Mountain Bike Reviews Forum banner
Cancel
Create thread New Forums

SRAM DUB crank arms not spinning freely, BB issue

Jump to Latest
1 - 15 of 15 Posts
J

JohnV2000

· Registered
Joined
·
28 Posts
Discussion starter · #1 ·
I bought a 2019 Stumpjumper Comp, 12 speed SRAM NX eagle, last fall. It has been riding very well for me, but since I am mainly a road cyclist, I only put about 300 miles on the bike in 6 months.

Yesterday I took the bike out and was going to clean and lube the chain before my next ride, and I noticed the cranks were not spinning freely. It feels like the bottom bracket is sticky. Previously, the cranks would spin very smoothly, but now, there is noticeably more effort required to spin the cranks. Its not awful, I could definitely still ride it, but its no where near as free spinning as it was before.

I take good care of this bike, I hose it down after every muddy ride. I use a garden hose, no pressure washer, and take care not to spray the bearing too much. I wipe it down with a towel immediately, and then lube the chain and dry the seals and stuff.

What can I do to make my cranks spin freely again? Do I need to replace my BB or just lube it somehow? I am a somewhat experienced mechanic, so I can definitely replace the BB myself. I am just not sure why the BB is not spinning freely anymore.

Thanks,

John
 
#2 ·
I'd pull the crankarms off, clean everything, inspect the bearings and reassemble torquing everything to spec. I think it's doubtful that the bearings are bad already.
 
#3 ·
Normally that happens when you do not put the correct spacers between the bottom bracket and the bottom bracket shell. Did you remove the bottom bracket last time you rode that bike?

Enviado do meu SM-G975F através do Tapatalk
 
Discussion starter · #4 ·
Nel79 said:
Normally that happens when you do not put the correct spacers between the bottom bracket and the bottom bracket shell. Did you remove the bottom bracket last time you rode that bike?

Enviado do meu SM-G975F através do Tapatalk
Click to expand...
Nope, I haven't taken anything like that apart on the bike since I bought it.
 
#5 ·
JohnV2000 said:
Nope, I haven't taken anything like that apart on the bike since I bought it.
Click to expand...
Then I would say the ballbearings got water on them somehow and during that time it got rust on them. Try to replace the bottom bracket they are not expensive and are easy to install

Enviado do meu SM-G975F através do Tapatalk
 
#6 ·
Nel79 said:
Then I would say the ballbearings got water on them somehow and during that time it got rust on them. Try to replace the bottom bracket they are not expensive and are easy to install

Enviado do meu SM-G975F através do Tapatalk
Click to expand...
You'd replace a bb without first inspecting it? IME it's highly unlikely the bearings are rusted, especially with that few miles on them. There are lots of reasons that it might feel a little draggy besides the bearings. Pull the crankarms and feel how the bearings spin.
 
#7 ·
J.B. Weld said:
You'd replace a bb without first inspecting it? IME it's highly unlikely the bearings are rusted, especially with that few miles on them. There are lots of reasons that it might feel a little draggy besides the bearings. Pull the crankarms and feel how the bearings spin.
Click to expand...
Just out of nothing?......... Rust ist the most reasonable reason in this case as water takes time to damage a component and last time he rode the bike it was fine, seems to me a god judgement call, but obviously when you uninstall the bottom bracket one will give it a look before replacing it, i don't think i need to say that

Enviado do meu SM-G975F através do Tapatalk
 
#8 ·
Nel79 said:
Just out of nothing?......... Rust ist the most reasonable reason in this case as water takes time to damage a component and last time he rode the bike it was fine, seems to me a god judgement call, but obviously when you uninstall the bottom bracket one will give it a look before replacing it, i don't think i need to say that

Enviado do meu SM-G975F através do Tapatalk
Click to expand...
I'm not meaning to argue but just saying that IME rusty bearings on a bb that new is a rarity. Our rental fleet gets hosed down after every ride and even after a year or more of that I've never seen it. Not saying it couldn't happen but I wouldn't suspect it.

Anyway it will become apparent if the op removes the cranks. I'm guessing they'll be fine but of course I could be wrong.
 
Discussion starter · #11 ·
mopartodd said:
Have you messed with the bearing preload adjustment at all?
Click to expand...
No, I haven't made any adjustments. I think I'll just remove the BB and inspect it. Maybe a little grease or cleaning it will fix it. If not, I'll buy a new one.
 
#12 ·
mopartodd said:
Have you messed with the bearing preload adjustment at all?
Click to expand...
this, make sure your preload ring is set properly, that plastic thing sram put on their cranks can fail from time to time.

Like said ddo what was suggested here, remove the cranks, make sure bearings are spinning nicely, no dirty somehow got into the spindle, clean everything, sram bb are not serviceable, but you can clean everything and regrease the spindle, make sure you check the install instruction to make sure all the right spacers are in the right place which they should since you didn't have a problem before, then re-install the cranks make sure preload is set correctly...

best case scenario this fix the problem, worst case scenario you need to spend $40 and get a new dub BB
 
#13 ·
No just remove the crank and see how the BB bearings spin. Try adding some grease around seals, put back together, adjust the preload accordingly and go from there to determine if you need to replace the BB.

Also ..follow the SRAM instructions on the dis and reassembling, and preloading of the crank...
 
#15 ·
Preload ring got tight, so try adjusting it.

Unless you ride under water, it's not the BB.

and don't lube or spray anything on the bb/crank arm interface. Grease/oil attracts dirt and dirt leads to wear and/or friction.

Just adjust the ring, non drive side, tiny allen head screw, loosen screw, back off ring, if cranks spin free then readjust and go ride.
 
Save
Like Like
1 - 15 of 15 Posts
You have insufficient privileges to reply here.
About this Discussion
14 Replies
9 Participants
Last post:
Donkeeboy
Mountain Bike Reviews Forum
posts
16M
members
534K
Since
1990
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!
Full Forum Listing
Explore Our Forums
General Discussion Downhill - Freeride California - Norcal Shocks and Suspension Passion