[Sandwich]

What's the best way to figure out how short of a BB I can use? My kids' hotrock allegedly came with a 128mm wide BB spindle. I feel like this is massively wide for a tiny person with tin hips. It looks like I can go 20mm narrower without affecting clearance of the crank arms or chainring. That should make for a better q factor and potentially better shifting.

 

[slimshady]

The spindle should be 127.5mm according to sheldon Brown:
https://www.sheldonbrown.com/bbsize.html

Is is a double or a triple? On SB's site the chain line isn't listed for that spindle width and similar ones, but I'd say you could at least go for 118 if mounting a single ring on the cranks.

 

[Sandwich]

This is a single. I think I have a spare Steelie in the basement. Maybe I can try a test fit

 

[Sandwich]

Hmmm...so I dug through my bin and found a 107 as well as a 110mm spare. I tried the 107 but A) there's no collar so the guide is a no go, and B) the chainline actually got messed up so there was pretty serious strain on the chain in the largest gear.

I then tried the 110 which also provided clearance and added a collar which allowed the guide to fit, but the chainline was still shitty (duh) and now the ring rubbed on the guide.

I'm running out of time to get this done by her birthday, and I'd like to have it complete by then. I'm thinking about ordering a 119, which should give me an extra 5mm per side, correct the chainline slightly and also provide clearance for the guide. If there still isn't clearance, then I can run without the guide, but the bike is so light that I no longer have to ditch it. What do you think?

 

[slimshady]

my son has been running without a guide/chainguard since he got is first pedal bike. Now he's on his third. Ditch the guide and call the day off, but first mind the chainline. It'll affect the chain retention way more than the guide.

 

[Sandwich]

Thanks, I appreciate the help. I'll order up a 119, ditch the guide unless she really starts dropping chains, and I can run the 107 or 110 if the lighter and correctly spaced BB doesn't show up in time. Better to have the bike together than be missing a part.

 

[Sandwich]

Titanium Bike Square Taper JIS Bottom Bracket Cartridge 103L 107L 110L 113L 119L | eBay

Strength titanium Axle. Use bearing inside, good quality, super smooth. Excellent waterproof bearing. Weight：145-159g.

www.ebay.com

any reason this won't work? These cheapie BBs are all over ebay, super light and my 5 yo doesn't need to worry about strength or longevity...but what is the difference between a traditional square taper and a folding bike Dahon/Brampton BB? Looks like it uses an external tool, but otherwise pretty similar???

 

[jstuhlman]

Titanium Bike Square Taper JIS Bottom Bracket Cartridge 103L 107L 110L 113L 119L | eBay

Strength titanium Axle. Use bearing inside, good quality, super smooth. Excellent waterproof bearing. Weight：145-159g.

www.ebay.com

any reason this won't work? These cheapie BBs are all over ebay, super light and my 5 yo doesn't need to worry about strength or longevity...but what is the difference between a traditional square taper and a folding bike Dahon/Brampton BB? Looks like it uses an external tool, but otherwise pretty similar???

i won't say she's gonna die, but...