Actual difference in stiffness between Next SL and XT.

None that I can tell. Is it because I weigh 142 pounds? I dunno. Maybe it’s like that new stem that is claimed to be 40% stiffer than the other guys stem. So 40% stigpffer than something with no flex to speak of equals who cares. I happened to need yet another 30 mm BSA BB and a chainring at the same time and rather than go the same route again with another $50 or so aluminum ring and another $50 or so BB I decided to simply retire the five year old cranks and purchase a new XT crank with its steel ring and $25 BB for just over $200. The XT is about 200 grams heavier on my scale than the Raceface but that isn’t that important to me. 

It just got me thinking about this whole stiffness metric that is a big selling point in bikes. Or boost. Yeah boost is stronger due to a better bracing angle but I have zero problems with non boost and can’t really tell that my new bike is boost. Faaa. Marketing.

I agree 100%.  Except those cranks with a 28.99mm spindle.  I can really feel the extra stiffness there.  It's a game changer.

As a heavy guy I like a pretty stiff bike all round and I'm totally fine with my XT cranks.  The only flex I feel and am a little annoyed at on my bike is fork flex and rear triangle flex (although that may be wheel flex since I haven't been boosted yet - I'm not sure).  As a bonus, XT cranks appear to be nearly bomb proof while I don't think the same can be said about the Next SL.

Don't get me started on the new 35mm bar standard; if there is one place on a bike where you don't want more stiffness this is definitely it but with a larger diameter bar you actually have to work harder on the design and construction to still make it flexible yet not fragile.  Whatever marketing person (I can pretty much guarantee you this didn't come from an engineer) dreamed up that new  "standard" deserves their own corner of hell.

I’m sure being a lightweight like myself means stiffness is really a non-issue for me.  35 mm was designed by Deda for road. I think Andre Greipel was the man they sponsored quite a while back with their 35 mm stuff. Greipel “the gorilla” was a good marketing animal being one of the top sprinters. I never notice differences in handlebar stiffness. Forks for me are all stiff enough. But I think it is interesting that some frame builders are now suggesting some compliance in a fame handles better. Is it Stanton or another British steel frame builder? NSMB did a test or interview recently.

I agree with your evaluation of cranks. At 185 pounds, I can't tell the difference in stiffness between the XTR (M985) cranks on my one carbon bike or the SixC (2018) on my other carbon bike.  BBs have been another story. The best thing that I did for my press-fit bb bike though was to pick up a Token Ninja thread-fit/press-fit BB, it fully resolved the creaking that I'd been having with the Shimano XTR press-fit BB on my Intense.

For a frame to rider smoothly, something has to give.  You can only get so far with suspension (with hardtails requiring frame compliance to offset the lack of rear suspension) , the rest has to either come from the components, the frame or the rider's body.

I remember owning a Kona Shred that was so stiff that it hurt my body just to ride it, and it got worse as the fork got closer to needing service. That was the last alloy hardtail that I ever rode, from then I've owned 4 separate Asian made Chromags (2x Rootdowns and 2x Stylus) and they've been a delight in comparison.

Side note, of all the bars that I've ridden, 35/31.8/25.4, carbon or alloy, the best feeling bars have been the Race Face SixC 35, they've just been a pleasure. I've had them on every bike for the past 4 years and I've even picked up a spare to keep around because I like them so much, they just feel great to me.

I have seen far too many race face carbon cranks fail to ever consider putting one on my bike. I have run Shimano cranks for many years and never think about them. Never had a problem until 2 weeks ago when I had a slow-speed tumble off a slippery bridge on lower Griffin. I didn't land very hard, but my newish XTR cranks bent so badly that I couldn't pedal. I consider this an anomaly, and replaced them with XT's which seem beefier. I ended up straightening the XTR's as an experiment (I don't plan to use them). It took all of my strength on the end of a 4-foot bar to bend them back. Still a fan of Shimano cranks.

I have heard of carbon crank failure and had an XX1 fail. It was a small hairline crack near the end. It creaked. The crack was under a boot so not likely impact damage but it was warranted by SRAM but there were no cranks so I applied the credit toward a Next SL. No complaints with my experience other than the 30mm bsa BB were not very durable. I could not get a season out of one. I last went with a ROTOR bb and it was better but still not great.

I weigh 200 loaded up ready to ride and I can't stand how stiff 35mm bars are. I run 31.8 carbon bars on all three of my main bikes. As for carbon cranks, i got 2200km out of a pair Next SL before the cinch chainring mount clocked, they were on my Sight that I used for Enduro racing. I got Next SL G4 as warranty and they scare the shit out of me. So I run them on my Norco Optic that I use for XC duty. On my new Range I will only run Alu cranks. I am looking to get alu Turbines to shed some weight.

Posted by: andy-eunson

None that I can tell. Is it because I weigh 142 pounds? I dunno. Maybe it’s like that new stem that is claimed to be 40% stiffer than the other guys stem. So 40% stigpffer than something with no flex to speak of equals who cares. I happened to need yet another 30 mm BSA BB and a chainring at the same time and rather than go the same route again with another $50 or so aluminum ring and another $50 or so BB I decided to simply retire the five year old cranks and purchase a new XT crank with its steel ring and $25 BB for just over $200. The XT is about 200 grams heavier on my scale than the Raceface but that isn’t that important to me. 

It just got me thinking about this whole stiffness metric that is a big selling point in bikes. Or boost. Yeah boost is stronger due to a better bracing angle but I have zero problems with non boost and can’t really tell that my new bike is boost. Faaa. Marketing.

Yes it's because you're 142lbs. I'm 225lbs with lots of leverage and I can feel the difference between bars, between stems, between rims, between frames. Though often I don't really get how flexy something is until I replace it. You're well under the weight for which most of these products are optimized which is awesome for you - you can get away with lighter gear so enjoy it!

Count me in the group that loves the SIXC 35 bars, I ran the old 35mm version in 770mm and last summer got a new pair of the 820mm which I cut down to 800mm... had them on my DH bike and now on my trail bike. They feel nice and damp to me. Grips are DMR Brendog Deathgrip in soft compound.

Also had SIXC 165mm cranks on DH bike for two years with no issues, nice and stiff and lots of rock strikes (with crank boots of course). Wouldn't go out of my way to get carbon cranks but I am ok running them. I weigh 215lbs.

Posted by: grambo

Count me in the group that loves the SIXC 35 bars, I ran the old 35mm version in 770mm and last summer got a new pair of the 820mm which I cut down to 800mm... had them on my DH bike and now on my trail bike. They feel nice and damp to me. Grips are DMR Brendog Deathgrip in soft compound.

I didn't realize how comfortable the SIXC35 bars were until I wrecked mine and switched to an alloy Atlas 35, which is painfully stiff. Now seems a good time to get the 820mm SIXC35.

Being even heavier than Craw, I can feel flex in everything also. I'm 240lbs and on XL or XXL frames and have had trouble with component and frame stiffness for years (never a problem with strength though). I love some of the newer, stiffer carbon frames, burlier XC forks, 35mm bars, beefier cranks, etc. Along with the trend to longer frames, the increased stiffness of frames has me completely happy with the fit and ride quality of my bikes. Finally!

I've used all varieties of XTR cranks for years and I've noticed that the latest M9000 lacked stiffness in torsion and bending. When putting the power down I can feel the crankarms twist which causes an odd droop in the pedal which I can feel through my shoes (stiff carbon soled shoes). Even worse is that I can get the crankarm to clank into the drive side chainstay of my XXL Tallboy 3. At first I thought this was a combination of flex in the crankarm and flex in the frame but this went away entirely when I switched to Next R cranks. The Next R cranks sit closer to the chainstay by 2mm so that's not the reason for the problem. After putting a bunch of time on each setup I'm sure difference is due to the combination of stiffer crankarms and spindle of the Next R cranks.

I'm 170 lbs and went through 2 Next SL crank warranties before I gave up. They were nice and stiff for sure, before they started coming apart at the spindle or cracking in the arm....

I am 260lbs naked and the only place I really feel flex is in the wheels/tires or if I am on a flexy frame I can definitely feel it. I have been running SixC cranks and bars for a bunch of years...with no issues. I am thinking about contacting Race Face as I did find some circular cracks in the back of the cranks this year though, replace with Turbines maybe?