riverdrifter

I'm not sure I'm using the correct terminology here, but I'm just wondering why some rear hubs are loud and others are quiet?

Five bikes in my family currently and they all have varying noise levels.

My Jamis road bike has a Formula hub with SRAM 12-26 8-speed cassette. It is completely silent, pedaling and coasting.

My vintage Raleigh with Shimano 3 speed is loud while coasting. So is my wife's Raleigh Alysa hybrid, it has a Sunrace 7 speed cassette.

My son has a full chromoly Framed single speed BMX that is extremely loud when coasting.

My my daughter has a GT mtb that has a Sunrace 8 speed cassette, and it's the second quietest of the bunch. Still much louder than my Jamis though.

Just one one of the many random thoughts I have when we are all riding together.

Thanks!

DorkDisk

Hi. The mechanisms have different mechanics and thus different sounds. Much is marketing and the sound is engineered. For cassettes, its the freehub mechanism (in the rear hub) that makes noise, not the actual cassette.

seamuis

There are a number of different freehub mechanisms and each one has its own distinct sound. A freehub is built into a hub shell (for use of a cassette) and a freewheel is threaded onto a hub. Classic freehubs and freewheels typically both use pawl/tooth ratchet system. A 3spd is typically an internally geared system and is completely different. They typically make a distinct sound when coasting (planetary gear system) For the classic pawl/tooth mechanism, the number of teeth, the number of pawls, as well as the angle of the teeth, all affect the sound. More teeth and and pawls, the louder it will typically be. BMX freewheels typically have more teeth and pawls for faster and more precise engagement, and are often much louder than road freewheels and freehubs. Shimano freewheels and freehubs typically have only two pawls and fewer teeth, so they are considerably quieter.

heres a good video covering some of the most common freehub mechanisms:

riverdrifter

Thanks for linking that video. Interesting stuff!

JanMM

Unless a freehub is louder because it is self-destructing, generally there is no correlation between sound level and quality of the mechanism.

seamuis

Nobody has mentioned quality, but different types do produce different type of sounds and varying levels of sound.

JanMM

Correct. OP mentioned loud vs quiet and some folks assume there must be something wrong with a freehub that's louder than what they are used to.

seamuis

Some people might, but that’s not what the OPs question is about.

burnthesheep

I definitely like a road hub with more engagement. If you climb out of saddle and you change gears and lay off the power for that one revolution so you don't jam gears/chain......it's nicer on a hub with more engagement. More fluid of a motion.

Also silly, but nice getting that perfect foot start position at a stop light/sign too.

The noise? You should be hammering it, not freewheeling. If you find yourself freewheeling in a paceline you're wrong also. You should lightly rotate the crank over so that when you do need to apply power there isn't a lag and consequential accordion in the line.

If on front downhill, hammer it and pull off just before the bottom and let the crew by. Then suck on at the end of the line as they're slowing going up. I absolutely hate group rides where someone freewheels all the downhills.

If you're worried about people running into people, see comment 1. Pull hard and pull off before the bottom.

MikeyMK

I almost never stop pedalling, as i use regenerative battery charging. But the sound of the freewheel is amplified through the large diameter hub motor so much it'd be enough to let pedestrians know i'm approaching..