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Lets talk bottom bracket drop.

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#3 ·
since we're talking drop, it'd be important to know what the drop is in relation to... so

what wheel size?
 
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#4 ·
plummet said:
What do you think Is too low, just right and too high?

Add your wheel size, travel and riding style.

I'm of the opinion that 15-20 mm drop is optimal for enduro bike/technical riding.
Click to expand...
But... you didn't mention your wheel size, and even that isn't enough. How much ground clearance do you have?

If we're going to ignore clearance: is there anyone that wouldn't accept a 200mm drop? Would be nice and stable. More is always better, but then we need to mitigate for the reality of clearance.

bb drop is a compromise based on how much ground clearance you need.

Probably real question: whats the min distance you can tolerate between chainring and ground? And how long is yur crankz.
 
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#6 ·
Considering BB drop is the product of wheel size in relation to BB height I prefer less drop. I would like to be around 13.75" or 14" height for 160mm. BB drop will be whatever it will be to have the clearance I want.

I've had too many pedal smacks at speed a few resulting in good crashes. I run 165mm and thin pedals to help but I would still prefer a taller BB. Sure lower bb's feel great in the corners but I would rather have more clearance and get used to cornering with a higher COG. Maybe we would stop sanitizing trails so much if BB's trended up?
 
#7 · (Edited)
plummet said:
My 15-20mm wis based on 27.5 165mm travel. I'm expecting that 29 could push to 25mm to have the same clearance.
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I’m generally inline with those numbers but sag/suspension progressivity is also a factor.

My Spur has 40mm of drop but it’s only 120mm of rear travel, the flex stays make it very progressive and I’m not throwing it down the chunkiest/steepest stuff. I don’t even have 165 cranks on it and all is well despite the big BB drop number.
 
#8 ·
Never been much of an Enduro sort- tend to ride mostly within XC to Mountain range.

On FS 29er's with 120-145 mm fork travel and 100-150 rear travel, BB drops range ~30-50... I don't notice much difference.



Sent from my KB2005 using Tapatalk
 
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#12 · (Edited)
The bikes travel makes a difference too, because 30% of 180mm is more than 30% of 100mm.

Most long travel 29’ers are between 29-35mm of bb drop. But some have over 40mm of drop (stumpy evo in low).

I’d be really interested to try lower bbs with shorter cranks, and see how that felt.
 
#14 ·
My SJEvo was really problematic with 170mm crank, even with the Cascade link that improves progression and rides higher.

Now I run the Williams Racing Mullet link which lowers the rear axle about 1" to correct for a 27.5" wheel, but with a 29" rear wheel. Then I placed the bike in the 'Low' position.

The end result is the BB height from the ground is 345mm/ 13.8" which is just heavenly. It's a HUGE improvement in ride performance, and not just pedaling.

Like DGUSMC pointed out, the low BB height on my Spur is no problem just because the effective ride height is higher because of less travel and the bike just sits higher.

I'm not stoked on super low BB heights and I'm not the only one. It's a common complaint that I hear these days.
 
#15 ·
nobody special said:
I can tell you my Stumpjumper Evo BB is too low. I can tell you my Commencal Meta BB is just right. I don't remember ever riding a bike and thinking "this BB is too high" but maybe I just forgot.
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Old school FR bikes were too high. Other than those, I'm with you. I would be happy to see every 140 to 170 bike bumped up 10 to 15mm. I would like to try super short cranks but I kind of see them as a silly work around for a problem that's easily solved. They make sense for DH bikes because there's just noway to have good clearance without jacking the BB up so high it will really hurt cornering, but for 140 to 170, we can just raise the BB.
 
#16 ·
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#17 ·
+100%. I could not have said this any better. I have had 2 big crashes in the last 2 years and both were from my pedal grabbing a embedded rock in the ground and stopping the bike suddenly. This of course was riding downhill at a good speed. I also run 165mm cranks. Thou, crank length doesn't really matter riding downhill as the pedals are level. YMMV...

slimat99 said:
Considering BB drop is the product of wheel size in relation to BB height I prefer less drop. I would like to be around 13.75" or 14" height for 160mm. BB drop will be whatever it will be to have the clearance I want.

I've had too many pedal smacks at speed a few resulting in good crashes. I run 165mm and thin pedals to help but I would still prefer a taller BB. Sure lower bb's feel great in the corners but I would rather have more clearance and get used to cornering with a higher COG. Maybe we would stop sanitizing trails so much if BB's trended up?
Click to expand...
 
Discussion starter · #18 ·
DHDad604 said:
+100%. I could not have said this any better. I have had 2 big crashes in the last 2 years and both were from my pedal grabbing a embedded rock in the ground and stopping the bike suddenly. This of course was riding downhill at a good speed. I also run 165mm cranks. Thou, crank length doesn't really matter riding downhill as the pedals are level. YMMV...
Click to expand...
What's your bike, type travel, wheel size and bb drop that caused the 2 crank smasher?
 
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