PF30 bottom brackets

cycleclinic

The wheels manufacturing bb is excellent. A bit of tub glue might actually work with the standard bb. It is keepihg the bearings in my look quiet. The praxis or wnf bb thought are good off the shelf solutions.

kleinstroker

AndyH01 wrote:

Before I sink £2k in a do it all gravel type bike as the my main commuter bike to be used all yr round @ 12 miles per day bike, how "good" are the GXP type BB - Its on £1k Planet X Titanium frame with Ultegra groupset? If the standard is likely to change how easy will a GXP type BB likely to be to convert. How reliable are they and can they be changed to a std threaded type if I do encounter any issues with them?
I currently have a TRek 2.1 which I think is std thread with a dura ace bb and in the 1st instance I would to swap out for this in the event of an issue with the new bike would they be compatible?
Thanks all

GXP is also a std thread and I'm not sure how you would have a GXP BB with an Ultegra groupset as the Utlegra Chainset doesn't fit in a GXP BB, GXP and Shimano BB are very very similar though

andyh01

I'm not sure how you would have a GXP BB with an Ultegra groupset - Having felt duped before as bike sold as a full 1005 groupset turned out fsa chainset /cheap brakes (back when I was more naïve) I double checked this, the spec say 68mm BB BSA and the answer I got bck when asked via email about BB reply was this;
The BB for the TI Bikes is a standard GXP threaded shell...

Will it have some type of adaptor or something? Groupset: Shimano's 6800 Ultegra (22-speed) groupset Ovalized seat and down tubes mate to a 68mm bottom bracket shell and chainset fc- 6800

munkster

A GXP (ie. SRAM) shell is the same as a Hollowtech II (ie. Ultegra) shell is the same as a BSA shell (ie. standard English threaded). As mentioned though, the GXP and HTII BBs themelves aren't the same. Sounds like someone's just got themselves confused to me, but you'd want to check it definitively yeah.

ps - is it this one by any chance? http://www.planetx.co.uk/i/q/CBPXTYPSHI ... a-6800-hdr

andyh01

I was looking at the tempest;
http://www.planetx.co.uk/i/q/CBPXTEMSHI ... ltegra-hdr
as takes rack/guards and bigger tyre clearance then the penckinflick/typhoon. Apparently according to PX and Ribble, its not best to stick 12kg/15Kg rack/seat post mount sql on a carbon bike or tow a kiddy trailer with a carbon frame... hence ti frame as wanted something to improve on current ali frame.

mikenetic

munkster wrote:

New bikes arrive at the LBS without the BB installed, generally, and so he LBs will fit it when they build up the factory fresh new bike.

Really? Every day is a school day... I didn't know that, and find it hard to believe but if you say so!

Point taken that it's not necessarily imminent but all BBs wear out (if you're doing significant miles) so my original "which BB should I forward plan for" question remains appropriate I feel, no hysteria here ;-)

That very much depends on the nature of the bike. If you're doing a frame-up build then you'll install the BB, but most mainstream brands are part assembled. It's normally more like the front end needs to be put together. Way cheaper to have a bike part built in the Far East and shipped out than ask a Euro/US mechanic to build it from scratch.

svetty

munkster wrote:

Wheels manufacturing works fine for me

Yeah, think I'm going to go down this route, my LBS will price match for me they say.

How have you found the Wheels Mfg BB so far? Have you put many miles into it? Did you fit it yourself? Do you need one or two of the BB install tools? The Wheels Mfg website says (x 2) but I'm not sure if that's what they mean.

Cheers!

Still smooth and silent after 1000 miles or so - mostly dry miles to be fair but includes a couple of days when I was caught out and got a soaking. Yes I fitted it myself with a home-made 'threaded bar' type press - you just need large enough washers to cover the frame BB orifice. No creaks so far......

munkster

Mine is on my winter bike that's going to do a couple of thousand mucky miles before the summers here so I'll be asking it a few questions. I have a headset press which is fine for press fit BBs.

BenderRodriguez

Stueys wrote:

PF bb's are a flawed design, purely there to reduce manufacture costs. It's nuts that we all now accept that glue is the answer to the highest stressed part of the bike. My money is that in five years time 60%+ of bikes are back on a threaded standard.

I thought that press-fit bottom brackets, such as the BB30, were introduced primarily to give a much larger diameter for the frame tubes to bond to and to give a stiffer oversized BB, especially with carbon frames. Also, to allow stiffer, lighter oversized BB axles.

In my experience a properly made BB30 BB is fine, although they do require accurate machining, which hardly makes sense if the goal was to reduce manufacturing costs.

Also, I would hardly view Loctite as just being a 'glue', and its use is standard, best-practice engineering when fitting bearings to housings.

sloppyschleckonds

BenderRodriguez wrote:

Stueys wrote:

SloppySchleckonds wrote:

PF bb's are a flawed design, purely there to reduce manufacture costs. It's nuts that we all now accept that glue is the answer to the highest stressed part of the bike. My money is that in five years time 60%+ of bikes are back on a threaded standard.

I thought that press-fit bottom brackets, such as the BB30, were introduced primarily to give a much larger diameter for the frame tubes to bond to and to give a stiffer oversized BB, especially with carbon frames. Also, to allow stiffer, lighter oversized BB axles.

In my experience a properly made BB30 BB is fine, although they do require accurate machining, which hardly makes sense if the goal was to reduce manufacturing costs.

Also, I would hardly view Loctite as just being a 'glue', and its use is standard, best-practice engineering when fitting bearings to housings.

To be clear this isn't my quote. I've had 3 BB30 frames since 2010 without issue. My LBS fit and recommend Loctite.

BenderRodriguez

SloppySchleckonds wrote:

To be clear this isn't my quote. I've had 3 BB30 frames since 2010 without issue. My LBS fit and recommend Loctite.

Sorry, post corrected.

thomasmorris

BenderRodriguez wrote:

Stueys wrote:

PF bb's are a flawed design, purely there to reduce manufacture costs. It's nuts that we all now accept that glue is the answer to the highest stressed part of the bike. My money is that in five years time 60%+ of bikes are back on a threaded standard.

I thought that press-fit bottom brackets, such as the BB30, were introduced primarily to give a much larger diameter for the frame tubes to bond to and to give a stiffer oversized BB, especially with carbon frames. Also, to allow stiffer, lighter oversized BB axles.

BB30 (30mm internal diameter bears pressed directly in to a frame) actually spaces the bearings closer together inside the BB shell. The shell width is still 68mm (like BSA 68mm), but the bearings are inside. So there is no over sizing of the frame that cannot be achieved with BSA 68mm, and the bearing are actually closer together so less stiff! (HTII and PF30 hold the bearings outside the 68mm width shells, so great bearing stance and axel support),

BB30 does allow larger internal diameter (30mm rather than 24mm), so allows wider axles. But if you're running them with 24mm cranks and a spacer, you loose any advantage there too.

The only advantage of BB30 is that they don't require a machined bb shell, which makes it cheaper to build light bikes. But when tolerances are messed up you get creaky BBs!

The came along PF30. PF30 works with BB30 axles, however the bearings are held in cups which are pressed in to the frame. The bearings sit further apart, so a wider bearing stance (stiffer), but the frame isn't actually any wider (not stiffer). However, you loose the advantage of lighter frames with this standard.

See diagrams here: http://wheelsmfg.com/bb30-vs-pf30

The OP has PF30...

Now, BB(90) or PF86, pressfit the bearings in to a wider frame. So the bearings are still the same width apart, but are held within the bottom bracket shell, allowing the shell width to be greater and so stiffer.

And BBRight is asymmetric, so it's like PF30, but allows the bottom bracket shell to be wider on the non-driveside (stiffer frame). Then there is BB386 and T47 standards on top of these!

If you have a PF30 (or BBRight) you can use the bottom brackets discussed to screw together the two bearing cups, for a more secure (none creaking fit).

stueys

Think Thomas covered it pretty well ;-)

Only things I would add is that the main driver of PF was production cost and weight, I don't think anyone really thought that a 24mm axles wasn't stiff enough (certainly shimano don't and they tend to be engineers first, salesman second). The wider bearing stance is a good thing but there's no reason why that can't be enabled without the move to PF (look at T47 or the Praxis solutions). Incidentally if you take a look at a Dogma you'll see a nice wide bottom bracket which happens to be threaded ;-)

Re using loctite, all decent mechanics will now do this. But I wouldn't argue that's good engineering practice. It's probably the highest stressed part of the bike and we are down to depending on glue to help ensure a trouble free fitting. It's less than ideal and is also contrary to the original advice from the manufacturers.

BenderRodriguez

Stueys wrote:

Re using loctite, all decent mechanics will now do this. But I wouldn't argue that's good engineering practice. It's probably the highest stressed part of the bike and we are down to depending on glue to help ensure a trouble free fitting. It's less than ideal and is also contrary to the original advice from the manufacturers.

Unless parts are robust enough to use a true interference fit that rarely or ever needs disassembly, such as a crankshaft, using a retaining compound most certainly is good engineering practice, not least because any fit that is not tight enough to actually deform the surface of the parts as they are mated will only have a limited area of contact. The compound will make the joint stronger, reduce fretting, corrosion and so on. As such, the use of retaining compounds is standard practice in engineering, particularly on lightweight components that cannot be made robust enough to withstand a true interference fit.

Plenty of cycle manufacturers also specify the use of a retaining compound when fitting press-fit bottom bracket bearings. For example, Time recommend the use of Loctite 648.

thomasmorris

Stueys wrote:

Think Thomas covered it pretty well ;-)

Only things I would add is that the main driver of PF was production cost and weight, I don't think anyone really thought that a 24mm axles wasn't stiff enough (certainly shimano don't and they tend to be engineers first, salesman second). The wider bearing stance is a good thing but there's no reason why that can't be enabled without the move to PF (look at T47 or the Praxis solutions). Incidentally if you take a look at a Dogma you'll see a nice wide bottom bracket which happens to be threaded ;-)

Re using loctite, all decent mechanics will now do this. But I wouldn't argue that's good engineering practice. It's probably the highest stressed part of the bike and we are down to depending on glue to help ensure a trouble free fitting. It's less than ideal and is also contrary to the original advice from the manufacturers.

In terms of buying new bikes BB30 is worse than the old BSA 68mm standard in virtually every way except weight. It would put me off buying that frame.

PF30 wouldn't put me off a frame though, not that it's a selling point either. Both have the same BB shell width (68mm) and bearing stance. With the screw together PF30 I think is just as secure. You get the option of using 30 mm axles but it also weighs a bit more.

There is nothing inherently wrong with press fitting. After all, the bearings in HTII, T47 and screw together PF30 are pressed in to the cups aren't they? What's wrong is that frame builders can't get the tolerances correct to press bearings directly in to their frames (or the frame material wears / stretches out over time).

Secteur

BenderRodriguez wrote:

I thought that press-fit bottom brackets, such as the BB30, were introduced primarily to give a much larger diameter for the frame tubes to bond to and to give a stiffer oversized BB, especially with carbon frames. Also, to allow stiffer, lighter oversized BB axles.

In my experience a properly made BB30 BB is fine, although they do require accurate machining, which hardly makes sense if the goal was to reduce manufacturing costs.

Also, I would hardly view Loctite as just being a 'glue', and its use is standard, best-practice engineering when fitting bearings to housings.

Right on all three points, and I agree entirely, though ThomasMorris's post is also very convincing and now I am unsure!

For most folks, this all goes out of the window when BB30's start to creak when they wear out or have been poorly fitted / maintained.

There's absolutely nothing fundamentally wrong with BB30 though, in my personal non expert opinion.

stueys

Ok, to clarify;
- A properly made PF, such as BB30, can be absolutely fine. But it requires consistently high manufacturing tolerances which the manufacturers have demonstrated over a number of years now they can't hit. Many of us (myself included) have PF bikes with no issues, equally every bike mechanic has a customer or ten who has recurring creaking issues. This problem didn't exist in threaded BB's
- All of my PF bb's have loctite on them. I'm not arguing that it's bad practice when fitting a PF, it helps reduce creaking and movement issues so definitely do. I am arguing though that it's a bad outcome that we've ended up using loctite to help correct ultimately a flawed design.
- The move to PF gained us nothing really, other than a tiny weight loss. It was driven by the manufacturers to reduce cost and also to try to create some differentiation in the marketplace. There's lots of people making money solving BB issues which didn't exist before PF. Ultimately you are more likely to see issues with a PF BB than a threaded one.

crankycrank

Agree 100% ^^^.

banditvic

Just ordered a C-Bear PF bb and he has stated to use Anti seize Grease for installation.

stueys

banditvic wrote:

Just ordered a C-Bear PF bb and he has stated to use Anti seize Grease for installation.

Bart gave the same advice on mine (fitted to an R5). I still used loctite but mainly because I resorted to what I knew. The quality of the product is very high so I suspected it would have been fine but cervelo had a run of frames with some poor tolerances so I played safe. It replaced a creaking rotor BB which had been in for only a year.

You'll like the C-Bear btw, I'm slowly going to move all my bikes over.