PF30 Bottom bracket in carbon frame...

7 replies · 619 views

bcgravel
26 posts
#1Feb 7, 2019, 9:43 AM
Bike: 2018 RLT RDO.
Bottom bracket interface: PF30-68mm shell
Crank: SRAM Force CX1 46t BB30
Purchased as an apex build, stripped it down and put all Force and Red components on it. Pretty awesome ride. After about 1500 miles, the stock SRAM PF30-BB30 drive side crank bearing locked up after a ride in wet conditions. This was the stock bottom bracket. I popped it out of the frame, knocked the bearing out of the plastic/cup and took some measurements to see if it was something I could replace since the non-driveside bearing was still silky smooth. This bottom bracket was great, and never made a single creak/noise for the 1500 miles of service. Turns out, the drive side, uses a proprietaty SRAM bearing that is 43.5mm diameter, 31mm inside diameter, and 7mm wide. Sram provides the shim/seal that snaps into the bearing, making it 30mm ID on the driveside. Anyway, the special bearing is not available anywhere so im forced to buy a new BB for this bike.

Im going to purchase a wheels MFG threaded PF30-BB30 bottom bracket. I plan on installing it and never taking it out of that BB shell. For service, I will be tap the bearings out and replace those readily available ones as needed down the road. Here are my following questions that I have for you experts out there?
Pertaining to the carbon PF bottom bracket….
                    Do you prefer using something that is a little more flexible for a shell to press in? like the Delrin/plastic SRAM solution?
                    Do you use pipe thread compound at the carbon/shell interface? Any threat to the carbon/resin over time?
                    The bike shop said I should use “carbon safe” grease…. Would a off the shelf moly grease or heavy duty lucas grease cause damage to the frame?
Im not a carbon fiber materials expert so i would like to ask for someones in depth opinion on this.
I am planning to install the wheels mfg bb with some free “carbon safe” grease the guy at the bike shop said he will give me and reply back in 3-4 months to give a report back on the status.
0
dangle
465 posts
#2Feb 8, 2019, 10:46 AM
bcgravel wrote:
Pertaining to the carbon PF bottom bracket….
                    Do you prefer using something that is a little more flexible for a shell to press in? like the Delrin/plastic SRAM solution?
                    Do you use pipe thread compound at the carbon/shell interface? Any threat to the carbon/resin over time?
                    The bike shop said I should use “carbon safe” grease…. Would a off the shelf moly grease or heavy duty lucas grease cause damage to the frame?
Im not a carbon fiber materials expert so i would like to ask for someones in depth opinion on this.
I am planning to install the wheels mfg bb with some free “carbon safe” grease the guy at the bike shop said he will give me and reply back in 3-4 months to give a report back on the status.

Personally, I like the Wheels threaded BB. I haven't had problems with standard cups though and I have 4 bikes with them. One went to the threaded Wheels setup when I had to replace a BB in the middle of CX season. Enough bearings had been in and out of that frame that I was worried about tolerances and wanted to do a metal sleeve. I have another to put on my second CX bike once we get on the right side of winter/spring.

Do NOT use pipe thread compound or any sort of loctite on the threaded bottom bracket.

I doubt that a basic molybdenum or one of the many Lucas Oil greases have been studied on carbon fiber. Just buy a tube of the basic Park Tools Polylube 1000. It's not very pricey, can be used on just about every bicycle component, and will last a long time. Don't go crazy with the grease though. Just a little bit on the shell and threads.
0
bcgravel
26 posts
#3Feb 9, 2019, 6:32 AM
I've done a little research on the Lucas Oil Xtra Heavy Duty grease since I purchased some back in December. I know park tool probably isn't drilling for oil to make petroleum grease for bikes. I also purchased some Park tool poly 1000 grease recently. After comparing the chemical data, descriptions of properties(viscosity at various temps), density, and physically using the products directly side by side. These two greases even have the same color, and scent also. Coincidence? I don't think so. I'm not going to confirm this by saying this is true(unless i was the guy working for park tool that buys grease from Lucas) but there is a 95% chance that they are the same product.

Park tool 4 oz. tube of poly lube 1000 grease online or local bike shop $6.95

Lucas Xtra heavy duty grease 16 oz. tub $4.50 at Menards or Home depot

I'm not cheap by any means, I just hate when companies relabel products they should let others(Lucas) continue to make and recommend using that. Instead of branding it under their name, decreasing the quantity, doubling the price and telling people this is the only stuff you should use.

I know my thread went from bottom brackets to grease but i figured i would put this information out there.

0
bnystrom
459 posts
#4Feb 13, 2019, 10:15 AM
I have the Wheels Mfg. PF30 BB and it's a very nicely made product. Grease the threads as they recommend and use whatever grease you have on-hand for the cups. "Carbon safe" grease is nothing but a marketing ploy; grease won't hurt carbon composites.
1
bcgravel
26 posts
#5Feb 13, 2019, 11:09 AM
bnystrom wrote:I have the Wheels Mfg. PF30 BB and it's a very nicely made product. Grease the threads as they recommend and use whatever grease you have on-hand for the cups. "Carbon safe" grease is nothing but a marketing ploy; grease won't hurt carbon composites.

What type of tool do you use to tighten the BB with? I borrowed a wrench from the shop to use, I just made the cups "snug" because theyre compressing carbon and without a socket, I'm not able to actually torque to a spec. The BB made some noise on the trainer last night, i suspect "snug" was not enough. I might have to drop $50 bucks and get the red two sided socket from wheels mfg to do it right and torque to 35-50nm as recommended.
0
bnystrom
459 posts
#6Feb 13, 2019, 12:01 PMedited
Initially I installed it with a tool that I cobbled together (dumb move on my part and I should know better), but shortly thereafter I picked up a Park BBT-29, which works fine. You do have to be somewhat careful due to the thin flanges on the Wheels Mfg BB. Wrenches can potentially slip and if you really over-torqued it, it may be possible to shear off a flange. I have no idea what the exact torque is on mine, but it's stayed tight and doesn't creak.

For extra security, you can always use a large bolt with some big washers (or a headset press, if you have one) to hold the wrench in place as you tighten the BB, but I didn't find that to be necessary. Just make sure that it's fully engaged and use one hand to hold the wrench on while you tighten the BB with the other.

Use common sense and you'll be fine. You don't sound like the "ham-fisted" type.
0
dangle
465 posts
#7Feb 15, 2019, 11:01 AM
bcgravel wrote:
Turns out, the drive side, uses a proprietaty SRAM bearing that is 43.5mm diameter, 31mm inside diameter, and 7mm wide. Sram provides the shim/seal that snaps into the bearing, making it 30mm ID on the driveside. Anyway, the special bearing is not available anywhere so im forced to buy a new BB for this bike.

Do you have any pictures of that? I have never heard of it and now I'm curious.
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bcgravel
26 posts
#8Feb 18, 2019, 10:59 AM
dangle wrote:

Do you have any pictures of that? I have never heard of it and now I'm curious.

Here are the photos below. This is a SRAM PF30 BB30 Bearing ID is 31mm, Bearing OD is 43.7. This plastic Shim shown installed and out is how sram keeps a special bearing. Spent alot of time digging around the internets and found a few in Europe but to get 2 bearings shipped it wasn't worth the $. Solution: Buy a wheels mfg bb. problems solved.
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