wheel bearings

cyclosteve

hi all I need to replace the bearings in my boardman 650 comp wheels . need advice what size bearings I req as I was told the rear are bigger than the front. I don't want to strip down till I got the replacements

rockmonkeysc

Go to your local Boardman stockists and ask them to supply you with the correct size bearings.
They're probably cup & cone, waste of time replacing the balls unless you can get new cups and cones as well.

cyclosteve

cheers will do never thought about changing cones

rockmonkeysc

If you replace the balls the pitting in the cones will destroy them in no time.

The Rookie

Stock Formula hubs using stock ball bearing sizes.

If the cones are OK, then just replace the balls, are you sure they need replacing and not just a strip, clean, regrease and rebuild (all they often need)?

cooldad

I've never needed to replace cups or cones. And some of my wheels are older than the average member age on here.

The Rookie

I have had wheels where the cones need doing, ride with the bearings not correctly preloaded and they fail relatively quickly.

rockmonkeysc

The cups and cones in Formula hubs which Boardman use are quite soft and don't last. The seals are crap as well so grease soon gets washed out.

cycleclinic

O.K if the hubs are cup and cone open the up and clean the cups and cones up. If there is pitting on the cups then the life span of the hub is limited. Cones from wheels manufacturing are available. They do enough that an exact or very close match will be possible. New balls shpould ideally be grade 10 chrome as these are the roundest and will pronlong the life of the cones and bearing cups. The cups are not replacable as you will not be able to buy spares.

If the cones are good and not pitted then replace the balls, if the cones have pitting replace the balls and cones. If the cups are pitted then new balls will get you a more miles and enough to buy new wheels.

Wheels manufacturing cones are ultegra standard or better. Grade 10 balls are round. Use these in a formula hub with a grease like rock n roll super web (does not get washed out easily) and you will have a hub that last longer between services and runs smoother. How do I know well I wonder.....

Oh get the bearing online from simply bearings e.t.c as bike shops will not stock this grade. Shimano balls are stainless and grade 25 at best which is good enough in reality. Oh and the nonsense about tgrade 10 balls being harder (they are are bit) and causing the cups to wear faster is well nonsense as it out of round balls that doo that nicely. the round the ball is less wear there is on everything. The harder the surface are the better but with formula cups you get what you have.

rockmonkeysc

The roundness of the ball has no effect on wear. Wear is entirely down to surface hardness. The difference between 10 grade and 25 grade is less than a micron (thousandth of a millimetre). 10 grade is used in high speed (10,000rpm plus), high precision applications, bicycle hubs are far from that. In engineering standards a bicycle hub is low speed and rather agricultural, very loose tolerance.
Also chrome bearings are softer than stainless steel, even if it's a low grade stainless.

cycleclinic

The roundness of a ball bearing is very relevent to how a hub wears. If it was not Shimano would not use grade 25 in there hubs and Campagnolo would not use grade 10. Hardness is relevent too but the steels used in ball bearings are really quite hard and there is little difference between then for the good grades. If the balls are grade 100 the variation in roundness causes the load to be unevenly distributed, they are also softer and wear the hub cups and cones faster.

Fact correction:
Stainless steel is harder than chrome steel. Wrong. 52100 chrome steel HRC value 60, stainless steel 440SC HRC value 58. Pretty close in the real world but stainless steel is not harder than chrome steel. Chrome steel is very hard that the whole point of it.
Diameter tollerance is less than 1 micron between grade 10 and grade 25. Wrong it is 1.2 microns.

Other important things;
Stainless steel is more prone to pitting (even though it is more corrosion resistant) than chrome balls that is important. Shimano use stainless bearing beacuse stainless steel balls are more resistant to rust than chrome balls. This problems is solved though by using a persistant grease and a fair bit of it. Hub performance is not affected but the chrome balls then do not rust. Renew the grease to keep the water out.
Grade 10 balls also have lower surface roughness half that of grade 25 balls.
Chrome balls have a higher load rating which is good for MTB hubs.
Chrome balls are more fatigue resistant so are less likely to break in service. That would ruin your hub quite quickly thankfully grade 25 SS balls don't break so this is an acadmeic gain.

Simply grade 10 chrome is a little bit better than grade 25 stainless for almost no extra cost.

A bicycle hub may be low speed but wear accumilates given the grade 10 balls work out at pennies each are you really suggesting not to use them?

I hope that helps.

The Rookie

While I accept your argument, I think a decent build with the correct preload is much more important than the grade or material of ball used, I have some shitty old wheel on my town hack bike but building the hub up properly means they last very well.

Also it's worth noting that different Shimano hubs have different sealing, the sub Deore have no rubber seal so a good robust waterproof grease is more important in them than it is in the better sealed hubs where the lubrication performance may be more critical, although personally I think a decent red rubber grease (I use Castrol) is the best grease for hubs.

rockmonkeysc

There's no point using more precise balls in your hubs unless the cups and cones are ground to a similarly tight tolerance and perfectly adjusted.
Using harder balls is also not a good idea, the balls are more easily replaced and cheaper than the cups and cones so they are the parts you want to wear.

cycleclinic

In fact using rounder balls in a cheap low tollerance hub prolongs the life of the cups and cones. You can tell this as the hub runs smoother with high grade balls compared to lower grade 100 or 300 balls. Weldite balls are grade 1000 and not even worth bothering with. Fit for caster wheels only.

Less round balls increase the wear rate on cups and cones so really you have missed the point I am trying to make. The cups and cones on cheap hubs are as hard as the chome balls because they are made from chrome steel or other hardened steels. Really how can rounder balls make a hub cups and cones wear faster. Please explain that one popcorn ready!

All hubs even XT or XTR need a persistant grease even the grease in XTR/dura Ace hubs after a while degrades and gets washed out if they are ridden enough (take a while though). The grease I use Rock n roll super web allows the hub to roll very well thankyou very much while being presistant. MTB hubs without seals should not be used on a bike. In fact the only quality hubs without seals are indoor track racing hubs. That should tell everyone something.

Correctly setting up the hub is very important in fact critical so I agree Rookie. I assume though a competant mechanic can set up a hub perfectly. In fact it how I define a competant mechanic from a less competant one.

rockmonkeysc

thecycleclinic wrote:

In fact using rounder balls in a cheap low tollerance hub prolongs the life of the cups and cones.

No it won't.

thecycleclinic wrote:

Less round balls increase the wear rate on cups and cones

No they won't

so really you have missed the point I am trying to make. The cups and cones on cheap hubs are as hard as the chome balls because they are made from chrome steel or other hardened steels. Really how can rounder balls make a hub cups and cones wear faster.

There are many hardening processes, some only harden the surface and some harden much deeper. The designer of the hub will have selected a bearing material to work best with the cups and cones being used.
Rounder balls won't increase wear rates but they also won't decrease wear rates unless your talking about massively out of tolerance balls which could potentially drag rather than roll.

The Rookie

I agree, the other tolerances involved, most critically the preload (or clearance setting) will be impossible to get to within microns, so bal roundness (ignoring the level of surface finish in the cups and cones) is totally irrelevant, that said if they are genuinely pretty much the same price then I would use a better one, but I wouldn't expect it to have any measurable effect.

kirby700

Ignoring all the tolerance issues etc. If the hubs are the same as my 26" wheeled boardman the hubs are a load of shit, rear wheel bearings might be available but the freehubs are impossible to source. Front wheel if fitted with the 15mm axle were some obscure sealed bearing and only available for £12 each. ( you need 2). Oh and halfords wont help.
However the bearings on the giant M475 shimano hubs are 6 years old and are brilliant to rebuild every few months.

cycleclinic

I did say the performace difference between grade 25 and grade 10 is pretty marginal in other words you won't feel it but as the balls are similarly priced why not. The performance difference I refer too is when you compare to grade 10 to grade 300 balls. Then the difference is a little more noticable. Most ball bearing you find in shops are grade 300 or worse (weldite) unless the shop stocks Shimano balls or Wheels manufacturing (both grade 25 stainless).

Yes the main problem with the boardman wheels is the lack of freehub availaibity. Having to service M475 hubs every few months is normal, the sealing just is not up to off road use. You need XT hubs for a hubs that does not let water in so quickly. That or a good cartridge bearing hub like Novatec D771/D772, Hope, DT Swiss.......

kirby700

Exactly. What I'm leading to is unfortunately new wheels......

gt-arrowhead

RockmonkeySC wrote:

thecycleclinic wrote:

Less round balls increase the wear rate on cups and cones

No they won't

Why is this not true?

Quite an interesting thread. All i can contribute is: Make sure you change bearings along with cups and cones if you want to get the most life out of your bearings. Even if your cups and cones are fine you may aswell change them since you are going to have to take your axle out.

The Rookie

Because in this case the roundness of the balls is irrelevant due to the greater out of true of the cups and cones, so however round the balls are, any wear will be much more likely to be attributable to the tolerances on those parts (plus the very course preload setting when the builder adjusts the cones).

cycleclinic

To explain further think of the hub as a two rollers with balls in between rotating against each other (turn the tube into a circle to get a hub). In a cheap hub there weill be imperfections in the cups and cones that will cause some of the grade 10 balls to be tight and other to be a bit loose. So wear happens at a certain rate. Replace the grade 10/25 balls with say grade 300 and the balls have imperfections (out of roundness) that make some balls an even tighter fit and other an even looser fit. So load is more unevenly distributed and wear happens faster. Seriously arguing that less round balls make a cheaper hub run just as well as rounder balls is like arguing that pointless putting good tyres on a cheap bike won't help it handle better.

The balls in Boardman hubs (joytech I believe) will be around grade 300. i.e good enough for the hubs to work for while but cheap enough to keep the cost of the hub down. I mean how when I set up a new cheap hub with grade 10 balls does it run smoother than with the grade whatever balls it came with, done that before when I had to take apart a new threaded hub and respace for 120mm for a 5 speed road bike. Given the hub felt a bit rough after setting it up I put grade 10 in there and that sorted it out quite well.

You can't change cups in most hubs. Only Campagnolo make the bearing cups available and they don't make MTB hubs.