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Trek BB90



 
 
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  #21  
Old August 10th 20, 05:11 PM posted to rec.bicycles.tech
Tom Kunich[_2_]
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Posts: 1,318
Default Trek BB90

On Monday, August 10, 2020 at 7:38:03 AM UTC-7, jbeattie wrote:
Ruckus, our local carbon repair shop, has a number of methods for fixing carbon BBs. I think they would just build up the shell and ream to dimension with something like Tom's bike. On standard BB30 shells, they can also bond-in a piece of tube made by Enve and just turn the bike into PF30. https://ruckuscomp.com/news/2015/10/09/30-is-the-new-30 Tom can also buy the OS bearings made for sloppy Trek frames.


A BB90 is nothing at all like a BB30 and cannot be repaired anything like the same manner.
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  #22  
Old August 10th 20, 05:57 PM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default Trek BB90

On Monday, August 10, 2020 at 9:11:51 AM UTC-7, Tom Kunich wrote:
On Monday, August 10, 2020 at 7:38:03 AM UTC-7, jbeattie wrote:
Ruckus, our local carbon repair shop, has a number of methods for fixing carbon BBs. I think they would just build up the shell and ream to dimension with something like Tom's bike. On standard BB30 shells, they can also bond-in a piece of tube made by Enve and just turn the bike into PF30. https://ruckuscomp.com/news/2015/10/09/30-is-the-new-30 Tom can also buy the OS bearings made for sloppy Trek frames.


A BB90 is nothing at all like a BB30 and cannot be repaired anything like the same manner.


A BB30 is exactly like a BB90 except that the shell width is 90.5mm and the ID is 37mm. It has an integrated shoulder and no snap ring, but repair would be the same except facing the shoulder after repairing the ID, assuming you had to repair the shoulder. https://carbonbikerepair.co.uk/wp/?p=1248 Trek also will do this, or so I am told. Do you work on your BBs? On both BB30/90 you knock bearings out and squeeze bearings in. From a user-service standpoint, the only differences is the bearing cartridge size and the installation tool for the 24mm ID bearing.

-- Jay Beattie.

  #23  
Old August 10th 20, 07:19 PM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 4,018
Default Trek BB90

On Mon, 10 Aug 2020 11:36:43 +0700, John B.
wrote:

:-) The classic method to repair out of round holes is (FIRST)
obtain a bearing with an O.D. larger then the current and then bore
the hole to fit the new bearing :-)


Yep. However, this was on a weekend during one of my irregular visits
to the parents in Smog Angeles. My father bribed me into going
downtown to fix the machine while he worked on something else. His
instructions were something like "Do whatever is necessary to get it
running by Monday morning. I won't complain". That translated into
working on it all night and forget about ordering parts. Swell.

What happened was that the factory had an order for some garments that
had to be in a few days. This machine was a key part of the puzzle.
It would have been easy enough to remove the attachments from the
mangled Pfaff sewing machine to another machine. However, the
available machines were all from different manufacturers, all with
different bed plates and attachment points. It would have taken a
full day.

My first thought was to braze some brass to the cast iron frame and
ream out the bearing hole. (Yes, it was that old and I don't recall
the model number). However, it would take all day to tear down and
re-assemble the machine. All I had was a home made fly cutter. The
mill was several years in the future. Remounting the drill press
horizontally was vetoed by my father.

So, I made a sanding drum from a plywood sandwich and wrapped it in
emery cloth. Using a hand drill, I would grind a little, insert the
main shaft, slide the bearing over the shaft, check the centering and
clearances, remove shaft/bearing, and grind some more. I would also
double check with a dial indicator bore gauge. When I was fairly
happy, I switched to finer sandpaper, and eventually to buffing
compound. I described inserting the bearing and brass shim in a
previous posting. I think the whole process took about 5 hrs.

I also found the cause of the out of round bearing hole during the
process. The counterweight on the crank arm was missing, probably
forgotten by the previous mechanic. To reduce vibration, someone had
over-tightened the drive belt, accelerating the damage. I
cannibalized a counterweight from a different Pfaff machine.
Apparently the shim and bearing worked well enough for my father to
mumble thank you a few weeks later. On a later visit, I noticed that
the machine was gone. I didn't ask what happened to it.




--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #24  
Old August 10th 20, 11:15 PM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default Trek BB90

On Mon, 10 Aug 2020 11:47:21 -0400, Frank Krygowski
wrote:

On 8/9/2020 8:14 PM, AMuzi wrote:
On 8/9/2020 11:47 AM, Tom Kunich wrote:
On Saturday, August 8, 2020 at 6:08:01 PM UTC-7, jbeattie wrote:
On Saturday, August 8, 2020 at 3:15:40 PM UTC-7, Tom Kunich wrote:
When I got my Trek Madone if became rapidly clear why it was so
cheap. The bearings in the BB90 were rather loose. Now there are
several methods of fixing this - one is to use a strong
locktite-type compound which locked the bearings in place and one is
the Trek way which is to put an oversize bearing in place of the
stock bearing.

With normal caution as an Engineer I chose the least damaging method
first. I followed the directions on the locktite and glued the "just
fits" bearing into place and allowed it to dry the requisite 48
hours.. Well, climbing one of the local hills last Tuesday the BB90
began to "click" in the same place every revolution on the drive
side pedal. This means the glued drive side bearing has come loose.
Inasmuch as I am presently working on the Colnago I won't look at
this until later. Another choice has come up - that is to check the
bearing that is presently in the Madone, to see if it is undersize.
That might be the case since the bearings more easily obtained from
Trek are Chinese and let's say they aren't the finest quality
bearing available. Hambini of one piece BB push in bearing fame who
hates BB90 also can supply NTN bearings which are exactly the right
size. NTN is a Japanese bearing manufacturer that supplies the best
bearings in the world.

So when I remove the bearing that is presently flopping around in
there I can closely measure it if I can remember where I put my
micrometers. Failing that I do have a digital caliper that is fairly
accurate to two decimal places. If the bearing that is in there is
undersized by any significant amount (which is common with Chinese
bearings.) I will get the bearing set from Hambini and install those
before going to the extreme of those oversize Trek bearings which
are so oversize that they can distort the bearing cups. This screws
up the bearing and generally causes premature failure though
"premature" is sort of an undefined term that might mean it only
lasts for 1,000 hours. Chinese bearings would probably only last for
twice that anyway. NTN bearings virtually last forever under the
sorts of loadings that the BB90 puts on them.

So presently I'm riding the Emonda and trying to go no lower than
the 28 tooth so that I can get a little more training in my legs. I
am presently at 80,000 feet of climbing when I would normally be at
double that. I normally close a year off with over 200,000 feet of
climbing. Judging from the way that my legs felt today after a
couple of 900 foot climbs I don't think that I will make 125,000 but
stranger things have happened.
You should also check the crank bolt torque and maybe swap the pedals
out, check the chain ring bolts and even the rear QR before pressing
in new bearings. Cyclical clicks can come from places other than the BB.

-- Jay Beattie.
Being on the drive side it cannot be crank torque, the pedals are new
so the bearings are extremely unlikely to be loose and usually make
noise at the ends of the crank revolutions both top and bottom.
Cyclical clicks in exactly the same location almost always means that
you have a loose bottom bracket bearing. But of course before I
disassemble anything I check everything out. That is what a bike
repair stand is for.



Before doing anything else, find an able willing assistant (who is not
our age with hearing impairment).

Get on your bike with your shoes and hold the front brake firmly tight.
Lean on something (doorway, chair back) with you other hand. Press as
hard as you are able on the right crank (around 3:00 position).
Backpedal and repeat for the left crank. Hard. Continue in that cycle as
assistant listens near the BB area, at the rear wheel and so on.* I find
a finger on a chainring bolt or RH cup/bearing or pedal spindle to
sometimes be edifying (you can talk with assistant as you do this so
there are no mangled fingers). A mechanic's stethoscope is also useful.

We replace some crank bearings at rider request which sometimes are a
misdiagnosis of a pedal/skewer/spoke/chainring bolt/saddle noise.


I strongly agree with Andrew's method. I've used it myself (although not
with an assistant).

If an assistant is helping and a mechanic's stethoscope isn't available,
a workable substitute can be a dowel, yardstick etc. Hold one end
touched to the suspected part and the other end held against one's ear.
Before buying the stethoscope, I used that trick on car engines.


Skilled mechanics use a large screwdriver :-) and as you say, one end
against the engine block and your ear against the other end.
--
Cheers,

John B.

  #25  
Old August 11th 20, 04:41 PM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 4,018
Default Trek BB90

On Tue, 11 Aug 2020 05:15:53 +0700, John B.
wrote:

On Mon, 10 Aug 2020 11:47:21 -0400, Frank Krygowski
wrote:
I strongly agree with Andrew's method. I've used it myself (although not
with an assistant).

If an assistant is helping and a mechanic's stethoscope isn't available,
a workable substitute can be a dowel, yardstick etc. Hold one end
touched to the suspected part and the other end held against one's ear.
Before buying the stethoscope, I used that trick on car engines.


Skilled mechanics use a large screwdriver :-) and as you say, one end
against the engine block and your ear against the other end.


Unskilled and lazy mechanics, like me, can't afford assistants. So, I
modified a commodity stethoscope by extending the rubber tube between
earpieces and the chestpiece. I didn't have any proper PVC or rubber
tubing handy, so I used some clear vinyl tubing from the hardware
store. I then attached a 4ft stick to the chestpiece with a rubber
band. I mounted the bicycle on my trainer, tied the bicycle down to
my deck rails with some rope for safety, and started riding.
Eventually, the clunking sounds appeared, which I located by waving
the stick around to various places along the drive train. The bell
head seemed to be best for low frequency clunks, while the drum side
was better for higher frequency grinding noises from bearings.

At one time, I considered doing this electronically, using an electret
microphone on the end of a stick, amplifying the sounds with a
smartphone, and listening with earphones. The advantage was that I
could do some vibration analysis using an audio spectrum analyzer app
to help identify the culprit. For lower frequencies, the built in
accelerometer might be useful for finding vibrations:
https://play.google.com/store/apps/details?id=kr.sira.vibration&hl=en_US
However, I never did anything with the idea.


--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 




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