# 83 mm Bottom Bracket XT cranks! (sort of...)



## Uncle Cliffy (Jul 7, 2006)

Nathan Riddle is a racer friend of mine and he came up with this mod for everyone trying to save all the grams they can: :thumbsup:

Shimano XT M771 cranks for 83mm BB shell bikes

What?! you say&#8230;Shimano only makes Saint cranks for 83mm BB shell bikes. Well technically you're right. However I've found a way around this weighty dilemma. If, like me, you have a bike with an 83mm BB shell and you refuse to run any other brand of crank-because you know that Shimano's are simply the best-and you feel for whatever reason that you simply don't need/deserve the strength and corresponding weight penalty of the indestructable Saints, then I may just have the solution for you!

1st step; Get yourself a set of the Shimano XT M771 or M761 "big gear" cranks. They are different from the regular XT cranks in that they come equipped with a 48/36/26t chainring combo and a slightly longer spindle-thats the important part- to accommodate the extra frame clearance these rings would need. They are available in 165mm, 170mm,175mm,and 180's too I think. Here's the tricky part. They're really hard to find in the States. If you're a shop rat you may be able to get a set of these cranks through BTI, where I got mine, or S.A.C. (Shimano America Corporation). These cranks were designed as "trekking" or "touring " cranks and are very popular over in Europe.

Now that you've gotten your cranks the modifications begin.

Remove the little black plastic spacer that sits on the bb spindle all the way up against the back side of the drive side crank arm.

If you're using a chain guide of any kind, or your bike has ISCG tabs (which I'm pretty sure you've said yes to at least one of the above if you have a bike with an 83mm shell) Get out the hack saw-This part sucks cause you're gonna do things that can't be taken back. Ok deep breath-Exhale. Cut off all 4 of your new granny ring posts as flush as you can against the spider. Don't of course cut off, or in any way damage, the part of the spider that you will be bolting your middle or big ring to. When cutting off the granny ring posts be careful not to hack into you're bb spindle-I found that using the little dust boot that goes in between the bb cups worked quite well as a guard. It should be pretty obvious before you tackle this step that you will never again be able to use this crankset as a triple setup or run any chainring on it smaller than 32t.

Now use a file and try to file those hacked off granny ring nubs as flush with the rest of the spider as you can. You'll have to believe me that every mm in this process counts so don't skimp on this step. Again you can use the same bb cup dust shield as a bb spindle guard so you don't nick the spindle.

Now that you've got everything cut & filed down. It's time to start assembly. Oh and if at some point in this process you happen to face your bb shell down to say 82mm all the better. No spacers anywhere in the system. BB cups thread into frame- no spacers. No dust shield/spacer between the cups on the inside of the BB shell-It won't fit (that's why it doesn't matter if you narf'd it up with the hack saw or file). I have an E-13 LG-1 chainguide bolted up to my ISCG tabs with no spacers in between the ISCG tabs & the "boomerang". If you are using an E-13 like me you will have to bolt your single chainring on in the "big ring" position. If you are using a 36t or smaller ring you may have to trim the inner "cage" of the top guide for clearance with the tops of the spider as it revolves.

If you follow all of the above steps you shouldn't have to take your cranks on and off 20 times like I did in this process. The spacing & spindle/crank overlap worked out perfectly. When all was said & done I ended up knocking about 3/4 lb off my bike, getting a great chainline, and getting better cornering clearance due to the lower Q-factor of this set-up. Saint cranks w/ single ring & BB 1030 grams vs. XT M771 w/ single ring & BB 730 grams. These cranks are listed as 900 grams w/bb but the difference between the 3 rings I pulled off and the single one I put back on was right around 200 grams.

Or you can just wait for the new Saint cranks to come out which are reported to be about 100 grams lighter than previous Saint cranks. My way's still a couple hundred grams lighter though(give or take). And definitely a little narrower in the 'ol Q factor. But, arguably not quite as strong and subjectively maybe not as cool looking.










https://www.nathanriddle.com/?p=117


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## Guest (Aug 8, 2008)

Uncle Cliffy said:


> Nathan Riddle is a racer friend of mine and he came up with this mod for everyone trying to save all the grams they can: :thumbsup:
> 
> Shimano XT M771 cranks for 83mm BB shell bikes
> 
> ...


Cool mod:thumbsup:

Just curious about how much spindle you still have biting on the non drive side. I had the same crankset on a 73mm shell with a 1mm ISCG adapter and 1 2mm spacer and the non drive arm would work itself loose and fall of. Just something to keep an eye on.


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## Uncle Cliffy (Jul 7, 2006)

sixsixtysix said:


> Cool mod:thumbsup:
> 
> Just curious about how much spindle you still have biting on the non drive side. I had the same crankset on a 73mm shell with a 1mm ISCG adapter and 1 2mm spacer and the non drive arm would work itself loose and fall of. Just something to keep an eye on.


I'm sure Nathan's got it dialed... 

There's probably not "plenty" of engagement, but it must be enough. Nathan's a ripper and in case you didn't read the rest of his blog; he was 3rd overall at the Downieville downhill ahead of Brian Lopes and Myles Rockwell! (10th in the XC) He's probably beat this set-up into submission by now.

Not to mention, he's also an instructor at United Bicycle Institute. :thumbsup:


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## Guest (Aug 8, 2008)

Uncle Cliffy said:


> I'm sure Nathan's got it dialed...
> 
> There's probably not "plenty" of engagement, but it must be enough. Nathan's a ripper and in case you didn't read the rest of his blog; he was 3rd overall at the Downieville downhill ahead of Brian Lopes and Myles Rockwell! (10th in the XC) He's probably beat this set-up into submission by now.
> 
> Not to mention, he's also an instructor at United Bicycle Institute. :thumbsup:


Ah right on, didn't read that far


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## bigfatadder (May 12, 2008)

Rubbish. Look at his avatar, he's only a child.


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## KomodoRider (Jul 14, 2004)

my only question is chain stay clearence? I know my Judge has 6inchs b/w the chainstays, (152mm) is that conversion going to be wide enugh to let the cranks clear the chainstays? 

OR 

what is the width of V-10 chainstays between were the crank arms pass? if any one could help I would have a new project for the fall.


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## bigfatadder (May 12, 2008)

Gah! Another child!


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## Uncle Cliffy (Jul 7, 2006)

bigfatadder said:


> Rubbish. Look at his avatar, he's only a child.


My secret identity; My son Ethan. Don't worry about that look on his face, he just smells something funny. :lol:

This is me and my first son Cameron:


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## KomodoRider (Jul 14, 2004)

dont worry thats not me or my kid, and now that I think about it im not even a sox fan... but im PISSED!!!!! hahha

but whats the width on that V-10?


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## singletrackin (Oct 15, 2004)

KomodoRider said:


> dont worry thats not me or my kid, and now that I think about it im not even a sox fan... but im PISSED!!!!! hahha
> 
> but whats the width on that V-10?


What happens when when/if the XT crank brakes? XT cranks were not designed for freeride/dh use. I know most people are trying to save every little gram they can but there is usually a price to pay for that. Broken parts, injury, etc. If you're ok with that than ride on.


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## dbabuser (Jan 5, 2004)

singletrackin said:


> What happens when when/if the XT crank brakes? XT cranks were not designed for freeride/dh use. I know most people are trying to save every little gram they can but there is usually a price to pay for that. Broken parts, injury, etc. If you're ok with that than ride on.


The key here is scale. Not everybody is built the same, or rides in the same manner. Therefore, not everyone needs the biggest and heaviest equipment they can find - that's just overkill. 
Your post would mean more if you actually had evidence of xt cranks not being strong enough, anyway...


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## Uncle Cliffy (Jul 7, 2006)

singletrackin said:


> What happens when when/if the XT crank brakes? XT cranks were not designed for freeride/dh use. I know most people are trying to save every little gram they can but there is usually a price to pay for that. Broken parts, injury, etc. If you're ok with that than ride on.


You gotta read the post man. He says if you don't need Saint's this may be an option. I don't think I'd do it since I'm borderline to big for it. (200 lbs.) But if you're a lightweight, XT's are plenty strong. :thumbsup:

The Athertons are pummeling XTR cranks in the UCI World Cup and Gee won the worlds with them; so XT's are probably fine for light use. :thumbsup:


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## DHgnaR (Feb 20, 2008)

Uncle Cliffy said:


> You gotta read the post man. He says if you don't need Saint's this may be an option. I don't think I'd do it since I'm borderline to big for it. (200 lbs.) But if you're a lightweight, XT's are plenty strong. :thumbsup:
> 
> The Athertons are pummeling XTR cranks in the UCI World Cup and Gee won the worlds with them; so XT's are probably fine for light use. :thumbsup:


I sat at 235 last season racing expert year round on a set of XT cranks... not one problem. I even had a few bike cartwheeling crashes where I'm sure the pedals had to have take a few hard knocks. I personally have total faith in the XT's. Them, along with Saints are the only 2 products from Shimano I'll run. The one negative to the XT's though is there is some flex compared to the Saints. 
Anyways, cool mod... I'd consider doing it if the new Saints weren't coming out.


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## Andrewpalooza (Dec 7, 2004)

I destroyed my drive-side M771 crankarm within two weeks of regular chairlift riding. If you are serious about downhilling (and you probably are if you have a 83mm shell) I think the peace of mind of the Saints are worth the weight penalty.


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## dbabuser (Jan 5, 2004)

Andrewpalooza said:


> I destroyed my drive-side M771 crankarm within two weeks of regular chairlift riding. If you are serious about downhilling (and you probably are if you have a 83mm shell) I think the peace of mind of the Saints are worth the weight penalty.


So you're the lightest and smoothest rider on the board, huh?


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## SHIVER ME TIMBERS (Jan 12, 2004)

cool mod...I too fat...sticking with the new saints


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## tacubaya (Jan 27, 2006)

XT are plenty strong.


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