Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Tapping M4 boss to M5

Notices
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.

Tapping M4 boss to M5

Old 10-19-21, 08:21 PM
  #1  
Tomm Willians
Senior Member
Thread Starter
 
Tomm Willians's Avatar
 
Join Date: Mar 2020
Location: Nevada County, California
Posts: 562

Bikes: Subject to change at any given moment but currently is...... Colnago Mapei, Colnago C40, Wilier Triestina Carbon, Wilier Triestina Ramato, Follis 472, Peugeot PX60, Razesa, Orbea Terra, Soma Pescadero and 1/2 owner of a Santana tandem.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 235 Post(s)
Liked 563 Times in 179 Posts
Tapping M4 boss to M5

Good evening all

I purchased some low profile M5 bolts for my bottle cages only to discover that Colnago apparently used an M4 at least at this time?. Iím fairly handy with tools but have never used a tap and die set, I assume I can re-tap these holes to M5 by simply running the appropriate cutter through the boss? Iíd hate to screw these up by finding out too late that itís not quite that straight forward
Tomm Willians is offline  
Old 10-19-21, 08:26 PM
  #2  
BCDrums
Recreational Road Cyclist
 
BCDrums's Avatar
 
Join Date: Sep 2013
Location: MetroWest, Mass.
Posts: 418

Bikes: 1990 Peter Mooney road bike

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 194 Post(s)
Liked 128 Times in 82 Posts
Originally Posted by Tomm Willians View Post
Good evening all

I purchased some low profile M5 bolts for my bottle cages only to discover that Colnago apparently used an M4 at least at this time?. Iím fairly handy with tools but have never used a tap and die set, I assume I can re-tap these holes to M5 by simply running the appropriate cutter through the boss? Iíd hate to screw these up by finding out too late that itís not quite that straight forward
Would seem easier to get some M4 bolts,
BCDrums is offline  
Old 10-19-21, 08:40 PM
  #3  
Tomm Willians
Senior Member
Thread Starter
 
Tomm Willians's Avatar
 
Join Date: Mar 2020
Location: Nevada County, California
Posts: 562

Bikes: Subject to change at any given moment but currently is...... Colnago Mapei, Colnago C40, Wilier Triestina Carbon, Wilier Triestina Ramato, Follis 472, Peugeot PX60, Razesa, Orbea Terra, Soma Pescadero and 1/2 owner of a Santana tandem.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 235 Post(s)
Liked 563 Times in 179 Posts
Originally Posted by BCDrums View Post
Would seem easier to get some M4 bolts,
Iíve looked for low profile blue anodized bolts in M4 but cannot find exactly what Iím looking for.
Tomm Willians is offline  
Old 10-19-21, 08:42 PM
  #4  
sweeks
Senior Member
 
sweeks's Avatar
 
Join Date: Sep 2004
Location: Chicago area
Posts: 2,010

Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"

Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 770 Post(s)
Liked 326 Times in 236 Posts
You'd have to drill out the bosses then tap the threads. If the frame is aluminum and the bosses are welded on, this might be possible, If the bosses are swaged in, or the frame is carbon, you might apply enough torque to cause the boss to spin. BCDrums' idea ^^ is much better.
sweeks is offline  
Likes For sweeks:
Old 10-19-21, 08:43 PM
  #5  
HillRider
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,262

Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!

Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 1821 Post(s)
Likes: 0
Liked 760 Times in 553 Posts
Originally Posted by BCDrums View Post
Would seem easier to get some M4 bolts,
+1. You can't just run an M5x0.8 tap through a threaded M4x0.7 hole without taking a great chance of breaking the tap, particularly if the bottle bosses are steel. If they are rivnuts, you stand a good chance of spinning the rivnut loose and then nothing will work.

You would have to drill out the existing holes with an M5 tap drill (4.2 mm or #19 drill bit) then tap new threads with an M5x0.8 mm tap.

Buying a few suitable M4 screws will be much easier and cheaper.
HillRider is offline  
Old 10-19-21, 09:16 PM
  #6  
krakhaus 
Senior Member
 
krakhaus's Avatar
 
Join Date: Sep 2012
Location: Palm Springs, California
Posts: 387
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 162 Post(s)
Liked 360 Times in 139 Posts
Ebay has some blue M4 bolt listings, but they're all in China. So, you could order those, or you could get some from the hardware store and hit them with this.

I've used it on a few things, and it looks just like anodizing if done right. Less durable, but if they ever chip, you can just do it again.
krakhaus is offline  
Likes For krakhaus:
Old 10-19-21, 09:18 PM
  #7  
due ruote 
Senior Member
 
due ruote's Avatar
 
Join Date: Dec 2006
Posts: 7,517
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 837 Post(s)
Liked 379 Times in 242 Posts
Thereís nothing worse than having something go sideways when you knew it was a bad idea to begin with.
I would just get some stainless M4 bolts. If it makes it easier you can just think of them as placeholders.
due ruote is offline  
Likes For due ruote:
Old 10-20-21, 12:03 AM
  #8  
Geepig
Senior Member
 
Geepig's Avatar
 
Join Date: Sep 2020
Location: Eastern Poland
Posts: 736

Bikes: Romet Jubilat x 4, Wigry x 1, Turing x 1

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 194 Post(s)
Liked 193 Times in 146 Posts
The tapping drill size for M5 is 4.2 mm, which is not much difference to the 4 mm thread root size of your M4, especially if you are going to have to hold the drill. You might get a nice pair of threaded holes, or you might not.
Geepig is offline  
Old 10-20-21, 05:01 AM
  #9  
TiHabanero
Senior Member
 
Join Date: Nov 2012
Posts: 3,790
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1417 Post(s)
Liked 844 Times in 449 Posts
If you simply store the bike with water bottles in place, then no one, including yourself, will see the bolts, and thus a potential problem has been averted. On one of my display bikes I have a "special to me" water bottle in place on the bike, and I will confirm the bottle bolts cannot be seen.
TiHabanero is offline  
Likes For TiHabanero:
Old 10-20-21, 05:48 AM
  #10  
fishboat
Senior Member
 
Join Date: Feb 2016
Location: SE Wisconsin
Posts: 1,470

Bikes: Lemond '01 Maillot Jaune, Lemond '02 Victoire, Lemond '03 Poprad, Lemond '03 Wayzata drop bar conv(Poprad), '79 AcerMex Windsor Carrera Professional(purchased new), '88 GT Tequesta(purchased new), '01 Bianchi Grizzly, 1993 Trek 970 drop bar conv

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 548 Post(s)
Likes: 0
Liked 472 Times in 279 Posts
There's probably more than a couple "silver" bolts on the bike. "Blue" must be pretty important to risk screwing up the holes in general. If they get messed up in the effort to make them M5...how's the next (post M5 re-work screw-up) bottle cage attachment going to look?

Some things matter..some don't. Put some silver M4 bolts in there, or paint the heads if you need to, and a week from now some other "thing" will capture your attention and the blue-bolt thing will be a distant, less important memory.
fishboat is offline  
Old 10-20-21, 05:58 AM
  #11  
BCDrums
Recreational Road Cyclist
 
BCDrums's Avatar
 
Join Date: Sep 2013
Location: MetroWest, Mass.
Posts: 418

Bikes: 1990 Peter Mooney road bike

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 194 Post(s)
Liked 128 Times in 82 Posts
Originally Posted by due ruote View Post
Thereís nothing worse than having something go sideways when you knew it was a bad idea to begin with.
It's a lesson I have learned. This would make a good signature!
BCDrums is offline  
Likes For BCDrums:
Old 10-20-21, 06:18 AM
  #12  
BCDrums
Recreational Road Cyclist
 
BCDrums's Avatar
 
Join Date: Sep 2013
Location: MetroWest, Mass.
Posts: 418

Bikes: 1990 Peter Mooney road bike

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 194 Post(s)
Liked 128 Times in 82 Posts
Originally Posted by Tomm Willians View Post
Iíve looked for low profile blue anodized bolts in M4 but cannot find exactly what Iím looking for.

https://www.probolt-usa.com/titanium...4x0-50mmx12mm/

This could be a candidate.
BCDrums is offline  
Likes For BCDrums:
Old 10-20-21, 06:20 AM
  #13  
hokiefyd 
Senior Member
 
hokiefyd's Avatar
 
Join Date: Feb 2017
Location: Northern Shenandoah Valley
Posts: 3,789

Bikes: '18 Redline Zander, '14 Surly Pugsley, '97 GT Vantara, '97 Trek MultiTrack 750, '70 Peugeot UO-18 Mixte

Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 1304 Post(s)
Liked 567 Times in 431 Posts
Originally Posted by BCDrums View Post
It's a lesson I have learned. This would make a good signature!
I second that, and liked the first mention of it. You already have this feeling that you're going down the wrong road. You already know it's the wrong approach and, for some reason, you can't turn back.

When you finally do screw it up...you get this empty feeling in your stomach, that feeling where you wish you had listened to that voice that told you not to proceed..
hokiefyd is offline  
Old 10-20-21, 06:52 AM
  #14  
Phil_gretz
Zip tie Karen
 
Phil_gretz's Avatar
 
Join Date: Aug 2009
Location: Fair Oaks Ranch, TX
Posts: 7,003

Bikes: '13 Motobecane Fantom29 HT, '16 Motobecane Turino Pro Disc, '16 Motobecane Gran Premio Elite, '18 Velobuild VB-R-022, '21 Tsunami SNM-100

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 1459 Post(s)
Liked 1,532 Times in 801 Posts
^ interesting observation. I think that a part of maturity is having the self control to resist the impulse to simply plunge forward with a plan that you know is unsound. I'm always so proud when those moments occur, and I step back from the abyss to reconsider my way. This has come with both age and mountains of mistakes along the way, though.
Phil_gretz is offline  
Old 10-20-21, 07:00 AM
  #15  
macstuff
Senior Member
 
Join Date: Jun 2021
Location: Tucson, Az.
Posts: 91

Bikes: A Blue One and 2 Green One's, then there's the Yellow one. And oh, yeah, a Black One. Did I mention the Red One?

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Liked 61 Times in 35 Posts
You can't just run a larger tap into a smaller thread to enlarge it, you would have to drill the old threads out first. (machinist drill register bit). Especially since the threaded bung you're talking about is probably no more that a few mm deep. It would just tear out the old threads and mess the hole up real good. the tap would have to be held firmly in a fixture as it turns to ensure it is going in straight. A long hole to be tapped is kind of self straightening for a hand tapping job but a shallow one will Hogg out.

Re-tapping the hole is a ruined frame waiting to happen.
If they make 5mm blue bolts, the same company makes 4mm blue bolts. Maybe not the packager you got the 5mm from, but the company that actually made them. Patience and looking around for the right bolts is the answer
Worst case scenarios:
Your bolt heads aren't blue
You ruin an expensive frame
macstuff is offline  
Likes For macstuff:
Old 10-20-21, 08:01 AM
  #16  
Tomm Willians
Senior Member
Thread Starter
 
Tomm Willians's Avatar
 
Join Date: Mar 2020
Location: Nevada County, California
Posts: 562

Bikes: Subject to change at any given moment but currently is...... Colnago Mapei, Colnago C40, Wilier Triestina Carbon, Wilier Triestina Ramato, Follis 472, Peugeot PX60, Razesa, Orbea Terra, Soma Pescadero and 1/2 owner of a Santana tandem.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 235 Post(s)
Liked 563 Times in 179 Posts
Originally Posted by BCDrums View Post
Thank you !
Tomm Willians is offline  
Old 10-20-21, 08:30 AM
  #17  
dsbrantjr
Senior Member
 
dsbrantjr's Avatar
 
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,229

Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta

Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1407 Post(s)
Liked 976 Times in 666 Posts
Originally Posted by Tomm Willians View Post
Iíve looked for low profile blue anodized bolts in M4 but cannot find exactly what Iím looking for.
If by "anodized" you mean aluminum, I avoid aluminum nuts and bolts (and spoke nipples) like the plague. They are weak and liable to both stripping and seizing, especially when mated to aluminum threads.
dsbrantjr is offline  
Likes For dsbrantjr:
Old 10-20-21, 06:58 PM
  #18  
sweeks
Senior Member
 
sweeks's Avatar
 
Join Date: Sep 2004
Location: Chicago area
Posts: 2,010

Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"

Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 770 Post(s)
Liked 326 Times in 236 Posts
Thanks for that source for titanium hardware! For several years I have purchased the odd titanium bits from Toronto Cycles and have been quite happy with their products. Sadly, the site seems to be closed since the pandemic started. I've replaced a lot of bolts, brake hardware, chainring bolts and crank hardware (below) with titanium on my "winter" bike... titanium doesn't corrode!


Original stainless steel hardware on the left; titanium replacements on the right,
sweeks is offline  
Old 10-20-21, 07:49 PM
  #19  
BCDrums
Recreational Road Cyclist
 
BCDrums's Avatar
 
Join Date: Sep 2013
Location: MetroWest, Mass.
Posts: 418

Bikes: 1990 Peter Mooney road bike

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 194 Post(s)
Liked 128 Times in 82 Posts
Originally Posted by sweeks View Post
For several years I have purchased the odd titanium bits from Toronto Cycles and have been quite happy with their products. Sadly, the site seems to be closed since the pandemic started.
I had bookmarked Toronto Cycles a few years back, never ordered from them, but they had a great website for colored, anodized connectors. When I saw Tomm's post I looked them up and was sorry to see that they had closed during the pandemic, and maybe permanently, who knows? It must be hard to make a business from customers who order two or four water bottle bolts.
BCDrums is offline  
Likes For BCDrums:

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.