Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

Press Fit Bottom Bracket

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Press Fit Bottom Bracket

Old 09-07-21, 09:34 PM
  #1  
Trek1100FeltZ5
Newbie
Thread Starter
 
Join Date: Sep 2021
Location: Omaha, NE
Posts: 12

Bikes: Felt Z5

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 6 Times in 5 Posts
Press Fit Bottom Bracket

Do I want to avoid a new bike using a press fit bottom bracket?
Trek1100FeltZ5 is offline  
Old 09-07-21, 09:57 PM
  #2  
10 Wheels
Galveston County Texas
 
10 Wheels's Avatar
 
Join Date: Nov 2007
Location: In The Wind
Posts: 32,773

Bikes: 02 GTO, 2011 Magnum

Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 1247 Post(s)
Liked 975 Times in 487 Posts
How Much $$$ is the bike?
__________________
Fred "The Real Fred"

10 Wheels is online now  
Old 09-08-21, 08:03 AM
  #3  
Trek1100FeltZ5
Newbie
Thread Starter
 
Join Date: Sep 2021
Location: Omaha, NE
Posts: 12

Bikes: Felt Z5

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 6 Times in 5 Posts
$4200
Trek1100FeltZ5 is offline  
Old 09-08-21, 09:16 AM
  #4  
10 Wheels
Galveston County Texas
 
10 Wheels's Avatar
 
Join Date: Nov 2007
Location: In The Wind
Posts: 32,773

Bikes: 02 GTO, 2011 Magnum

Mentioned: 18 Post(s)
Tagged: 0 Thread(s)
Quoted: 1247 Post(s)
Liked 975 Times in 487 Posts
I put 39,000 miles on a Felt 85
__________________
Fred "The Real Fred"

10 Wheels is online now  
Old 09-08-21, 01:32 PM
  #5  
Trek1100FeltZ5
Newbie
Thread Starter
 
Join Date: Sep 2021
Location: Omaha, NE
Posts: 12

Bikes: Felt Z5

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Liked 6 Times in 5 Posts
Thank you
Trek1100FeltZ5 is offline  
Old 09-08-21, 02:30 PM
  #6  
cb400bill
Forum Moderator
 
cb400bill's Avatar
 
Join Date: Jul 2007
Location: Kalamazoo MI
Posts: 20,616

Bikes: Fuji SL2.1 Carbon Di2 Cannondale Synapse Alloy 4 Trek Checkpoint ALR gravel Viscount Aerospace Pro Colnago Classic Rabobank

Mentioned: 54 Post(s)
Tagged: 0 Thread(s)
Quoted: 2806 Post(s)
Liked 4,885 Times in 2,892 Posts
Thread moved from Introductions to Road.
__________________
Originally Posted by Retro Grouch View Post
Fenders protect you from tire splatter. Mudguards protect you from tyre splatter.







cb400bill is offline  
Old 09-08-21, 02:33 PM
  #7  
datlas 
Should Be More Popular
 
datlas's Avatar
 
Join Date: Dec 2007
Location: Malvern, PA (20 miles West of Philly)
Posts: 39,388

Bikes: 1986 Alpine (steel road bike), 2009 Ti Habenero, 2013 Specialized Roubaix

Mentioned: 535 Post(s)
Tagged: 2 Thread(s)
Quoted: 19054 Post(s)
Liked 5,803 Times in 2,847 Posts
Controversial topic. Life will be simpler with a threaded BB, but it should not be a deal-breaker necessarily.
__________________
Originally Posted by rjones28 View Post
Addiction is all about class.
datlas is online now  
Old 09-08-21, 02:36 PM
  #8  
shelbyfv
Expired Member
 
shelbyfv's Avatar
 
Join Date: Jun 2007
Location: TN
Posts: 10,140
Mentioned: 32 Post(s)
Tagged: 0 Thread(s)
Quoted: 3012 Post(s)
Liked 3,923 Times in 1,999 Posts
Major manufacturers are moving away from press fit. There are plenty of choices now with threaded. If you are dead set on a particular bike with press fit, investigate whether one of the threaded work arounds exists for that bike. If so, lay one in for the future.
shelbyfv is offline  
Likes For shelbyfv:
Old 09-08-21, 03:00 PM
  #9  
deacon mark
Senior Member
 
Join Date: Sep 2009
Posts: 1,885

Bikes: Habanero Titanium Team Nuevo

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 357 Post(s)
Liked 154 Times in 104 Posts
I will not buy a bike with press fit BB they are a pain at times and need much more regular service. A threaded BB is a thing of beauty and ease of use in some cases lasting many years and miles.
deacon mark is offline  
Old 09-08-21, 03:11 PM
  #10  
Iride01 
Plz hurry Dec 22!
 
Iride01's Avatar
 
Join Date: Jul 2017
Location: Mississippi
Posts: 11,888

Bikes: Tarmac Disc Comp Di2 - 2020

Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 4866 Post(s)
Liked 3,387 Times in 2,349 Posts
I wouldn't let the BB type determine what bike you get. Many other things are more important.

If I had the choice between two bikes that I considered equal in every other way and one was a threaded BB and the other press fit, then I'd choose the one with the threaded BB.

However if the bike with the press fit was a prettier color, then hands down I'd go for the press fit!
Iride01 is offline  
Likes For Iride01:
Old 09-08-21, 03:18 PM
  #11  
PeteHski
Senior Member
 
PeteHski's Avatar
 
Join Date: May 2021
Posts: 3,840
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 1813 Post(s)
Liked 1,994 Times in 1,270 Posts
It has never been a big deal for me. I currently have one bike threaded and one press fit. Both are hassle free. Previous bike was press fit too and had no issues.
PeteHski is online now  
Likes For PeteHski:
Old 09-08-21, 04:09 PM
  #12  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 11,673

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T-Lab X3

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 2174 Post(s)
Liked 1,211 Times in 742 Posts
There can be alignment issues with monocoque carbon fiber constructions and pressfits, but they’re neither common nor insurmountable, either on the production end or user end. Metal frames are easier to manufacture in this sense.

All things equal, it doesn’t matter what the BB type is.
chaadster is offline  
Likes For chaadster:
Old 09-08-21, 07:27 PM
  #13  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 1,410

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 849 Post(s)
Liked 342 Times in 246 Posts
Avoid BB90. The rest are probably ok. Just get a thread-together or one-piece BB and avoid the $20 plastic junk.
smashndash is offline  
Likes For smashndash:
Old 09-08-21, 08:05 PM
  #14  
Koyote
Senior Member
 
Join Date: Sep 2017
Posts: 6,060
Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 5567 Post(s)
Liked 8,457 Times in 3,656 Posts
There are plenty of good threaded BB bikes out there, with more mfrs going back to them all the time. If it is a worry for you, you should just go threaded.
Koyote is online now  
Likes For Koyote:
Old 09-09-21, 03:47 AM
  #15  
Lazyass
Senior Member
 
Join Date: Jul 2008
Location: Minas Ithil
Posts: 9,335
Mentioned: 66 Post(s)
Tagged: 0 Thread(s)
Quoted: 2430 Post(s)
Liked 628 Times in 388 Posts
If you have a frame with a press fit shell you can run an adapter. After all my trials and tribulations with BB30, mainly creaking, I've come to the conclusion that not all bearings are manufactured to the perfect spec. I finally have a set of bearings that are silent with no locktite, the ones that came with my Kuota carbon cranks. As far as installation, ect, after awhile you get it down like anything else. I have no problems working on them now and whoever said they need much more regular maintenance is wrong. After you get them properly installed and silent you can ride thousands upon thousands of miles and not have to touch them.

If I had to choose one or the other I wouldn't choose press fit but it wouldn't be a deal breaker.
Lazyass is offline  
Likes For Lazyass:
Old 09-09-21, 04:13 AM
  #16  
Troul 
:D
 
Troul's Avatar
 
Join Date: Oct 2013
Location: Mich
Posts: 5,937

Bikes: RSO E-tire dropper fixie brifter

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 2,067 Times in 1,386 Posts
if the bb pf30 i use could have came with threads instead & contain the same crank arm install assembly, it might be the real chicken dinner for me. not the case, so I just anticipate replacing the pf30 more often than the threaded stuff. I haven't tried anything more expensive other than the OEM pf30 unit, so I probably am making more scheduled work in the end. 15 minutes & $15 isn't too much to clean, swap, & lube it for the scheduled work...
__________________
-Oh Hey!
Troul is offline  
Old 09-09-21, 05:12 AM
  #17  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 11,673

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T-Lab X3

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 2174 Post(s)
Liked 1,211 Times in 742 Posts
Whether you pressfit cups into the frame or thread them in, the bearings are always pressfit. If it’s good for the goose, it’s good for the gander… Any issues are to do with design and manufacturing, not with the nature of pressfit. Threaded BB inserts can just as easily be misaligned in carbon fiber monocoque if the design (engineering) isn’t good.
chaadster is offline  
Old 09-10-21, 10:54 AM
  #18  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 1,410

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 849 Post(s)
Liked 342 Times in 246 Posts
Originally Posted by chaadster View Post
Whether you pressfit cups into the frame or thread them in, the bearings are always pressfit. If it’s good for the goose, it’s good for the gander… Any issues are to do with design and manufacturing, not with the nature of pressfit. Threaded BB inserts can just as easily be misaligned in carbon fiber monocoque if the design (engineering) isn’t good.
This is meaningless. It's way, way easier to get the tolerances on a machined plastic or meta part right than a molded carbon shell. Yes, press fit is not inherently a problem. But pretty much 0 bike manufacturers are capable of consistently nailing press-fit bottom bracket tolerances. The best PF BB shells are machined alloy. This is what Look does.

so when someone says "press fit bad", they're obviously not saying that the entire concept of press fit is bad. They're saying that much of the time, the manufacturer is going to screw it up and you're going to need help. And that comes from an adapter of some sort.
smashndash is offline  
Old 09-10-21, 10:59 AM
  #19  
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 11,673

Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée, '17 Dedacciai Gladiatore2, '12 Breezer Venturi, '09 Dahon Mariner, '12 Mercier Nano, '95 DeKerf Team SL, '19 Tern Rally, ‘21 Breezer Doppler Cafe+, ‘19 T-Lab X3

Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 2174 Post(s)
Liked 1,211 Times in 742 Posts
Originally Posted by smashndash View Post
This is meaningless. It's way, way easier to get the tolerances on a machined plastic or meta part right than a molded carbon shell. Yes, press fit is not inherently a problem. But pretty much 0 bike manufacturers are capable of consistently nailing press-fit bottom bracket tolerances. The best PF BB shells are machined alloy. This is what Look does.

so when someone says "press fit bad", they're obviously not saying that the entire concept of press fit is bad. They're saying that much of the time, the manufacturer is going to screw it up and you're going to need help. And that comes from an adapter of some sort.
I guess people should say what they mean. I do and did.
chaadster is offline  
Likes For chaadster:
Old 09-13-21, 06:59 AM
  #20  
Hiro11
Senior Member
 
Join Date: Jun 2010
Posts: 2,573

Bikes: To the right: opinions, not facts.

Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 754 Post(s)
Liked 419 Times in 217 Posts
I had been vehemently anti-press fit for years. I wouldn't buy a bike with a press fit BB... then I bought a bike with press fit. I currently have two bikes with press fit, neither has been an issue over many thousands of miles. I've been persuaded that (properly manufactured) press-fit is just fine. It's worth noting that every other bearing in the entire world is press fit, apparently other industries can figure this out.

I think one major factor in the negative press around press fit is that some of the largest brands (notably Trek, Specialized and Cannondale) are also some of the worst at properly manufacturing press fit BB shells. Also, some standards (example: BB86) seem less reliant on perfect tolerances than others. Having said that I have a cross bike with the supposedly awful BB30 bottom bracket. I haven't had to touch that BB30 (notably high quality NTN bearings in a precisely made titanium shell) since 2017 despite riding it through countless rain storms, mud pits, dust clouds etc. It still turns smooth as silk. In that time, I've replaced two threaded bottom brackets on my (significantly cheaper) gravel/adventure bike. So, I don't know what to believe.
Hiro11 is offline  
Likes For Hiro11:
Old 09-13-21, 08:44 AM
  #21  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 1,410

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 849 Post(s)
Liked 342 Times in 246 Posts
Originally Posted by Hiro11 View Post
So, I don't know what to believe.
It seems that you have a pretty nuanced grasp of the situation. Pressfit vs threaded is not what determines the quality of a bottom bracket. Just like how frame material doesn't determine the quality of a bike.

The optimal race bike would use pressfit. Either BB86 for shimano or BB386 for DUB/30mm. It's lighter, stiffer and theoretically allows for better alignment. There is no doubt about that. The only ? is how you would achieve the tolerances required for optimal performance on a carbon frame. With threaded, there is a floor on how bad the frame can be because you have to put in metal inserts and tap them. The tap won't fit if the hole is 1mm undersized. Plus you can safely machine metal to pretty precise tolerances.

I'll go as far as to say that BSA is a suboptimal solution for the modern race bike. There are 3 reasons for this.

1) BSA is not accommodating of 30mm spindles. BSA 30 bottom brackets use less material than BSA (24) to be able to slip a 30mm spindle through. This leads to less stiffness.

2) threaded adds weight. PF has less redundant material in the bottom bracket area. I think I've seen people claim a delta of about 100g.

3) outboard bearings are generally not a great idea. Yes, pulling the bearings outboard on a BSA shell from square taper to a 24 or even 30mm spindle allows for a lighter, stiffer overall setup. But you're not going to match the stiffness to weight ratio of an inboard T47 setup like what Trek uses. And definitely not the stiffness to weight ratio of something like BB386EVO.

That being said... these are all EXTREMELY marginal issues compared to the plague that is poor manufacturing. You'd be hard pressed to notice any of these issues on a perfectly manufactured BSA 30 bike vs a BB386EVO bike.

Overall... we should be pushing manufacturers to adhere to tight tolerances and should hold them accountable when they sell multi-thousand dollar frames that are out of whack. The specific standard they use is far less relevant than most people believe.
smashndash is offline  
Likes For smashndash:
Old 09-13-21, 10:44 AM
  #22  
Troul 
:D
 
Troul's Avatar
 
Join Date: Oct 2013
Location: Mich
Posts: 5,937

Bikes: RSO E-tire dropper fixie brifter

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked 2,067 Times in 1,386 Posts
never had a pf bearing fail. the plastic shell is what gives up on the assembly ime. OEM stock bicycle with a pf30 FSA bb cracked around the pf30's lip & sent it in the bb.
__________________
-Oh Hey!
Troul is offline  
Old 09-13-21, 04:37 PM
  #23  
Point
Senior Member
 
Join Date: Mar 2005
Posts: 428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Liked 15 Times in 11 Posts
Originally Posted by smashndash View Post
It seems that you have a pretty nuanced grasp of the situation. Pressfit vs threaded is not what determines the quality of a bottom bracket. Just like how frame material doesn't determine the quality of a bike.

The optimal race bike would use pressfit. Either BB86 for shimano or BB386 for DUB/30mm. It's lighter, stiffer and theoretically allows for better alignment. There is no doubt about that. The only ? is how you would achieve the tolerances required for optimal performance on a carbon frame. With threaded, there is a floor on how bad the frame can be because you have to put in metal inserts and tap them. The tap won't fit if the hole is 1mm undersized. Plus you can safely machine metal to pretty precise tolerances.

I'll go as far as to say that BSA is a suboptimal solution for the modern race bike. There are 3 reasons for this.

1) BSA is not accommodating of 30mm spindles. BSA 30 bottom brackets use less material than BSA (24) to be able to slip a 30mm spindle through. This leads to less stiffness.

2) threaded adds weight. PF has less redundant material in the bottom bracket area. I think I've seen people claim a delta of about 100g.

3) outboard bearings are generally not a great idea. Yes, pulling the bearings outboard on a BSA shell from square taper to a 24 or even 30mm spindle allows for a lighter, stiffer overall setup. But you're not going to match the stiffness to weight ratio of an inboard T47 setup like what Trek uses. And definitely not the stiffness to weight ratio of something like BB386EVO.

That being said... these are all EXTREMELY marginal issues compared to the plague that is poor manufacturing. You'd be hard pressed to notice any of these issues on a perfectly manufactured BSA 30 bike vs a BB386EVO bike.

Overall... we should be pushing manufacturers to adhere to tight tolerances and should hold them accountable when they sell multi-thousand dollar frames that are out of whack. The specific standard they use is far less relevant than most people believe.
So, why is press fit “optimal”? There has been no correlation shown between any measure of stiffness and efficiency. Numerous threads on this site have been dedicated to that one. Weight maybe, but we’re talking about pretty small amounts when the bike and rider are taken in account as a whole. A 100 gram savings for a 160 lb rider/bike combination is a 0.137% advantage, and then only really on climbs. A BSA bottom bracket is limited to the diameter of the axle as you stated. A 24 mm axle is stiffer torsionally than say an old 17 mm square taper (higher “J” value), but any amount of “wind-up” (very small) in the axle will be returned with essentially no loss of energy during the pedal stroke. As for external bearings, they don’t add anything to stiffness since that is a function of the frame construction, not the location of the bearings in the BB area.
Point is offline  
Old 09-13-21, 04:54 PM
  #24  
smashndash
Senior Member
 
Join Date: Feb 2018
Posts: 1,410

Bikes: 2017 Specialized Allez Sprint Comp

Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 849 Post(s)
Liked 342 Times in 246 Posts
Originally Posted by Point View Post
So, why is press fit “optimal”? There has been no correlation shown between any measure of stiffness and efficiency. Numerous threads on this site have been dedicated to that one. Weight maybe, but we’re talking about pretty small amounts when the bike and rider are taken in account as a whole. A 100 gram savings for a 160 lb rider/bike combination is a 0.137% advantage, and then only really on climbs. A BSA bottom bracket is limited to the diameter of the axle as you stated. A 24 mm axle is stiffer torsionally than say an old 17 mm square taper (higher “J” value), but any amount of “wind-up” (very small) in the axle will be returned with essentially no loss of energy during the pedal stroke. As for external bearings, they don’t add anything to stiffness since that is a function of the frame construction, not the location of the bearings in the BB area.
For a metal bike, sure. Jan Heine also makes the same "planing" argument where he claims that the springiness of a flexy metal bike will allow you to go faster. But we can agree that the optimal race bike is probably made of carbon right? And not metal? Which means that you can throw your ideas about energy return out the window. Carbon doesn't return energy the same way metal does. If you made a carbon frame as flexy as an old steel bike, it would feel like wooden garbage.

lighter is always better holding all things equal. I shouldn't have to explain more.

A wider bearing stance has some benefits, but yes. Moving the cups themselves outboard doesn't help with stiffness. The only purpose of that was to make room for a 24mm spindle. That's my point. BSA is a hack because it doesn't allow for the frame to fully optimize the construction wrt the bearing stance. An optimal race frame would use something like T47 (Trek) where the frame itself has a wider shell and the bearing stance is also wider.

Also I will disagree that torsional stiffness is the only benefit of a larger spindle. You also have a regular ol bending moment. Sure, with an infinitely stiff frame, this wouldn't matter. But a stiffer spindle will do a better job of transferring the load across the shell and will thus keep the bearings in alignment. At least, that's what I think.
smashndash is offline  
Old 09-13-21, 08:47 PM
  #25  
jaxgtr
Senior Member
 
jaxgtr's Avatar
 
Join Date: Jul 2006
Location: Jacksonville, FL
Posts: 5,947

Bikes: Trek Domane SLR 7 eTap, Trek Emonda ALR 6, Trek FX 5 Sport

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 457 Post(s)
Liked 942 Times in 568 Posts
Originally Posted by Trek1100FeltZ5 View Post
Do I want to avoid a new bike using a press fit bottom bracket?
Is it BB30, then yes. Do not pass go, do not collect $200. I got rid of a Synapse due to the BB30 noise. It drove me nuts.
__________________
Brian | 2023 Trek Domane SLR 7 eTap | 2016 Trek Emonda ALR 6 | 2022 Trek FX Sport 5
Originally Posted by AEO View Post
you should learn to embrace change, and mock it's failings every step of the way.










jaxgtr is offline  

Thread Tools
Search this Thread

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

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.