crandress 

Hello everyone, I spend most of my time in the classic and vintage section, but thought this might be a better place to pose this question. I am upgrading my mountain bike components and looking at Shimanos 3x9 Alivio. However, they make to models of 3x9 cranks. One uses a square taper bottom bracket, the other uses outboard or through bottom brackets, not sure the exact terminology. I am pretty heavy, 275 to 290. So is on of these technologies better for a heavy rider? My gut says the square taper is better, but that is without any technical knowledge of the two. So which is better for a heavy rider?

Thanks in advance! Chris

wsteve464

I'd go with the hollow axle, outboard bearings as they are very easy to install replace plus a large selection of differing levels of quality, Should be no problem for your weight, I started back riding at around 260lbs have hollow axled cranks on all my bikes both Sram and Shimano.

crandress 

Thank you! Regards!

tallbikeman

The tapered square axles are an older design that is still being spec'd on lower model line bicycles. There a lot of hollow axle standards out there and choosing one may mean some study of the various product specifications. The bottom brackets themselves have seen several new standards as far as width and circular dimension. MTB design in particular has brought about a raft of bottom bracket changes in dimensions and specifications. Be sure to accurately measure your bottom bracket dimensions before looking to purchase a new crank and axle setup. I believe that both square taper and hollow axle technologies are strong enough for your weight. I've known a rider who broke Campagnolo record cranks like toothpicks but not their square taper axle ends. For decades I've used Profile racing cranks made in Florida . They are of chrome moly construction with a hollow 19 or 22mm 48 spline axle of chrome moly or titanium construction. I doubt they can be broken without significant abuse. The bike frame would probably break first. I weigh 240lbs and also ride several bicycles with JIS square taper crank axles and 180mm cranks. I have never broken a crank arm or an axle during my decades of riding. Good luck with your project.

dabac

Best BB I’ve had was an ”eff-a-gee”(Apparently banned three-letter combo)/SKF square taper BB.
The only drivetrain part that’s still original on my main commuter.
At 6000+ miles/year I’ve lost count of how many miles it has held up.
And I got the bike used!