Replacement crankset choices??

Hi,

I have a 2007 Langster which has a Sugino Messenger crankset - well, half of one anyway as it's missing the non-drive side crank arm!

Since not being able to find a replacement arm (170mm, black) I'm considering replacing the whole lot!

So... from the original specs I believe the bike has a 'sport cartridge square taper bottom bracket' which is 68 x 103mm.

What are my options with regards to replacing this? Can I use a triple (or double) and convert to a single? Can I use an alternative bottom-bracket??

Thank you,

Mike

Are you on a limited budget?

The langster is basically my station bike so anything that is installed has to be functional and not flashy (that might catch the attention of scumbag thieves).

So, something decent, reliable but reasonably priced - holy grail!!

:)

Shimano Alfine is widely #approved if you're buying new

https://www.rosebikes.com/article/shimano-alfine-fc-s501-crankset/aid:670759

Or just any second-hand SS crankset off the classifieds here will be fine. Make sure you ask the seller what BB you need.

Had a brief look at the Alfine - not sure it works with my frame/BB :$

It comes with a BB so no worries there

I've got a proper beater set of miche cranks and bb £25?

I'm rubbish with BB and what frames they fit. I know some frames can get converters or sleeves to enable other (newer) BB to be used., but it's all Greek to me!

Any pics? Location? BB?

I'm in London, Camden to be exact.....I'll have to dig them out, but silver arms and black chainring.
But heres a stock photo.

^ buy this! Less hassle

What fizzy said.

As long as they'll fit my frame, they should do the job. If you can fire me over a pic or two that'd be grand.

I'm near Westminster so could meet halfway too :)

I'm pretty positive the bb is the same length as your current.
I'll have a look for them when I get the chance.

Got a black Miche crankset 170mm with bb, do for for 20, no chainring though.

PM'd you

The bottom bracket (BB) is the interface between your frame and the cranks. But I guess you know this already. :)

As such, it needs to suit both.

The "68" refers to the width (left to right) of the frame's bottom bracket shell (where the BB fits) in millimetres : a 68mm shell is English/British/BSc standard and one of the most common there is.

The "103" refers to the width (left to right) of the spindle in millimetres: different cranks need different width spindles to achieve the same chainline: the distance from the centre of the rear hub to the centre of the rear sprocket. With a single-speed/fixed wheel drivetrain, the front and rear chainlines need to match as close as possible and is usually 42mm.

Typically, a road double has a 41mm and 46mm chainline (inner and outer rings respectively) and a triple, 40/45/50mm. You could get away with the 1mm of the inner ring of a road double, but any of the others will require you adjust the chainline via the BB.

Particularly with a triple and possibly with a double, and depending on your frame, if you bring the crank in too far the crank arm or spider will strike the chainstay.

TL/DR
A 68mm shell gives you lots of options, but a "track"/single ring crank will give you the least grief, especially if it's intended for a 103mm BB, as you'll be able to use the BB you already have.

Out of interest, would this chainset work (as a single speed)? The inner ring has the same tooth count as my sugino, and I guess the chain line should be ok? I think I've read that people either remove the outer ring and replace with a chain/bash guard, or grind the teeth down?

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