Hello, I usually praise myself for being technical minded and have successfully solved most of my MTB problems but I cant for the love of god understand BBs.
I'm looking for a new crankset for my Ghost SE 1800 (2012) but I cant find out what kind of BB I need.
The bike actually has an Octalink V2 cranks and a BB ES25. Now my plan is to get smth fancier like a hollowtech 2 system.

Now on a little research I did I found BB ES25 comes in different sizes. There are some numbers that show different versions but I cant figure out what they mean.

So my first question is how do I figure out which one do I have without removing the BB as I dont have the tools to do so. (I couldn't find it even in the bike manual as it only wrote: bottom bracket - BB ES25
My second question is how do I look for another BB that fits my frame. (Ill most likely look for it online as I felt prices on my local shops were a bit salty)
I don't know if this is relevant but I've converted my bike in a 1x9 setup with a narrow/wide chainring.
Thank you!

Should just have a standard threaded BB
https://www.amazon.com/Shimano-Alivi...JB0639K5G7CVC9
That will fit both 68mm and 73mm width BBs, you just use spacers which it will come with if you have a 68mm. You will also need a Parktool bbt-9 bb tool that pops up in the "frequently bought together" section to install it. You will also need a crank puller and different BB tool for your current crank and BB. The parktool BBT-22 and CCP-22C or the cheaper alternatives.

Thnx for the replay. I'm actually thinking of bidding on this one here
FSA GRAVITY GRID crankset 175mm including BB | eBay
It says it supports both 68 and 73mm. One of the reasons i was concerned is cos I thought that those numbers show the diameter of the threads and it wouldnt fit but now I'm believing it has to do with the length of the BB (or am I still wrong)?
Im not interested in tools to change it as I'll go into a local shop to change it. I'm looking to pick one that fits to buy.

You could ask your LBS to help find a bb and crank. They will have the experience to know what you need. It's hard to know what to buy without the right tools. There are 3 things to consider for the bb:
1) bb shell width (a frame measurement-usually 68mm or 73mm
2) bb spindle width
3) bb interface-square taper, octalink or ISIS.

Its hard to find that out without a caliper. The chairing on the crank also need to support the # of speeds on the cassette (more gears will be a narrower chain), pedal axle width, and bb threading (either English threaded or Italian usually).

Dave

The dims. refer to the width, not the dia. as Canker mentioned. I've switched old octalink BBs in both road and mtbs to externally cupped ones. rather than buy tools which I'd never use again for the old BBs, I had the LBS pull them for a few bucks and a beer or two.

Thank you all for replies. Unfortunately asking LBS's didn't help much as they're mostly still in the dinosaur age in my area working with square spindle types BB. Also me not knowing the names of the parts in my native language got em confused as I've learned them mostly on the internet in english. But I guess if I find the right parts they can at least mount em so for now I'm not buying tools.

How about getting help from REI? As far as I know, they're the only distributor for Ghost in the U.S. They should be very familiar with it.

Dave

Well unfortunately I'm not located in the US. I'm in Albania (europe) and that's why is a bit hard finding decent parts and mechanics here. I even sent an e-mail to the official Ghost support contact but haven't heard back from them.
But after more research I've come to the conclusion that I most likely have standard BSA english threads. From what I saw my existing BB ES25 comes also with italian threading but that is mostly used on road bikes. Also the axel length 67 or 72 doesn't seem to matter much as most BBs are 68 with option to be 73 with spacers.

Hope I'm not missing anything

Gotcha. 68mm english threaded BBs are definitely very common.. Just did one on a road bike last week. It is getting more common for MTB BBs to be oversized too, so you might see more of the 73mm BBs. The 68mm or 73mm measurement is the width of the frame where the BB is mounted (axle width is different). You probably can't go wrong with a Hollowtech 2. There are 2 external bearing cups, and the crank (the crank and axle are 1 piece). How many gears do you have in the front? I wonder if you can figure out what crank to get based on that (the triple gear cranks usually need the longest axles usually).

Dave

How do you like the Ghost? I have seen them in stores here and they look really cool, how does it ride?

If you are replacing with Hollowtech 2 (external cups) all you need to know is press fit or threaded. In your case it is threaded. English threaded. Hollowtech 2 uses the same bottom bracket for 68 and 73 shells, with spacers for 73mm shells. The spindle (what someone on this thread is calling axle) is attached to the crank arm so there is only one length.

Haha I think you made a mistake by asking this question as I can talk for ages about this But I'm trying to cut it as short as I can.

So I got this bike second hand just a bit more than a year ago at 210euro. (you can find older posts of mine in this forum dating around march 2016 asking for opinions on different bikes I was considering back then).
This was my very first bike and I came from a 0 experience in biking world. Like a research nerd I am I did a lot of research before buying but I came to the conclusion that it was worth pretty much nothing as I had a very little amount of money to play with so I couldn't get anything decent at that money. So I decided to concentrate on a nice frame and upgrade slowly as time passes by. So pretty much the reason I got this is cos the frame looked nice! When I got it it was pretty much untouched with all stock OEM parts.

If you're curious about the parts you can look at this catalog here and find SE1800 version (mine is black and yellow)
https://www.ghost-bikes.com/fileadmin...atalog2012.pdf
It even had the original tires when I got it and pretty much in good condition so whether they were never changed or the previous owner got exactly the same ones remains a mistery

Till now I've changed:
1. The brakes (bought a pair of Shimano Hydros from a friend of mine.
2. The Pedals (NukeProof Neutron EVO) from crc.
3. Converted it to a 1x9 drivetrain (bought a cheap 17$ unbranded narrow/wide chainring from ebay) and removed the front shifter and derailleur.
4. Changed the grips as the original ones had very little grip and gave me a hard time sometimes.

So now I was looking to buy a nice Fox Talas shocks (2010 version I think it was. second hand from a local LBS) but my crankset seems to be near the end of its life so considering money is always an issue crankset takes priority now. Also my philosophy is when smth brakes replace it with smth better so I don't want to just replace the BB (which would have been a lot cheaper). This is why I'm looking for a Hollowtech II or Sram GXP system. (have also looked at FSA and RACE FACE alternatives but damn things are really expensive).
Worth to mention as this is my only bike and it is a pretty much all in one. I commute around 15-20 km a day with this. I go on road tours, uphills, downhills (not rough ones), technical climbs ect.. I also took part on a XC race once

I've lost a lot of weight, made countless friends and few close ones since I've gotten into this "business". At least once a week we make a trip somewhere. Discover new places, new trails and stuff like that. Sometimes just gather on a cafe shop and discuss about bikes, modifications, upgrades, PRO races ect... So my life has changed a lot for good since I got into mtbing

Getting back to your question you can see from the above that I'm really attached to my Ghost cos I associate it with everything I've mentioned so far.
I've ridden lots of my friends bikes (also some really expensive ones) and in none of them I was a comfy as I am on my Ghost but that's partly to the setup as I couldn't setup em the way I liked just for a short test and partly cos I don't think I can be very objective on this matter. The only exception was a 27.5 KTM which I immediately loved and told to my self my next bike is defo going to be 27.5! I've also tried a few 29ers but they felt weird (I guess not my type)

Well pretty much this was it

New Stuff the BB bearings are external and the axle is a tube attached to the right crank arm.

It sounds like you're having a lot of fun with the bike! That's what it's all about. The drivetrain looks pretty nice, I think that's mid range or so for Shimano. The thing about upgrades to the drivetrain is that they aren't a very significant change (going from Acera to Alivio or Deore for instance). As you go up the line, the components get lighter, but aren't as durable. There might be some difference in shift quality though.

My bike is an older Specialized Hardrock Sport with no suspension. The front shifter was an Altus (which is pretty low level) and finally gave out. Someone on the forum sent me a newish Alivio front derailleur, and it shifts a lot quicker.

Out of curiosity, are you using the original Acera crankset? Can you post pics of the teeth? Usually the front chainrings are the last thing to go on a drivetrain. The cassette and chain wear together, and you can usually keep the same chainrings till they start to look like shark fins lol. Are you having issues with the chain jumping off the front? It would help to have a little more info on what's happening.

Dave