Background Info: I have a Nimbus Performer Giraffe that seems to be a pre-2018 version (it has 140mm polished silver cranks with a noticeable Q-factor, a Nimbus Gel saddle with a KH seat body and white KH bumpers, and no visible serial number). While it was in like-new condition two years ago when I purchased it from the original owner, this unicycle now has 100+ street miles, several hundred freemounts and dismounts, thousands of idling cycles and hops, and has even survived a few UPDs.
However, its bottom bracket has not handled the abuse well and now requires an overhaul. I was quite surprised to find an old-fashioned loose-ball bearing bottom bracket with a 68mm shell width and a 120mm spindle. My usual approach is to replace the bottom bracket entirely with a sealed cartridge version.
Question: What spindle size should I use for the replacement bottom bracket? I can go with a 120mm spindle, or purchase a 122mm spindle (as suggested on the UDC UK website), but I imagine I could probably use a shorter spindle too. It looks like the newer version of the Nimbus Giraffe uses a 103mm spindle.
The distance between the wheel cogs is about 81.5mm. It seems that the original 120mm spindle positions the top cogs about 10-15mm further apart (I can’t measure this myself right now). It looks like a 107mm spindle would align the cogs in the same vertical plane.
Does anyone (UDC? @rogeratunicycledotcom?) have experience installing a shorter spindle?