Bottom Bracket size on an 856?

[Colin]

Anyone know what size it is?
I think it's a UN51 but do I have to know the width and size of cup in mm?
I've seen a sealed one for sale and as this is the only thing I've ever worn out on my XP-X (856) then maybe a sealed one is a good idea?
Or can anyone recommend other options?

You know what would be a really good idea to alleviate all of these constant "what size" questions?

How about we gather the spec's for each model of bike, assuming we get them from people who know what they are talking about.......
Maybe Kiwi or one of the other moderators would collect them and post them in one document, just like the original sales brochures for the bikes which appear to have disappeared from K2's site?

Or I'll do it if you want............

[jinder]

68 x 110

[kiwi]

i am 99 percent sure jinder is right even tho this chart says otherwise,the 1000,2000,3000, were the same frame(basically)

[junkster]

I agree - my 855 was that sized bracket and I think I am right in saying the actual frames were identical.

Dan  [smiley=beer.gif]

[Colin]

Dan.
Sorry? who do you agree with, Jinder or Kiwi's chart?

Kiwi,
This is exactly the sort of chart I had in mind to help people out, it out to be on the FAQ's !  

And then we can add to it for the older models,

In fact, I have just found the '98 spec sheet for a 757 downloaded from Girvin.com and that states 68 x 110 and has also got all of the other details.
I think this was the same frame as an 856 wasn't it?

I'll have to scan it and post it .....sometime......

Thanks, the BB I was looking at is
"107mm overall width
For 68mm cup bottom brackets, NOT for 73mm types."
....thought it was a bit cheap............ [smiley=coolfrown.gif]

Col

[Simon]

My 856 (from new) came with 68X108MM b/b,its still fitted.
Simon.

[Colin]

Hmmmm............
Does that mean that 110mm is the nominal size but they adjust to suit a liitle bit each side...?
Confused.......

[kiwi]

757 downloaded from Girvin.com and that states 68 x 110 and has also got all of the other details.
I think this was the same frame as an 856 wasn't it?

Not exactly the 657 was the same the x57s werte very very similar except the swingarm pivot was on the back of the downtube instead of the back of the seat tube.I am not 100 pwercent sure the bb didnt change too.....althoughg your info says it didnt!

[Sprucey]

Hi Guys,

I'll try and clear up the confusion here.

Most (but not all) MTB bottom brackets are sealed, disposable items these days. Royce used to make a great trafitional BB in the UK but sadly no more.

There are two key measurements:-

1) The Shell size/width
This is the width of the frame at the BB cup. It is likely to be either 68mm or 73mm. Most Euro frames are 68mm and a lot of US frames tend to be 73mm but you must measure the frame (My 856 is in the loft - if no one gets there first I will measure it tonight when I get home)
Shimano BBs tend to be sheel size specific but other makes (eg Truvativ) often are multi fit by using spacers)

2) Axle length.
This is the length of the axle from end to end. Common sizes are 108, 110, 113,118 122 etc. all measured in mm.

The axle length is NOT generally bike specific. It is normally determined by the type of crankset being used. Most suppliers/manufacturer's websites will state a BB axle length for each chainset they make.

The two most common sizes are 113mm and 118mm but there are anomolies - recent Shimano LX cranksets require a special 122.5mm BB axle!

Most cyclists try to keep the Q-factor or lateral distance between the pedals as low as possible - hence usng shorter axles (108mm/110mm). This is where the type of bike frame will come into play. Bikes with low/normal chainstays might stop you using a shorter bracket as there would not be enough clearance between the chainrings and the frame.

Also, beware using too narrow a BB as some front mechs won't push the cahin that far in and you will have problems changing down to the small granny ring up front.

Colin, if you want some advice feel free to call - Mark www.ukbikestore.co.uk  02392 528 932 (UK)

[kiwi]

i am pretty sure sprucey that 68/110 is what we need,so what will you sell us from commonly available bb,s

[Colin]

Sprucey,
Excellent! Thanks!
Are the contact details:
Mark www.ukbikestore.co.uk  02392 528 932 (UK)
for you? or someone else?

This explains a few things!
See my previous posts regarding Bottom Brackets failing...."Re: Strange knocking sound"
http://idriders.com/cgi-bin/YaBB_K2/YaBB.pl?board=news;action=display;num=1100244937;start=1#1
Mine started making a nasty "Cracking" noise and when the LBS finally replaced my BB, the chain rings ended up slightly out of adjustment (further out..). I was baffled at the time, but made them adjust the front derailleur to be correct. Obviously they had fitted a slightly different axle width to what I originally had fitted from new (original 68 x110?) Maybe the current one I have fitted is 68 x 113...?
The current BB is also starting to make a bit of noise, (probably due to too much mud and too enthusiastic washing with the hosepipe jet!)
So, I was thinking of a sealed unit, would this overcome the mud and the washing?
Anyone got any experience of sealed unites, do they last longer, need less maintenance?
Also, I've seen a few ISIS ChainSets and so would need to change the BB for these. Anyone got any experience of these? Any Better?

Is this an example of a standard one?
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=56193&item=7137558977&rd=1

I suppose the difference betwwen UN40 and UN51 is just LX or better spec? Or is it another thing I have to consider?

I guess Kiwi's asked my other question, what do they cost in the UK?

Cheers [smiley=beer.gif]

Col.

[Sprucey]

Hi Colin,

those are my contact details at my bike business.
(But I was a dyed in the wool Proflex rider long before ukbikestore!)

All BB units are sealed these days -we don't sell any other type.

Sounds to me like you are right - the shop probably fitted a 113mm as that was probably all they had in stock (bikes with 110mm are few and far bewteen). They should have reset the front mech but....

BBs can last anything from a few months to years - depends on use, type of riding terrrain, bike washing etc etc). If it's gone it will make the noises you refer to and you will get a wobble if you grasp the crank arm on each side of the bike and wiggle them.

If you have a square taper axle & chainset - don't bother change until you need to change the c/set - stay with sq taper. Splined (Shimano Octalink and the ISIS system) are lighter, stiffer and in my opinion better BUT it's not worth the change just for a new BB.

New systems include FSA's exo which is a separate BB with the bearing cups on the outside of the BB shell and also the new Shimano Hollowtech 2 cranks (and FSA and Raceface) which come with integrated BBs and now go down the hierachy as far as LX. save your money and get one of these when and if your complete chainset needs replacing in the future.

For "proper" off road riding don't go any lower than Shimano Deore level - fantastic value at £11.95
http://www.ukbikestore.co.uk/acatalog/info%5fBBUN52B13%2ehtml
If you can afford it, the XT version it's lighter with better quality bearings at £16.96
http://www.ukbikestore.co.uk/acatalog/info%5fBBUN73%2ehtml

You will need some special tools to remove the crank arms and get the BB out and into the bike.

I use XT in my bikes.

A local bike shop may charge a few pounds more (we are a mail order company) but they may also fit it for free if you pay full retail - good value in my book.

Feel free to call if it will help - you are under no pressure to buy anything from me - that's what this site (the Proflex one) is all about. I have met many of the contributors on this site in person incl. Kiwi while travelling in the land of the long white cloud, so I think they will vouch that I don't bite!

Sprucey
(Mark Spruce)

[Colin]

That's great info, and thanks for your contact details for assistance, I just didn't want to ring someone out of the blue and say "I was given your number by some bloke on an Internet site................." <GRIN>

Great bike shop site, and yes those BB's aren't too expensive at all, the tool to change them bumps it up a bit and I guess is specific to different models...?

Thanks for the advice on the ISIS/OCTOLINK, I guess they are mutually incompatible?

Your bike shop's now in my Favourites!

Thanks
Colin

[kiwi]

have met many of the contributors on this site in person incl. Kiwi while travelling in the land of the long white cloud, so I think they will vouch that I don't bite!

tis true tis true,sprucey and i had never met ,he emailed a coupla times,and rang,next thing he was walking up my front path....we were like long lost freinds,yakking away quaffing wine more yakking bit o sight seeing we didnt even have time for a ride....although my bb would have crapped out...sothe short story is a sqare splined 68 x 110 shimano lxorxt,,beauty just what i need!!!!!