386 BB while using a 30 mm spindle. HELP!

Discuss light weight issues concerning road bikes & parts.
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DEADRE
Posts: 42
Joined: Sat Apr 24, 2010 3:20 am

by DEADRE

My current bike runs a 386 bottom bracket & as of now I’m using a BBinfinite along w/ a THM Clavicula crankset. The problem with the current set up is that, when you spin the crankset, it only does a few revolutions & base on the video counter, it counts down up to 6 (see below video) (I have tested the AX lightness Morpheus as well & the countdown, was 6 as well). If you have never encountered this problem before, basically the outcome is, that you’re not pedaling at a 100% & putting more effort on every pedal strokes just to match a fellow rider at the same speed, thus equaling to an earlier fatigue & not to mention a 50 mile ride feeling like you did 100 miles. Bottom line at every stroke, there is literally resistance, NO, that type of resistance from riding, the other resistance as if your holding the brakes while pedaling (I hope that made sense).

https://www.youtube.com/watch?v=CXCLogS7EG4

On the second video, British bottom bracket & Campagnolo crankset set up. As you can see, the crankset spins freely, this is at a 100%, counter counts up to 22.

https://www.youtube.com/watch?v=XEzRqheGfl8

So here is my predicament, I already have invested $$$$ on the THM, & would really like to continue using it, ONLY IF. One of you good Samaritans out there can recommend, from EXPERIENCE, what BB brand you are using on a BB386 while using a size 30 mm spindle (THM, AX, Rotor, Cannondale, Sram, Campagolo Over torque etc….)
Please make sure that your BB386 w/ a 30 MM spindle spins like the Video #2, before replying, if not, we are in the same boat!

Thank you in advance if anyone out there can help!

by Weenie


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Calnago
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Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

You’re comparing apples and oranges. I’m presuming your BB Infinite Bottom bracket has bearings packed with grease, probably some seals as well, correct? It spins very well to my eye. The Super Record crank in the video below is running with Campy’s Cult bearings with no grease (just light oil) and no seals. The fact that the bearings are ceramic doesn’t have nearly the effect on it’s ability to spin like that as does the fact that there is no grease or seals in the bearings. That’s how a Campy SR crank properly installed spins. However, as long as you’re not experiencing any actual binding or tight spots in the revolution of your crank, you should be just fine. The BBinfinite BB is a solid unit which just presses into the frame’s BB shell, so unless there is a defect in the unit itself, the bearings should be nicely aligned and square to each other, something you can’t always be perfectly sure of when you press in two separate cups into a pressfit BB shell. Providing there is no excessive preload or spacer problems, it’s probably just fine but if you want assurances you should send that video with your questions to the guys at BBInfinite. I’ve spoken to them at length before and the owner is very passionate about the product so I’m sure they’d want to make sure things are right with your setup. He really wanted to send me one of their units for Campy, but quite honestly imo there’s nothing better than properly installed Campy cups with the Ultratorque cranks.
That crank in the second video is Ultratorque by the way, so it’s not a 30mm spindle, but really I don’t think the size of the spindle is a factor here.
Oh, and yes, I’ve installed a Campy Ultratorque crank in a Time frame with the 386 shell. Used the appropriate Campy cups. So, while not the 30mm spindle in the Overtorque cranks (not being produced anymore by the way), they spin just like the second video, which is also not a 30mm spindle.
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mrlobber
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by mrlobber

I'm sorry, but even from the "hardest turning" to "lightest turning" cranks & BB's there would be at maximum 1-2W difference, which turns the statements of "50 mile ride feeling like a 100 mile" ride to complete BS.

Sure, some last watts can matter (as discussed ad nauseum in numerous aero bike threads), but only in borderline competitive situations, which definitely is not the case here.

I have a BB386 bike with Clavicula as well, and I'm using NTN bearings in BB.

It doesn't spin xxx times (as does the BB of some other BB30 bike I have), but there hasn't been a case where I wouldn't have been able to ride 100 km on one bike vs 150 km on the other BECAUSE of an artificial crank spinning difference.
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ms6073
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by ms6073

DEADRE wrote:
Wed Nov 28, 2018 1:15 am
it only does a few revolutions & base on the video counter, it counts down up to 6 (see below video)
Compare your results to that of a Shimano DA BB-86 setup and you will be more than happy with your results. So while I agree with the other comments, if you really want to give in to such OCD tendencies :lol:, then I would ask if when installing the crank for the first time, was the spindle able to be pushed in using finger pressure or did it have to be tapped in with a mallet? If it has to be tapped in/out with a mallet, then I would suspect that the bearing alignment has been altered ever so slightly and the misalignment is imposing additional drag. While I have minimal experience with BB-386, I have used BB-86, BB-30, and PF-30 and in all instances, found that if I had to pound the crank in, it nearly always pushed the nds bearing out of alignment. Putting the spindle in the freezer was one solution to help reduce the need to pound in cranks, but long term (especially with Hollowgram SRMs), I opted to polish the spindles ever so slightly to reduce the outer diameter until the crank could be inserted with finger pressure.
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hambini
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by hambini

The point that Ms6073 is valid and sound advice.

My other point would be a spin test is a poor test to ascertain friction. You need some load on the bearings, spinning them freely does not load them enough.

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