4mm screws that take 5mm Allen key? (thinly-disguised rant...)



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Guest
I'm setting up my new semi-custom FS. LBS said that
Thompson's super-duper stem was the only one that fit the
size/angle spec, so I said "OK".

I'm putting this thing together and grab my trusty 5mm allen
key that fits all the brake screws, the saddle adjustment
screws, the seatpost clamp screws....even the cap screw on
the steering tube.... and probably a few more things that
don't come to mind right now...

Oops...some genius has used 4mm screws on the Thompson
stem's clamp.

Understood that there's some sort of engineering manual
somewhere that says for such-and-so a load, 4mm is
sufficient.

But geeze!....knowing that 5mm fits just about everything
else - including a subassembly on the very part in
question....and 5mm would definately carry the load...what
kind of mentality would use 4mm? They do the same thing on
their seatposts. The *world* uses 5mm, but do they? Nooooo,
it's gotta be 4mm. What is it with these guys? Some kind of
engineer thing?

That's the rant part...

The question (I think I already know what the answer is
going to be...but what the heck?): is there any such thing
as 4mm bolts that take a 5mm key so I can get back on the
Good-Right-And-Holy path of as few tools needed as possible
for adjustments in the field?
--
PeteCresswell
 
> Oops...some genius has used 4mm screws on the Thompson
> stem's clamp.
>
> Understood that there's some sort of engineering manual
> somewhere that says for such-and-so a load, 4mm is
> sufficient.
>
> But geeze!....knowing that 5mm fits just about everything
> else - including a subassembly on the very part in
> question....and 5mm would definately carry the load...what
> kind of mentality would use 4mm? They do the same thing on
> their seatposts. The *world* uses 5mm, but do they?
> Nooooo, it's gotta be 4mm. What is it with these guys?
> Some kind of engineer thing?
>
> That's the rant part...
>
> The question (I think I already know what the answer is
> going to be...but what the heck?): is there any such thing
> as 4mm bolts that take a 5mm key so I can get back on the
> Good-Right-And-Holy path of as few tools needed as
> possible for adjustments in the field?

The only explanation I can come up with is that since there
are 4 bolts holding the face plate to that stem, they
decided to go with a smaller bolt to save weight. You see
the 2-bolt stems all have big thick bolts because they have
to bear twice the load.

I have Thomson stems on two of my bikes, and I have to
say... I'm not that impressed. They aren't that light and
they aren't that easy to adjust (4 bolt face plates are a
pain to torque properly without binding!). I don't like the
eccentric steerer clamp, as it, too, is more difficult to
adjust. They *do* say "Thomson" on them, but I see myself
going back to a lighter weight 2-bolt stem on my next bike.

As far as your question, I would hazard a guess that: NO,
they don't make 4mm bolts that have a 5mm head. Even if they
do, it seems unlikely the head would fit into the bored
holes in the face plate.

John M ...I like their seat posts though.

PS, doesn't your multi tool have both a 4mm and a 5mm in it?
 
(Pete Cresswell) wrote:
> I'm setting up my new semi-custom FS. LBS said that
> Thompson's super-duper stem was the only one that fit the
> size/angle spec, so I said "OK".
>
> I'm putting this thing together and grab my trusty 5mm
> allen key that fits all the brake screws, the saddle
> adjustment screws, the seatpost clamp screws....even the
> cap screw on the steering tube.... and probably a few more
> things that don't come to mind right now...
>
> Oops...some genius has used 4mm screws on the Thompson
> stem's clamp.
>
> Understood that there's some sort of engineering manual
> somewhere that says for such-and-so a load, 4mm is
> sufficient.
>
> But geeze!....knowing that 5mm fits just about everything
> else - including a subassembly on the very part in
> question....and 5mm would definately carry the load...what
> kind of mentality would use 4mm? They do the same thing on
> their seatposts. The *world* uses 5mm, but do they?
> Nooooo, it's gotta be 4mm. What is it with these guys?
> Some kind of engineer thing?
>
> That's the rant part...
>
> The question (I think I already know what the answer is
> going to be...but what the heck?): is there any such thing
> as 4mm bolts that take a 5mm key so I can get back on the
> Good-Right-And-Holy path of as few tools needed as
> possible for adjustments in the field?

Suck it up and carry a 4-mm; most multi-tools have
one, anyway.

Bill "new FSA carbon seatpost (roadie) also uses 4s" S.
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]...
> I'm setting up my new semi-custom FS. LBS said that
> Thompson's
super-duper
> stem was the only one that fit the size/angle spec, so I
> said "OK".
>
>

Should've bought a real Thomson stem. They still use 4mm hex
bolts but they're made a hell of a lot better than those
cheap Thompson knockoffs!!! ;^p''''

But seriously, suck it up like Sorni said and carry a 4mm.
Also make sure the steerer and the inside of the stem are
completely clean and free from any grease contamination.
Then grease the threads on the bolts in the clamp and put a
little grease under the head. Those little suckers bind
over time if put in dry and you'll have to drill 'em out to
get the stem off. Take turns tighening each one until the
torque needed is reached. The reverse is true when removing
if a bolt gets tight go back and snug the opposite one a
bit to free it.

Enjoy the stem, they really are the best.

Mike
 
Pete Cresswell says:

> is there any such thing as 4mm bolts that take a 5mm key

No, but if you grind/file the other end of your 5mm key down
to 4mm, you'll be all set (and it will be lighter, too...)

Steve ;-)
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]...
>
> The question (I think I already know what the answer is
> going to be...but
what
> the heck?): is there any such thing as 4mm bolts that take
> a 5mm key so I
can
> get back on the Good-Right-And-Holy path of as few tools
> needed as
possible for
> adjustments in the field?
> --
> PeteCresswell

Yeah.....those 4mm Allen keys sure are heavy... :p
 
RE/
>But seriously, suck it up like Sorni said and carry a 4mm.
>Also make sure the steerer and the inside of the stem are
>completely clean and free from any grease contamination.
>Then grease the threads on the bolts in the clamp and put a
>little grease under the head. Those little suckers bind
>over time if put in dry and you'll have to drill 'em out to
>get the stem off. Take turns tighening each one until the
>torque needed is reached. The reverse is true when removing
>if a bolt gets tight go back and snug the opposite one a
>bit to free it.
>
>Enjoy the stem, they really are the best.

I carry all that stuff in the form of a Crand Bro's multi-
tool...it was more the principle of the thing...like the
cars where they place the oil filter so you have go be a
controtionist to change it...or the oil fill thingie
where you have to hold the oil can out at arm's lengh to
fill it...

OTOH, this stem gives new meaning to the word "solid"....

How come there shouldn't be grease on the steerer tube?
--
PeteCresswell
 
RE/
>Yeah.....those 4mm Allen keys sure are heavy...

But if you're in the field, there's a diff between having to
fiddle with two tools and just one. Maybe not a huge diff,
but it's still two things to retrieve from the saddle pack,
two things to replace, and two things to avoid dropping in
the grass while fooling around with the stem and
simultaneously holding both tools, the cap screw, and the
spacers in one hand. I was more questioning the mentality of
a designer that ignores all that than complaining about an
extra allen key - which I have anyhow.

Too much coffee again, I guess.
--
PeteCresswell
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]...
> RE/
> >But seriously, suck it up like Sorni said and carry a
> >4mm. Also make
sure
> >the steerer and the inside of the stem are completely
> >clean and free from any grease contamination. Then grease
> >the threads on the bolts in the
clamp
> >and put a little grease under the head. Those little
> >suckers bind over
time
> >if put in dry and you'll have to drill 'em out to get the
> >stem off. Take turns tighening each one until the torque
> >needed is reached. The reverse
is
> >true when removing if a bolt gets tight go back and snug
> >the opposite one
a
> >bit to free it.
> >
> >Enjoy the stem, they really are the best.
>
> I carry all that stuff in the form of a Crand Bro's multi-
> tool...it was
more the
> principle of the thing...like the cars where they place
> the oil filter so
you
> have go be a controtionist to change it...or the oil fill
> thingie where
you have
> to hold the oil can out at arm's lengh to fill it...

I know, but if you look at the clamp pieces there isn't much
room for bigger bolts. I guess they decided on giving you
more material for strength rather than bigger bolts for
convienence.
>
> OTOH, this stem gives new meaning to the word "solid"....
>
> How come there shouldn't be grease on the steerer tube?

I had trouble with mine slipping after installing my new
fork. Apparently I got some grease on it when I passed it
through the headset. I cleaned it off and no more slipping.
That,and it says to do so in Step 4.
http://www.lhthomson.com/docs/stem_instr.pdf . ;^) The
clamp relies more on friction than constricting force to
hold the steerer.

Mike
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]... I was
more
> questioning the mentality of a designer that ignores all
> that than
complaining
> about an extra allen key - which I have anyhow.
>
> --
> PeteCresswell

I know, I know.... I was just being sarcastic.
Sarcasm....the lowest form of humour. You're spot on about
having to be a contortionist to remove oil filters.
Especially on Japanese cars. Maybe it's the Japs revenge
for Hiroshima? :)
 
"Curlb" <[email protected]> wrote in message news:40dde34c@news1...
>
> "(Pete Cresswell)" <[email protected]> wrote in message
> news:[email protected]... I
> was more
> > questioning the mentality of a designer that ignores all
> > that than
> complaining
> > about an extra allen key - which I have anyhow.
> >
> > --
> > PeteCresswell
>
>
> I know, I know.... I was just being sarcastic.
> Sarcasm....the lowest form of humour. You're spot on
> about having to be a contortionist to remove oil filters.
> Especially on Japanese cars. Maybe it's the Japs revenge
> for Hiroshima? :)

Ever try to remove a filter on a 96-02 cavailer/sunfire with
the 2.2l engine, and auto tranny.... instructions do include
"remove passenger side wheel...."

And thats a north american car....

Ford r worse... unless u like to have 3rd degree burns.

I agree with the statement about Jap ****...

Micheal
 
RE/
>news:[email protected]...

Ahhh! the coup de Grace: "WARNING: Use only specially-
designed Thomson shims with the Thompson Stem. Standard
shims will not work."

I'm guessing that "shims" are what I call "spacers".

What, are these guys on drugs?
--
PeteCresswell
 
RE/
> "WARNING:

It gets even better: "WARNING: Torque Wrench Required For
Assembly....".... well, I guess my comments about ease of
adjustment in the field were kind of off-base...
--
PeteCresswell
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]...
> RE/
> > "WARNING:
>
> It gets even better: "WARNING: Torque Wrench Required For
Assembly...."....
> well, I guess my comments about ease of adjustment in the
> field were kind
of
> off-base...
> --

Goddam Pete, just send the damn thing to me and buy a
Weyless stem!!!!! ;^)

You can fix it in the field if you have to. Just reset it at
home with the torque wrench.

Mike
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]...
> RE/
> > "WARNING:
>
> It gets even better: "WARNING: Torque Wrench Required For
Assembly...."....
> well, I guess my comments about ease of adjustment in the
> field were kind
of
> off-base...
> --
> PeteCresswell

Having stripped out a few 5mm stem clamp bolts, I welcome a
manufacturer who specifies torque for their fasteners.
 
You should just grind slots in all the fasteners on
your bike. That way you only have to carry a flat-
bladed screw-driver.
 
"(Pete Cresswell)" <[email protected]> wrote in message
news:[email protected]...
> RE/
> >Yeah.....those 4mm Allen keys sure are heavy...
>
> But if you're in the field, there's a diff between having
> to fiddle with
two
> tools and just one. Maybe not a huge diff, but it's still
> two things to retrieve from the saddle pack, two things to
> replace, and two things to
avoid
> dropping in the grass while fooling around with the
> stem and
simultaneously
> holding both tools, the cap screw, and the spacers in one
> hand. I was
more
> questioning the mentality of a designer that ignores all
> that than
complaining
> about an extra allen key - which I have anyhow.
>
> Too much coffee again, I guess.
> --
> PeteCresswell

You accuse the designer of ignoring all but do you actually
know anything about designing parts like stems? How do you
know they're not opting for smaller, higher strength bolts
in favor of some other design parameters - like better
clamp load distribution, less material needed at high
stress points, etc. I think the 4-bolt face plate on
Thomson stems is one of the best designs around for
applying handlebar clamp loads and in consideration of the
effects of a bolt failure.
 
KLydesdale wrote:
> "(Pete Cresswell)" <[email protected]> wrote in message
> news:[email protected]...
>> RE/
>>> "WARNING:
>>
>> It gets even better: "WARNING: Torque Wrench Required For
>> Assembly....".... well, I guess my comments about ease of
>> adjustment in the field were kind of off-base...
>> --
>> PeteCresswell
>
> Having stripped out a few 5mm stem clamp bolts, I welcome
> a manufacturer who specifies torque for their fasteners.

You mean you're actually supposed to /adhere/ to specs?!?

Bill "fascinating concept" S.
 
KLydesdale wrote:

> You should just grind slots in all the fasteners on
> your bike. That way you only have to carry a flat-
> bladed screw-driver.

Why? I'd rather just carry a multi-tool with the common size
hex wrenches in it.

John M
 
RE/
>You accuse the designer of ignoring all but do you actually
>know anything about designing parts like stems?

If you take everything I know about designing parts like
stems, roll it up into a ball, and place it on the edge of a
razor blade it will look like a golfball in the middle of
the New Jersey Turnpike.

> How do you know they're not opting for smaller, higher
> strength bolts in favor of some other design parameters -
> like better clamp load distribution, less material needed
> at high stress points, etc. I think the 4-bolt face plate
> on Thomson stems is one of the best designs around for
> applying handlebar clamp loads and in consideration of the
> effects of a bolt failure.

I was looking at it from the outside: commenting on the
designer's criteria for a good design - apparently favoring
things like you mention, but not considering ease of
maintainence.

--
PeteCresswell