# What is an E-Type Bottom Bracket?



## papajohn (Feb 1, 2004)

I was looking online for chainguide/bashrings. I found both the Blackspire NS-1 and Evil E-Thirteen SRS product descriptions included the requirement for an E-Type Bottom Bracket. What the hell is that?

I have a Maverick ML-7 that requires an E-type FRONT DERAILLEUR. But I am unfamiliar with what is meant by an E-Type Bottom Bracket.

Is anyone using either of these chainguides/bashguards, and can explain what is meant here?

Tnanks for taking the trouble.

John W.


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## RED5 (Jan 4, 2004)

E-type's are basically used on bikes that don't have a seat tube (ei: Big Hit or other interrupted seat tube bikes) or other such post for attaching a regular derailleur. They mount under the Bottom Bracket cup and are usually attached to the frame with a little screw to keep them from moving.

E-Type derailleur
<img src=http://cambriabike.com/shift&der/images/shim_xt_m750_e-type_fd.jpg>

Regular Derailleur
<img src=http://cambriabike.com/shift&der/images/shim_xt_m751_fd.jpg>


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## COmtbiker12 (Jan 12, 2004)

It pretty much mounts on your bottom bracket.


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## .WestCoastHucker. (Jan 14, 2004)

papajohn said:


> ...........I have a Maverick ML-7 that requires an E-type FRONT DERAILLEUR. But I am unfamiliar with what is meant by an E-Type Bottom Bracket..........................
> John W.


i think it is referring to the flange cup on the bottom bracket that is used to sandwich the boomerang against the bottom bracket shell on the frame

either that, or it uses the e-type mount on the frame for mounting the guide also


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## knollybikes.com (Jan 8, 2004)

*Yes, it's the flanged cup...*

... that's the drive side cup on your BB. Most "ISIS" style BBs have cups without a flange, unless they are DH or possibly FR specific. Then they incorporate a flange on the driveside cup to sandwich the "boomerang" for a chain guide. ISCG tabs are supposed to replace having to squish the boomerang between the BB cup flange and creat a system with a bit more precision (and resistance to rotation).

Anyway, as WCH and red5 said, some frames (like our V-tach and your ML-7) don't have a conventional seat tube: you have to use an e-type mount front derailleur as there is nowhere to mount a conventional seat tube mounting front derailleur.

For a frame to properly use an E-type front derailleur, you need to have a flanged cup BB. Typically, the BB will come with a spacer that you replace with the E-type mounting plate. The plate can be the one that comes with the SHimano derailleur (shown in WCH's picture) or it can be the actual chain guide plate (i.e. e-13 DRS or MRP LPR) which replaces the one that came with the Shimano derailleur. Also, your frame must have a M5 fixing bolt, which stops the system from rotating, and will correctly position the front derailleur rotation wise around the BB.

If you have a BB like the Raceface ISIS Signature DH, you will notice that it comes with a "ring" that you put between the driveside of the BB shell and the cup flange. This ring is removed and replaced by the E-type mount or plate.

If you have newer cranks like the Raceface Diabolus X-drives, they actually come with three rings: the BB is designed for either 68 or 73mm wide BB shells: if you have a 68mm wide shell, you use two rings to make it 73mm wide (one on each side); then you must use the third ring to space out the drive side cup even further (to compensate for a chainguide or e-type plate). If you have a BB mount chain guide or an e-type front derailleur, then again, you replace that third ring with the chain guide plate or e-type mount.

Did that make sense?

Let me know if not, and I'll try to explain it a little bit better.

good luck - the Maverick is a super nice frame!


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## MINImtnbiker (Mar 2, 2004)

*You don't need an E-type front derailleur with a Maverick*

Papajohn, don't bother with any of this. Just go to http://www.maverickamerican.com --> products --> frames then you'll see the Maverick D-Mount. Then give Maverick a call and order one. You can use an Ultegra or Dura Ace triple front derailleur. I use a D/A one. It's super light, and works better than an XT and XTR due to the stiffer spring.


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## .WestCoastHucker. (Jan 14, 2004)

MINImtnbiker said:


> Papajohn, don't bother with any of this. Just go to http://www.maverickamerican.com --> products --> frames then you'll see the Maverick D-Mount. Then give Maverick a call and order one. You can use an Ultegra or Dura Ace triple front derailleur. I use a D/A one. It's super light, and works better than an XT and XTR due to the stiffer spring.


it's a chainguide question not a derrailleur one...


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## two_chaintugs (Jan 17, 2004)

*E-type BB's are a wee bit wider than "normal"*

to accomodate the E-type derailleur boomerang - or in your case, the chainguide mount. You can run an E-type BB without the boomerang, but will likely need a BB spacer to even things out. And, like a couple others said: there's a flange on the drive side that holds the boomerang against the BB shell. I recall that the part number for Shimano will have an "E" in it, as in BB-ES70E for 2004 LX Octalink E-type BB.

The E-13 SRS instructions actually recommend using the boomerang mount option over the ISCG bolts for two reasons: superior alignment with your crank/chainring as they are both on the exact same axis, and to avoid frame damage on really hard hits to the chainguide - since the boomerang would rotate instead of transfering all the force to the ISCG mount holes.

That said, my P.2 frame has ISCG mounts and I use them with my Evil-SRS guide since I tend to change BB and cranks from time to time.

You DO realize that you likely can't have two boomerangs co-exist on the same E-BB? So, if you want to run the E13-DRS (for two rings like the MRP LRP model) you may need to try the special Maverick front d-mount thing.

--Ben


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