Shimano Dura-Ace bearing count...PLEASE!
11-13-07, 01:01 AM
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Shimano Dura-Ace bearing count...PLEASE!
I'm looking to perform a ceramic bearing upgrade on my Dura-Ace 7801-sl wheelset. I am in the process of buying bearings and since they are loose balls and sort of pricey I don't wanna buy more than what I need. I know that the rear hub takes 3/16" loose balls and the front hub takes 1/4" loose balls. I am a little confused on the quantity at this point. Several differenet sites are giving me different numbers and I am confused. Is it 18, 20 or 22 loose balls in the front hub? Is it 18, 20 or 28 in the rear. Any help would be greatly appreciated and thanx in advance!
11-13-07, 01:37 AM
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It gives size but not ball count. I'd bet on 22 front and 20 rear.
I think you may have gotten the wrong info for the front wheel....
https://techdocs.shimano.com/media/te...9830608637.pdf
https://techdocs.shimano.com/media/te...9830608638.pdf
I think you may have gotten the wrong info for the front wheel....
https://techdocs.shimano.com/media/te...9830608637.pdf
https://techdocs.shimano.com/media/te...9830608638.pdf
11-13-07, 07:55 AM
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The front hub takes 1/4"? Are you sure? If you want to be 1000% sure crack open the hubs and count + measure them yourself. Don't bother looking for this info online.
11-13-07, 09:49 AM
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Counting what's in the hub already is only good if it was put together right the last time!
11-13-07, 06:23 PM
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According to Shimano's web site the 7800 Dura Ace front hub takes 28 (14 per side) 3/16" balls if loose balls are used and 3/16" balls in a retainer but the site doesn't specify the number of balls if the retainer is used.
The 7800 rear hub also takes 28 3/16" loose balls.
Tellyho is right. Ceramic bearings are an extravagant waste of money with no significant benefits. Do it if you have the cash to squander but don't expect any improvement to your bike's performance.
The 7800 rear hub also takes 28 3/16" loose balls.
Tellyho is right. Ceramic bearings are an extravagant waste of money with no significant benefits. Do it if you have the cash to squander but don't expect any improvement to your bike's performance.
11-13-07, 06:47 PM
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Oh they make a difference alright. I don't think you could quantify it as more than a watt or two. It would be 1000% more relevant if you're racing.
11-13-07, 09:11 PM
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Where do you get grade 5 bearing balls?
The figures I've seen say ceramic hub bearings save far less than one watt and, indeed, the total energy absorbed by properly adjusted steel bearings is less than a watt at bicycle speeds and loads so, even if the ceramic balls cut it in half, the improvement is infinitesimal.
The figures I've seen say ceramic hub bearings save far less than one watt and, indeed, the total energy absorbed by properly adjusted steel bearings is less than a watt at bicycle speeds and loads so, even if the ceramic balls cut it in half, the improvement is infinitesimal.
