Question about dodgy wheel bearings

[ColinJ]

You know the universal law. The more spares you have, the less likely they are the right spares.

Well, mine are 6001 - 2RS so it looks like I'm in luck if I need to change them!

Update:

The front QR was a bit too tight. The wheel spins for 2+ minutes with the QR slackened. Spin time may not be that important, but it surprises me that loosening the QR allows the wheel to spin for more than 4 times as long. Could pressure from an overtight QR cause otherwise good bearings to temporarily seize?

I took the rear wheel out to check and the bearings seem okay in that wheel too!

There is no sign of any damage to the tyres or inside the mudguards so I don't think trapped debris could possibly have been the problem. (It would have been incredibly unlucky for that to have happened 4 or 5 times anyway.)

I have taken the opportunity to scrub the tyres, wheel rims, spokes, cassette, and hard-to-reach parts of the frame which were all looking grubby after a month of riding on salty/gritty roads.

 

[gbb]

Re my previous post. I have posted pictures like this before but I suppose I have to substantiate my statement above.

View attachment 80494

A seal does more than just keep water out. It also keeps the grease in and acts as a recycle buffer for the churning grease. If you remove the seal, the grease moves to the path of least resistance and the balls run dry. Have a peek inside this bearing I removed from a Campag wheel. Seal friction is nothing to worry about, it is extremely low.

A discussion YS...no more, its an interesting subject
You make it sound like a reluctant chore, you don't HAVE to substantiate you post, partly its true, but you're seeing the problem one dimensionally, from a bearing life perspective. To me that's not the only imperative...the ability to spin freely is more important.
I don't know your background YS and much of what you say above is true but you've disregarded what Campag, Fulcrum et al have concluded, that is one seal will give less friction than two and there is therefore a positive benefit. There is also a loss of course and you highlight it perfectly, loss of grease.
But, weigh the two up, free running bearings that may not last as long (even though that is a mid to long term problem, i'm talking maybe 2 years for that to happen)...or stodgy bearings that will last longer. Free running bearings will win every time for me. I expect to replace bearings anyway, they are a consumable, designed to be replaced. Cost isn't an issue, £3 to maybe £5 each, i'll happily sacrifice that every 2 or 3 years for free running wheels
I wouldn't dismiss the fact that bearing manufacturers have developed low friction seals for no good reason, they do have a big effect. When I first got my Fulcrums, TBH I was VERY disappointed, i remember freewheeling down a slope and the bike was just slowing too fast, new wheels I thought and its made things worse. I went straight out and brought -2RSLs...instantly better...hugely.

Its all a compromise, no-one's right, no-one's wrong...both seals if you want longer life out of your bearings (and its still no guarantee)...or one seal if you want to make your wheels run freer.

 

[Smurfy]

PS - If you can't get the technique right of spinning the wheel using just one hand to hold it, hold it both sides and get someone to spin it for you.

1. Support each side of the wheel with your first finger slightly curled around the spindle, so that tip of finger points to chest.
2. Use one or both thumbs on a spoke to spin wheel backwards.

 

[Smurfy]

Could pressure from an overtight QR cause otherwise good bearings to temporarily seize?

Shouldn't make any difference, unless the spacer between the inner bearing races is slightly too short. For sealed bearings, the spacing between the outer races (i.e. hub shell width) should always be exactly the same as the inner races (i.e. spindle spacer). If the spindle spacer was slightly too short, the bearings would be loaded up by the skewer. Check the exploded diagram for your hub, and see if the spindle has shoulders, or a spacer to position the inner races correctly, and prevent the bearings from being loaded laterally by skewer tightening.

By the way, 6001 2RS is a standard part number, so may be cheaper from a non cycle supplier, although pay attention to the different clearance options, and don't be tempted by the cheapest no-name product you can find.
http://simplybearings.co.uk/shop/advanced_search_result.php?keywords=60012RS

 

[Yellow Saddle]

A discussion YS...no more, its an interesting subject
You make it sound like a reluctant chore, you don't HAVE to substantiate you post, partly its true, but you're seeing the problem one dimensionally, from a bearing life perspective. To me that's not the only imperative...the ability to spin freely is more important.
I don't know your background YS and much of what you say above is true but you've disregarded what Campag, Fulcrum et al have concluded, that is one seal will give less friction than two and there is therefore a positive benefit. There is also a loss of course and you highlight it perfectly, loss of grease.
But, weigh the two up, free running bearings that may not last as long (even though that is a mid to long term problem, i'm talking maybe 2 years for that to happen)...or stodgy bearings that will last longer. Free running bearings will win every time for me. I expect to replace bearings anyway, they are a consumable, designed to be replaced. Cost isn't an issue, £3 to maybe £5 each, i'll happily sacrifice that every 2 or 3 years for free running wheels
I wouldn't dismiss the fact that bearing manufacturers have developed low friction seals for no good reason, they do have a big effect. When I first got my Fulcrums, TBH I was VERY disappointed, i remember freewheeling down a slope and the bike was just slowing too fast, new wheels I thought and its made things worse. I went straight out and brought -2RSLs...instantly better...hugely.

Its all a compromise, no-one's right, no-one's wrong...both seals if you want longer life out of your bearings (and its still no guarantee)...or one seal if you want to make your wheels run freer.

Your perception of seal friction is skewed. The "benefit" of removing a seal is miniscule and so small that it will not present in the way that your experiment shows. There is no way that you can perceive or demonstrate or measure a drag resistance of less than half a gram in the way that you proposed. Stodgy is not an apt way to describe the real scenario either. Further, labyrinth seals are available for these bearings, simply spec ZZ and you will have contactless seals without the disadvantage of a missing seal.
The only time an unsealed bearing should be employed is when it is running in an oil bath.

 

[Yellow Saddle]

Well, mine are 6001 - 2RS so it looks like I'm in luck if I need to change them!

Update:

The front QR was a bit too tight. The wheel spins for 2+ minutes with the QR slackened. Spin time may not be that important, but it surprises me that loosening the QR allows the wheel to spin for more than 4 times as long. Could pressure from an overtight QR cause otherwise good bearings to temporarily seize?

I took the rear wheel out to check and the bearings seem okay in that wheel too!

There is no sign of any damage to the tyres or inside the mudguards so I don't think trapped debris could possibly have been the problem. (It would have been incredibly unlucky for that to have happened 4 or 5 times anyway.)

I have taken the opportunity to scrub the tyres, wheel rims, spokes, cassette, and hard-to-reach parts of the frame which were all looking grubby after a month of riding on salty/gritty roads.

Your observation is accurate. On a Mavic wheel, especially the Aksium, the QR can preload the bearing, hence the method of adjusting the cone. Have a look at the dealer website where the cone preload is explained. If the cone is used twice or, if it is adjusted badly, you'll get exactly what you describe. The cone on a Mavic Aksium has an crush core that expands when tightened and locks the preload position in place.
Bearing preload is a big problem with cartridge bearings and most hub manufacturers deal with it by manufacturing, pretending to manufacture or attempting to manufacture the hub spacing to good tolerance. It isn't successful, as we know from the shortened life of bearings in such hubs. Mavic's attempt to bring adjustability to the problem is an honest attempt at good engineering. Unfortunately it is expensive since you have to replace the cones when you remove the bearings.

 

[downfader]

Did you have any swarf in the grease? My pedal started doing something a bit like that, took it apart and it looks like every now and again a chip of metal flowed into the bearings causing a crunch. No idea where the chip came from but removed and regreased and it works ok again.

I also broke the rear axle on my Alex/Shimano wheel recently that was fitted to the Genesis. That made an incredible noise when it went. Luckily I was right outside a bike shop intending to buy pedals,but then stranded some 8 or 9 miles from home in full bikey kit. Whatever the issue is I hope you find out what is happening.

 

[Rohloff_Brompton_Rider]

In contrast to YS' pov this seems to suggest that bearing seals contribute to 50% of bearing drag...

http://velonews.competitor.com/2014...ag-can-eliminate-dropping-two-bearings_321169

 

[ColinJ]

In contrast to YS' pov this seems to suggest that bearing seals contribute to 50% of bearing drag...

http://velonews.competitor.com/2014...ag-can-eliminate-dropping-two-bearings_321169

But if it is 50% of something tiny, then it would not be very significant? It looks like maybe a maximum of a couple of Watts according to that article. Significant if one was racing, but pretty irrelevant to me pottering about the Yorkshire/Lancashire hills. That horrid noise and vibration certainly wasn't though!

Did you have any swarf in the grease? My pedal started doing something a bit like that, took it apart and it looks like every now and again a chip of metal flowed into the bearings causing a crunch. No idea where the chip came from but removed and regreased and it works ok again.

I also broke the rear axle on my Alex/Shimano wheel recently that was fitted to the Genesis. That made an incredible noise when it went. Luckily I was right outside a bike shop intending to buy pedals,but then stranded some 8 or 9 miles from home in full bikey kit. Whatever the issue is I hope you find out what is happening.

I haven't looked inside the hubs. At the moment I am reluctant to mess about with them when they appear to be perfectly okay with the wheels out of the bike. I might reassemble the bike and try it again with the front QR tension loosened a bit because I think it was 40%-ish too tight. Maybe that was the cause of the problem ...

I checked the axle and it is fine. I was worried that it might have snapped and only be held together by the QR!

The problem was not subtle. I'm amazed that a mechanical system can instantaneously go from quiet and efficient to horribly noisy and rough, then back to quiet and efficient again for no apparent reason and not leaving more obvious signs of what was going on. Parts generally tend to wear out, jam or snap and a simple inspection then reveals what the problem is.

 

[Yellow Saddle]

In contrast to YS' pov this seems to suggest that bearing seals contribute to 50% of bearing drag...

http://velonews.competitor.com/2014/03/bikes-and-tech/technical-faq/technical-faq-much-drag-can-eliminate-dropping-two-bearings_321169

Nope. Where did I suggest otherwise? Don't put words in my mouth.

Bearing drag is measured in grams of effort which translates to about one or two watts at about 25kph. It changes with speed but that's a long story. In other words, when cycling forward, bearing drag pulls you back by a couple of grams. Inside that (bearing) drag is the resistance felt due to the grease viscosity and volume and, seal friction and bearing/race interaction.

Depending on how much grease is in the bearing, seal drag could be a large portion of the overall drag or small portion. I can't say, I don't have the bearing in front of me and you cannot specify what you want to put in front of me.

Having said that - bearing drag is small, very small, overall bike drag at 25mph requires about 300 watts of energy, most of that overcoming wind drag. Remember, bearing drag is only, say, 3 watts or 100th.

That's the perspective.

Now, within that perspective, what's the advantage of removing the beaing seals? Well, 0.25% if you remove all the bearing seals on the bike. Yes, all. The BB seals, the BB seals, the hub seals, the pedal seals, the lot. Further, if you remove all the grease from all the bearings, you'll save a whopping 0.75% of energy, or thereabouts.

Now, where's the perspective? Where's your 50% now?

These tactics (of removing seals and replacing grease with oil) is fine if you are attempting to beat the Hour record by 1 second. But commuting? C'mon...
Racing your mates?....Get real.

I never committed to figures and I alluded why - different bearings have different fill. There are even different types of rubber for the seals and of course, different seals, as I mentioned. However, within the small percentages of overall energy we're looking at, it is all just measurement noise.

Please retract your statement which alludes that I suggested otherwise.

 

[Yellow Saddle]

But if it is 50% of something tiny, then it would not be very significant? It looks like maybe a maximum of a couple of Watts according to that article. Significant if one was racing, but pretty irrelevant to me pottering about the Yorkshire/Lancashire hills. That horrid noise and vibration certainly wasn't though!


I haven't looked inside the hubs. At the moment I am reluctant to mess about with them when they appear to be perfectly okay with the wheels out of the bike. I might reassemble the bike and try it again with the front QR tension loosened a bit because I think it was 40%-ish too tight. Maybe that was the cause of the problem ...

I checked the axle and it is fine. I was worried that it might have snapped and only be held together by the QR!

The problem was not subtle. I'm amazed that a mechanical system can instantaneously go from quiet and efficient to horribly noisy and rough, then back to quiet and efficient again for no apparent reason and not leaving more obvious signs of what was going on. Parts generally tend to wear out, jam or snap and a simple inspection then reveals what the problem is.

Your QR can never be too tight. It should be so tight that the lever leaves a white mark in your hand. There is another thread active here where we discussed the problems associated with QRs that can't tighten but the same problem exists for QRs that aren't tightened enough.

 

[Rohloff_Brompton_Rider]

Nope. Where did I suggest otherwise? Don't put words in my mouth.

Bearing drag is measured in grams of effort which translates to about one or two watts at about 25kph. It changes with speed but that's a long story. In other words, when cycling forward, bearing drag pulls you back by a couple of grams. Inside that (bearing) drag is the resistance felt due to the grease viscosity and volume and, seal friction and bearing/race interaction.

Depending on how much grease is in the bearing, seal drag could be a large portion of the overall drag or small portion. I can't say, I don't have the bearing in front of me and you cannot specify what you want to put in front of me.

Having said that - bearing drag is small, very small, overall bike drag at 25mph requires about 300 watts of energy, most of that overcoming wind drag. Remember, bearing drag is only, say, 3 watts or 100th.

That's the perspective.

Now, within that perspective, what's the advantage of removing the beaing seals? Well, 0.25% if you remove all the bearing seals on the bike. Yes, all. The BB seals, the BB seals, the hub seals, the pedal seals, the lot. Further, if you remove all the grease from all the bearings, you'll save a whopping 0.75% of energy, or thereabouts.

Now, where's the perspective? Where's your 50% now?

These tactics (of removing seals and replacing grease with oil) is fine if you are attempting to beat the Hour record by 1 second. But commuting? C'mon...
Racing your mates?....Get real.

I never committed to figures and I alluded why - different bearings have different fill. There are even different types of rubber for the seals and of course, different seals, as I mentioned. However, within the small percentages of overall energy we're looking at, it is all just measurement noise.

Please retract your statement which alludes that I suggested otherwise.

Get real dude, this ain't a court of law.

 

[Yellow Saddle]

Get real dude, this ain't a court of law.

Well, be polite and don't slag me off.

 

[Yellow Saddle]

Well, be polite and don't slag me off.

And don't call me dude.

 

[Rohloff_Brompton_Rider]

And don't call me dude.

Histrionic personality disorder?