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Old 03-08-22, 01:16 PM
  #85  
Psimet2001 
I eat carbide.
 
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Join Date: Jan 2006
Location: Elgin, IL
Posts: 21,627

Bikes: Lots. Van Dessel and Squid Dealer

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Oh my...

What a way to get my gears grinding.

A few disclaimers: 1.Hambini is a hack and a non-starter. 2.I took the time to watch the Bike Radar guy while making a cup of coffee and spent half the time yelling at him about all that he was wrong about. 3. I lived through and was a mechanic during all of these BB transitions.

Pressfit is a fabulous idea but just horribly executed in the bike industry for a myriad of reasons. Every single engineer with good intentions has tried. They have all failed. The only good pressfit solutions that I have seen operate reliably are the ones that are simply thread together BB's that are installed in a pressfit shell.

The alignment bit - OMFG are you kidding me? Have none of you ever done an ounce of machining?? A molded carbon bearing pocket is harder to align than a machined and threaded feature. In fact composite materials and manufacturing processes make horrible bearing pockets. That combined with the inability to reliably manufacture tight tolerance bearing pockets that don't change shape under load over time make it a really poor application. I did like one comment on the Bike Radar video. The guy in the video likes to say the problem is simply that we can't produce with good tolerances as if to imply everyone in manufacturing just doesn't know what they're doing. The comment took aim at that by saying, "flying cars are by far the best application of cars but they can't seem to be reliably manufactured".

Also on alignment - I have these amazing tools that I use to chase threads, using tight tolerance guides to assure alignment and then another set of guides to allow me to machine the BB face to be perpendicular all while at room temp and on the bike. The closest equivalent on the PF side uses a fixturing cone.

BTW - I do clean up and face all PF bores as well. You'd be amazed at how many are done so very badly.

Durability/longevity. etc. - For the same level of components (quality and type of bearings and seals) threaded BB's outlast the PF equivalent.

Even the carbon experts like Rukus that I have listened to talk about this issue admit you have to use locking compounds like loctite in order to get reasonable performance out of a PF BB. This completely ignores the fact that that bikes last and need service including replacing BB's at some point. Unthreading a BB and replacing it while in the field at an event means I can get the rider back into the mix. Banging and pressing a loctite BB out and cleaning up the pocket and re-prepping and bonding a new one in the field ...

*The OVERWHELMING majority of creaking and noise complaints people have that they boil down to BB and crank issues (most shops even jump to that) are NOT in fact BB or crank issues. One of my favorites was a lady who kept having creaking issues. Took it to a shop that I know and love with good mechanics. They replaced the BB. It came back. They replaced it again. It came back. They replaced the BB and crank. It came back. Then they recabled the bike and replaced everything they could while doing a complete overhaul. It came back. They then told her the bike was crap. It was a Van Dessel that I had originally sold and she bought used. Before chucking it she came out to me to have me look at it ( a bit of a drive from the city). Though basic, systematic troubleshooting I was able to determine the noise was coming from the seat post that, at her ride height, was bottoming out against the riv-nuts for the bottle cage. I cut a couple mm off the end of her seatpost and the bike has been silent since. I've seen all sorts of BB creaks end up being: headsets, seatpost binders, seatpost clamps, saddles, dropouts/hangers, QR skewers, TA Bolts, pedals, and hub driveshells. It is very seldom the actual BB.

To say a PF BB is better because it eliminates the middle bits of material that "aren't needed" is a bit like saying you can tie a worm up with fishing line and catch fish. The important parts of the process are the bait to attract the fish and the line to reel it in. The hook is a poor substitute for not being able to get the fish on to the line efficiently.
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