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PostPosted: Fri Jun 03, 2011 10:03 am 
Retro Guru
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Joined: Wed Apr 04, 2007 1:03 pm
Posts: 253
Location: Surrey
Hi all,

I've just fitted a SLX Hollowtech II chainset (SL-M660) and Shimano XT/SLX Bottom Bracket (M770/M660) to a Rocky Mountain Blizzard 2007 which has a 73mm B Bracket width so I used one 2.5mm spacer on the drive side.

The Chainline looks wrong compared to what I removed which was a deore chainset with a un72 73mm bbracket 113mm wide.

Anyone have any experience on this?

It seems that by installing without any bbracket spacers might be a good idea.

Also the distance between the crank arm and chainstay is 14mm exactly on both sides with the one 2.5mm spacer installed.

Thx all


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PostPosted: Fri Jun 03, 2011 10:36 am 
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
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Location: Yorkshire, England
SLX and modern stuff uses 50mm chainline, retro stuff used 47.5mm chainline, though saying that the 113 might well have given you ~50mm chainline anyway depending on the cranks.

It'll work fine, go ride and find out. You may need to tweak your front mech if it has in fact shifted slightly.


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PostPosted: Thu Jun 09, 2011 1:30 pm 
Old School Grand Master
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Joined: Mon Jun 25, 2007 8:37 am
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Location: Whiskey bent & hellbound!
I've got a 2006 Blizzard and have installed the BB with no spacers.


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PostPosted: Tue Sep 13, 2011 8:46 am 
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(Sorry for resurrecting this post but previous info is needed)

Hi all :D

After riding for a while on RM Blizzard 2007/Slx Chainset 73mm BB with configuration = one 2.5mm spacer on the drive side as stated in shimano tech sheet. I've come to the conclusion that the chainline is wrong.

When in middle ring 32t and largest cog on cassette 32t the chainline (angle) seems too acute, resulting in some grinding noise. Which I assume will wear the chain prematurely as well as sounding like the chain is about to snap.

1. Should I run without any spacers at all( Like Neil G above) or will this affect the BB Sleave ( or anything else for that matter).

or

2. Can I run with one 2.5 mm on the non drive side.

Hope someone has some experience with this, all help much appreciated.

Kona-853


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PostPosted: Tue Sep 13, 2011 4:31 pm 
retrobike rider
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Location: Yorkshire, England
You are running it to spec, sat at 50mm chainline. It would be very hard for it not to be at that position. (give or take tolerances)

You can run without the 2.5mm spacer on the none drive side, but you may need to modify the sleeve (take the lips off) or run without the sleeve but this reduces it's ability to seal out stuff n dirt ;). Otherwise it will be crushed.
As it's 73mm b/b then there should be no problems clamping the crank down to the splines (afaik)
Easiest way is to give it a try without the sleeve there.

BUT you then have a lopsided pedal system, even more so if you switch the spacer to the other side.


These the original SLX ring, I didn't test mine out long enough but them I'm only to 8 speed at the back.. My Middleburn I use on the SLX crank do have a grinding noise though.


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 Post subject: THX
PostPosted: Thu Sep 22, 2011 10:15 am 
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Location: Surrey
Thx for help

FYI I'm using a shimano HG53 chain but I assume that is fine unless the higher shimano chains are better with more aggressive chain angles?

:D


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