Has anyone swapped BB on a BMC Roadmachine?

Discuss light weight issues concerning road bikes & parts.
bilwit
Posts: 1192
Joined: Sun Apr 03, 2016 5:49 am
Location: Seattle, WA

by bilwit

Not sure there's any good options to help tie that thing down. A metal-sleeved BB seems like the only good option. I'm about to get mine punched out and replaced soon with a plastic-sleeved BB and I think I'm just going to have to take the "shove it under and hope of the best" approach..
Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:03 pm
I will continue to argue that all we are getting screwed from a maintenance perspective when it comes to everything internal and integrated. Nothing but headaches that keep bikes in the shop instead of on the road. This industry has a long way to go to get to solutions that represent real gains for the consumer.
Eh just seems like a lazy afterthought design choice by BMC. They could have made it so that the plastic bit at the bottom that has an alternative piece that routes mechanical cables also had a hydraulic-specific sleeve that routes the it externally around the BB, then back into the chainstay like how Firefly does it.

by Weenie


TimW
Posts: 491
Joined: Sat May 09, 2009 1:52 pm
Location: England, UK

by TimW

AlgaeHater wrote:When I swapped out the drivetrain on my RM 02, I encountered the same problem. I installed a threaded BB from Wheels Mfg:

https://www.competitivecyclist.com/whee ... ExOmJiODY=

Very happy with this BB. Solid construction that's unlikely to creak. I installed the same BB on my Timemachine Road as well.
I built my RM01 from frameset. Did this, Sigma Sport sell these in UK. Bonus, no creaking either.



AlgaeHater
Posts: 64
Joined: Sun Jan 27, 2019 2:53 am

by AlgaeHater

Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:03 pm
gurk700 wrote: ↑
Wed Jan 30, 2019 7:08 am
Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:06 am
Just take a moment to contemplate incredible stupidity of this design. Even the most flexible cable would still interfer with the crank axel. If left long enought, at some point the axel would wear through the hose. I love Switzerland. On my visits there I have never encountered any person or thing that would lead me to believe that this was possible. Shame.
100% agree. Cervelo, Sworks, Felt and multiple models of these brands. Never had this issue.

Axle wouldn't eat through the hose as the spindle is completely contained in the BB shell that doesn't spin, but doesn't change the fact that it's bad design. I know the photo makes you think the BB is already installed and you still can see the cable. But I haven't installed the BB seeing how it's gonna be blocked by the cable. The one time I attempted I couldn't cause the cable pushed the plastic BB off axle.

Anyway... Just gonna order an all metal BB.
Yes, this is true, but I never use the plastic sleeves. My BB's always seem to spin better without them - even with careful and correct install. :noidea: And how would one even make sure a sleeve is sitting correctly with a tough hose pushing against it. The sleeve would end up jammed against the crank axle. In that situation it is theoretically possible for the crank axle to wear through the sleeve and then the hose.

I will continue to argue that all we are getting screwed from a maintenance perspective when it comes to everything internal and integrated. Nothing but headaches that keep bikes in the shop instead of on the road. This industry has a long way to go to get to solutions that represent real gains for the consumer.
While I don't think the plastic sleeve is necessary from a structural standpoint, it is designed to keep dust and water off the crankshaft. Not sure I would want to install a BB without the sleeve.
2019 Bianchi Oltre XR4 eTap
2019 BMC Timemachine Road 01 Di2
2018 BMC Roadmachine 02 Di2

AlgaeHater
Posts: 64
Joined: Sun Jan 27, 2019 2:53 am

by AlgaeHater

Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:03 pm
gurk700 wrote: ↑
Wed Jan 30, 2019 7:08 am
Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:06 am
Just take a moment to contemplate incredible stupidity of this design. Even the most flexible cable would still interfer with the crank axel. If left long enought, at some point the axel would wear through the hose. I love Switzerland. On my visits there I have never encountered any person or thing that would lead me to believe that this was possible. Shame.
100% agree. Cervelo, Sworks, Felt and multiple models of these brands. Never had this issue.

Axle wouldn't eat through the hose as the spindle is completely contained in the BB shell that doesn't spin, but doesn't change the fact that it's bad design. I know the photo makes you think the BB is already installed and you still can see the cable. But I haven't installed the BB seeing how it's gonna be blocked by the cable. The one time I attempted I couldn't cause the cable pushed the plastic BB off axle.

Anyway... Just gonna order an all metal BB.
Yes, this is true, but I never use the plastic sleeves. My BB's always seem to spin better without them - even with careful and correct install. :noidea: And how would one even make sure a sleeve is sitting correctly with a tough hose pushing against it. The sleeve would end up jammed against the crank axle. In that situation it is theoretically possible for the crank axle to wear through the sleeve and then the hose.

I will continue to argue that all we are getting screwed from a maintenance perspective when it comes to everything internal and integrated. Nothing but headaches that keep bikes in the shop instead of on the road. This industry has a long way to go to get to solutions that represent real gains for the consumer.
While I don't think the plastic sleeve is necessary from a structural standpoint, it is designed to keep dust and water off the crankshaft. It also prevents not just the brake hose, but internal Di2 wires from rubbing up against a spinning shaft. Not sure I would want to install a BB without the sleeve.

Whoops sorry for the double post
2019 Bianchi Oltre XR4 eTap
2019 BMC Timemachine Road 01 Di2
2018 BMC Roadmachine 02 Di2

User avatar
TonyM
Posts: 3252
Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

I actually though that the plastic sleeve is also there in order to avoid the rubbing with Di2 or hydraulic brake cables on the crankshaft.

Mr.Gib
Posts: 3594
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

AlgaeHater wrote: ↑
Wed Jan 30, 2019 9:12 pm
Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:03 pm
gurk700 wrote: ↑
Wed Jan 30, 2019 7:08 am
Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:06 am
Just take a moment to contemplate incredible stupidity of this design. Even the most flexible cable would still interfer with the crank axel. If left long enought, at some point the axel would wear through the hose. I love Switzerland. On my visits there I have never encountered any person or thing that would lead me to believe that this was possible. Shame.
100% agree. Cervelo, Sworks, Felt and multiple models of these brands. Never had this issue.

Axle wouldn't eat through the hose as the spindle is completely contained in the BB shell that doesn't spin, but doesn't change the fact that it's bad design. I know the photo makes you think the BB is already installed and you still can see the cable. But I haven't installed the BB seeing how it's gonna be blocked by the cable. The one time I attempted I couldn't cause the cable pushed the plastic BB off axle.

Anyway... Just gonna order an all metal BB.
Yes, this is true, but I never use the plastic sleeves. My BB's always seem to spin better without them - even with careful and correct install. :noidea: And how would one even make sure a sleeve is sitting correctly with a tough hose pushing against it. The sleeve would end up jammed against the crank axle. In that situation it is theoretically possible for the crank axle to wear through the sleeve and then the hose.

I will continue to argue that all we are getting screwed from a maintenance perspective when it comes to everything internal and integrated. Nothing but headaches that keep bikes in the shop instead of on the road. This industry has a long way to go to get to solutions that represent real gains for the consumer.
While I don't think the plastic sleeve is necessary from a structural standpoint, it is designed to keep dust and water off the crankshaft. It also prevents not just the brake hose, but internal Di2 wires from rubbing up against a spinning shaft. Not sure I would want to install a BB without the sleeve.
My understanding is that the sleeve was all about protecting the BB bearings from dirt and water. Thing is, I have never found any dirt or water in any bottom bracket of any my bikes - ever. Now di2 and other electronic cables, yeah, you don't want anything rubbing against those.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

Andres
Posts: 61
Joined: Mon Mar 09, 2009 10:10 am

by Andres

I've built a few RM's and there are a couple of tricks that I've used depending on the BB. Sram BB's are a little easier since they have overlapping sleeves, so you can press the drive side first, and use the spindle of the crank itself to line it up and get the opposite side to go in straight before fully pressing it in. The other method I used was dismounting the rear brake caliper and pushing it into the frame so the hose is being forced down. The thread together BB's are also a good idea. A bad BB for these frames is definitely a 4130 without a sleeve, I can only think of Kogel making one that has a sleeve for all of you out there using a 30mm spindle crank (me).

bilwit
Posts: 1192
Joined: Sun Apr 03, 2016 5:49 am
Location: Seattle, WA

by bilwit

Andres wrote: ↑
Thu Jan 31, 2019 5:27 pm
I've built a few RM's and there are a couple of tricks that I've used depending on the BB. Sram BB's are a little easier since they have overlapping sleeves, so you can press the drive side first, and use the spindle of the crank itself to line it up and get the opposite side to go in straight before fully pressing it in. The other method I used was dismounting the rear brake caliper and pushing it into the frame so the hose is being forced down. The thread together BB's are also a good idea. A bad BB for these frames is definitely a 4130 without a sleeve, I can only think of Kogel making one that has a sleeve for all of you out there using a 30mm spindle crank (me).
C-bear does too, a little hard to source though

AlgaeHater
Posts: 64
Joined: Sun Jan 27, 2019 2:53 am

by AlgaeHater

The main reason I swapped out the plastic Shimano PF86 was because it had already started to creak after 500 miles of riding. It also bothered me that the BB is not servicable - you're not supposed to re-use it after taking it apart for cleaning/regreasing. After installing the metal threaded BB, I've had zero noise from either of my BMCs. Only drawback is that it weighs about 40g more.
2019 Bianchi Oltre XR4 eTap
2019 BMC Timemachine Road 01 Di2
2018 BMC Roadmachine 02 Di2

utku
Posts: 4
Joined: Sun Mar 25, 2018 12:48 am

by utku

Sorry for going off topic, but, is that a frame protector you're using on the downtube? I have a RM02 and dropped the chain twice so far. Both times the chain got stuck between the inner ring and the frame near the bottom bracket. It looks like what you have might prevent further damage there.

gurk700
Posts: 277
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:03 pm
gurk700 wrote: ↑
Wed Jan 30, 2019 7:08 am
Mr.Gib wrote: ↑
Wed Jan 30, 2019 7:06 am
Just take a moment to contemplate incredible stupidity of this design. Even the most flexible cable would still interfer with the crank axel. If left long enought, at some point the axel would wear through the hose. I love Switzerland. On my visits there I have never encountered any person or thing that would lead me to believe that this was possible. Shame.
100% agree. Cervelo, Sworks, Felt and multiple models of these brands. Never had this issue.

Axle wouldn't eat through the hose as the spindle is completely contained in the BB shell that doesn't spin, but doesn't change the fact that it's bad design. I know the photo makes you think the BB is already installed and you still can see the cable. But I haven't installed the BB seeing how it's gonna be blocked by the cable. The one time I attempted I couldn't cause the cable pushed the plastic BB off axle.

Anyway... Just gonna order an all metal BB.
Yes, this is true, but I never use the plastic sleeves. My BB's always seem to spin better without them - even with careful and correct install. :noidea: And how would one even make sure a sleeve is sitting correctly with a tough hose pushing against it. The sleeve would end up jammed against the crank axle. In that situation it is theoretically possible for the crank axle to wear through the sleeve and then the hose.

I will continue to argue that all we are getting screwed from a maintenance perspective when it comes to everything internal and integrated. Nothing but headaches that keep bikes in the shop instead of on the road. This industry has a long way to go to get to solutions that represent real gains for the consumer.
There is no arguing integrated systems come with a price. If it's worth it or not is another conversation.
Thing is though I have seen bikes with internal and integrated designs which did not have this issue at all :)

Oh well.

gurk700
Posts: 277
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

utku wrote: ↑
Thu Jan 31, 2019 10:56 pm
Sorry for going off topic, but, is that a frame protector you're using on the downtube? I have a RM02 and dropped the chain twice so far. Both times the chain got stuck between the inner ring and the frame near the bottom bracket. It looks like what you have might prevent further damage there.
That's a magnet thingy from last owner. I assume it's for cadence measuring purposes. I'll be taking them off as my power meter measures cadence within.
However the RM's do come with a stock catcher. I've never needed it as the chain never dropped but I assume that should be enough?

gurk700
Posts: 277
Joined: Fri Jan 20, 2017 7:40 pm

by gurk700

TonyM wrote: ↑
Wed Jan 30, 2019 7:50 am
My RoadMachine02 did not have this problem.

The cable is too short IMHO.
It really isn't. I haven't even connected the cable end to the brake levers yet and have a lot of slack. I can force the cable to go down a little but it's so stiff that it comes up to what you see in the photo by default and pushes the BB axle off of the cups.
Like others mentioned, I will be getting a one piece metal BB

mr4fox
Posts: 266
Joined: Sat May 15, 2010 2:01 pm

by mr4fox

fwiw i put a dura ace BB in my BMC TMR01 and it creaked like crazy!!! ive had the best luck with nylon cup BBs like HSC in that frame so far ....but jsut nervously installed an alu cup ceramicspeed :o my point is Myabe BMCs BB tolerances comnbined with Shimanos BB tolereances arent a good match?

but back to you dilema...can you pull the cable housing back through so the caliper end is about at the BB, then install the BB then push it back though (so it slides and guides itself und the BB?

by Weenie


User avatar
TonyM
Posts: 3252
Joined: Thu Jan 22, 2015 4:11 pm

by TonyM

The 2018 BMC RoadMachine 02 ONE (which I use as my winter and rain bike) that I bought was delivered with an Ultegra BB but I replaced it immediately with a Dura Ace 9100 BB also but so far no creak 8)


@ OP:
How are you solving your problem now?

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