Rear Shock bolt keeps snapping

[Sven137]

HI

 

this is the 2nd time its happened.. when i went through a dip and the bike was at the bottom i heard a loud crack and the rear shock bolt snapped at at the bottom of the shock

 

I weight 90kg and am on a 29" Yeti

 

Are there diffrent thicknesses of bolts for the rear ? or am i riding wrong as i want going that wast and the dip was small .. it was at the Enchanted Forest at NF 

[Phatman]

Check that your shock is working properly and fully unlocked, and that all your pivot points are pivoting properly.

[Vetseun]

Your shock could be bottoming out.

Somewhere sommit aint workin right.

I would seriously consider a visit to a good lbs.

Good luck

[Ozzie NL]

Time to start slimming down boet

[Eddy Gordo]

Check your shocks air pressure.

[Sven137]

Check your shocks air pressure.

 

The shock air pressure was about 12 13 bar Bar as i followed a youtube tutorial of only allowing 25% travel on the rear shock when sitting and adjusted the pressure accordingly which was 13 bar

[MrJacques]

Titanium bolts could be an option, but check the other things like pivots, shock pressure (according to sag, not pressure), etc. first. With the shock loose you should be able to check that the suspension cycles easily.

[(Deon)]

Are you the first owner?

Who replaced the first bolt and with what?

How old is the bike?

[Eddy Gordo]

Is the bolt braking on the same spot?

[Sven137]

Are you the first owner?

Who replaced the first bolt and with what?

How old is the bike?

 

The Bike was built for me... Yeti Frame, Cannondale front fork...;

 

the bolt was replaced at LBS in Northgate

 

Bike about a year old now

 

Is the bolt braking on the same spot?

 

Yes.. same bolt same place

[Goodbadugly]

Titanium bolts could be an option, but check the other things like pivots, shock pressure (according to sag, not pressure), etc. first. With the shock loose you should be able to check that the suspension cycles easily.

Nope.

High tensile steel.

[PhilipV]

Were you sitting down going through the dip?

You need to be out of the saddle to allow your legs to absorb the bump. Your calves are better shock absorbers than anything Fox or Rockshox can make.

The combined force of the dip and your weight will be too much if sitting down.

If you were standing up and this happened, then something is seriously wrong.

[Captain Fastbastard Mayhem]

What Philip says.

 

Also check if the bolts are torqued correctly, and whether there's a missing spacer or washer or bushing etc. Any gap in the mounting will result in a weak spot and will most likely result in a sheared bolt.

[RiverInTheRoad]

Dismantle your suspension linkage, replace pivot bearings and lube us manufacturer recommends. 

The bolt shouldn't snap even if you  are heavy and used incorrect technique. 

[MrJacques]

Nope.

High tensile steel.

 

Yeti offers a titanium upgrade kit, although I don't think it's for the op's bike. But high tensile steel would work as well. They actually list the reason for breakages as people inflating the shock to too high pressure.

 

https://store.yetisnowmx.ca/products/shaft-lower-shock-titanium-upgrade-kit-7-parts

[Plentipotential]

I'm on a Giant Trance and replace that bolt about every 2 years, also weigh too much.

 

1. Stainless steel fasteners are not as strong as high tensile fasteners unless you buy A4 - 80 stainless steel.

2. Titanium fasteners also come in a variety of materials and for strong you need a Grade 5 heat treated.

3. Standard high tensile fasteners with a head marking of 8.8 have a tensile strength of 800 Mpa. Stainless steel A2 - 50, 500 Mpa, Stainless A2 - 70, 700 Mpa. Titanium Grade 2, 344 Mpa and Grade 5 heat treated, 950 Mpa.

 

Cheap solution? Socket head cap screw Grade 12.9, 1200 Mpa. Make sure you get unplated as hydrogen embrittlement caused by plating will effect tensile strength.