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What are the theaded holes in this E-type front derailleur for?

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What are the theaded holes in this E-type front derailleur for?

Old 01-22-12, 05:24 PM
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hardyt
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What are the threaded holes in this E-type front derailleur for?

This (Shimano tech site) E-type derailleur has a bracket with threaded holes/eyelets at the 2 o'clock (above the 'e' in "ChainBlocker") and 8 o'clock positions. What are the holes for?

I'm interested because this FD is on my bike and I'm looking for a chain guard. I'm thinking this e-type FD will make mounting most after-market chain guards difficult or impossible. These holes look like they were put there for a chain guard, but googling "Shimano chain guard" doesn't help explain the threaded holes.

Thanks!

Last edited by hardyt; 01-22-12 at 05:30 PM.
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Old 01-22-12, 05:45 PM
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Chainguard?
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Old 01-22-12, 06:22 PM
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This is a guess but I think the hole at 2:00 is to mount a "chain watcher", i.e. a metal or plastic finger that sits close to the inside of the granny ring and prevents the chain from falling off to the inside. The hole at 7:00 may be for an anti-suck device to prevent chain suck.

anyone have better info?
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Old 01-22-12, 07:18 PM
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What do you mean by chain guard?, the E-type FD is really designed to be fitted onto a frame which is designed for it, and has the correct mount fitted, with out these fitting will be hard, if not impossible. A chain guard used with one of these would be of the bash guard type (see Blackspire or E13 for examples), for using single or double front chainrings off road, not a chain guard for keeping the chain off you legs.

The example you have given (C101) is a basic E-type BB, but has the same principles of the more commonly seen ones, like the SLX & XT versions, althougth these don't have the 'chainblocker' plate. additional info on fitting, along with how the crank is also fitted with this type of FD can be seen here http://www.shimano.com/publish/conte...stallation.pdf

Would suggest that if you bike does not have the correct mounts above the BB, then fitting this type of FD will give a complex solution for a situation where a normal FD could give a simple solution.
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Old 01-22-12, 07:20 PM
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Originally Posted by HillRider View Post
This is a guess but I think the hole at 2:00 is to mount a "chain watcher", i.e. a metal or plastic finger that sits close to the inside of the granny ring and prevents the chain from falling off to the inside. The hole at 7:00 may be for an anti-suck device to prevent chain suck.

anyone have better info?

I'm pretty sure that the E-type derailleurs were meant for frames that had extremely short "seat tube" and tabs welded to the BB shell. I think.

There have been a couple variations on the "E-type" mount: http://en.wikipedia.org/wiki/Deraill...rs#Mount_types
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Old 01-22-12, 07:21 PM
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I think Jim C.'s got it. I think.
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Old 01-22-12, 07:25 PM
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Originally Posted by Jeff Wills View Post
I'm pretty sure that the E-type derailleurs were meant for frames that had extremely short "seat tube" and tabs welded to the BB shell. I think.

There have been a couple variations on the "E-type" mount: http://en.wikipedia.org/wiki/Deraill...rs#Mount_types
I thought the E-type mounts were for frames with non-round seat tubes or for full-suspension bikes with basically no seat tube so there was no place to fit a clamp-on type. No?
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Old 01-22-12, 07:31 PM
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Originally Posted by HillRider View Post
I thought the E-type mounts were for frames with non-round seat tubes or for full-suspension bikes with basically no seat tube so there was no place to fit a clamp-on type. No?
Sometimes they're on inexpensive bikes, even with conventional seat tubes, and this C101e would be on such a bike (inexpensive). I think one advantage on such a bike is that it's super easy and fast to install the front derailleur during assembly.......no up/down or alignment adjustment necessary (or possible).
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Old 01-22-12, 07:36 PM
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Originally Posted by HillRider View Post
I thought the E-type mounts were for frames with non-round seat tubes or for full-suspension bikes with basically no seat tube so there was no place to fit a clamp-on type. No?
Ummm... well... what's the "seat tube adapter" (S. M. L) for then?
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Old 01-22-12, 07:52 PM
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Googling MTB chain GUIDE/tensioner will get you the info on those mounting holes, but it's probably not what you had on mind.
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Old 01-22-12, 09:02 PM
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Originally Posted by Jeff Wills View Post
Ummm... well... what's the "seat tube adapter" (S. M. L) for then?
They have a semi-circular (well, not even half a circle, maybe about 1/3 of the arc) plastic piece that wraps part way 'round the seatpost, just kinda braces up against it.

I have an e-type my Trek which has a normal diamond frame. The only thing of note that accomodated the E-type was the BB. UN-26, 54, etc have e-type variations and the only difference (AFAIK) is that the shoulder in the plastic cup is a thicker to allow for the extra thickness of the derailer's loop that fits in between the BB shell and the drive side cup.

Mine pretty much negates the need for a chainwatcher on the inside. When shifting to the small ring there's pretty much a metal wall there to keep the chain on.

Now onto the OP's question... I'm not sure what the holes are for but if I was after running a chainguard I'd go with a single chainring personally.

Last edited by LesterOfPuppets; 01-22-12 at 09:05 PM.
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Old 01-22-12, 10:02 PM
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Originally Posted by Burton View Post
Googling MTB chain GUIDE/tensioner will get you the info on those mounting holes, but it's probably not what you had on mind.
Link please? I did google, but nothing came up that looked like it would work with those holes. Thanks for all the enthusiasm everyone! Sorry for stumping you all.
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Old 01-22-12, 10:57 PM
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Originally Posted by HillRider View Post
This is a guess but I think the hole at 2:00 is to mount a "chain watcher", i.e. a metal or plastic finger that sits close to the inside of the granny ring and prevents the chain from falling off to the inside. The hole at 7:00 may be for an anti-suck device to prevent chain suck.

anyone have better info?
Like LesterOfPuppets mentioned, the entire E-type derailleur mount is a de facto chain watcher, they're about the most derailment-proof FD setup ever. The type shown in the document also does not require the seat tube to have a dedicated E-type threaded hole, since the bracket simply hugs the frame's seat tube to prevent rotation.

E-type FDs don't interfere with a chainguard attached to the outer chainring, that's a common setup. I'm using the word "chainguard" to mean the sort that keeps your pants out of the chain, not a bashguard designed to intercept log strikes and stuff.
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Old 01-23-12, 08:03 AM
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I was figuring the OP meant this type of chainguard:



There are aftermarket ones that are split to work around front derailers, forget who makes them though.
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