Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 09-12-05, 02:04 AM   #1
Todd Richards
GranitCurbVia53x11Sprint
Thread Starter
 
Todd Richards's Avatar
 
Join Date: Oct 2004
Location: rocky beautiful coast of Maine
Bikes: Cervelo R2.5 Campy Record 10, Dean Ti 'Cross, Merlin Agilis (road), Litespeed Obed (mb), Basso (ss/fixie)
Posts: 186
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
31.7 bar 31.8 stem will it fit?

Deda Newton 31.7 diameter bar and a new Thomson X-2 31.8 diameter stem.... is this so close it doesn't matter? Please nobody write "It should work" without previous experience, I'll be haulin' on this thing in field sprints... need to know for sure from somebody that's done the same....

todd richards (NEW Merlin Agilis with Campy ! )
Todd Richards is offline   Reply With Quote
Old 09-12-05, 06:03 AM   #2
shane45
Ouch!!!
 
Join Date: Apr 2005
Location: Canada
Bikes:
Posts: 453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Anything will work if you bend, squeeze, twist, or distort two pieces together with enough force.

Why you would want to do this is beyond me however. You clearly know that the two sizes do not match, and yet you want to use them anyway? And not only use them, but RACE with them??!!!
shane45 is offline   Reply With Quote
Old 09-12-05, 06:37 AM   #3
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Bikes:
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
^^^^.....Actually, the two are close enough to be considered interchangable.
sydney is offline   Reply With Quote
Old 09-12-05, 06:44 AM   #4
shane45
Ouch!!!
 
Join Date: Apr 2005
Location: Canada
Bikes:
Posts: 453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
"Close enough" is for hand grenades. I prefer my components to match exactly, especially if I'm racing with them.
shane45 is offline   Reply With Quote
Old 09-12-05, 06:48 AM   #5
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Bikes:
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
^^^^....Sure
sydney is offline   Reply With Quote
Old 09-12-05, 06:50 AM   #6
juicemouse
Senior Member
 
juicemouse's Avatar
 
Join Date: Mar 2005
Location: Happy Valley
Bikes:
Posts: 813
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by shane45
"Close enough" is for hand grenades. I prefer my components to match exactly, especially if I'm racing with them.
So you're one of those types that only uses a bar and stem from the same manufacturer, then? Your fears are ungrounded.
__________________
It is my belief that every person in this world has something to teach, and everything to learn.

In memory of Jim Price (aka. sydney) ...
juicemouse is offline   Reply With Quote
Old 09-12-05, 06:55 AM   #7
Map tester
I am not a car
 
Map tester's Avatar
 
Join Date: May 2004
Location: Decatur, GA
Bikes: Giant Revel 1, Surly Ogre
Posts: 747
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
From Inside Traiathalon, full article link

Making it work: Have a brew, fix your bike
By Lennard Zinn
Inside Triathlon technical writer
This report filed December 10, 2002
A can of beer always helps to make problems seem less important, but sometimes, it can actually fix bike problems! Aluminum beverage cans are 0.1mm thick and are easy to cut with a knife or a pair of scissors, rendering them quite useful for making minor spacing adjustments on a bike.
__________________
"Bad facts make bad laws." FZ
Map tester is offline   Reply With Quote
Old 09-12-05, 07:13 AM   #8
AndrewP
Senior Member
 
Join Date: Sep 2001
Location: Montreal
Bikes: Peugeot Hybrid, Minelli Hybrid
Posts: 6,521
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
A beer can shim will give .2 mm increase in diameter which is twice the amount needed. Stem are supposed to be tightened down onto the bars. The .1 mm reduction will be within the elastic limit of the stem deformation so go ahead and do it.
AndrewP is offline   Reply With Quote
Old 09-12-05, 08:10 AM   #9
Gomez308
Senior Member
 
Gomez308's Avatar
 
Join Date: Oct 2004
Location: GA
Bikes:
Posts: 365
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
.1 millimeters = 0.00393700787 inches
I doubt anyone's tolerences are that close anyway.
Gomez308 is offline   Reply With Quote
Old 09-12-05, 08:12 AM   #10
shane45
Ouch!!!
 
Join Date: Apr 2005
Location: Canada
Bikes:
Posts: 453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by juicemouse
So you're one of those types that only uses a bar and stem from the same manufacturer, then?
No - I'm one of those types that makes sure my handlebar diameter matches the nominal stem size.
shane45 is offline   Reply With Quote
Old 09-12-05, 08:26 AM   #11
Nessism
Senior Member
 
Nessism's Avatar
 
Join Date: Jun 2004
Location: Torrance, CA
Bikes: Homebuilt steel
Posts: 2,332
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This question comes up every so often and I get a laugh out of the worry worts

The REAL size of the bars is 1-1/4 INCH. When converted to metric units this works out to 31.75 mm. Some companies round off this number to 31.7 and others round to 31.8. Key thing is that both are the SAME.

Keep it real please.

Ed
Nessism is offline   Reply With Quote
Old 09-12-05, 08:33 AM   #12
juicemouse
Senior Member
 
juicemouse's Avatar
 
Join Date: Mar 2005
Location: Happy Valley
Bikes:
Posts: 813
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by shane45
No - I'm one of those types that makes sure my handlebar diameter matches the nominal stem size.
As Gomez308 points out, most manufacturers (possibly Thompson excepted) don't hold that tight a tolerance on the clamp diameter, so even if you match nominal specs from different manufacturers it's entirely possible to end up with more than a 0.1mm mismatch. This really isn't an issue at all, unless you're neurotic. I'd bet that having 4 bolts instead of 2 makes much more of a practical/functional difference.
__________________
It is my belief that every person in this world has something to teach, and everything to learn.

In memory of Jim Price (aka. sydney) ...
juicemouse is offline   Reply With Quote
Old 09-12-05, 08:36 AM   #13
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Bikes:
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Nessism
This question comes up every so often and I get a laugh out of the worry worts

The REAL size of the bars is 1-1/4 INCH. When converted to metric units this works out to 31.75 mm. Some companies round off this number to 31.7 and others round to 31.8. Key thing is that both are the SAME.

Keep it real please.

Ed
You are kidding.... right? What would the muppets do to entertain themselves? Actual measurement of some TTTs advertized as 31.8, showed mesurements of 31.8,31.85 and almost 31.9.

Last edited by sydney; 09-12-05 at 08:57 AM.
sydney is offline   Reply With Quote
Old 09-12-05, 09:40 AM   #14
rufvelo
Senior Member
 
rufvelo's Avatar
 
Join Date: Jun 2005
Bikes:
Posts: 4,202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It's true. The manufacuring tolerances are such that very often 31.7 thru 31.9 are all the same specification. You're lucky if the bar and especially the stem is perfectly rounded
rufvelo is offline   Reply With Quote
Old 09-12-05, 09:41 AM   #15
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Bikes:
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Nessism

The REAL size of the bars is 1-1/4 INCH. When converted to metric units this works out to 31.75 mm. Some companies round off this number to 31.7 and others round to 31.8. Key thing is that both are the SAME.
I've heard that story.Makes one wonder why a manufacturer not in the US woud pick 11/4" as a 'standard'? Another story is that 31.7 was introduced by deda,but most othwers go with 31.8.
sydney is offline   Reply With Quote
Old 09-12-05, 09:57 AM   #16
Nessism
Senior Member
 
Nessism's Avatar
 
Join Date: Jun 2004
Location: Torrance, CA
Bikes: Homebuilt steel
Posts: 2,332
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It's not unusal for the bike industry to pick standards around BSA units; a couple of big ones that come to mind are steerer tube sizes and frame tubing sizes: 22.2mm = 7/8", 25.4mm = 1", 28.6mm = 1-1/8", 31.75mm = 1-1/4", 35mm = 1-3/8"
Nessism is offline   Reply With Quote
Old 09-12-05, 10:01 AM   #17
sydney
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Bikes:
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Nessism
It's not unusal for the bike industry to pick standards around BSA units; a couple of big ones that comes to mind are steerer tube sizes and frame tubing sizes: 22.2mm = 7/8", 25.4mm = 1", 28.6mm = 1-1/8", 31.75mm = 1-1/4", 35mm = 1-3/8"
And that all happened long ago too.
sydney is offline   Reply With Quote
Old 09-12-05, 10:29 AM   #18
poopncow
MADE IN HONG KONG
 
Join Date: Aug 2005
Location: Washington DC
Bikes: some but not enough
Posts: 1,763
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ah... manufacture tolerances....mmmmmm.....elastic deformation......ohhhhh.... metric SAE conversions...... 5.56.....7.62....yummy

Not sure if this is how the bike people do it, but if my guys don't do this....watch out!

The internal diameter of the clamp should alway be slightly bigger than the ouside diameter than the bar. there is a gap between the face plate and the stem or a gap in the ID on the stem. Cranking down on the screws closes the gap is reduced . But wait, the clamp does not grip the bar completely all around. This is esp true with open face plates. What ends up happening is that the front and back of the bar is in contact with the front of the face plate and the back of the stem, and that is it! There is hardly contact all around. This is enough to hold every thing together. So if the tolerance of the 31.7 bar can go as high as 31.9, the stem would be 31.95 (or such). And the lower end tolerence of the bar may be 37.6! Stacking tolerences, there can be .35mm delta ! (just throwing out numbers, not stating that they are the case) . A bar and clamp is good as long as the contact between the bar and clamp occurs at the front and back. (ok, the face plate and stem deforms a bit and wraps itself around the bar some) If the bar is bigger than the ID of the clamp, the contact is not fore and aft, but at the top and bottom (near the split line) and will hold up the clamp. Eventually, as the metal deforms, it'll loosen up again. If the difference is larger than some number, the joint will never clamp right.
poopncow is offline   Reply With Quote
Old 09-12-05, 11:04 AM   #19
bandregg
Senior Member
 
Join Date: Jul 2004
Location: Knoxville, TN
Bikes: 2008 ANT Custom 29er, 2005 Independent Fabrications Club Racer, 2004 Specialized Langster S-Works, 2001 Litespeed Tuscany, 2004 Titus Racer-X
Posts: 185
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I ride Dade Pista handlebars which is listed as 31.7 on an FSA OS-115 stem which is listed as 31.8. I race this and with properm torque haven't had any movement at all.
bandregg is offline   Reply With Quote
Old 09-12-05, 08:53 PM   #20
Moose
mousse de chocolat
 
Moose's Avatar
 
Join Date: Jul 2001
Location: Northeast Ohio, USA
Bikes: Masi Speciale Fixed, Fuji America Fixed, "Modernized" Gitane
Posts: 1,141
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by bandregg
I ride Dade Pista handlebars which is listed as 31.7 on an FSA OS-115 stem which is listed as 31.8. I race this and with properm torque haven't had any movement at all.
Hallelujah! Just what the OP asked for.
__________________
I feel more like I do now than when I first got here.
Moose is offline   Reply With Quote
Old 09-12-05, 10:30 PM   #21
poopncow
MADE IN HONG KONG
 
Join Date: Aug 2005
Location: Washington DC
Bikes: some but not enough
Posts: 1,763
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
That would have been too easy!
poopncow is offline   Reply With Quote
Old 11-20-13, 04:17 AM   #22
Constantin23482
Newbie
 
Join Date: Nov 2013
Bikes:
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by shane45 View Post
"Close enough" is for hand grenades. I prefer my components to match exactly, especially if I'm racing with them.
Haha wow! I really don't know what to say. You post this propaganda and expect people to believe you? And now that you know that you are wrong you don't even apologise for spreading the wrong information. Do you even know what a millimeter is over there? It is a 0.1 mm difference!!!!!!!!!!!!!!!!!!!!!!!!
Constantin23482 is offline   Reply With Quote
Old 11-20-13, 08:06 AM   #23
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Posts: 28,844
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 66 Post(s)
Quote:
Originally Posted by Nessism View Post
This question comes up every so often and I get a laugh out of the worry worts

The REAL size of the bars is 1-1/4 INCH. When converted to metric units this works out to 31.75 mm. Some companies round off this number to 31.7 and others round to 31.8. Key thing is that both are the SAME.

Keep it real please.

Ed
+1 This is exactly right and I always thought Deda was boarder line fraudulent in calling their bars and stems 31.7 when everyone else calls them 31.8. They made some riders think, just like this thread shows, they HAD to buy their stems too and that's not correct. It is indeed a rounding change, not a dimensional difference.

As Nessism further notes, Imperial measurements are very common in the bike industry, even from European or Asian makers and designers.
HillRider is offline   Reply With Quote
Old 11-20-13, 09:38 AM   #24
Darth Lefty 
Disco Infiltrator
 
Darth Lefty's Avatar
 
Join Date: May 2013
Location: Orangevale CA
Bikes: '76 Paramount, 02 Hardrock, '98 C'Dale XR800, '04 Burley Samba, '15 Priority Classic
Posts: 5,690
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 104 Post(s)
Don't try and worry what the diameter of the bar is after you cinch down the stem on it.
Darth Lefty is offline   Reply With Quote
Old 11-20-13, 10:27 AM   #25
Crankycrank
Senior Member
 
Join Date: Jan 2009
Location: San Diego, CA
Bikes:
Posts: 717
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Quote:
Originally Posted by bandregg View Post
I ride Dade Pista handlebars which is listed as 31.7 on an FSA OS-115 stem which is listed as 31.8. I race this and with properm torque haven't had any movement at all.
This. Similar setup for me. 31.7 bars in a 31.8 stem. After five years there has been no movement, no problems. I undo the mounting bolts to re-grease every year and have never found any type of unusual marks or damage on the bar clamping area.
Crankycrank is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 11:28 PM.