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PostPosted: Fri May 14, 2010 12:40 pm 
Devout Dirtbag

Joined: Thu Jul 16, 2009 5:13 pm
Posts: 107
Location: Devon
Hi, does anyone know what would be a suitable replacement BB for a 1991 Kona Cinder Cone? It's still running the original Suntour LTD with greasealer, but at almost 20 years old I feel it's probably going to need replacing before too long. I've kept it well greased and it seems OK at the moment, but be good to know what will fit (shimano octalink?) when the inevitable happens...

I want to keep the current Suntour XC LTD crank and Suntour Powerings if possible, mainly for cost reasons, though if you can't get BB's to fit Suntour anymore, then I may have to go Shimano for BB & crank :(

Info I'd like is what size i.e. 68/70/73???, 113/118/121 etc??? Looked at a shimano BB on CRC and the description was somewhat confusing:

Specifications:
• V2 MTB compatible
• E-type no
• Chain Line 47.5 & 50mm
• Spindle 22.2 chrome-moly steel/hollow type adapter aluminium

What the hell does that lot mean????

Cheers :)


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PostPosted: Fri May 14, 2010 12:58 pm 
Old School Grand Master
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Joined: Wed Feb 20, 2008 12:21 pm
Posts: 5782
Location: Lost in Translation
bertberr wrote:
Hi, does anyone know what would be a suitable replacement BB for a 1991 Kona Cinder Cone? It's still running the original Suntour LTD with greasealer, but at almost 20 years old I feel it's probably going to need replacing before too long. I've kept it well greased and it seems OK at the moment, but be good to know what will fit (shimano octalink?) when the inevitable happens...

I want to keep the current Suntour XC LTD crank and Suntour Powerings if possible, mainly for cost reasons, though if you can't get BB's to fit Suntour anymore, then I may have to go Shimano for BB & crank :(

Info I'd like is what size i.e. 68/70/73???, 113/118/121 etc??? Looked at a shimano BB on CRC and the description was somewhat confusing:

Specifications:
• V2 MTB compatible
• E-type no
• Chain Line 47.5 & 50mm
• Spindle 22.2 chrome-moly steel/hollow type adapter aluminium

What the hell does that lot mean????

Cheers :)

Starting with the last part, most of those details refer to aspects of Shimano's Octalink spline interface. The axle is 22.2mm in diameter, steel, hollow, and uses the V2 spline pattern - the second variant of Octalink. ''E type" refers to a specific type of front derailleur that attaches to a mounting plate clamped by the fixed flange of the drive-side bottom bracket cup (and "no" means that this unit isn't designed with that attachment in mind). "Chain Line" refers to the distance between the central plane of the bike frame, and the plane of the middle chainring - i.e. a measure of how far the drive train sits from the centre of the bike.

The late, great Sheldon Brown has better, fuller explanations of most of those terms:

http://www.sheldonbrown.com/glossary.html

e.g.

http://www.sheldonbrown.com/gloss_n-o.html#octalink

and

http://www.sheldonbrown.com/gloss_e-f.html#etype

When your Suntour bottom bracket gives up the ghost, you should be able to replace it with a similar sqare taper unit from another manufacturer - a Shimano UN72 for example. You may even find a New-old-stock (NOS - i.e. old but unused) Suntour model on eBay or via the classified section here.

The shell width of your frame should be 68mm (you can measure this easily with a ruler) and the spindle length will probably be around 122mm. To be certain, you need to take the cranks off and measure the spindle with a caliper - but perhaps somebody else knows for sure. I don't.


Last edited by one-eyed_jim on Fri May 14, 2010 1:04 pm, edited 1 time in total.

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PostPosted: Fri May 14, 2010 1:04 pm 
Gold Trader
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Joined: Wed Aug 19, 2009 4:57 pm
Posts: 1428
Location: Stansted
Learning the art of the bottom bracket takes a few hours to master.

You can just clean up and slot in new bearing into your current bottom bracket and all should be fine.


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PostPosted: Fri May 14, 2010 1:39 pm 
Devout Dirtbag

Joined: Thu Jul 16, 2009 5:13 pm
Posts: 107
Location: Devon
OK, that all makes a lot more sense now - cheers :wink:

Hadn't thought about just replacing bearings, are they loose or in a cage in these Suntour BB's?

Re taking the BB out for inspection, it's probably the only job that I've yet to tackle on the bike (mainly down to not needing to), so is it fairly straight forward, and do I need any special tools baring in mind its a Suntour, or would any BB extraction tool from CRC do the trick?


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PostPosted: Fri May 14, 2010 1:57 pm 
Old School Grand Master
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Joined: Wed Feb 20, 2008 12:21 pm
Posts: 5782
Location: Lost in Translation
bertberr wrote:
Hadn't thought about just replacing bearings, are they loose or in a cage in these Suntour BB's?

They're usually caged for ease of factory-assembly. You can replace caged balls with loose balls of the same diameter. But the spindle often needs replacing before the balls do: the bearing tracks become pitted.

Quote:
Re taking the BB out for inspection, it's probably the only job that I've yet to tackle on the bike (mainly down to not needing to), so is it fairly straight forward, and do I need any special tools baring in mind its a Suntour, or would any BB extraction tool from CRC do the trick?

Most older bottom brackets use the Campagnolo pattern of a peg spanner for the lockring(s), a pin spanner for the adjustable cup, and a big (36mm) flat spanner for the fixed cup (see "adjustable type" here):

http://www.parktool.com/repair/readhowto.asp?id=93

That lot would set you back quite a few quid. I think I wouldn't bother. If the cranks turn smoothly without play, leave it all alone.

Pictures are very helpful when you're asking for specific advice about tools, etc. There are many, many variations on the market, and advice given blind - even with the best intentions - can be misleading.


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PostPosted: Fri May 14, 2010 2:07 pm 
East Midlands Deputy AEC
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Location: Ashby-de-la-Zouch
I replaced the suntour bb in my 91 Cindercone in about 93 and as I don't have any suntour- specific tools knocking about I don't think you'll need any. I changed to an Action Tec (titanium axle and roller bearings), on the basis of weight and longevity. You wont believe the weight of that suntour axle when you remove it :shock: .


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PostPosted: Tue Sep 28, 2010 9:46 am 
Devout Dirtbag

Joined: Thu Jul 16, 2009 5:13 pm
Posts: 107
Location: Devon
Thought I'd add to this old post rather than create a new one on the same subject...

Having removed the BB assembly (with the help of a piece of copper tube and a home made pin spanner :shock: ), I noticed that it was the spindle that was the culprit - badly pitted. Bearings (caged) seemed OK, though I didn't much like the way the cage edges just 'sat' in the cups - surely you're only getting benefit from one side?

Anyway, measured spindle with caliper and it was 129mm... :? Thought it would be 122 or 127 - a standard size. Would it matter if I fitted a 127, as it's only 2mm shorter / 1mm each side won't make much difference will it?

Due to the design of the current set-up, and potential cost of replacing spindle, bearings and even cups if I decide to go loose (they're worn from the underside of the cage), think I'll just opt for a UN54.


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PostPosted: Tue Sep 28, 2010 6:22 pm 
retrobike rider
retrobike rider

Joined: Sun Jan 24, 2010 11:37 am
Posts: 776
Location: On the move !
Had to replace the BB on my 91 cindercone tip find
due to being badly corroded, just put in a shimano
un 54 .... not that lite .... but works just fine ,
would be worth looking for a un 72 or something
of higher quality
Mick :)


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PostPosted: Tue Sep 28, 2010 6:47 pm 
retrobike rider
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Hadn't seen this post before.

XC LTD in 1991 (it's first year) used the same bottom bracket as the XC Comp (which was second from top in the range). Assuming it is that bottom bracket it'll weigh ~350g give or take a few grammes.

A UN54 will be quite a bit lighter

It should be a '3S' bottom bracket (probably stamped on the axle somewhere), which is a 68mm shell and asymmetric. But then it should measure quite a bit shorter at 121.5mm ( I think ?)
But a current equivalent is 127mm length.


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PostPosted: Tue Sep 28, 2010 7:02 pm 
Devout Dirtbag

Joined: Thu Jul 16, 2009 5:13 pm
Posts: 107
Location: Devon
OK, well you're dam close with that weight! Including the three little external o-rings each side :!: the whole gubbins come in at 345g.

Got the verniers out again and the axle is 128.93mm..., so do you reckon the 127mm is OK? I hope so as that's the longest they make on a 68mm shell, failing that I'll need to take out a mortgage on an Action-Tec if I want anything longer.

What surprised me is not only the length of time its lasted (almost 20 years of continual use, albeit with regular grease injections) but also how one minute it seemed OK and the next there was a definate grumbling, yet the pitting on the spindle was quite heavy suggesting it had been pretty second hand for some while...


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