Replacement of Serotta ST Bearings

[George Ab]

This post may be useful if you ever need to service the ST bearings on your Ottrott or Legend.

There are a couple of reference posts concerning on paceline:

http://forums.thepaceline.net/showthread.php?t=136131
http://forums.thepaceline.net/showthread.php?t=90987 http://forums.thepaceline.net/showthread.php?t=110305

This is my DIY ST bearing replacement and I assume no liability for its use.

To determine if bearing needs to be replaced. "If you can hold your dropout in a fixed location but move the seatstay boss outward from the dropout, then you have non-adjustable bearing play and they should be replaced." In my case there was no bearing play, but with unknown service history it was prudent to reset the maintenance.

Parts Used:

2 X Bearing P/N SMR686C2OS7NB2 (see notes)

2X Wave Washers P/N W0492-007-S (see notes)

Remove ST Bolt. I removed the ST nut with a 8mm 12 point socket and 3 mm Allen wrench. The walls of the socket have to be fairly thin as the nut is slightly recessed into the chain stay. Most sockets are 8 point, but my local auto parts store had a 12 point.




Remove Old Bearing. The bearing has to be pressed or driven out (not in) as there is a recess in the seat stay that will not allow bearing to be pressed in. You can drive out the bearing with a punch. However, I made a fixture to assure force necessary to drive out bearing is only applied to outside edge of bearing. The fixture is a M8 bolt with a M8 nut on the inside and the outside of bearing for support. The bolt has to be fished between the chain stay and seat stay, so you will have to gently move the stays to make room for the nut, then screw in bolt until it comes out the outside of bearing and secure with a nut. Support the chain stay on a surface that will not mar or damage the stay. Now you are ready to drive out the bearing. I used a punch to get to the head of the bolt as there is not much clearance due to the opposite chain stay. A couple firm hammer taps on head of bolt to drive bearing out of chain stay and bearing came out.



Install New Bearing. After cleaning the area where the old bearing was, I put a dash of wheel bearing grease on outside of bearing and mating surface to assist re-insertion. I pressed in bearing using the same 8mm bolt, nut and old bearing so pressure is on outside edge of bearing vice bearing race. Tightening the bolt to press bearing into the seat stay until it meets recess. It goes in easily; stop when you feel resistance.



Reinstall ST Bolt. Place wave washer between seat and chain stays, reinsert the bolt and nut. Use a drop of medium strength thread lock on the bolt threads and tightened nut to 60 in-lbs.

Notes:
The bearing originally used is Boca Bearing part number SMR686C-YZZ #5 NB2. It is a 6x13x5 mm, stainless steel ceramic hybrid radial bearing with stainless seals. I used a similar spec bearing, stainless steel with ceramic bearings with same load characteristics and same internal lube. However, I opted for a rubber seal vice stainless seal part number SMR686C2OS7NB2. Per bearing manufacture the rubber sealed bearing has better sealing characteristics for dirty environments; requiring no maintenance and lube is good for life of bearing. Bearings were $16 each. This would also work fine SMR686C-2YS: https://www.amazon.com/Pack-SMR686C-...ustrial&sr=1-2



The wave washer measures 12.5mm OD, 8.9 ID, and .18mm thick. Opted for a stainless steel variant with 4 pounds of deflection which is standard for loading a bearing of this size. Part number is W0492-007-S. Purchased from zorotools for about $1 each with minimum order of packet of 25. Other manufactures and part numbers are springmaster part number W61360 (non stainless), W61370R (stainless), Seastrom part number 5805-23 for $3.15 each.



The very bike that was part of the 2003 Masters Cycling Team and graces the last page of the 2004 catalog is good as new. Love my Serotta!

[pbarry]

Awesome thread! This shold be a sticky!

[Gat64]

Spectacular! Thanks for taking the time to post your procedure. Safely locked in my bookmark vault....

[mnoble485]

Could be best first post ever!

Mike

[Dromen]

As an Ottrott owner, this is very sooooothing.

[Peter P.]

That was a great story-Thanks for spreading the tips!

[George Ab]

Thanks for the input. I have garnered much information from Paceline. So when I started the research and replacement of the bearing I thought it would be a way of giving back to the forum.

[Dale Alan]

Excellent info and pics,thanks for posting.

[Ahneida Ride]

I believe that the original bearing were not stainless.
There in originates a lot of the problems.

S should have sourced a better bearing.

[Ahneida Ride]

and great post !!!!!! thanks a million ...

[Brian Smith]

Originally Posted by Ahneida Ride

I believe that the original bearing were not stainless.
There in originates a lot of the problems.

S should have sourced a better bearing.

The original bearings were, in fact, with stainless races, or what is nominally termed "stainless" by sellers.
An assortment of varying bearing suppliers were used at various points, and bearings of greater expense were, in fact, sourced. The selection of bearing suppliers was not informed by the directive of "whichever is the best on earth, beyond the point of discernible improvement." It's a "wear" part.

I participated in sourcing some at one point, and my efforts in that regard were small compared to those of others. I think that often people speak about "S" with excess authority.

[Brian Smith]

Originally Posted by George Ab

This post may be useful if you ever need to service the ST bearings on your Ottrott or Legend.


Remove Old Bearing. The bearing has to be pressed or driven out (not in) as there is a recess in the seat stay that will not allow bearing to be pressed in. You can drive out the bearing with a punch. However, I made a fixture to assure force necessary to drive out bearing is only applied to outside edge of bearing. The fixture is a M8 bolt with a M8 nut on the inside and the outside of bearing for support. The bolt has to be fished between the chain stay and seat stay, so you will have to gently move the stays to make room for the nut, then screw in bolt until it comes out the outside of bearing and secure with a nut. Support the chain stay on a surface that will not mar or damage the stay. Now you are ready to drive out the bearing. I used a punch to get to the head of the bolt as there is not much clearance due to the opposite chain stay. A couple firm hammer taps on head of bolt to drive bearing out of chain stay and bearing came out.

This is useful stuff posted above.
One should use a bit of caution here: there is no mention of any manner employed to limit the outward deflection of the seat stay during said hammer taps. The carbon stay could easily suffer damage, particularly in cases wherein the outer bearing race is firmly attached to the seat stay boss. A removable locktite product was used in later years, and in many examples we received back for refinish at the factory left out in the elements there was corrosion affixing the bearing race to the stay. This procedure would likely not produce the desired result, and the bearing may leave its outer race in the seat stay in its removal. The 8mm nut is an inexpensive item that could be worthy of essay, but I wouldn't consider it to be foolproof. The photo shows how unlikely the nut is to contact the outer race of the bearing. It will, however, clear the .41" inner lip of the seat stay boss to gain purchase on other parts of the bearing.

Lastly, it isn't M8 for the bolt size, despite the 8mm nut. The standards don't quite work that way. M5 would be a better word choice.

[dekindy]

Since the bearing is designed for up and down movement the check is for side to side play?

My LBS was kind of nonchalant regarding in that it will be very obvious when it needs attention? Unless you ride in the wet a lot it is unlikely to need changing?

Won't it make noise or handling feel differently when it needs replacing or is it such that if you don't catch it in time can cause major damage?

[pbarry]

Originally Posted by Brian Smith

The original bearings were, in fact, with stainless races, or what is nominally termed "stainless" by sellers.
An assortment of varying bearing suppliers were used at various points, and bearings of greater expense were, in fact, sourced. The selection of bearing suppliers was not informed by the directive of "whichever is the best on earth, beyond the point of discernible improvement." It's a "wear" part.

I participated in sourcing some at one point, and my efforts in that regard were small compared to those of others. I think that often people speak about "S" with excess authority.

Thanks, Brian.

[Highpowernut]

Ok, so after reading this. I have a couple questions.
Idk if my frame has st bearings or not. (Hsg aero)

Does anyone have a tool or photos? I might be willing to make a copy.

Here is a photo of my frame, is there a bearing or just a bolt???


Thanks
Wayne


Some people wonder if they made a difference, Marines don't have that problem.
Ronald Reagan