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

For discussions about bikes and equipment.
jb
Posts: 1782
Joined: 6 Jan 2007, 12:17pm
Location: Clitheroe

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

Post by jb »

The Hope hubs that were on my mtb I got second hand off the Hope race team they did 12+ years on that bike and then got transferred to a road bike for a further 4 years but doing triple the milage. I retired them eventually because the discs became obsolete & expensive to replace. They never had a bearing change in all that time and are still silky smooth.
Some of our adventures together were on the those very same roads in Colins photos :)

PS they were also bonded together before Hope started making hubs out of forged billets.
Cheers
J Bro
zenitb
Posts: 832
Joined: 7 Aug 2018, 9:59pm
Contact:

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

Post by zenitb »

Ah right J Bro .. possibly a Hope "Big Un" with its unique 5-bolt disk mount ? Or something even earlier? These were truly visionary hubs and deservedly put Hope on the map. Must have been great to get one of the originals ...
Hope Big Un
Hope Big Un
Not sure what was in your hub but looking at the Hope website they state they use INA bearings ... my MTB trails rider friend has had to change his Hope bearings fairly infrequently so we can probably put INA on the "good" list of bearing suppliers ... mind you at £160 for a rear hub (compared with Colin's £40 XT hubs) they blummin' well ought to be !!!!

Things have not always been rosy for Hope - try this google search :

https://www.google.com/search?client=fi ... roken+axle

On a Shimano rear axle the bearings are almost at the END of the axle both sides - the key patented breakthrough in HyperGlide hubs. This ended at a stroke the snapped axle issue that plagued freewheel hubs. This innovation has been abandoned in sealed bearing hubs with one of the main bearings being back where the old freewheels put them - nearly in the middle of the axle - causing bending moment on the axle (and the wear to be unevenly distributed, as I have seen on my Formula hub). So axles have been widened to try and make them less prone to bending. This might be the issue that "did for" the Hope 2 axles shown in the search above .. that or the stress raisers on the original "stepped" aluminium axle design they used.
Exactly where freewheel axles used to break in the 70s !!!
Exactly where freewheel axles used to break in the 70s !!!
from https://ridemonkey.bikemag.com/threads/ ... le.199632/

That said you can see from the threads that Hope stood behind their product and came up with thickened replacement axles, both in alu and steel ... and released the thicker EVO2. not sure your Formulas, Quandos, Novatecs and their branded incarnations from Whyte, SRAM, Specialised et all would do the same for you though..

I am still keen to find out more about NBK and XERO bearings and where they stand on the resilience front. Maybe I will have to ask the great Hambini .. he seems to have strong views on the subject :-) :-) :-) https://www.hambini.com/warning-counter ... -bearings/

As an aside I can see the two hubs I have taken apart have different ways of setting up preload - J Bro I think you have hinted at this in your post.

1. The Novatec hub (XD642SB-B12) uses what I think is the more modern method (???) where you "just tighten up the bolts" to a specified torque. In this hub all the inner bearings of the four sealed bearings are separated by "alu tube" spacers - which appear to take the side load directly. Presumably the two main bearings are held apart just enough in the precisely machined hub shell that the right sideways preload is applied across these two key bearings ???? At least when the bearings are new?? (not sure though .. would be happy to be corrected / contradicted ..? )

2. The Formula (DHT148 a.k.a. SRAM MTH 746) hub has two nuts mimicking the conventional cone adjustment nuts you would use on a cup and cone hub and you have to manually adjust the side to side preload. There are no "alu tube" spacers between the sealed bearings in this hub, so nothing to prevent you from over-tightening the axle and killing the bearings with excessive side to side preload. This is the hub I see people reporting problems with on the internet (in its various branded guises). Its not helped by one of the securing bolts being reverse threaded on a very thin alu main axle - and I suspect a fair number of the failures are people not seeing the very faint markings advising this is a reverse thread - then stripping the alu threads off the axle trying to get it apart.

Any clues/advice on the two varieties of side preload would be appreciated. Maybe we could build a "sealed bearing FAQ" post with all the key info, axle types, recommended bearing suppliers etc... ?

Sorry about the long post... I am probably over thinking as usual :-)
User avatar
531colin
Posts: 16083
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

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

Post by 531colin »

jb wrote: 14 Apr 2021, 12:08am The Hope hubs that were on my mtb I got second hand off the Hope race team they did 12+ years on that bike and then got transferred to a road bike for a further 4 years but doing triple the milage. I retired them eventually because the discs became obsolete & expensive to replace. They never had a bearing change in all that time and are still silky smooth.
Some of our adventures together were on the those very same roads in Colins photos :)

PS they were also bonded together before Hope started making hubs out of forged billets.
Thats a staggering achievement! Is that all on the original bearings and original grease?
It means that several things are absolutely cock-on; preload; lubrication ; sealing.
Your experience with Hope and mine with XT demonstrates that both cassette and loose-ball hubs can be made to work.
The Hope stuff is expensive, and I rather doubt you would get the same results with (say) Formula, but I'm happy to be proved wrong!
I have been retired from Spa for the best part of 9 years (where did that go?). when I was at Spa, we saw more Hope hubs with busted flanges than Shimano, and Shimano's market share would be a great deal more. I think at the time the hubs were advertised as "machined from billet" as if that was a good thing; I think Shimano (and Campag.) forge theirs.
Hopefully Hope (sorry, couldn't resist) have put their flange troubles behind them now; I wish them well, a proper innovative British business.
markjohnobrien
Posts: 1037
Joined: 4 Oct 2007, 8:15pm

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

Post by markjohnobrien »

zenitb wrote: 14 Apr 2021, 2:31pm Ah right J Bro .. possibly a Hope "Big Un" with its unique 5-bolt disk mount ? Or something even earlier? These were truly visionary hubs and deservedly put Hope on the map. Must have been great to get one of the originals ...
big un.JPG

Not sure what was in your hub but looking at the Hope website they state they use INA bearings ... my MTB trails rider friend has had to change his Hope bearings fairly infrequently so we can probably put INA on the "good" list of bearing suppliers ... mind you at £160 for a rear hub (compared with Colin's £40 XT hubs) they blummin' well ought to be !!!!

Things have not always been rosy for Hope - try this google search :

https://www.google.com/search?client=fi ... roken+axle

On a Shimano rear axle the bearings are almost at the END of the axle both sides - the key patented breakthrough in HyperGlide hubs. This ended at a stroke the snapped axle issue that plagued freewheel hubs. This innovation has been abandoned in sealed bearing hubs with one of the main bearings being back where the old freewheels put them - nearly in the middle of the axle - causing bending moment on the axle (and the wear to be unevenly distributed, as I have seen on my Formula hub). So axles have been widened to try and make them less prone to bending. This might be the issue that "did for" the Hope 2 axles shown in the search above .. that or the stress raisers on the original "stepped" aluminium axle design they used.

hope breakage.jpg
from https://ridemonkey.bikemag.com/threads/ ... le.199632/

That said you can see from the threads that Hope stood behind their product and came up with thickened replacement axles, both in alu and steel ... and released the thicker EVO2. not sure your Formulas, Quandos, Novatecs and their branded incarnations from Whyte, SRAM, Specialised et all would do the same for you though..

I am still keen to find out more about NBK and XERO bearings and where they stand on the resilience front. Maybe I will have to ask the great Hambini .. he seems to have strong views on the subject :-) :-) :-) https://www.hambini.com/warning-counter ... -bearings/

As an aside I can see the two hubs I have taken apart have different ways of setting up preload - J Bro I think you have hinted at this in your post.

1. The Novatec hub (XD642SB-B12) uses what I think is the more modern method (???) where you "just tighten up the bolts" to a specified torque. In this hub all the inner bearings of the four sealed bearings are separated by "alu tube" spacers - which appear to take the side load directly. Presumably the two main bearings are held apart just enough in the precisely machined hub shell that the right sideways preload is applied across these two key bearings ???? At least when the bearings are new?? (not sure though .. would be happy to be corrected / contradicted ..? )

2. The Formula (DHT148 a.k.a. SRAM MTH 746) hub has two nuts mimicking the conventional cone adjustment nuts you would use on a cup and cone hub and you have to manually adjust the side to side preload. There are no "alu tube" spacers between the sealed bearings in this hub, so nothing to prevent you from over-tightening the axle and killing the bearings with excessive side to side preload. This is the hub I see people reporting problems with on the internet (in its various branded guises). Its not helped by one of the securing bolts being reverse threaded on a very thin alu main axle - and I suspect a fair number of the failures are people not seeing the very faint markings advising this is a reverse thread - then stripping the alu threads off the axle trying to get it apart.

Any clues/advice on the two varieties of side preload would be appreciated. Maybe we could build a "sealed bearing FAQ" post with all the key info, axle types, recommended bearing suppliers etc... ?

Sorry about the long post... I am probably over thinking as usual :-)
Hope are very picky about their bearings and the bearings you mention from INA are custom made.
Raleigh Randonneur 708 (Magura hydraulic brakes); Blue Raleigh Randonneur 708 dynamo; Pearson Compass 631 tourer; Dawes One Down 631 dynamo winter bike;Raleigh Travelogue 708 tourer dynamo; Kona Sutra; Trek 920 disc Sram Force.
jb
Posts: 1782
Joined: 6 Jan 2007, 12:17pm
Location: Clitheroe

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

Post by jb »

zenitb wrote: 14 Apr 2021, 2:31pm Ah right J Bro .. possibly a Hope "Big Un" with its unique 5-bolt disk mount
Sorry about the long post... I am probably over thinking as usual :-)
Hope of course made their name making extremely good tandem hubs, which put high loadings on the bearings.

Funny thing is when I did a factory visit to Hope the chap who took us round denied they ever made tandem parts, almost like it was an embarrassment to have their trendy MTB range associated with tandems. But maybe he hadn't worked there long enough.

The hubs I have were associated with flange failures but I never have done any of that fancy trixie stuff, so I guess they were ridden well below the safe limit with me at least. I thought putting them on my road bike with no suspension & thin tyres might break them but they survived.
DSC_0872~2.JPG
Cheers
J Bro
Post Reply