Bottom Bracket Drop

[aatores]

Anyone have some insight into BB drop? I've seen as small as 50mm (super high BB for cyclocross) and as big as 80mm. Some say lower BBs (bigger drop) are more stable but Dave Moulton disagrees saying:

"The argument usually put forward for a low bottom bracket is that it lowers the center of gravity and therefore improves stability. I do not subscribe to this theory because center of gravity is not really an issue on a bicycle, and raising or lowering it has little effect on stability."

Any thoughts?

[Ken Robb]

On bikes with level or nearly-level top tubes a lower BB lowers standover and lets me ride a bigger frame which makes it easier for me to have higher bars relative to my saddle.

My favorite bikes (around 60cm c-c) have all had BB drops of 75-80mm. I can't say I loved them BECAUSE of that but the one bike I had with 70mm drop felt twitchy to me. There are too many other variables for me to make a definitive statement on the subject.

[Fixed]

1+ for lower b.b. drop
But that is just me
Cheers

[tiretrax]

I always thought it was more for clearance - if there's a ride of 150+ lbs on top, 5 cm shouldn't matter much.

[tigoat]

As with other dimensions on the bike, as long you as you in the range, it really does not make a whole lot of difference whether you have a 60 mm drop or a 70 mm drop, performance wise. Some builders will believe or subscribe to one way or another so it is pretty much a preference more than anything else. However, if the BB is too low, your cranks/pedals might hit the road if you lean a lot. On the other hand, if it is too high, then you might be sitting higher than necessary. I personally prefer to have a higher BB (less drop) to maintain my ideal saddle to bar drop without shortening the head tube too much.

[ultraman6970]

Some people can't tell but others can tell when the difference in BB drop is like 5 mm, but there are other aspects too like the length between the wheels axles and what do the builder and the rider want to achieve. Then you have to add the human factor in how the rider actually handles the bike.

My personal experience is that I can tell the differences in 5mm but at the same time like wild handling bikes, other guys like bikes like they where an 18 wheeler.

[dgaddis1]

The frame is the frame ATMO

[jmoore]

IMO, whatever the builder specs is the correct bb drop

[Peter P.]

I just switched from a 70mm drop frame to an 80mm drop BB.

Honestly, I can't tell much of a difference.

[PSC]

I had a bike with a 65 mm drop and 32 mm tires and every time I would get on the bike it felt like I was mounting a horse. Definitely like being lower, even though it may not be that much I do feel a difference.