Cartridge bottom bracket- what is it?

Chief Broom

Über Member
Newbie question! I recently bought a Dawes discovery 201 which has a cartridge bottom bracket and im wondering what this is exactly and also whether its a feature of budget bikes. I think the wheels have pressed bearings- is this good/bad or normal with todays bikes. Any info much appreciated.
 

sasquath

Well-Known Member
Cartridge BB is the standard from early 2000s?, it's an upgrade from cone and cup type. Pressed bearings, againd you've got machine bearing in place of cone and and cup system, both harder to maintain at home but much less of maintenance needed. And both pretty much standard in all but cheapest of chinesium.
 

Cycleops

Legendary Member
Location
Accra, Ghana
Cartridge BBS have been in use for yonks and are still popular today. They can go on for intergalactic mileages with little maintenance. Once they had separate bearings but now superseded by the cartridge type. Their only drawback is they are relatively heavy.
Pressed bearings can be a little trickier to install than separate bearings types but you can make a press from a length of threaded rod, washers and nuts.
 
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OP
Chief Broom

Chief Broom

Über Member
Thanks Cyleops/sasquath im glad to hear theyre not an inferior budget option- im really liking this bike but did wonder if the components were up to it! Im guessing when replacement is necessary it means a visit to a bike shop [after ive done some intergalactic mileage] ^_^
 

sasquath

Well-Known Member
Thanks Cyleops/sasquath im glad to hear theyre not an inferior budget option- im really liking this bike but did wonder if the components were up to it! Im guessing when replacement is necessary it means a visit to a bike shop [after ive done some intergalactic mileage] ^_^
You can always invest in couple of tools and DIY it. Would probably break even first time though.

As for BB intergalactic mileage, with very cheap bikes it may be ~1000miles judging by my £179 viking. I probably lost QC lottery. £9 eBay replacement is on ~2500 miles and no wear signs.
 
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Location
London
I would be inclined take it out and grease the threads pretty soon, well within the first year anyway, even if a new bike.
Always a chance that they can seize in and manufacturers sometimes skimp on the grease.
Be careful not to crossthread putting it back in though.

Get some good tools and the Park Book of Bike Maintenance. And take your time.

Must admit I didn't follow this advice myself, barely did any work on my bike for the first few years, but then I did get one seize in.
 
Location
London
. Their only drawback is they are relatively heavy.
Call me perverse (and re my other thread) i rather like this - makes me feel I'm getting my moneysworth. Shimano UN55s* often seem to me to be two or three times heavier than their size would imply. Great :smile:

* discontinued of course - though there is a replacement.
 
Location
London
Shimano UN300 is the best Shimano Cartridge now as the UN55 has been discontinued (wahhh) , and it's still not expensive, circa £20. I'll go as far as saying some of the more modern BB's are inferior in how long they last - lighter yes, but don't last.
verdict out I think on how the UN300 shapes up against the revered UN55.
I don't know. Any experts any views?
Personally I thought it would never be discontinued (I thought they would just keep churning them out for a continuous modest profit) , but that shows how much I know.
i did though pick up two second hand new ones cheap in that golden period when they were thought old-fashioned/past it and hadn't passed over to revered retro. £3.50 and £7.50 as i recall.
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
verdict out I think on how the UN300 shapes up against the revered UN55.
I don't know. Any experts any views?
Personally I thought it would never be discontinued (I thought they would just keep churning them out for a continuous modest profit) , but that shows how much I know.
i did though pick up two second hand new ones cheap in that golden period when they were thought old-fashioned/past it and hadn't passed over to revered retro. £3.50 and £7.50 as i recall.
I've a UN300 in my MTB that's been used extensively in slop and is now on the commute. Been on a fair few months, and is silky smooth. The UN55 finally died previously - got a little rough and 'free spinning', although was fine in use.
 
Location
London
I've a UN300 in my MTB that's been used extensively in slop and is now on the commute. Been on a fair few months, and is silky smooth. The UN55 finally died previously - got a little rough and 'free spinning', although was fine in use.
Do you know what the main difference is between them?
My Hewitt came with external bearings (i didn't know enough at the time about the real choices) but I have a good quality Deore square taper chainset ready to go on if that starts misbehaving. Hollowtech II you've been warned - step out of line and I'll be giving you a Basil Fawlty thrashing.
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
Do you know what the main difference is between them?
My Hewitt came with external bearings (i didn't know enough at the time about the real choices) but I have a good quality Deore square taper chainset ready to go on if that starts misbehaving. Hollowtech II you've been warned - step out of line and I'll be giving you a Basil Fawlty thrashing.
From the UN300 and UN55 ?

Yes. Slightly wider body on the UN300 - doesn't taper like it did on the 55, and the non-drive side bearing looks to be changeable as it sits flush with the 'sleave', rather than 'inside'. There is then an additional seal on the locking cup (again alloy). Just a revised construction with an extra seal.
 
The 201 has a square taper cartridge bottom bracket which is my choice for long term durability. It should be trouble free for quite a few years of all weather daily commuting. When it wears out you fit a new cartridge.

The 201 is a nicely specced budget everyday ride that will last as long as any other bike and longer than many.
 
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