Old Sarge

I know this could go in the Mechanics sub-forum, but out of respect for all the wisdom I'm getting from the 50+ group I would like to ask y'all this question.

While riding yesterday I happened to look straight down and noticed the distance between my crank-arm and the bearing assembly where it passes through the bearing assembly in the frame (is that called a bottom bracket?). It seemed like quite a distance and I wondered if this was normal. My non-scientific measurement makes it out to be 5/16 to 3/8. In case I have totally messed up the description I am including two pictures which should be worth a couple of thousand words.

doctor j

I think it's OK. I just looked at the same side of my '06 Fuji, and the gap appears to be about the same. Unless you are experiencing a mechanical issue of some sort, just ride it.

It appears that you have a square taper sealed cartridge bottom bracket, same as Ol' Fuj.

Here's how one looks. I replaced the bottom bracket on Ol' Fuji at approximately 13,000 miles (give or take). This is the one that was replaced. Why I saved it, I don't know. Well, maybe I do now.

Siu Blue Wind

It if makes you feel any better, I can put my whole pinky finger in mine.

Old Sarge

doctorj, you saved it to show me what it is. Siu Blue Wind, it does make me feel better. I hadn't noticed it before....guess I never looked straight down at it before. I just didn't want any issues down the line. I love riding the bike. It only has about 60 miles to date.

Barrettscv 

It's OK. The bottom bracket on your bike has a long axle. The crank arm is a taper fit onto the axle, the gap is a product of that design and is not adjustable. I would expect that the long axle is needed to help the crank arm clear the chainstays. Look to see if the the arm clearance at the frame (between the bottom bracket and the wheel axle) looks reasonable.

JanMM

Don't be afraid of the Bicycle Mechanics forum - you would have gotten an honest, respectful response there, too.

Old Sarge

I enjoy reading the Bicycle Mechanics forum, and have learned a lot there, but here feels like home and y'all are my friends. And I'm shy around strangers.

fietsbob

Other companies that make cranks and BB's design the arms to come in to meet the shorter spindle,
AKA low-profile..

The cranks you have came on the bike , part of the product manager's choice
to meet the Target Price Point.. so the bike fit Your budget.

You should know the right side is where the action is..

there the crank, and the chainrings and the gear cluster on the rear wheel,
have to be such that the chainline is sorted out for better shifting..
centerlines match so chain sideways flex is least.


left side is not so critical ..

lhbernhardt

As long as the cranks are not "loose" (you can grab and crank and jiggle it and nothing moves), everything should be fine. If the crank moves the least bit sideways, or if the whole bottom bracket slides side to side, you just might have a problem...

Luis

Mr. Beanz

You're good! The BB style you have is the old cartridge type. Pedals bolt onto the spindle from the outside so the bearings are in the cartridge (blue bike left 1998 style)

The new style is a long shaft that is connected to the crank, runs thru the BB shell then the arm bolts on with those two little bolts you see on the white bike crank arm. Then the thick silver thingie is the bearings rather than onthe inside liek the old sytle. The new style is called an "outboard bearing" set up. THe bearings sit on the outside and make for a stiffer BB snce the bearings are further out


BBstyle by gulpxtreme, on Flickr

Old Sarge

Thanks, Mr.Beanz. Great pictures explaining it. The last mechanical work I did on a bicycle, some 55 years ago, involved something to do with clothes pins, playing cards, and spokes. I haven't made that modification to my current bike yet.