Retrobike Forum Index

It is currently Tue Sep 18, 2018 5:42 pm

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 11 posts ]  Go to page 1, 2  Next
Author Message
PostPosted: Tue Mar 13, 2018 4:14 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
User avatar

Joined: Mon Aug 27, 2012 9:56 pm
Posts: 2289
Location: Eilean Siar
Just fitted a new Shimano BB93 bottom bracket for their hollowtech cranks to my Black Sheep.

I know the rule of thumb that with a 68mm shell two spacers go on the drive side and one on the non drive side and for a 72mm shell it's one on the drive side and none on the other.

Now, to get the chainring to clear the chainstay i've had to put all three on the drive side. :shock:

I'm using this singlespeed so the XTR 9020 crank has a 32 tooth Absolute Black oval ring fitted, and it would seem there is no way a 34 tooth would clear without hitting the stay, the 32 however does clear.

The thing is, when checking the crank arm spacing against the stays they are near as damn it perfect left and right.... so I'm presuming three spacers on the drive side is ok?

Just worried about torque load on the cup as there's a couple of mm less threaded into the shell on the drive side.... :oops:

Your opinions please gents!


Attachments:
bb1.jpg
bb1.jpg [ 259.04 KiB | Viewed 720 times ]
bb2.jpg
bb2.jpg [ 248.62 KiB | Viewed 720 times ]
bb3.jpg
bb3.jpg [ 251.11 KiB | Viewed 720 times ]
bb4.jpg
bb4.jpg [ 184.55 KiB | Viewed 720 times ]
Top
 Profile  
 
 Post subject: Re:
PostPosted: Tue Mar 13, 2018 4:24 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
User avatar

Joined: Mon Aug 27, 2012 9:56 pm
Posts: 2289
Location: Eilean Siar
EDIT:

I've just checked my front chainline which is apparently supposed to be 52mm for SS MTB from centre seat tube to centre chain and it is cock-on 52mm, so at least that's ok! :?


Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Mar 14, 2018 12:45 am 
Gold Trader
Gold Trader
User avatar

Joined: Fri Jan 23, 2009 2:30 pm
Posts: 14712
Location: Surrey
The BB shell on that frame looks pretty darn wide. Don't want to ask a silly question but is it wider than 73mm, possibly an 83mm one? Might explain why you've got clearance issues when using a crank/axle with a 73mm max length?


Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Mar 14, 2018 10:15 am 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
User avatar

Joined: Mon Aug 27, 2012 9:56 pm
Posts: 2289
Location: Eilean Siar
silly questions are allowed, but it's only 68mm wide! :P


Attachments:
BB68mm.jpg
BB68mm.jpg [ 259.11 KiB | Viewed 652 times ]
Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Mar 14, 2018 5:53 pm 
retrobike rider
retrobike rider
User avatar

Joined: Fri Aug 08, 2008 2:36 pm
Posts: 17796
Location: Yorkshire, England
They run crank arms a long way away from the stays nowadays.

While it might be wrong and I assume you followed the Shimano Documents for fitting the crank and BB etc.

If it works, use it :-)


Top
 Profile  
 
 Post subject: Re:
PostPosted: Thu Mar 15, 2018 10:08 am 
Dirt Disciple

Joined: Fri Mar 17, 2017 2:01 pm
Posts: 73
I’d be wary about how much thread will be engaged with that many spacers on one side.


Top
 Profile  
 
 Post subject: Re:
PostPosted: Fri Mar 16, 2018 9:55 am 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
User avatar

Joined: Mon Aug 27, 2012 9:56 pm
Posts: 2289
Location: Eilean Siar
I know, that's why I was asking, not too sure myself. :?

I guess I could install a 2.5mm spacer between the spider and the bearing, slip it on the axle before I push it through the bearing cup?

That would give me the same distance but only two spacers between the cup and the BB shell?

Shall have a rummage through my spares and see if I can find anything suitable, if not I may ask on here if someone could turn something down for me.


Top
 Profile  
 
 Post subject: Re:
PostPosted: Fri Mar 16, 2018 10:46 am 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
User avatar

Joined: Mon Aug 27, 2012 9:56 pm
Posts: 2289
Location: Eilean Siar
just got this on ebay... perfect for the job 8)

https://www.ebay.co.uk/itm/BBB-BBO-91-S ... SwoR9aBGqg


Top
 Profile  
 
PostPosted: Sat Mar 17, 2018 10:27 am 
retrobike rider
retrobike rider

Joined: Mon Jan 26, 2009 10:10 pm
Posts: 233
Location: Lancashire
Some new bottom brackets have longer threads designed for chain devices have a look on chain reaction shimano saint hollow tec two on offer £15 as an example explains it in the description


Top
 Profile  
 
 Post subject: Re:
PostPosted: Sat Mar 17, 2018 10:34 am 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
User avatar

Joined: Mon Aug 27, 2012 9:56 pm
Posts: 2289
Location: Eilean Siar
Thats a great shout, if I didn't already have a new BB93 I'd have snapped that up! 8)



EDIT: in fact for £15.99 i'd be stupid not to... off to log in to CRC :wink:


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ]  Go to page 1, 2  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: rochester21 and 7 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group