- Posts: 3180
- Joined: Fri Apr 15, 2011 5:55 pm
- Location: Two Rocks, WA
I have some Thorn cranks and having asked in the Thorn forum to identify the correct model and which size BB for a 54mm chainline I think I need a 113mm one.
http://www.thorncycles.co.uk/forums/ind ... 8.msg14315
Now Surly say " 73mm shell width, threaded standard English (1.37" x 24t)"
Now the question:
I've found two BB's which I think would do the job but am not 100% sure which is the superior one. I suspect its this:
But, being wrong often enough I thought I'd throw into the mix:
So yeah, am I right thinking these are the correct "type" of BB needed?
Is the UN-73 superior like I suspect?
Or is the UN-55 the usurper to the role?
Or have I gone completely mad and am looking at completely the wrong type of BB for my square taper crankset?
- Posts: 8240
- Joined: Mon Aug 24, 2009 2:08 pm
- Location: Brisbane, Queensland
- Posts: 587
- Joined: Fri Jun 10, 2011 8:37 pm
- Location: Adelaide
- Posts: 252
- Joined: Sat Aug 28, 2010 10:21 pm
- Location: Sydney
I measured the original one as 119.5mm so ordered the Shimano 118mm which is just a fraction short for the derailleur high/low settings.
A 122.5mm one arrived today so hopefully will get to install on weekend and get the shifting perfect.
- Posts: 5122
- Joined: Mon Mar 12, 2007 2:23 pm
- Location: Yangebup
The UN-73 is a 68mm BB won't work with your frame rifraf. Unless jenson have got it wrong on their picture, that is clearly showing a 68mm BB as it's stamped on it
Surly troll has a 73mm wide shell vs the standard 68mm. YEP Surly troll has an oversized BB.
One that Surly specs with the Troll is Shimano UN-55, 73 x 122mm. Hollow spindle, square taper, so go with the UN-55
- General Australian Cycling Topics
- Info / announcements
- Buying a bike / parts
- General discussion
- The Bike Shed
- Cycling Health
- Cycling Safety and Advocacy
- Women's Cycling
- Bike & Gear Reviews
- Cycling Trade
- Stolen Bikes
- Bicycle FAQs
- Serious Biking
- Audax / Randonneuring
- Retro biking
- Fixed Gear/ Single Speed
- Electric Bicycles
- Dragsters / Lowriders / Cruisers
- Children's Bikes
- Road Racing
- Road Biking
- Time Trial
- International and National Tours and Events
- Cycle Touring
- Touring Australia
- Touring Overseas
- Touring Bikes and Equipment
- Western Australia
- New South Wales
- South Australia
- Northern Territory
- Country & Regional
- The Market Place
- Member to Member Bike and Gear Sales
- Want to Buy, Group Buy, Swap
- My Bikes or Gear Elsewhere
- Cycling Brands
- Cell Bikes
- Malvern Star
- Santa Cruz
- Custom Builders
- Generic Carbon