Bottom bracket

devhads

I'm getting a new cross frame and it's got a PF30 bottom bracket shell. I currently have a CX50 chainset with Hollowtech II BB. What are my options? I've seen all sorts of adapters online but are they any good. If so which type should I go for, the options seem to be
1) A sleeve which reduces size and adds threads to use a HT2 BB
2) the KCNC adapter which has it's own bearings but reduces the size to accept the 24mm spindle
3) Spacers which reduce the size for the 24mm spindle but you need to fit a PF30 BB
4) New chainset and PF30 BB (recommendations for chainsets around same level as CX50?)

Is PF30 really better than Hollowtech as I've read, and if I used an adapter would I be negating any benefit from having the bigger sized shell. Is it the oversized shell or spindle which is supposedly better? I've also read the bearings in Hollowtech BB's are not very good (too small), any ideas about the PF30 bearings?

Sorry for the massive amount of questions.

Monty Dog

2 - KCNC or even better Praxis Works - being a single unit ensures the optimum alignment of the bearings.

bobley

2 of my bikes have got KCNC bottom brackets in. One is a Shimano PF89 replacement and the other is the PF30 to Hollowtech. Both have worked well so far. As much as I'd love to get a carbon PF/BB30 crank on my crosser I know in reality I would never be able to tell the difference to the CX50 in there now.

http://www.planetx.co.uk/i/q/BBSRPFKCNC ... 30-adapter

devhads

bobley - I had the PlanetX one fitted in the end by my LBS. I put road wheels on and road 40 miles at the weekend, the last 39.5 of which it creaked like crazy. I'd fitted the cranks so guessed that to be an issue rather than the BB fitting as the mechanic who fitted it is very good. Got home, took cranks off, greased, torqued correctly and initial findings on the turbo seem to have improved the situation, yet to find time for a proper test. Did you do anything special with the KCNC adapter, I've heard some people use Loctite when installing to eliminate any creaks?

devhads

Went for a test ride this afternoon, all sorted.

Lesson learnt properly grease and torque everything before riding :oops:

Kieran_Burns

Monty Dog wrote:

2 - KCNC or even better Praxis Works - being a single unit ensures the optimum alignment of the bearings.

I replaced the BB30 in my Felt F65X with a Praxis kit (which being a gaming geek is inutterably cool 8) ) and it's great. The BB30 was just rubbish IMHO but the Praxis is very easy to fit and replace.

pinno

Uh? Your actually talking about Bottom Brackets?

I'm in the wrong forum.

FransJacques

I used the wheels manufacturing one to go from a Red BB30 to Dura ace hollowtech and didn't notice too much of a difference. One thing I'd say is BB30s are much more sensitive to bearing side load than Hollowtech so pay a lot of attention to how hard you screw in the left side crank arm. Without the wavey-washer it's easy to overdo it.

I'd add that when I took off the adapters (made from Delrin, a very hard plastic) they were absolutely destroyed by a very muddy season of cross. So not a bad £22 spent...