SRAM MTH-506 R hub, query RE bearings & hubs

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RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

531colin wrote: 10 Apr 2021, 10:30am You are probably right! Its too easy to assume "everybody knows....."
The "preload" is the compressive force on the bearing which is there all the time, before service loads are imposed, and during use.
You need "just enough" preload so that you can't wobble the rim when the wheel is mounted in the bike.
If you set up the hub like that when its out of the bike, and then put it in the bike and tighten the Q/R, you are putting an enormous load on the (relatively small) contact area. (Because the Q/R compresses the axle). This quickly results in the case hardening getting worn away on the cones, as in the other thread.
Note that hubs with cassette bearings aren't (usually?) provided with means for adjustment of bearing preload.

Okay just seen Bruce's comment
All you really need to know is that there should be a little free play in the bearings which just disappears when the QR is used to secure the wheel in the frame. Everything else is pretty straightforward.
Have bookmarked the thread for future reading when I'm next doing maintenance :)
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

Thats it.
Or you can probably find enough bits and pieces knocking around to make a "hub vise".
Thats a confusing term for a way of adjusting the bearings while the axle is under a compressive load from the Q/R.
viewtopic.php?f=5&t=143125&start=15...at the bottom of this page.....
You need a bit of metal with a hole big enough for the axle to fit into...in my case, an old headset/lockring spanner.
Put the cassette end of the axle in the hole; at the non-cassette end, put an M6 nut on the skewer. Now, when you tighten the skewer, the axle is compressed between the locknut at the cassette end and the opposite axle end. So now you can adjust the bearing with the axle under compression from the Q/R.
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

531colin wrote: 10 Apr 2021, 12:30pm Thats it.
Or you can probably find enough bits and pieces knocking around to make a "hub vise".
Thats a confusing term for a way of adjusting the bearings while the axle is under a compressive load from the Q/R.
viewtopic.php?f=5&t=143125&start=15...at the bottom of this page.....
You need a bit of metal with a hole big enough for the axle to fit into...in my case, an old headset/lockring spanner.
Put the cassette end of the axle in the hole; at the non-cassette end, put an M6 nut on the skewer. Now, when you tighten the skewer, the axle is compressed between the locknut at the cassette end and the opposite axle end. So now you can adjust the bearing with the axle under compression from the Q/R.
That's a very handy little tool :thumbsup:
zenitb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by zenitb »

RecumbentRide wrote: 10 Apr 2021, 12:38am Well I'll be buying Shimano for my next set of hubs and though I'd like to try the cartridge bearing option Shimano don't seem to offer this so I'll be stuck with C&C for now. .....
It looks like Shimano ARE tentatively moving towards sealed bearing hubs - See this schematic RR ... (my red arrows)
Shimano FH-MT401 schematic
Shimano FH-MT401 schematic

This is a 135mm OLN hub (not sure what width you need?) although obviously there are 142mm and 148mm versions.

Given you are currently on an "unoffical" (3rd party Sunrace) 12 speed cassette at the moment this would also give you the "opportunity" to buy the pukka Shimano microspline cassettes, and matching "HYPERGLIDE+" chain. It wont break the bank either .. remember Tredz will knock a fiver off this price with their discount code...

Tredz deal
Tredz deal

We have already had a discussion about this hub and the cup and cone diehards (that includes me BTW) have expressed some reservations but its worth noting none of us have even seen this hub yet so the jury is actually out regarding reliability etc. See..
viewtopic.php?f=5&t=137349&p=1479886#p1479886

Its so cheap I am tempted to get one just to try it out but I have no 12 speed bikes ATM and have no real desire to move there yet, if at all.

See what you think ... it may be the sort of thing you are interested in RR ?
RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

Thank you for that. That'll be another excuse to spend more money on some goodies :wink:

There is a video on this hub here.
zenitb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by zenitb »

RecumbentRide wrote: 11 Apr 2021, 1:28am Thank you for that. That'll be another excuse to spend more money on some goodies :wink:

There is a video on this hub here.
Good spot regarding the disassembly video - it was interesting to see how the hub unbolted and how the individual parts fit together - not that dissimilar now to how some of the Novatec or (SRAM badged) Formula sealed bearing hubs I already have work.

The real issue with these bearings is likely to be the quality of the sealed bearings provided in them when new. They appeared to have bright blue seals in the video although I couldn't see any branding.. I wonder if Shimano make these themselves or take advantage of the wide range of commodity suppliers and outsource this part to a specialist bearing producer ? (this after all being the main benefit of using sealed bearings). Given this is a Deore level hub you would expect the sealed bearings to be decent .. not the "no name" stuff you get on ebay... although I cant see Shimano going to FAG or SKF.

I noticed the video didn't cover taking the main bearings out of the hub shell (the only actual difficult bit !!) I have yet to swap the bearings in any of my Novatec/Formula sealed bearing hubs and am currently contemplating the different bearing "pullers" available... In the past Shimano would specify any special tools needed for servicing themselves .. and the special tools have been expensive but of good quality. I suspect this time they will just "point us at the market" though .. and leave us to source something - I have been looking on eBay. A good subject for another thread I guess...

Best of luck with the MTH-506 replacements RR ... It would be good to know what you end up getting in the end and how you get on with them .. especially if you go down the Shimano sealed bearing route...
zenitb
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Shinano see sealed bearings as downmarket ?

Post by zenitb »

Ok final post on this ..promise. Its really based on the other videos that the YouTuber RecumbantRide spotted had on his channel

It transpires that although Shimano have moved to sealed bearings on the FH-MT401 hub shown earlier in the thread, they have RETAINED CUP AND CONE on the more up market FH-MT500 hub .... which otherwise has the same spec (135mm, disk, MicroSpline etc) ...

Up market hub with real balls :-)
Up market hub with real balls :-)

... and YouTube disassembly vid: https://www.youtube.com/watch?v=C40jLF-L8VY

To me this is very interesting since I think Shimano are trying to tell us that cup and cone hubs are their up market offerings and sealed bearing hubs are going to be their budget offerings. This makes a lot of sense since it costs money to face harden bearing races in a forged cup and cone hub wheras simply boring out a cast hub and hammering in a commodity bearing is a cheaper process with much less investment in machinery, forging technology, heat treating etc.

I am watching this with interest since I love the engineering Shimano put into their technology and dont want them to go down the SRAM route of just stamping their name on hubs they buy from other commodity suppliers...
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by jb »

First off they don't hammer in anything, secondly cartridge bearings by reputable manufacturers who make nothing else but bearings are by and far superior to anything Shimano could make. Brucey has issues with the lubrication that's used, but for the majority of sales it won't make a ha'porth of difference.
Granted, the axle has to have very good tolerances so there is no excess preload but that's not an issue these days.
Cup and cone allow Shimano to make their free hubs in the way they are with no extra bearings but that's about it.
Cheers
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RecumbentRide
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by RecumbentRide »

Yea I've kind of gone off the FH-MT401 hub. Can a £30 odd hub be of sufficient quality for long mileages?
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

jb wrote: 11 Apr 2021, 10:32pm First off they don't hammer in anything, secondly cartridge bearings by reputable manufacturers who make nothing else but bearings are by and far superior to anything Shimano could make. Brucey has issues with the lubrication that's used, but for the majority of sales it won't make a ha'porth of difference.
Granted, the axle has to have very good tolerances so there is no excess preload but that's not an issue these days.
Cup and cone allow Shimano to make their free hubs in the way they are with no extra bearings but that's about it.
At the risk of repeating myself, I'll....errr....repeat myself....
531colin wrote: 9 Apr 2021, 3:37pm
RecumbentRide wrote: 8 Apr 2021, 10:35pm ......... I imagine cartridge offers a lot of advantages.......
To the manufacturer, rather than the end user.
Cheap as chips to buy, just press it in and off you go. No setting the preload, no complex tooling.
However, the bearings are made for use in indoor machinery at high revs; very different to low revs on a bike out in the weather.
There is not enough grease in them, and its high temperature grease, not sticky stuff with corrosion inhibitors.
Cartridge bearings in a bike are always too small for the load, as the parts sizes were set when there was no option except making the bearing an integral part of the structure.
The preload on your cartridge bearing varies depending on the fit when its pressed in and also in hubs depending on the spoke tension because spoke tension distorts the hub shell.
Still, never mind, you can flog them as "sealed bearings" which the user thinks means "keeps the water out" when in fact it means "no user serviceable parts in here"
In a rear hub, left and right spoke tensions are quite different, so the distortion of the hub shell produced by spoke tension load is different for the different sides of the hub. So a different bore for each side of the hub, because its bored to take the bearing before its built, not after.
Closing the Q/r also compresses the axle.
So, at best, the best quality cartridge bearings you can buy, if you stick them in a bike hub they are working under a random preload....like badly-adjusted cup and cone.
jb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by jb »

I'm not particularly disagreeing but:
Hubs are been made significantly meatier these days to cope with distortion & the compression due to the skewer can be compensated for to a certain extent (and fat axles don't have compression issues as far as I can tell). Certainly modern manufacturing methods have enabled designs to be different from the past as its no longer as big an expense to have a high tolerance on a part size. However at the end of the day its a trade off between the bad things that can happen to a cartridge bearing hub and the bad things that can happen to a cone hub with bad adjustment and grease contamination which is just about impossible to avoid in a home workshop situation - once they require re-lubricating that is. Knocking out a cartridge bearing and pressing in a new one leaves far less room for bad adjustment especially in Hope type designs with no threads to tighten.

I've seen more failed cones than collapsed bearings but your experience may be different being in the trade.
Cheers
J Bro
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

You only refer to contaminated grease in connection with traditional cup and cone bearings.
However, contamination is more likely to be a problem in cassette bearings, because the ball bearings are smaller, they are in close-fitting cages, and they run (generally) in a "deep groove". In cup and cone bearings there is plenty of room for a bit of muck to be simply pushed out of the way.
A comparison would be between building a watch and a bilge pump....a bicycle hub works in conditions closer to a bilge pump than a watch.
jb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by jb »

531colin wrote: 12 Apr 2021, 1:35pm You only refer to contaminated grease in connection with traditional cup and cone bearings.
However, contamination is more likely to be a problem in cassette bearings, because the ball bearings are smaller, they are in close-fitting cages, and they run (generally) in a "deep groove". In cup and cone bearings there is plenty of room for a bit of muck to be simply pushed out of the way.
A comparison would be between building a watch and a bilge pump....a bicycle hub works in conditions closer to a bilge pump than a watch.
True, they are sensitive to the tiniest spec, but sealed deep groove ball races are usually assembled in clean room conditions and never see human contact, If you try re-lubricating them you are risking it.
Cheers
J Bro
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531colin
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by 531colin »

jb wrote: 12 Apr 2021, 11:23pm
531colin wrote: 12 Apr 2021, 1:35pm You only refer to contaminated grease in connection with traditional cup and cone bearings.
However, contamination is more likely to be a problem in cassette bearings, because the ball bearings are smaller, they are in close-fitting cages, and they run (generally) in a "deep groove". In cup and cone bearings there is plenty of room for a bit of muck to be simply pushed out of the way.
A comparison would be between building a watch and a bilge pump....a bicycle hub works in conditions closer to a bilge pump than a watch.
True, they are sensitive to the tiniest spec, but sealed deep groove ball races are usually assembled in clean room conditions and never see human contact, If you try re-lubricating them you are risking it.
I haven't got any hubs in use which are old enough to vote, but I have got a couple of pairs which approach double figures. There are on roughstuff bikes, so not high mileage, (more "high days and holidays" type bikes) and I have a fair idea when I built the wheels because they are carbide rims which marked the end of re-rimming the wheels every several years. I have kept the hubs going by annual greasing, at first by drilling the hub barrel and injecting grease; however, if you do this the freewheel dries out eventually, so in more recent years I have injected SFG into the driveside and regular grease into the left side.

Would you envisage getting that sort of life out of cassette bearing hubs? and would that be by re-greasing or replacing bearings?
Genuine question, I have little experience of cassette bearing hubs.

EDIT.....not as good an idea as I thought on how old the hubs are....this pins down one set..
https://www.flickr.com/photos/52358536@ ... 1575543324
https://www.flickr.com/photos/52358536@ ... 2068552796
https://www.flickr.com/photos/52358536@ ... 1590445522
https://www.flickr.com/photos/52358536@ ... 1590364388
https://www.flickr.com/photos/52358536@ ... 1589837172
thats a tour I did in the Lakes in 2012, and I fitted carbide rims to that bike when I got home.
zenitb
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Re: SRAM MTH-506 R hub, query RE bearings & hubs

Post by zenitb »

531colin wrote: 12 Apr 2021, 8:36am
....
jb wrote: 11 Apr 2021, 10:32pm .......cartridge bearings by reputable manufacturers who make nothing else but bearings are by and far superior to anything Shimano could make. .....
Cup and cone allow Shimano to make their free hubs in the way they are with no extra bearings but that's about it.
....
Interesting JB ... as per colin my experience of sealed bearing hubs is very limited - however they are starting to become part of the "zenitb fleet" by default as new bikes come into my "family and friends" circle and I am expected to fix them... so I have dug out a couple of my current hubs, pulled them apart and photographed the bearings...

First up is an "NBK" bearing
NBK bearing in Novatec XD462SB-B12 rear hub
NBK bearing in Novatec XD462SB-B12 rear hub
Then there is a "XERO" bearing
XERO bearing in SRAM MTH746 (a.k.a Formula DHT148) rear hub
XERO bearing in SRAM MTH746 (a.k.a Formula DHT148) rear hub
These are both expensive hubs .. would you say NBK and XERO are reputable bearing manufacturers JB ? Or are you refering only to FAG, SKF etc ?

PS: The driveside bearing on the XERO bearing hub is a bit notchey (I guess the inferior placement of the bearings vs. Shimano HG means the driveside bearing is near the middle of the axle and takes most of the hammer ? - and this is born out on this hub - the non-driveside is silky smooth). Have not done many miles on this bike at all although what I have done has been at Bike Park Wales so maybe a few landings etc...disapointing its on the way out though.. I have 10 year old Deore hubs that have done the same runs at BPW and a LOT more miles which are still fine.

PPS: the XERO bearings are the swishier LBLU version which I have read only has contact seals on the "outer" side of the bearing (minimising friction), wheras the NBK bearings are the 2RS variety with contact seals on both sides including the "blind" inner part of the hub where I guess they are not strictly necessary. Strange because the Novatec hub with the 2RS bearings is theoretically the more top of the range/expensive one...
Last edited by zenitb on 14 Apr 2021, 12:08am, edited 1 time in total.
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