MacRetro chat and rides thread

[velomaniac]

I commute every day, not big miles but it all counts !

 

[RobMac]

And another thing :shock:

Has anybody had any noticeable flex from a M751 chain set (cranks presumably)? :?

googled it Rob :? I certainly havent heard anyone talk of flex in them, not even.. ok wont go there

After lengthy scientific testing under laboratory (living room) conditions I've found that a
XT M751 chain set flexes significantly more than a XT M770 chain set :shock:

 

[clubby]

Don't think there would be more flex in the cranks themselves, more to do with Octalink vs external bottom bracket. Are the bottom brackets new or worn? Knackered bearings will move around. Also, we're you comparing them on the same bike?

 

[RobMac]

Both new B/B's, M770 on the Pig and the M751 on the Voodoo (both 175mm cranks).

 

[clubby]

Both new B/B's, M770 on the Pig and the M751 on the Voodoo (both 175mm cranks).

I think you've answered you're own question there. The pig would be stiffer in the bb area. The HT2 style bb also makes a huge difference. So yes the overall set up would be a lot stiffer. But I still don't think the cranks themselves would flex much more.

 

[highlandsflyer]

I would expect the newer cranks are either lighter or stiffer. Perhaps both, but they are both hollow so doubt much difference.

 

[velomaniac]

So that actual question was which bike, the Pig or the Voodoo is more flexy at the bottom bracket.
Your science wouldn't stand up to peer revue Robmac. Both cranks on identical bottom brackets on the same frame is the experimental model you should have used with loads of graphs and statistics and a long list of references, gawd science is boring :facepalm:

 

[RobMac]

The Reynolds 850 Voodoo with M751 C/S (appears) to flex more than the 4130 triple butted chromo Pig with M770 C/S.
BTW Science isn't boring but the scientist are

 

[The Ken]

Is it not more likely the frame - Is 853 not generally a bit flexier than chromo? (not talking physical properties just down to likely tube thicknesses)

 

[RobMac]

OK guys Im not going to bore the tit's off you with this any longer Im going to do more field testing with this one

Thanks muchly ...................