Chainsets

JonS123

IS there any real significant in the different types of BB/chainset - eg hollotech, octolink, etc, currently I am on a good old square tapered one, which needs new chainrings (and considdering most chainrings cost as much as a new chainset im buying a new one so I can have nice new shiny cranks!) and need to upgrade the drivetrain anyway, but cant figure out if any of these new types are better, creative marketing or just the way foward

Mr Plum

Essentially the only real difference is that external bottom brackets are lighter and stiffer due having a wider diameter and hollow axle. There's no real difference in durability/life cycle, i.e. the more you pay (the better quality the bearings) generally the longer it will last assuming it has been installed correctly. Generally external bottom brackets will be of a higher quality than the cartridge type square taper bottom brackets - the higher end chainsets are usually designed to work with an external bottom bracket.

With regards to getting a new chainset, if you've not got your eye on anything specific then there's a lot of good sales on at the moment so I'd start there and get the best thing I could afford with decent discount that's compatible with the stuff I've already got.

rolf_f

TBH, for an older bike I'd just get something like this: http://www.spacycles.co.uk/products.php ... 2b0s109p45

Cheap to buy, smart, cheap to maintain. Should fit current BB but ring them up and they'll tell you what you need to know.

JonS123

I have a un73 on a older bike (and I think current one has one to) and thats never broke on me, square taper FTW!

Looking at what id be spending on something external, think i'll be sticking to what I have and just using it for the new bike fund instead

pdw

Agreed - benefits of external BBs seem marginal at best. I certainly can't feel any different in stiffness between my bikes that I could attribute to the BB, and the external BBs do seem more exposed to the elements. Maybe less of a problem on the road, but they seem to suffer off road.

My first external BB on an MTB lasted six months. I recently changed the UN73 BB on my winter road bike for the first time in 14 years (and it turns out it probably didn't need replacing anyway). Not a statistically significant sample, obviously.

rolf_f

JonS123 wrote:

I have a un73 on a older bike (and I think current one has one to) and thats never broke on me, square taper FTW!

For what it's worth, my Dawes is square taper and running a £15 Shimano BB. So far, it must have done at least 6000 miles on that BB in all weathers without complaint.

Mr Plum

Rolf F wrote:

JonS123 wrote:

I have a un73 on a older bike (and I think current one has one to) and thats never broke on me, square taper FTW!

For what it's worth, my Dawes is square taper and running a £15 Shimano BB. So far, it must have done at least 6000 miles on that BB in all weathers without complaint.

CRC were doing square taper bottom brackets for about £7 IIRC - think they were branded 'RPM'. Bought one and replaced the one that was on the winter trainer/commuter after it had done just under 6000 miles. Turns out the old one was knackered anyway and I didn't even realise. New one is decent, and if I can find them that cheap I'll probably replace it every 5000 or so miles just as a matter or course.

craker

I bought one of the £5 CRC bottom brackets for my fixie. The bearings are going fine but I couldn't get it to screw into the bb shell - it just kept spinning. I've replaced it with the CRC £10 bb (UN54 I think) and that has screwed in nice and firmly. Huge relief to find out I hadn't damaged my BB threads.

Lesson = £5 it'll probably work and keep going for ages but if something does go wrong it's only a fiver.