better wrap and corresponding shifting was a good tradeoff.
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BdaGhisallo
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by BdaGhisallo

Calnago wrote:
Mon Apr 09, 2018 4:01 pm
I'm not surprised that SKY is using a new hanger. As they were one of the ones that were "modifying" the position of the B-Link to better work with their bikes as far as rear wheel removal goes last year, going against Shimanos guidleines. So, I would suspect that this hanger might even put things even a bit further back than Shimano's specs for their DM hanger. The modification they used is shown somewhere in this thread, and another thread on the forum, and I've tried it out. It works when all you need is a smidge more setback in order to get the rear wheel out easier.

It could be entirely down to the angle of the photo, but it almost looks like the Pina DM hanger does not have as much vertical drop as the one on the Bianchi I posted earlier, which would tie in with what you are postulating.

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Calnago
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by Calnago

Hard to say, but it's not so much the vertical drop as the rearward distance. The mod that I've seen on SKY bike was such that it rotated the B-Link rearward, away from the stop a bit, so that it was extended as far rearward as possible. This allows the wheel to be removed more easily without the cassette fouling on the upper pulley, which is really where the hangup was and does occur. The Bianchi I can't speak to, but in any case, a solid one piece hanger is a much better mounting point than a B-Link (which is super solid), but if it's attached to a piece of cheese hanger, then it's all for naught. I'll look forward to seeing Campy's version of it.
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Toby
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by Toby

pdlpsher1 wrote:
Sat Jan 20, 2018 6:52 am
Try find a mass produced bike with a T47 BB.
Ibis Hakka MX

Oh, and y'all make my head hurt. A lot. I think I learned some things reading this thread though, so thanks to everyone and especially Calnago!

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Calnago
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by Calnago

Well, good for you for actually getting throught the whole thread, if that's what you did. There is a lot of good information in here, and I finally got around to testing a bunch of combinations once and for all, with different chainlengths, cassette combos, and b-screw adjustments to really understand the nuances of the new Shimano road derailleurs. Mabye one of the biggest takeaways for me was in confirming that chainlength is really critical if you want to be able to really dial in the rear derailleur. The b-screw really can take a lot of slack out of the chain and in combination with the chain length plays a big role in getting that upper pulley as close to the cassette as possible, regardless of which cassette you are using, but without the correct chainlength, it can be difficult or impossible to dial it in as good as it can be if the chain is the correct length for the partiuclar cassette you are using.

If I was running Shimano now, and had a bunch of interchangeable wheels with various sizes of cassettes like I do with Campy, I would also have a Shimano chain that matched each of those cassettes, especially since it's so easy to just swap them out now with the Shimano Quik-Link. And do measure the chain length using Big/Big, not run through the derailleur, exactly as Shimano describes in their tech manual. It can result in different lengths depending on the cassette size. This is in contrast to the long standing Campy way of getting the correct chain length with the chain on small/small and run through the derailleur. In the past, I may have just used the small/small method (same as campy) for shimano as well, and this by and large has been fine. And it still is the best method for the current Campy stuff up to 11spd at least, not sure about the newest 12sp stuff yet. But during this process I was able to see for myself that the small/small method may not always result in the most optimal chainlength for the new Shimano derailleurs, so determine the chainlength for the cassette you want to use as per Shimano’s guidelines.

So, for me, the exercise I went through in this thread was much more valuable in learning the nuances of the newest Shimano derialleurs as opposed to proving a couple of points about the direct mount hanger.

Cal
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