I was too until I made the SLK-Carbon Pro swap. I can tell that the CP cranks (or maybe its the Ti BB axle) have some lateral give when compared to the SLKs, when I am standing on the pedals hammering up a hill. I don't think it makes any difference in my speed, it's just a different feeling. It's not good or bad, just different. These are on a Cervelo R3, which is a pretty stiff frame. On a less stiff frame the different feel might be less noticeable.SDizzle said:I'm of the opinion that NO ONE can tell the difference between cranks of one "stiffness" and another
I'm not an engineer, but the design of the SL-K and other integrated cranks that rely on one bolt just seem like an accident waiting to happen. Mind you, I have 3 FSA cranksets, and my favorite is the Energy MegaExo. Aluminum, but has the benefit of the integrated BB and is solid as a rock. I love FSA stuff, but they don't have this solved yet.johnmyster said:I own six sets of integrated cranks. DA 7800. Truvativ Elita GXP. FSA Gossamer. Raceface Atlas. Raceface Deus. FSA SL-K. All integrated.
All of them at one time or another, four of them have suffered from the dreaded "crank won't stay tight" syndrome. Guess which ones. It's taken some time to resolve the problem on each, but I could get it to go away with various facing, shimming, and spacing strategies. Eventually it always came back, which is why the Elitas got replaced by the Gossamers (cross bike), and the SL-K got replaced with Dura Ace (road bike). Next time the RaceFace ones (mtn bikes) give me trouble, they'll probably be replaced by XT cranks.
Why? Because the Gossamers and the Shimano designs use one bolt to tighten up the system, and then pinch bolts to secure it all in place. That's the way to go my friend. Just having one bolt to bring it all together and hold it there (k-force, sl-k, truvativ, raceface, etc.) is a recipe for disaster, because it doesn't tolerate any variation in bottom bracket width. That's the bottom line, and I'm sticking to it. I'm not saying it doesn't work, because it will, but it requires more attention (periodic checking to make sure it's still tight) and quite a few more headaches than the gossamer integrated and shimano integrated pinchbolt designs...
Actually, the Truvativ cranks do tolerate variation in BB width. The left-side bearing has a sleeve permanently pressed into it, and when the bolt is tightened down, this sleeve is pinched between a shoulder on the spindle and the left crankarm. On the drive side, the spindle floats freely in the bearing.johnmyster said:Just having one bolt to bring it all together and hold it there (k-force, sl-k, truvativ, raceface, etc.) is a recipe for disaster, because it doesn't tolerate any variation in bottom bracket width.
Me too. My DA 7800 cranks are getting tossed for some Record carbons/Record BB (130 bcd, though - not compact). I don't really care about the carbon. I just think they're nicer than just about everything out there, including DA 7800 (and THM Claviculas, which don't exactly look like they're made for the 400 mile weeks I've been putting in...).cthomas said:I want to go carbon, but will be going Campy with the "old fashioned" square taper BB.
The difference isn't obvious unless you know what to look for. If you look at the non-drive-side BB cup, you'll see that an aluminum sleeve has been pressed into it, giving it an inner diameter of 23mm (I think). The drive side cup, on the other hand, has no sleeve and an ID of 25mm. If you were to put the BB on the spindle and tighten the bolt, you'd see that the drive side cup slides freely but the non-drive-side cup is fixed tightly.johnmyster said:I'm holding the truvativs, and don't see anything special about them.
From what I've heard, the pinch-bolt design patent was held by Bullseye and Shimano just waited for the patent to expire before making the same kind of thing.johnmyster said:Shimano must have patented the pinch bolt setup, and didn't let anybody but FSA license it from them. Problem is, you can't really do that with a carbon crank, so FSA has only done it with their alloy setups.
I had this pair of Storck Power Arm carbon cranks and Phil Wood square taper Ti BB installed on my Trek OCLV. I was really happy with their stiffness until it developed a creak that I couldn't vanquish. I wanted to go compact, and was able to win a set of SLKs on eBay for a really good price. Once I installed them, my bike gained close to half a pound in weight. Overall I’m happy switching to FSA compact, but it did result in a little weight penalty. Maybe I’ll get some Zero Gravity brakes to compensate. Now, that’s a good excuse.cthomas said:I want to go carbon, but will be going Campy with the "old fashioned" square taper BB.