Bicycle Mechanics - 1x9...bottom bracket help please.

My father in law wants a bike, but he's VERY intimidated by gears, and doesn't even want to tackle the "problem" of learning how to work a bike that has both front AND rear gears. (the horrors!)

However, he needs some form of gearing to handle the rolling hills at his age and health. He's not THAT old, and no a bike isn't an unsafe gift...and it's partially for his health that the entire family wants him to have it. He just currently leads one of those horrible sedentary chemically augmented American lifestyles. A little time on a bike should fix that.

I'm converting a Fuji Touring into a 1x9 for him. I.e. replacing the stock TruVativ Touro road triple with a Truvativ Isoflow Single 42t crank. Of course, I'll need a different BB (Power Spline)...but I'm having trouble determining which size.

Has anyone here done something similar...and what size did you use?

A 108 mm BB as for a double should be fine. If you wan't it to be perfect you are going to come up against the problem of ideal specs vs actual specs. Actualy check the Truvativ website and see what the specs are for the single chainring crank.

I have a Truvativ Elita triple with an ISIS spline that according to specs uses a 118 mm BB spindle however I have it setup with a 108 mm BB spindle and a 2 mm spacer and its spot on. In practice you will have a little leway.

Regards, Anthony

It might be difficult to find Power Spline BBs in the correct length. It's a Truvativ proprietary design for their low end cranks.

You might want something to keep the chain on the chainring. Single chainring derailleur bikes are occasionally known to drop the chain.

My father in law wants a bike, but he's VERY intimidated by gears, and doesn't even want to tackle the "problem" of learning how to work a bike that has both front AND rear gears. (the horrors!)

However, he needs some form of gearing to handle the rolling hills at his age and health. He's not THAT old, and no a bike isn't an unsafe gift...and it's partially for his health that the entire family wants him to have it. He just currently leads one of those horrible sedentary chemically augmented American lifestyles. A little time on a bike should fix that.

I'm converting a Fuji Touring into a 1x9 for him. I.e. replacing the stock TruVativ Touro road triple with a Truvativ Isoflow Single 42t crank. Of course, I'll need a different BB (Power Spline)...but I'm having trouble determining which size.

Has anyone here done something similar...and what size did you use?

It might be easier on both of you, to use a gear hub in the back like a Nexus 8, then you don't have chainline or maintenance issues, just needs a couple of drops of oil, once in a while.

It might be easier on both of you, to use a gear hub in the back like a Nexus 8, then you don't have chainline or maintenance issues, just needs a couple of drops of oil, once in a while.

I think this is a good idea, too, IF the OP hasn't already bought the derailer drivetrain and doesn't mind spending a little extra. However, no modern internal gear hubs are oil lubricated. They all use grease. Even Sturmey-Archer switched the AW over in the early 90's. Not that this is a concern; grease lasts longer and lubricates better. But it won't be a couple drops of oil, it'll be a servicing every 5 or 10k miles or so ;).