(Original post closed) After sending 2 sets of Next SL’s back because of pedal thread inserts coming loose, I was sent a pair of SixC cranks.
Probably had 10 rides with them fitted and one pedal insert is now loose.
That’s me with RF carbon cranks,I’m afraid.
Just a rant is all, and maybe a little PSA for anyone contemplating buying these things.

Just as an aside, are you a particularly heavy/hard rider? Doesn’t excuse an item for not being fit for purpose of course, but just wondering cos I’ve seen a couple of Next SL’s fail recently (though warrantied without quibble to be fair), and am running SixC’s myself now (purchased because of the worries with Next SL’s).

I do clip the odd rock with a pedal, but not that harsh on kit compared to some.

I’m two pairs of Next SL’s down. Most recent set have cracks in the carbon on the frame facing side of the crank, on the none drive side the pedal insert was loose as was the axle insert.

In all honesty as a composite engineer, cranks are one of the last places I would use carbon fibre. Or at very least ones designed the way the ones on the market are and with the materials they use.

As a MTBer if I did choose carbon cranks it would not be Race Face ones.

Slight hijack…
Andy, don’t suppose you’re in the carbon tubing department?
I’m after some for a frame I’m making 😉

Assume you were using pedal washers?
I’m quite glad I seem to have been lucky & had no issues with my Next SL for over 2 years, although they are the pre Cinch versions. Glad I didn’t wait for the newer version given the reports I keep seeing if this happening with RF carbon cranks.

My SL’s were pre Cinch (3 years since I first built the bike)
mboy: I’m 6’1″ and just under 13stone, on the skinny side if anything. Plus I’m on the very light side of not very hardcore.

Steel cranks the future I’m sure.

I don’t want to tempt fate but I’m 6 months in to SIxC ownership and super chuffed with no issues

I have 14 year old carbon cranks still going strong, it’s hardly untested technology

Yep, and other companies make it work reliably. My Next SLs were absolute rubbish, 2 different carbon/metal failures. They removed too many grams and replaced them with optimism I think.

On my third set of Sixc’s now (pre cinch and cinch) and wouldn’t have anything else.

Never had any trouble (touches wood).

I did have one set of Raceface (SixC) carbon cranks that appeared to be proving that they can get the al/Carbon interfaces right, now I don’t.
Never ever again will I buy them. (There isn’t an emoji with an angry enough face)

mickmcd – Member
Steel cranks the future I’m sure.

Lets not be hasty here, there are more sensible options 😉

Stevie – ‘fraid not. I buy tubes from Easy composites for none-structural purposes, not sure about using them for your application. Didn’t someone post some good links in your thread? You could always make your own. Isn’t that hard and you can add pad up around joints. Needs to be done gradually and drop plies of gently away from the joint.

edit: you could always give the guys at Robot Bike Co a shout and see if they would supply some of their tubing as it’s a nice project for a kids bike not some guy trying to make a full down hill bike thats going to go badly!