As far as I can see a BB and a Headset do very similar jobs and we (generally and excepting the most recent press fit BB's) expect a BB to be threaded and everyone finds it very easy to fit/replace BB's with relatively simple and cheap tools.
Headset fitting seems to be stuck in the 'interference fit' school of engineering which either involves presses or ****ting with a hammer. Both seem to offer opportunity for damaging either the component or the frame and the former needs a relatively costly press to ensure a good job.
Using a headset that screwed into the frame would (with a suitably faced head tube) remove the risk that seems inherent in doing this job, even with the right tools.
What have I missed?
I think you've just invented another standard!
I've have more issues over the years replacing BBs than I've had replacing headsets. BBs also only turn one way so it has L and R hand threads that don't unscrew in use.
My latest bike has a press fit (BB86) BB 😉
I can see that precession might be an issue, I guess, but given the narrow arc that steerers go through is it likely to be a problem in reality?
Why can't we have integrated bb's in the same vein as integrated headsets? It seems odd to me that we fit a bearing into a piece of ally or plastic & then fit that into the frame, why not just fit the bearing into the frame? Especially now that we need even more specialist tools with the BB30 standard.
I'd rather have the bearing carrier replaceable.
Anything that scraps the frame when the bearing siezes and then spins in the frame is a bad thing, imo.
If the threaded headset cups did loosen and tighten in use it would possibly be a bit of a mare maintaining the preload with aheadsets. Makes me wonder why this wasn't seen as an issue with BB and chainsets, but then again I've had to tighten far more chainsets than headsets.
BBs also only turn one way so it has L and R hand threads that don't unscrew in use.
do you never backpedal?
stems used to be threaded, as did fork steerers, you used to screw the fork and stem into the headset, it was a right carry on
I'm sure you remember that headsets used to be threaded, not into the frame, but onto the steerer itself. They were always coming loose because of the vibration forces coming up through the forks. I used to go on rides with headset spanners it was so bad. Perhaps the same would happen with threaded rather than pressed in cups?
You'd never align the logos, everyone with a Chris king would explode...
On the principle - why are seatposts not "keyed" so they are always in the centre?
So when they seize you can twist and pull to get em out..
And the extra time and machining involved in making them would mean you'd end up paying more, for the frame and seatpost..
I was going to suggest that manufacturers only do it to give me the opportunity to **** my bikes with big hammers but to be honest, fitting headsets aren't the only things I 'fix' on my bike with a hammer.
Hammers rule.
Is there one press out there that will do all sizes of headset and press fit bottom brackets with the right adapters? If there were I wouldn't mind investing a bit of money but it does seem to be that you need more and more expensive tools to look after you bike.
And I agree on threaded headsets they were a pain to adjust.
Is there one press out there that will do all sizes of headset and press fit bottom brackets with the right adapters?
A long bolt or length of threaded rod and some big washers has done for the majority of my pressing needs. Occasionally you need to improvise with a socket or bit of wood.
avdave2 - MemberIs there one press out there that will do all sizes of headset and press fit bottom brackets with the right adapters?
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Park do one, [url= http://www.parktool.com/product/home-mechanic-bearing-cup-press-hhp-3 ]HHP-3[/url] but a piece of theaded bar, some nuts and washers is just as simple like torsoinalake said.Is there one press out there that will do all sizes of headset and press fit bottom brackets with the right adapters?
On the principle - why are seatposts not "keyed" so they are always in the centre?
So when you inevitably fall off the seatpost twists in the frame before snapping/before penetrating you.
one reason: cost
rob jackson - Member
On the principle - why are seatposts not "keyed" so they are always in the centre?
and again.
Mind you when they next run out of ideas, threaded heaset cups and frames may become the new must-have standard.
I have made a home made press with threaded rod but to be honest the rubber mallet seemed better. The park tool doesn't seem any different really to the home made ones. Actually the HHP-2 looks like it does everything with guides but over a £100 quite an investment.
I think it's going the other way for a good reason. Press fit BB is a good thing in my opinion, no threads to get damaged/cross threaded. So headsets have it right already I reckon and BB's are just starting to follow suit.
Also on a slightly pedantic note I'm pretty sure BB threads are actually being loosened by the turning motion of the cranks/axle. The right hand cup is a left hand thread and the left hand one is normal.
As above, press fit great for headset, happy enough with threaded bb's but press fit would be OK. My current frame came with one bb thread threaded backwards....
On the same lines, and speaking of carbon frame design, why do carbon frames have one piece bb shells but bonded in headset cups? Why not just a one piece tube bonded inside the headset? Going to be a nightmare changing the bottom cup on the C456.
Also on a slightly pedantic note I'm pretty sure BB threads are actually being loosened by the turning motion of the cranks/axle. The right hand cup is a left hand thread and the left hand one is normal.
Its the other way around, RHS is a RH thread. LHS is a LH thread, therefore tightening as you pedal (forwards - as someone mentioned back pedalling up there ^^)
No definitely not, that's pedals. BB's are the other way. I know that for definite. You screw the right hand cup in backwards thread and the left hand cup in normally.
Right is right for pedals and BB's are the other way around. Been using that rhyme for a decade.
Edit. Just checked Sheldon and he agrees with me
http://sheldonbrown.com/brandt/left.html
I've just realised. Although I'm right about the thread direction I've realised that having a left hand thread on the right hand cup will tighten it into the frame... which seems weird... however as you pedal the axle there is a bearing between the axle and the cup housing so as the crank turns forwards the bearing spins and pushes the opposite way on the other side of its face where it touches the cup.
So it does tighten in but it's a left thread on the right hand cup.
Paul
On the principle - why are seatposts not "keyed" so they are always in the centre?
Rob, but I did notice on Jamis touring bikes the stem is keyed to the fork steerer meaning as long as they got the key in the right place during manufacture the stem is always straight in relation to the forks.
Right is right for pedals and BB's are the other way around. Been using that rhyme for a decade.
Thats what I use...for pedals. My confusion, apologies. So indeed, why are BB the other way around? I dont think it is to do with "precession" as Sheldon calls it...
Edit. Just seen your post chilled and it is because of precession forgot about the bearing rotating the other way.
I think keying seatposts would make aligning frames in the frame building phase much more costly to get right.
Think about the costs/viability of a key in a 1mm steel tube, or a 2-3mm aluminium one.
Also how would you machine the seatpost? Most are turned.
Hoverboards like in back to the future. That's what we need!