Currently run a pair of M665 SLX cranks with the pedal inserts and stiffer axle compared to the M660.

Anyone know how the latest Zee, SLX675 and XT785 cranks compare in terms of stiffness?

I think its bobbins unless you are very powerful or heavy

I had SLX, deoere [ square taper] and XTR

All the flex was frame and not crank IME and i could not tell which I was riding tbh without looking down

I am sure they will claim to be stiffer – like kashmina is has less friction – whether you will notice I dont know

If you are looking for an excuse to upgrade I’d say whichever is the most expensive is the stiffest.

Nah, its for a new build next year, not an upgrade.

I could def feel the difference between SLX665 and more boggo shimano, and even standard SLX660, although the latter could be just down to running shorter 170 cranks on the 665.

If you think you might be able to tell the different stiffness of 170 vs 175 then I suspect I can’t tell you anything.

Lol, scampers last post is post of the week for me!

lol!

I missed out a question mark to my last sentence, but thanks for confirming what I thought anyway.

Well, are you both able to answer my original question or not?

you will think you can tell the difference whether it is there or not we are unsure,
is that the right answer?

I couldnt tell the difference between my deores and the saints I replaced em with!

i noticed a difference going from isis to ht2, I even bent a few axles

fwiw the new zee cranks look to be identical to deore but with a chunkier axle and pedal inserts

thanks for confirming what I thought anyway.

What did you think would be the stiffest out of your options? I’d like to confirm that for you if at all possible.

As kimbers suggests I’ve thought zee is possibly as stiff as 665 with the stiffer axle and inserts, but heavier, being non hollow tech, but have no idea about the latest slx/xt. Regarding crank length I was wondering if this effected if cranks felt stiffer, but I guess not.

Affected*

Like everyone else here, all I can do is humour you, if you can tell the difference! Most sensitive legs ever!

Quite possibly, but there again I’m not one for believing shaving grams off my bike weight will improve my performance 😉

Never said owt to the contrary! Doing some riding would improve my performance far more!

I can tell the difference between Octalink Hollowtech cranks compared to Deore HT2 (open C section arms) and LX and XT HT2 set ups but that is understandable.

Could I tell the difference between HT Octalink and non-HT ones? I doubt it as the difference is very slight (mainly weight is the benefit) and there are plenty of flex in the load path from my legs to the bike frame.

Which brings me back to HTII cranks – you foot, sock, your shoe bindings, shoe sole, SPD/pedal pin interface, pedal axle etc are all sources of flex. Obviously the crank is the longest length so any give will have a larger effect but as the cheaper non-HT2 cranks are slightly heavier I suspect the stiffness in simple directions is quite close, they are also probably a bit tougher than thinner walled ones. The closed section cranks should have an advantage in torsional stiffness but is that important when you compare it to the other sources of flex in the load path?

The steel pedal inserts – do they actually benefit stiffness or are they there to be tougher? A DH/freeride set of cranks are likely to experience more shock loads and the tougher thread material and increased area for bearing load into the aluminium arm are beneficial. It actually adds an extra interface between the insert and the arm which is a potential weakness.

Stiffer axle – again it’s probably more there for the shock loading from jumps etc to stop it deforming when you consider all the flex that is in the frame to BB cup, BB cup to bearing etc.

I’m not saying there isn’t a difference in stiffness but I’d like to see the results of a verified model or some real load testing as I suspect a majority of the effect is placebo – you know there is a difference so its playing on your mind. Can you tell the difference between the drive side and non-drive side crank on a HTII because a pressed fitting is a lot different to the clamped one.

A simple test for all doubters… with you bike stationary, lean it over and apply weight with the outer pedal in the 6 o’clock position, as if cornering~ the amount of flex in the crankarm is surprisingly large~ the difference in leverage between a 170 and 175 arm is sufficient to compound this.

Of course, the majority of the stiffness in a crank is utilised for efficient pedalling and so lateral flex is not likely to be as noticeable, but it is undoubtedly there.

Considering Shimano themselves claimed that the last generation Saint cranks are “over 200% stiffer” than XT, it is fairly apparent that there is quite some variation in characteristics~ with that in mind, pretty sure it’s safe to say that with design for purpose, Zee will be significantly stiffer.

A simple test for all doubters… with you bike stationary, lean it over and apply weight with the outer pedal in the 6 o’clock position, as if cornering~ the amount of flex in the crankarm is surprisingly large~ the difference in leverage between a 170 and 175 arm is sufficient to compound this.

How much flex in the frame? How much visible flex when you’re applying force to the crank in the same way you do when applying power when pedalling? How precisely calibrated are your legs? How did Sean Kelly manage to win so many sprints on a Vitus frame which had more BB flex than you’d ever get from the flexiest crank?

A simple test for all doubters… with you bike stationary, lean it over and apply weight with the outer pedal in the 6 o’clock position, as if cornering~ the amount of flex in the crankarm is surprisingly large~ the difference in leverage between a 170 and 175 arm is sufficient to compound this.

Are you confusing the whole bike flexing for crank stiffness?

what they say its the bike [frame. tyres, wheels] that flexes not the crank

What they said.

pretty sure it’s safe to say that with design for purpose, Zee will be significantly stiffer

I’m not!

ALL cranks flex!
Some, a lot more than others, if you cannot understand or won’t believe this simple fact but still feel the need to comment on this thread you need to take a break from your computer.
Maybe even leave the house, perhaps for a cycle.

I’m taking a break.Leaving the house and going for a cycle.

I believe cranks flex btw…I’m not convinced that through my flexible soled shoes and my pedals that I can differentiate it from all the other things flexing on my bicycle.

just thought I would pop back to this and see the replies…

Of course all cranks flex, but you need to quantify it to see if it will affect you and do so compared to all the other flexibilities in the system to be able to decide if you need it.

The new Saint cranks are quoted as being 2x stiffer than XT. But in which load case and what is the actual typical deflection in this load case? It might be 0.5 mm compared to 1 mm of the XT in a load case with a 120kg person doing a 6ft drop off riding a very stiff hard tail onto concrete. Not something that is going to worry me as my riding would be less demanding.

I won’t fret over a bit of difference in stiffness between the modern Shimano cranks. But granted other might as their bike, budget and needs are different to mine and probably lots of other people. As for Zee – tbh I think there is a HUGE difference between the level of technology that goes into Zee and that of Saint. Zee is a budget groupset for people who dont want the more XC orientated group sets. I would see it as being a tougher and more gravity version of Deore in some components (eg cranks) and SLX in others (eg RD cage length).

If I remember one of the magazines did a test on some cranks a while ago in a jig to measure the deflection of the arms. The difference between the real ‘noodle’ cranks and the stiffest was les than 1mm. I doubt many people could tell the difference once fitted onto a bike frame that will flex along with wheels, shoes etc.

Im suprised nobodys mentioned youngs modulus yet