outboard bearings, simple question

[jp]

here is a simple question: whats all this about 'outboard bearings'?
this is in reference to bbs and cranks. this is something that i
could google, but i'd rather get the forum response. i hear about
them here more than anywhere else.

 

[Chalo]

jp wrote:
>
> here is a simple question: whats all this about 'outboard bearings'?
> this is in reference to bbs and cranks. this is something that i
> could google, but i'd rather get the forum response. i hear about
> them here more than anywhere else.

They are a relatively new approach to coping with the size constraints
of the venerable British threaded bottom bracket shell.

British, Italian, French and other similar threaded shells have only
enough room for a passable set of bearings supporting a slender
(16-17mm), nearly solid steel spindle. Making bottom brackets
lighter, stiffer, and stronger requires a larger spindle diameter than
the old shell design supports. Over the last ten years or so, larger
22mm spindles came into use along with very thin-section bearings.
The spindles varied in success, but the bearings have proven to be
less reliable than earlier designs.

Around 1990, Magic Motorcycle made cranks with a 25mm spindle and
bearings held in threaded cups just outside the bottom bracket shell.
Recently, Shimano, Campagnolo, FSA, and others have come to market
with designs that use Magic Motorcycle style outboard bearing cups.
The new generation of cranks uses 24mm spindles with shims to center
them in the 25mm bearings.

All these designs are compatible with threaded BB shells, but none of
the cranks, spindles, or bearing cups are compatible with earlier
crank and BB designs. They must be used together as a system.

They appear to be a design success in that they are lighter and more
rigid than earlier cranks and BBs. The jury is still out on long-term
durability, but indications suggest that they are better than the last
generation of 22mm "pipe spindle" bottom brackets with inside-the-
shell bearings.

Chalo

 

[jim beam]

Chalo wrote:
> jp wrote:
>> here is a simple question: whats all this about 'outboard bearings'?
>> this is in reference to bbs and cranks. this is something that i
>> could google, but i'd rather get the forum response. i hear about
>> them here more than anywhere else.
>
> They are a relatively new approach to coping with the size constraints
> of the venerable British threaded bottom bracket shell.
>
> British, Italian, French and other similar threaded shells have only
> enough room for a passable set of bearings supporting a slender
> (16-17mm), nearly solid steel spindle. Making bottom brackets
> lighter, stiffer, and stronger requires a larger spindle diameter than
> the old shell design supports. Over the last ten years or so, larger
> 22mm spindles came into use along with very thin-section bearings.
> The spindles varied in success, but the bearings have proven to be
> less reliable than earlier designs.
>
> Around 1990, Magic Motorcycle made cranks with a 25mm spindle and
> bearings held in threaded cups just outside the bottom bracket shell.
> Recently, Shimano, Campagnolo, FSA, and others have come to market
> with designs that use Magic Motorcycle style outboard bearing cups.
> The new generation of cranks uses 24mm spindles with shims to center
> them in the 25mm bearings.
>
> All these designs are compatible with threaded BB shells, but none of
> the cranks, spindles, or bearing cups are compatible with earlier
> crank and BB designs. They must be used together as a system.
>
> They appear to be a design success in that they are lighter and more
> rigid than earlier cranks and BBs. The jury is still out on long-term
> durability, but indications suggest that they are better than the last
> generation of 22mm "pipe spindle" bottom brackets with inside-the-
> shell bearings.
>
> Chalo
>

well said.

 

[[email protected]]

On Sun, 30 Sep 2007 09:33:50 -0000, Chalo <[email protected]>
wrote:

>jp wrote:
>>
>> here is a simple question: whats all this about 'outboard bearings'?
>> this is in reference to bbs and cranks. this is something that i
>> could google, but i'd rather get the forum response. i hear about
>> them here more than anywhere else.
>
>They are a relatively new approach to coping with the size constraints
>of the venerable British threaded bottom bracket shell.
>
>British, Italian, French and other similar threaded shells have only
>enough room for a passable set of bearings supporting a slender
>(16-17mm), nearly solid steel spindle. Making bottom brackets
>lighter, stiffer, and stronger requires a larger spindle diameter than
>the old shell design supports. Over the last ten years or so, larger
>22mm spindles came into use along with very thin-section bearings.
>The spindles varied in success, but the bearings have proven to be
>less reliable than earlier designs.
>
>Around 1990, Magic Motorcycle made cranks with a 25mm spindle and
>bearings held in threaded cups just outside the bottom bracket shell.
>Recently, Shimano, Campagnolo, FSA, and others have come to market
>with designs that use Magic Motorcycle style outboard bearing cups.
>The new generation of cranks uses 24mm spindles with shims to center
>them in the 25mm bearings.
>
>All these designs are compatible with threaded BB shells, but none of
>the cranks, spindles, or bearing cups are compatible with earlier
>crank and BB designs. They must be used together as a system.
>
>They appear to be a design success in that they are lighter and more
>rigid than earlier cranks and BBs. The jury is still out on long-term
>durability, but indications suggest that they are better than the last
>generation of 22mm "pipe spindle" bottom brackets with inside-the-
>shell bearings.
>
>Chalo

Dear Chalo,

The original 1892 outboard bearings:

http://collection.rydjor.com/bikecollection/1892exp1.htm

You can see why they brought it inboard--I expect that you'd tear it
off with one good stomp.

Plus . . .

--daylight showing through inch-pitch chain and sprocket

--cool half-link style chain

--direct-pull spokes

--solid red rubber tire eliminates all inflation questions

--clamp-on front fork coasting pegs for comfortable downhill riding

--slotted crank-footpeg interface for perfect adjustment

--high-capacity water-carbide headlight

--innovative front brake designed to avoid wearing out costly rims

Cheers,

Carl Fogel

 

[A Muzi]

jp wrote:
> here is a simple question: whats all this about 'outboard bearings'?
> this is in reference to bbs and cranks. this is something that i
> could google, but i'd rather get the forum response. i hear about
> them here more than anywhere else.

You could try here:
http://campagnolousa.com/
or just ride over to the local bike shop.

'Outboard bearings' is a term we now use to describe bearings which are
outboard. Really. Nothing mysterious.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[still me]

On Sun, 30 Sep 2007 09:33:50 -0000, Chalo <[email protected]>
wrote:

> Making bottom brackets
>lighter, stiffer, and stronger requires a larger spindle diameter than
>the old shell design supports.

I think lighter is the only issue here. BB's are plenty strong as is.
It's only when you want to start using other materials for the axle
that you need to make it larger, and then you need a new way to handle
bearings.

Considering that the weight difference only matters to TDF class
riders and Porsche drivers who need the latest in tech to be kuel, it
would be nice if this didn't catch on. (But, my wishes never come
true).

 

[Chalo]

still me wrote:
>
> Chalo wrote:
> >
> > Making bottom brackets
> >lighter, stiffer, and stronger requires a larger spindle diameter than
> >the old shell design supports.
>
> I think lighter is the only issue here. BB's are plenty strong as is.

I beg to differ. If square-taper spindles were strong enough, then
BMXers would use them, and I would use them. But both BMXers and I
break such spindles off, so we used stronger equipment long before
external bearing BBs became available. Others contributors to this
group have also broken square-taper spindles.

The first time it happened to me, it surprised me. The second time, I
got a broken face and $8000 worth of dental work. There will be no
third time!

> It's only when you want to start using other materials for the axle
> that you need to make it larger, and then you need a new way to handle
> bearings.

Most of the 24mm spindles I have seen, and all of the 22mm spindles,
have been made from hardened steel, like a square-taper.

> Considering that the weight difference only matters to TDF class
> riders and Porsche drivers who need the latest in tech to be kuel, it
> would be nice if this didn't catch on. (But, my wishes never come
> true).

It's true that the weight differences are not significant for most
people. But those are not the only differences.

Chalo

 

[Mike Jacoubowsky]

> They appear to be a design success in that they are lighter and more
> rigid than earlier cranks and BBs. The jury is still out on long-term
> durability, but indications suggest that they are better than the last
> generation of 22mm "pipe spindle" bottom brackets with inside-the-
> shell bearings.

Fortunately, there's one piece of incorrect information in your post. The
new design tends to be a bit heavier, not lighter, than the lighter
in-the-shell bearing designs. For example, my FSA carbon with ISIS Ti bottom
bracket is considerably lighter than nearly all of the current offerings.

I say "fortunately" you're incorrect about the new designs being lighter
because I think it's a very good thing that we've seen at least one area
where something other than ultra-light weigh has won the hearts & minds of
the designers. Durability & stiffness seem to be the driving force behind
the new cranks, and that, to me, is a very good thing. Stiffer cranks
doesn't just mean it feel better when you stomp on it; it also shifts better
because the chainrings aren't moving around so much. And durability is an
obvious good thing (although, for reasons I can't figure out, I'm still
riding an FSA Ti bb that probably has 25-30k miles on it.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"Chalo" <[email protected]> wrote in message
news:[email protected]...
> jp wrote:
>>
>> here is a simple question: whats all this about 'outboard bearings'?
>> this is in reference to bbs and cranks. this is something that i
>> could google, but i'd rather get the forum response. i hear about
>> them here more than anywhere else.
>
> They are a relatively new approach to coping with the size constraints
> of the venerable British threaded bottom bracket shell.
>
> British, Italian, French and other similar threaded shells have only
> enough room for a passable set of bearings supporting a slender
> (16-17mm), nearly solid steel spindle. Making bottom brackets
> lighter, stiffer, and stronger requires a larger spindle diameter than
> the old shell design supports. Over the last ten years or so, larger
> 22mm spindles came into use along with very thin-section bearings.
> The spindles varied in success, but the bearings have proven to be
> less reliable than earlier designs.
>
> Around 1990, Magic Motorcycle made cranks with a 25mm spindle and
> bearings held in threaded cups just outside the bottom bracket shell.
> Recently, Shimano, Campagnolo, FSA, and others have come to market
> with designs that use Magic Motorcycle style outboard bearing cups.
> The new generation of cranks uses 24mm spindles with shims to center
> them in the 25mm bearings.
>
> All these designs are compatible with threaded BB shells, but none of
> the cranks, spindles, or bearing cups are compatible with earlier
> crank and BB designs. They must be used together as a system.
>
> They appear to be a design success in that they are lighter and more
> rigid than earlier cranks and BBs. The jury is still out on long-term
> durability, but indications suggest that they are better than the last
> generation of 22mm "pipe spindle" bottom brackets with inside-the-
> shell bearings.
>
> Chalo
>

 

[Chalo]

M-gineering wrote:
>
> Chalo wrote:
> >
> > Most of the 24mm spindles I have seen, and all of the 22mm spindles,
> > have been made from hardened steel, like a square-taper.
>
> you should go out more: Shimano 105, Tiagra, LX etc are all made out of
> 'Surinam Oak'!

I'm not familiar with the term. Do you mean mild steel?

It's true that my perception of these things is an overview, since I'd
rather poke myself in the eye with a stick than use a Shimano crank on
my own bike.

Chalo

 

[still me]

On Sun, 30 Sep 2007 21:19:45 -0000, Chalo <[email protected]>
wrote:

>still me wrote:
>>
>> Chalo wrote:
>> >
>> > Making bottom brackets
>> >lighter, stiffer, and stronger requires a larger spindle diameter than
>> >the old shell design supports.
>>
>> I think lighter is the only issue here. BB's are plenty strong as is.
>
>I beg to differ. If square-taper spindles were strong enough, then
>BMXers would use them, and I would use them. But both BMXers and I
>break such spindles off, so we used stronger equipment long before
>external bearing BBs became available. Others contributors to this
>group have also broken square-taper spindles.

Perhaps I should have qualified my post with "for road bikes" and "for
riders smaller than a mountain" Square taper works with out fail
for decades for the rest of us. Admittedly, the tapers on the crank
can wear from misadjustment (or loosening while riding), but the BB
lasts for years and years if kept clean for most of us.

>The first time it happened to me, it surprised me. The second time, I
>got a broken face and $8000 worth of dental work. There will be no
>third time!

My sympathies, but you are definitely the exception to the rule.

 

[M-gineering]

Chalo wrote:
> still me wrote:
>> Chalo wrote:
>>> Making bottom brackets
>>> lighter, stiffer, and stronger requires a larger spindle diameter than
>>> the old shell design supports.
>> I think lighter is the only issue here. BB's are plenty strong as is.
>
> I beg to differ. If square-taper spindles were strong enough, then
> BMXers would use them, and I would use them. But both BMXers and I
> break such spindles off, so we used stronger equipment long before
> external bearing BBs became available. Others contributors to this
> group have also broken square-taper spindles.
>

But I wouldn't be surprised if more contributors here have replaced
bearings on outboard sets than they have seen broken spindles, in spite
of teeny weeny spindles having been the norm for over a century.

>
> Most of the 24mm spindles I have seen, and all of the 22mm spindles,
> have been made from hardened steel, like a square-taper.
>

you should go out more: Shimano 105, Tiagra, LX etc are all made out of
'Surinam Oak'!

/Marten

 

[M-gineering]

Chalo wrote:
> M-gineering wrote:
>> Chalo wrote:
>>> Most of the 24mm spindles I have seen, and all of the 22mm spindles,
>>> have been made from hardened steel, like a square-taper.
>> you should go out more: Shimano 105, Tiagra, LX etc are all made out of
>> 'Surinam Oak'!
>
> I'm not familiar with the term. Do you mean mild steel?
>

Surinam's main official export product is Bauxite, ie aluminium ore
/Marten