Mountain Bike Reviews Forum banner
1 - 20 of 121 Posts

·
Registered
Joined
·
1,902 Posts
Discussion Starter · #1 · (Edited)
(Note: wordy preliminary review...)


This joins Tr!ckstuff's Exzentriker as the only eccentric BBs that will fit a conventional BB shell.


The Forward Component eBB consists of a burly pair of heat treated stainless steel cups, and a rotating aluminium insert which has a set of enduro cartridge bearings pressed off center into them, and is fixed in place by 6 set screws. Rotating the insert allows you to adjust the chain-stay length by 15mm, which should allow you an unlimited choice of ratios by careful chain-ring-cog selection and/or the use of a half link. The installation tool for the cup is provided, and the eccentric insert adjustment needs a 2.5mm allen. Installation and adjustment was trouble free, but it takes more time than standard eBBs. The component has a nice raw finished with tight tolerances. In short, it is nicely made, and installs and works as described.


Compared to a standard external bearing cup, this unit is definitely heavier - 148g per cup compared to ~42g for a Shimano. Most of the weight is in the thick stainless steel cup, which provides space for the set screws, and rigidity for the eccentric adjustment. The BB shell should be faced for any external BB cup installation, but this is more important with this eBB due to the independent eccentric adjustments.

Another limitation is that you can only use it on 68mm shells, as the additional space required for the eccentric insert and locking mechanism uses up 5mm of additional space, which is what crank makers allow with spacers for 73mm BB shell compatibility. However, with the right crank, I was able to get it to fit a 73mm BB shell (more about that later).

The 6 setscrews used to lock the eccentric do not have to be very tight, and there is a warning that over torquing them may cause damage to the insert, especially near the thin side but the bearing. Because the installation tool is held in place by the same 6 setscrews, it is pretty easy to get a feel for how tight they need to be. If the tool will stay put installing the cup with a 16" headset wrench, then it's not going to move with the eccentric insert. And on the topic of warnings, Forward Components recommends the eccentric be only used in the "high" position (shaft above the center of the BB shell) so that there is more material in the eccentric to support the loads. This means you will always increase your BB height.


Once the cups are installed, the eccentrics are inserted (fully greased) and the crank inserted. All 12 setscrews are loosened (6 per side) and both eccentrics can be turned in unison by your fingers. When the correct chain tension is obtained, the drive side setscrews are snugged down. Then the non-drive side eccentric is adjusted to center it in the middle of the play, and it is snugged down. Pretty easy, and it works fine, but 12 setscrews does take a bit longer. I found that if a setscrew on the drive-side ends up aligned with the chain-stay, and due to the geometric peculiarities, it can be near impossible to access that setscrew. To finish snugging down the eccentric, I had to remove the crank (pretty easy really). However, I re-faced the BB shell a tiny bit (ie: one turn of the tool), and reinstalled the cups, and now all the setscrews are easily accessible with the crank installed.


Standard MTB cranks (104 BCD) need to have the granny ring mount shaved down to clear the larger BB gearing cup. Some road cranks, which have a larger BCD may clear without any modification. Forward Components emailed me that they were working on a tool to shave down the granny mounts so that a granny ring could be remounted with spacers. So I figured I'd wait for the tool. However, I didn't get my username for nothing, and being restless, I started looking at my 73mm BB shelled frame that needed a tensioner (IGH application). After measuring out a Shimano FC-M532 crank, I figured it would work if I completely remove the granny ring mounts. And the FC-M532 crank was pretty inexpensive.


Here is the crank mounted on a 73mm BB shell with the Forward Component's eBB. 3 spacers are supplied to allow the crank arms to clear the eccentric insert, minimum one per cup, and the 3rd allows for some chain line adjustment. This crank has been installed with no spacers, the shape of the spider was such that if I shave off the granny ring mount completely, it would clear the eBB cups. With one spacer on the non-drive side, I had the correct spacing for a 73mm BB shell. So far so good.

Caveats:

I had some reservations about corrosion (road salt when commuting), the eccentric insert is raw aluminium, and the set screws are steel. I liberally greased the inserts, and used anti-seize on the set screws. I don't expect any creak issues with this design, but that, and longevity will take time to determine.

By the nature of the design (spacers on the axle instead of on the cups), the bearings ride further inboard than on conventional external units. Some Shimano axles are taper walled, so by moving the bearing seat inboard, it sits on a thinner walled part of the hollow axle - how this affects longevity remains to be seen.

And as I said before, you'll probably have to shave off the granny ring mounts.

Compared to the Exzentriker:

I don't have one, but from what I've heard, they work fine. The main difference is price, the Exzentriker cost more that 2x. However, it is available in various colours, has a simple one screw adjustment, and is lighter. I almost bought one, but was balking at the price (bad exchange rate!), if Forward Components had waited longer to announce their eBB, I would probably be writing about both.

Conclusions:

BB are one of those things that you install and ignore, unless they cause problems. This one works fine so far, and provides chain tension adjustment, which means you can convert any hard-tail or URT bike to a SS or IGH without a dérailleur style tensioner. This one I can recommend.
 

·
Registered
Joined
·
7,386 Posts
Great. Loads of relevant detail, good pics and no hype. Thanks.
 

·
Sweep the leg!
Joined
·
3,803 Posts
This just occurred to me. Unlike an EBB, the Bb cups are solidly treaded into both sides. If one BB cup is rotated the other rotates as well. With this system, would it be possible to have one side rotate without the other? In other words, let's say you rotate the drive side 15 degrees to obtain optimal chain tension. Is it easy to match the non-drive side the same 15 degrees of rotation? My concern would be that the spindle would no longer be parallel with the BB shell centerline. Thus the spindle axis would not be perpendicular to the bearing surfaces and would put pressure on the bearings and then there'd be problems.

To that end, is there any reference markings on the cups other than the set screws to aid in that alignment?

I'm really curious because as soon as I have the extra money I'd like to get one to put in a bike I have.
 

·
Registered
Joined
·
737 Posts
Caffeine Powered said:
To that end, is there any reference markings on the cups other than the set screws to aid in that alignment?

I'm really curious because as soon as I have the extra money I'd like to get one to put in a bike I have.
The set screws are in the fixed "outer" part that screws into the BB shell, so they don't change position. Your reference would be the milled "scallops" on the circumference of the eccentric cup.
The "Exzentriker" does have index marks for this purpose, but the best way is to set them up is by adjusting the drive side tension first (obviously you have to follow this adjustment with the non-drive side) and then set the final position by finding the null point equidistant from where you can feel a bit of resistance as you turn the eccentric one way and then the other. I use this method for the "Exzentriker" .

It's harder to explain than it is to do (for me at least :rolleyes: ) and it's really not any big deal, you don't have to do it that often.
 

·
Registered
Joined
·
1,902 Posts
Discussion Starter · #8 ·
Caffeine Powered said:
This just occurred to me. Unlike an EBB, the Bb cups are solidly treaded into both sides. If one BB cup is rotated the other rotates as well. With this system, would it be possible to have one side rotate without the other? In other words, let's say you rotate the drive side 15 degrees to obtain optimal chain tension. Is it easy to match the non-drive side the same 15 degrees of rotation? My concern would be that the spindle would no longer be parallel with the BB shell centerline. Thus the spindle axis would not be perpendicular to the bearing surfaces and would put pressure on the bearings and then there'd be problems.

To that end, is there any reference markings on the cups other than the set screws to aid in that alignment?
There are no marks on the FC version. You set the chain tension by turning both together - they will bind if they get too far out of phase. Then you snug down the set screws on the drive side. The non-drive side will still be able to rotate a few degrees back and forth, and you just have to find the center of that play, either by marking the limits with a pen, or eyeballing the scallops. In practice it is pretty easy. You'll spend more time loosening and tightening the 12 set screws.
 

·
Out spokin'
In cog? Neato!
Joined
·
12,961 Posts
Too bad there's no way to make the FC EBB work with a square taper crank.

Is there?

Thanks,
Sparty
 

·
Registered
Joined
·
1,902 Posts
Discussion Starter · #10 ·
Sparticus said:
Too bad there's no way to make the FC EBB work with a square taper crank.

Is there?
You'd have to make a 24mm shaft with a square taper and preload adjustment on it - and the Q-factor would be horrendous (unless you could find some retro non-low-profile square taper cranks...)

What you really want is one of these:
<img width="600" src=" http://forums.mtbr.com/attachment.php?attachmentid=211243&stc=1&d=1163458870">
Unfortunately it never got produced.

I don't have any issues using the external bearing cranks, they work well.
 

·
Out spokin'
In cog? Neato!
Joined
·
12,961 Posts
itsdoable said:
...

I don't have any issues using the external bearing cranks, they work well.
I would happily use an external bearing crank if only one was available in 195mm length.

Darn it. Thanks just the same.

--Sparty
 

·
Registered
Joined
·
4,657 Posts
Very interesting. Do you think this is as good of an option for custom bikes? Meaning designing a custom bike with the intention of using the FC product to tension the chain, over regular EBB's or Paragon dropouts?
 

·
Registered
Joined
·
737 Posts
Wish I Were Riding said:
Very interesting. Do you think this is as good of an option for custom bikes? Meaning designing a custom bike with the intention of using the FC product to tension the chain, over regular EBB's or Paragon dropouts?
Not for me - in an ideal world a "standard" EBB or Paragon sliders would always be my choice for a custom SS.
However, both the Exzentriker and the Forward Components BB's give the possibility of using a frame that you already own and like without having to faff around with ugly, noisy and just in-the-way mech. hanger mounted tensioners (and without getting the welding gear out !) I'd rather use one than have track ends anyway..

They work, and work well IMHO - the only downsides seem to be slightly fiddly access for adjustment and limited crank choice.
 

·
Registered
Joined
·
1,902 Posts
Discussion Starter · #14 ·
Sparticus said:
I would happily use an external bearing crank if only one was available in 195mm length.

They are kind of pricy though. I thought there was a German company making custom cranks too.


Wish I Were Riding said:
...Do you think this is as good of an option for custom bikes?...
No reason why you can't do it, but I'd think that you'd be better off with something that was not designed to retrofit into an exisiting frame. But people like things like the Eno Eccentric hub, enough to buy a new non-ss frame for SS use.
 

·
Registered
Joined
·
4,657 Posts
itsdoable said:
No reason why you can't do it, but I'd think that you'd be better off with something that was not designed to retrofit into an exisiting frame. But people like things like the Eno Eccentric hub, enough to buy a new non-ss frame for SS use.
That's kind of what I'm thinking about. I have Paragons, and they have worked fine. I don't like the look much. I have EBB's, and they are fine too. I wish they didn't add so much weight to the frame. I might have to just try the Eno some day like PeT did.
 

·
Out spokin'
In cog? Neato!
Joined
·
12,961 Posts
Thanks for that pic & info

itsdoable said:
They are kind of pricy though. I thought there was a German company making custom cranks too.

...
In the past, Zinn's square taper custom length cranks were made by High Sierra Cycle Center, then labeled for Zinn. I own 3 sets of these cranks (in 195mm length) sans the Zinn label by going direct to HSCC (and saving hundreds of dollars in the process).

But alas, the cranks in your photo above are not offered on HSCC's site (although the square taper variety are still offered there). So either Zinn is making his own custom length cranks or HSCC has a non-compete agreement that has not expired or Zinn is sourcing these from someone else entirely.

Buying those cranks and the FC EBB would certainly be an expensive retrofit. Might as well buy a new custom frame.

Anyway, thanks again.

--Sparty
 

·
@adelorenzo
Joined
·
1,670 Posts
Sparticus said:
I would happily use an external bearing crank if only one was available in 195mm length.

Darn it. Thanks just the same.

--Sparty
It would take some trickery, but you could get to 190 mm with this set-up. Replace the current bearings with ones that have a narrower ID (19 mm or 22 mm) and run a set of 3-piece BMX cranks. You might have to machine a tube spacer for the inside, as the stock ones likely won't fit.
 

·
Rockstar
Joined
·
137 Posts
Andy R said:
The set screws are in the fixed "outer" part that screws into the BB shell, so they don't change position. Your reference would be the milled "scallops" on the circumference of the eccentric cup.
The "Exzentriker" does have index marks for this purpose, but the best way is to set them up is by adjusting the drive side tension first (obviously you have to follow this adjustment with the non-drive side) and then set the final position by finding the null point equidistant from where you can feel a bit of resistance as you turn the eccentric one way and then the other. I use this method for the "Exzentriker" .

It's harder to explain than it is to do (for me at least :rolleyes: ) and it's really not any big deal, you don't have to do it that often.
One of my customers has stated that his Trickstuff Exzentriker requires you to remove the crank before readjusting. I am not sure if he means one crank arm, or both. Has this been your experience, or is this perhaps a unique situation based on specific component combinations?
 

·
Registered
Joined
·
737 Posts
forwardcomponents said:
One of my customers has stated that his Trickstuff Exzentriker requires you to remove the crank before readjusting. I am not sure if he means one crank arm, or both. Has this been your experience, or is this perhaps a unique situation based on specific component combinations?
Well, presumably he means that it's a bit difficult to access the drive side eccentric cup in order to rotate it, as it's obstructed by the spider and chainring. There will be this same issue with the FC setup too presumably?

What the Exzentriker really needs to facilitate adjustment is a couple of notches or shallow blind holes on the periphary of each eccentric cup so that one could use a "C" spanner to adjust them - this C spanner need only be a light affair so you could easily carry it along with your normal trail tools. I keep meaning to modify mine and make the spanner but I just haven't got round to it yet, - I'll do it next time I strip it down....in the meantime I just rotate the cup with some slip-joint pliers (with duct tape protected jaws so as not to damage the finish). As long as you break the grip of the locking barrel nut (by loosening the allen screw and then tapping it back in) the eccentric rotates easily enough. If it doesn't then it's time to strip it and clean/regrease it.

Removing the crank for access?? Then how does one check the position, since you then have no chainring or chain in place either? Presumably by an endless trial and error process I suppose but not really practical. I don't think that particular cranks would make access more difficult - I'm using XT cranks and had to machine off the granny ring bosses for clearance anyway.

So, the Exzentriker isn't without its faults, and if your FC version had been available a year ago then I would probably have bought that instead. At the end of the day, the opinion seems to be that they both do what they were designed for:thumbsup: and with something like this the user always will have to put up with, and adapt to, a few little idiosyncrasies
 

Attachments

·
Registered
Joined
·
86 Posts
forwardcomponents said:
One of my customers has stated that his Trickstuff Exzentriker requires you to remove the crank before readjusting. I am not sure if he means one crank arm, or both. Has this been your experience, or is this perhaps a unique situation based on specific component combinations?
You do not need to remove any of the crank arms to adjust it although it can be kind of tight to get hold of the Exzentriker on the drive side. The trick is to really get it released by loosens the fixing bolt AND makes sure the nut (silver thing on the pic) has released, it tends to get stuck... Then it moves very smooth and is easy to adjust.


I was a bit late there :)

Interesting product from Forward Components and great review! :thumbsup:
 

Attachments

1 - 20 of 121 Posts
Top