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Differences in pivot bearings between different bikes / brands

2465 Views 9 Replies 8 Participants Last post by A. Rider, Nov 28, 2021

skyno

Discussion Starter · Nov 22, 2021

I have had the opportunity to own and try a bunch of different full suspension bikes over the years and I ride them pretty hard. I know this is totally anecdotal, but I have noticed that, all other things being equal, the pivot bearings of some bikes seem to perform and last way longer before needing replacement / service than others.

I have had a few Specialized bikes and my brother has had a bunch that I have been riding over the years (Stumpjumpers, Enduros, Epics, Levos, Kenevos) and it seems like the bearings on all those bikes almost never creak or feel stiff no matter what we put them through.

The Trek Slash I previously had was constantly creaking / making noise (especially the rear) and it seemed like I was constantly cleaning / regreasing or replacing and it was a pain to do on this bike - that bike was just very noisy in general - made owning this otherwise great bike not worth it for me

I have had 3 different Ibis bikes (Mojo HD, Ripley, Ripmo) and while they aren't as creaky and noisy as the Trek, they seem to stiffen up relatively quickly, especially on the Ripmo.

I have had 2 different Rocky Mountains (Altitude and Slayer) and they used mostly bushings and weren't noisy but needed more maintenance to keep them feeling smooth, although the maintenance was much easier.

I am not a Specialized fanboy or anything and there is a lot about Specialized that I don't love, but it seems like for some reason I have had amazing experiences with the bearings on their bikes compared to others.

I was curious if others have had similar experiences?

Also, when you notice the bearings starting to feel stiff / creak, do you usually clean and regrease or just replace them?

Thanks for your input!

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dan l

· #2 · Nov 22, 2021 (Edited)

I think bearing quality is one part of a very complicated equation.

I have had a Santa Cruz Bronson v1, Bronson V3, and now a 5010 V4. The v1 Bronson would smoke lower bearings on a regular 9 month interval. One time a bearing broke in halves and the pivot shaft was taken out. The v3 Bronson never required bearing replacement with approximately 5000 miles of use. The 5010 is too new to judge, but it is aging like the v3 Bronson.

To my knowledge, the bearing supplier is the same across all the bikes. What is different is the mechanical design. My only point in bringing this up is this is not a black or white issue. It’s complicated with many factors involved.

A good bike has quality bearings and solid engineering behind it. You need both. Some people have opinions about that, but opinions are cheap, repairs cost money and time. People with opinions never seem to be around when repairs are being made with peoples time and money.

Funny how that tends to be the case….

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slimat99

· #3 · Nov 22, 2021

I've never owned a frame that had junk bearings. It's not something I would worry about. Bearing life will be more a factor of how exposed and or how well they are sealed, and the lateral forces they experience because of the suspension design.

When my bearings feel a little gritty I pop the outer seal, clean and repack. I only replace when a bearing is totally shot because PF interfaces don't like to be fooled with. The fewer times you mess with PF the better. While I've never damaged a frame or linkage from replacing bearings, it's just my policy to leave PF alone when I can.

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skyno

Discussion Starter · #4 · Nov 22, 2021

Thanks for the responses and good points about separating out the quality of the bearings themselves from other factors. I would be surprised if all the higher end bike manufacturer's didn't use high quality bearings on all of their higher end bikes since the cost of the bearings themselves has got to be minuscule when looking at the overall costs.

I was more thinking that the difference could be how exposed / sealed the bearings are and what kind of loads hey are under with the different pivot and suspension designs could be making the difference? - and I am totally open to the fact that my sample size is very small and could just be pure chance

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HuckingKiwi

· #5 · Nov 23, 2021

I would be surprised if higher quality bearings even makes a difference. Most bikes use deep groove ball bearings which are designed mainly to handle radial loads. Because of the way bikes are used the bearings are loaded in a radial and axial manner. The general rule is that deep grove ball bearings should not be subject to an axial load that is more than 25% of the static load rating. For example a 6901 bearing that has static load rating of 1.46kN (328.22 lb) should be limited to around 360N (82 lb) of axial loading. Full complement bearings like Enduro Max would increase those figures but chances are that bearings in mtb frames are loaded beyond their specifications.

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Dorp to falt

· #6 · Nov 23, 2021

A lot of bearing issues are cause by poor bearing seat machining tolerances. Then add in welding and a surface treatment. The bearings never had a chance.
Some manufacturers have a better grip on the bearing fits. Some designs are easier to manufacture.

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Cleared2land

· #7 · Nov 24, 2021

I think in most bikes that have experience with have Enduro MAX pivot bearings. They are a common specialty pivot bearing.

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HuckingKiwi

· #8 · Nov 28, 2021 (Edited)

I was studying for one of my engineering course and for fun I decided to see if my assumption that bearings in mtb frames were overloaded was true. I measured the lengths of the linkages on a random bike and made a GeoGebra model to find the angles that the linkages would make when the shock was compressed to 50% of its travel. To simplify the analysis I went with a coil shock with a 450lb spring (which was the spring rate recommended for a rider of 180lb on that bike). Usually I found that the first bearings to go bad were the main bearings on the link driving the shock so that was the force that I solved for.

The result showed that at this position the bearings would be loaded with 369lb each. As a reference that particular bike had a 6901 bearing at that location and a 6901 bearings usually have a static load rating of 1.46kN or 328lb. So at 50% travel with a 180lb rider that bearing was loaded beyond its static rating. Afterwards I realized that I forgot to include the force generated by the IFP pressure so the actual force is going to be slightly higher.

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Shark

· #9 · Nov 28, 2021

^
I was thinking exactly the same thing.

Sent from my SM-G991U using Tapatalk

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A. Rider

· #10 · Nov 28, 2021

HuckingKiwi said:
The result showed that at this position the bearings would be loaded with 369lb each. As a reference that particular bike had a 6901 bearing at that location and a 6901 bearings usually have a static load rating of 1.46kN or 328lb. So at 50% travel with a 180lb rider that bearing was loaded beyond its static rating. Afterwards I realized that I forgot to include the force generated by the IFP pressure so the actual force is going to be slightly higher.

These type bearings used at those sorts of pivot points should die far far earlier than they do then.

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