Thorn Cycles Forum
Technical => General Technical => Topic started by: Skitch on December 02, 2018, 09:34:18 am
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Hi. Just doing some routine maintenance on my pre-owned 2008 Raven Tour and decided to check out the bottom bracket as it looksed a bit ropey, it’s taken quite a bit to remove the BB itself not the eccentric shell. Due possibly to 3 reasons. 1 the length of time it’s actually been installed??. 2 someone in the past has tightened the retaining screws of the eccentric shell in the wrong position into the thinnest part of the shell damaging the internal threads, lastly I think the BB I’ve removed could be the wrong size as it’s a 73mm Shimano UN-54 with a over all length of 110mm..
I’m thinking it should be a 68mm but unsure of the overall length? Can anyone advise please. Cheers Ian.
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Just replaced my BB on my 2012 Nomad, was a pain to remove. Replaced like for like.
Looking at the original it reads: BBC UN55, 73 BC1.37 x 24 MM110. Suspect your Raven will run the same part. I would double check with SJS and get them to ship you the correct parts.
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Thanks Dave. I didn’t expect a response that Quick. 👍. Yeah there not easy to remove I had to put mine in a vice with some towel to protect the outer shell which had been damaged internally anyway so I think I’ll have to get a replacement from SJS yeah I’ll check with them as you suggested. Cheers.
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Not yet had to replace my bottom bracket on a Thorn Raven Tour 2009. I did purchase a replacement for spares and was advised by SJS Cycles that it was 68mm 110 that was required. I purchased the UN55 68mm 110.
As Dave B mentioned the UN55 73mm, I would recheck with Thorn to get a definitive answer.
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68mm https://www.sjscycles.co.uk/bottom-brackets/eccentric-bottom-bracket-insert-fits-raven-tour-mk1-sport-tour-only/
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My Nomad Mk II takes a 73mm bottom bracket.
When I looked at this page, it tells me that some bikes used a 68mm eccentric.
https://www.sjscycles.co.uk/eccentric-shells-spares/?geoc=US
I would suggest measuring it to see what the shell width actually is before ordering a new bottom bracket or eccentric.
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68 mm on the three Raven Tour frames used by myself and wife.
73 mm on my Raven Sport Tour.
All the above frames were old stock, now discontinued.
Current Raven frame could be different.
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Current Raven frame could be different.
My Raven (2012 frame, bought in 2013) has a 73 mm BB shell, UN55 being the usual Shimano BB.
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All Raven TOUR’s ever have been 68mm shell and this eccentric https://www.sjscycles.co.uk/bottom-brackets/eccentric-bottom-bracket-insert-fits-raven-tour-mk1-sport-tour-only/
(https://www.sjscycles.co.uk/bottom-brackets/eccentric-bottom-bracket-insert-fits-raven-tour-mk1-sport-tour-only/)
Later Raven SPORT Tours and all RAVEN’s have 73mm, but the Raven TOUR was always 68mm.