Trek1100FeltZ5

Do I want to avoid a new bike using a press fit bottom bracket?

10 Wheels

How Much $$$ is the bike?

Trek1100FeltZ5

$4200

10 Wheels

I put 39,000 miles on a Felt 85

Trek1100FeltZ5

Thank you

cb400bill

Thread moved from Introductions to Road.

datlas 

Controversial topic. Life will be simpler with a threaded BB, but it should not be a deal-breaker necessarily.

shelbyfv

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.

deacon mark

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.

Iride01 

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!

PeteHski

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.

chaadster

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.

smashndash

Avoid BB90. The rest are probably ok. Just get a thread-together or one-piece BB and avoid the $20 plastic junk.

Koyote

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.

Lazyass

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.

Troul 

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...

chaadster

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.

smashndash

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.

chaadster

I guess people should say what they mean. I do and did.

Hiro11

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.

smashndash

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.

Troul 

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.

Point

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.

smashndash

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.

jaxgtr

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.