Question about dodgy wheel bearings

[ColinJ]

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.

Well, that one I do take issue with!

A few years back I changed the bearings in my rear MTB hub (bought a box of 10, which is why I have spares now). At the same time, I replaced the rear tyre with an absolutely massive knobbly for extra comfort on our rocky local bridleways. I went out on the bike and it felt awfully slow. I assumed that the extra drag was due to the new tyre. I hated riding the thing and was going to sling the tyre and get a smaller one, but then the brakes developed a fault and I have not ridden the MTB since. (It was about the time that I got ill, and I never got round to fixing it.)

Getting to the point ... I eventually put the MTB in a stand to work on it and I discovered a huge amount of friction in the rear hub. I needed to use an awful lot of arm power to spin the back wheel and it then stopped after freewheeling for only about 1/4 of a revolution! The problem turned out to be due to an overtight QR. When I adjusted the QR to a more sensible tension, the friction problem went away. An easy flick of the pedals can now spin the rear wheel for a couple of minutes. The QR is still tight enough to hold the wheel in place, and there is no play in the hub.

Thinking about it, I only started doing QRs up tighter after pulling the rear Aksium out when climbing a steep hill standing up. I have never managed to pull out a wheel which uses a Shimano or Campagnolo QR.

 

[downfader]

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.

Overtightening could possibly cause a minor issue. I sent the genesis off for a spoke repair to another shop last year as the LBS guy I trusted had moved to snother job. The guy who did the wheel had tightened the wheel so tight it took my entire 15 stone of strength to remove the fittings when the tube punctured.

I echo your concerns about taking the hub apart. I'm pretty hands on with things like fitting brakes, pedals, etc but bearings take respect

 

[gbb]

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.

You'll have to take my word (although I don't suppose you will) that I have demonstrated to myself that single seal runs freer than double and low friction runs freer than standard bearings. Ive physically done it. Disbelieve if you choose, that's your right.
I'm a maintenance engineer, ive perhaps fitted more bearings to industrial applications, conveyors, high speed equipment, cycle wheels and BBs etc etc..than you've possibly ever even seen (possibly...I don't know your background)..I know bearings from a hands on perspective.
Stodgy not apt ?...so what, you don't even like the description, a bit pedantic isn't it ?...stodgy, slow, sluggish....you know EXACTLY what I mean. Chill out, you sound a bit evangelical. Your way will give a benefit, so will mine, just different benefits.

 

[Yellow Saddle]

Well, that one I do take issue with!

A few years back I changed the bearings in my rear MTB hub (bought a box of 10, which is why I have spares now). At the same time, I replaced the rear tyre with an absolutely massive knobbly for extra comfort on our rocky local bridleways. I went out on the bike and it felt awfully slow. I assumed that the extra drag was due to the new tyre. I hated riding the thing and was going to sling the tyre and get a smaller one, but then the brakes developed a fault and I have not ridden the MTB since. (It was about the time that I got ill, and I never got round to fixing it.)

Getting to the point ... I eventually put the MTB in a stand to work on it and I discovered a huge amount of friction in the rear hub. I needed to use an awful lot of arm power to spin the back wheel and it then stopped after freewheeling for only about 1/4 of a revolution! The problem turned out to be due to an overtight QR. When I adjusted the QR to a more sensible tension, the friction problem went away. An easy flick of the pedals can now spin the rear wheel for a couple of minutes. The QR is still tight enough to hold the wheel in place, and there is no play in the hub.

Thinking about it, I only started doing QRs up tighter after pulling the rear Aksium out when climbing a steep hill standing up. I have never managed to pull out a wheel which uses a Shimano or Campagnolo QR.

A QR should be tight. Tighter than most people believe to be true. QRs, unlike axle nuts, preload the bearings many bearings (depending on design) and therefore the bearings have to be adjusted so that the QR does the final preload job. It is something that takes mechanics in training quite a while to learn to get right. If you look at a Shimano QR instruction manual they explain it quite nicely.

Because QR tension affects bearing preload, the best way to get it more constant is to tighten it and the white mark in your hand is a good enough indicator of consistency.

 

[Yellow Saddle]

You'll have to take my word (although I don't suppose you will) that I have demonstrated to myself that single seal runs freer than double and low friction runs freer than standard bearings. Ive physically done it. Disbelieve if you choose, that's your right.
I'm a maintenance engineer, ive perhaps fitted more bearings to industrial applications, conveyors, high speed equipment, cycle wheels and BBs etc etc..than you've possibly ever even seen (possibly...I don't know your background)..I know bearings from a hands on perspective.
Stodgy not apt ?...so what, you don't even like the description, a bit pedantic isn't it ?...stodgy, slow, sluggish....you know EXACTLY what I mean. Chill out, you sound a bit evangelical. Your way will give a benefit, so will mine, just different benefits.

Yes, you have mentioned it but not demonstrated it. It is obvious though but you are missing the point. It is not relevant in the overall scheme of things. You may as well remove the grease and oil the bearing, too... but I'm repeating myself.
Further, appealing for me to take your expertise as the gospel in bearing maintenance is no good. I judge concepts on first principles, not badges, medals or bluster.

You didn't even get my point about labyrinth seals which are frictionless.

I've made this point before and I'll do it again. There on the corner where you work is a new building going up. If you go there tomorrow you'll see a concrete truck and a concrete pump truck in action. You'll see there's a bloke there directing the pump nozzle into the shuttered moulds with rebar sticking out of it. He's done that for 30 years. However he knows nothing about reinforced concrete structures. He just knows how to pour cement.

 

[Rohloff_Brompton_Rider]

Yes, you have mentioned it but not demonstrated it. It is obvious though but you are missing the point. It is not relevant in the overall scheme of things. You may as well remove the grease and oil the bearing, too... but I'm repeating myself.
Further, appealing for me to take your expertise as the gospel in bearing maintenance is no good. I judge concepts on first principles, not badges, medals or bluster.

You didn't even get my point about labyrinth seals which are frictionless.

I've made this point before and I'll do it again. There on the corner where you work is a new building going up. If you go there tomorrow you'll see a concrete truck and a concrete pump truck in action. You'll see there's a bloke there directing the pump nozzle into the shuttered moulds with rebar sticking out of it. He's done that for 30 years. However he knows nothing about reinforced concrete structures. He just knows how to pour cement.

You sound like a nasty patronising person.

 

[Yellow Saddle]

You sound like a nasty patronising person.

Stick to the debate. Bearing construction and installation.

 

[Rohloff_Brompton_Rider]

You started it, dude.

 

[Yellow Saddle]

Here's a Shimano QR instruction manual. It makes for interesting reading because I think 90% of Shimano wheel owners don't understand how tight the QR should be. We have a wheel rubbing thread on here right now that demonstrates the problem. But, the problem comes with bearing preload too. If the mechanic adjusts the cones for a loose QR and you tighten it, the bearings are too tight and vice versa. For best bearing (and frame) life the mechanic and rider should be in agreement that the QR should be tight. Very tight. That way the bearing preload is perfect each time the wheel is installed. Unfortunately the advent of lawyers lips or as Health and Safety likes to call it, safety tabs, on forks, means that each time the front wheel is installed the bearing preload changes or potentially changes.

 

[zacklaws]

Hmm ...

Now I am wondering whether it might actually be the rear wheel causing the problem! It feels like the front and sounds like the front, but sometimes it is hard to pin these things down, especially when panic braking from speed.

Colin, I'm wondering myself now with what you have described happening, being Mavic wheels and think it could be the back, your freewheel is dry and your experiencing the "Mavic growl" . Its a common problem with Mavic wheels and I was plagued with it last year and its just a quick job to oil the pawls with a light mineral oil. It terrified me first time it ever happened. I cannot remember either if you was riding with me last year on Season of the Mists when mine started halfway round and on occasions till we got to the end after we met up at the last checkpoint.

 

[gbb]

Overtightening could possibly cause a minor issue. I sent the genesis off for a spoke repair to another shop last year as the LBS guy I trusted had moved to snother job. The guy who did the wheel had tightened the wheel so tight it took my entire 15 stone of strength to remove the fittings when the tube punctured.

I echo your concerns about taking the hub apart. I'm pretty hands on with things like fitting brakes, pedals, etc but bearings take respect

The irony is Downfader, cartridge bearings are very easy to fit IF you treat them correctly and have the right equipment.

Yes, you have mentioned it but not demonstrated it. It is obvious though but you are missing the point. It is not relevant in the overall scheme of things. You may as well remove the grease and oil the bearing, too... but I'm repeating myself.
Further, appealing for me to take your expertise as the gospel in bearing maintenance is no good. I judge concepts on first principles, not badges, medals or bluster.

You didn't even get my point about labyrinth seals which are frictionless.

I've made this point before and I'll do it again. There on the corner where you work is a new building going up. If you go there tomorrow you'll see a concrete truck and a concrete pump truck in action. You'll see there's a bloke there directing the pump nozzle into the shuttered moulds with rebar sticking out of it. He's done that for 30 years. However he knows nothing about reinforced concrete structures. He just knows how to pour cement.

You really are a first class pointy object, completely unable to carry on a sensible conversation. Your way or no way eh?
Sorry ColinJ...

 

[mybike]

The irony is Downfader, cartridge bearings are very easy to fit IF you treat them correctly and have the right equipment.

I remember an occasion when I fitted a bearing in a washing m/c drum. Put the bearing in the freezer for a few hours beforehand to make it easier & it fell right through the housing. Yep, they'd sold me the wrong bearing.

 

[ColinJ]

Come on chaps - stop arguing among yourselves!

I should say that I am not talking about loosening QRs from 'tight' to 'light', I am talking about from 'bloody tight' to 'tight'! I almost had to put an extension on the QR lever to undo it but even after loosening it I still had to use a firm push from the palm of my hand to do it up.

Colin, I'm wondering myself now with what you have described happening, being Mavic wheels and think it could be the back, your freewheel is dry and your experiencing the "Mavic growl" . Its a common problem with Mavic wheels and I was plagued with it last year and its just a quick job to oil the pawls with a light mineral oil. It terrified me first time it ever happened. I cannot remember either if you was riding with me last year on Season of the Mists when mine started halfway round and on occasions till we got to the end after we met up at the last checkpoint.

I came across that description when searching for advice. Ha ha - I just searched again and WHAT DID I FIND from 3 days ago? I skim through most threads on CC but somehow missed that one!

When I was cleaning the cassette I thought that the freehub mechanism felt stiff - it took more of a push to turn it than it really should. Also ... I did notice that if I span the rear wheel in the stand and left it to freewheel, the wheel drove the cranks round for a few seconds. I'll take it to bits tomorrow and check it out.

 

[Smurfy]

It is something that takes mechanics in training quite a while to learn to get right.

Easily done using a pair of spacers that are the same width as the frame dropouts.

 

[Yellow Saddle]

Easily done using a pair of spacers that are the same width as the frame dropouts.

No. That assumes that the correct adjustment just happens to be exactly the width of the nominal frame dropout or hub width. That would be a pure coincidence.

The correct adjustment will appear too loose when the wheel is out of the frame and exactly right with the wheel clamped in the frame.
What most people don't realize is the elasticity of steel causes the adjustment to change when the wheel is clamped. This only happens with QR because it applies pressure over the hub whereas nutted axle only strain the axle between the jamb nut and outside nut.

This is easily demonstrated. Put the bike on a stand and remove the wheel. Adjust the cone so that there is minuscule play at the bench. Now fit the wheel loosely (QR loosely closed) and demonstrate to yourself that there is play when the wheel is manipulated at the outer edge. Now open the QR nut, tighten it and start clamping. You'll notice the cone play disappearing. The trick is to have both variables come together at the right moment, when the QR is tight.

Once you have this setting right and then measure the OLD, you may or may not come to 130/135/100 mm, but that like I say will be a co-incidence.

Cones that are under and overtighted place too much strain on bearings and shorten their life dramatically.