2020 Transition Spur

[rigidftw]

I've got this thing in late 2020 and it is one great piece of kit.

The frame and fork came from Switzerland, barely used by the previous owner, which seemed to be more sensible than getting a complete bike and changing most of its parts to my liking.
I did not think this through though. Import taxes were eye-watering.
But apart from a annoying creak coming from the seatpost (30.9mm post w/ shim in 31.6mm seat tube), that I could fix just by changing to a dropper post with the correct diamerer it's been faultless.

The 36t chainring I used initially proved to be too big for both the frame and the kinematics. I rubbed the clear cote off the chainstay and sitting down up a climb it tended to bob around A LOT.
I changed it to a 34t chainring and there have been no further issues.

...apart from the SID Ultimate fork that I got with the frame. Within in 3 months it had developed quite a lot of bushing play, Ultimately the lowers were replaced by SRAM/Rockshox, I sold the fork and went with a 120mm Pike Ultimate instead.

 

[rigidftw]

I occasionally changed the stem, bars, seat and pedals but overall it had stayed relatively unchanged since August 2021.

And what fun is that?

So I decided to take off the trouble-free drivetrain and convert this thing to singlespeed.

But not the easy way with the tensioner in place of the rear derailleur. The tensioner needs to be mounted to the ISCG tabs.

 

[clubby]

What a weapon. I’ve a Sentinel and have often thought of adding a Spur as a shorter option. Great handling bikes Transitions.

 

[rigidftw]

What a weapon. I’ve a Sentinel and have often thought of adding a Spur as a shorter option. Great handling bikes Transitions.

Indeed they are!

 

[rigidftw]

By the way, that glove compartment under the top tube is a neoprene pencil case with two holes added so it mounts to the accessory bosses.

 

[rigidftw]

I am trying to adapt this RooX Roller-Coaster.

Back in the day, it would have looked like this:

https://www.vitalmtb.com/community/Dami,47426/setup,46085

My ISCG variant is more appropriate, but it is an ISCG03 mount and the two mounting bosses on the Spur are positioned according the the more modern ISCG05 standard.

So I need a different mounting bracket.

This was the first go:

 

[rigidftw]

Unfortunately the bosses on the frame are offset to the outside by 3mm.

Which meant the hardware was touching the chainring and on top the chainline was way off. 15mm off.

This called for version two:

Much better, but not perfect.

 

[rigidftw]

This is version three.

This time the bracket will be printed by proper company specialising in 3D printing, instead of friends with DIY printers.
And maybe, if I'm lucky, the design changes improved the part enough for it to hold up fine, despite not being made from metal.

 

[This-is-my-Field]

That's mega.

 

[rigidftw]

Couple of challenges: Lots of chain growth, chain skipping on the King cog and it seems I put too thick of a grease inside the freewheel mechanism, so that the spring behind the ratchet is held back a little.

The rear pulley was also changed for a bigger one with narrow-wide tooth profile. Seemed like a good idea.