Frame Design

grinch
Posts
197
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10/15/2013
Location
CA
Fantasy
278th
8/4/2024 9:26am

Bit of a shop rat question. I know santa cruz have lifetine warrantee on pivots but im wondering how much a shop would charge for labour to replace all the pivots? Is there a bike company that has the easiest most inexpensive pivot replacement set up? Im kind of looking at devinci as well

1
9/7/2024 3:21pm Edited Date/Time 9/7/2024 3:28pm

I'm super frustrated, as this has happened to my previous design as well. 

My single pivots keep cracking right here, around the main pivot shell. I knew this would be a high stress area so I even added a gusset here. My guess is that the angle between this gusset and the downtube is too acute and putting stress on the weld, causing the crack. 

What are people's recommendation? Add yet another gusset on top at a shallower angle? or just change the angle of the existing one? 

This is a short travel titanium single pivot that hasn't been hucked off anything more than probably 5 feet. 

20240906 143502 0v1.1-pviot-closeup3
Biketechspert
Posts
36
Joined
8/19/2020
Location
Woodbridge, VA US
Fantasy
1409th
9/7/2024 3:28pm
I'm super frustrated, as this has happened to my previous design as well. My single pivots keep cracking right here, around the main pivot shell. I knew...

I'm super frustrated, as this has happened to my previous design as well. 

My single pivots keep cracking right here, around the main pivot shell. I knew this would be a high stress area so I even added a gusset here. My guess is that the angle between this gusset and the downtube is too acute and putting stress on the weld, causing the crack. 

What are people's recommendation? Add yet another gusset on top at a shallower angle? or just change the angle of the existing one? 

This is a short travel titanium single pivot that hasn't been hucked off anything more than probably 5 feet. 

20240906 143502 0v1.1-pviot-closeup3

if theres a way to do one smooth gusset, thats the move cause a lot of sharp corners are going to cause a lot of stress in a small area.

Could also help if i could see the frame woithout the rear triangle on it and where specifically the cracks are helping. 

1
9/7/2024 7:13pm
if theres a way to do one smooth gusset, thats the move cause a lot of sharp corners are going to cause a lot of stress...

if theres a way to do one smooth gusset, thats the move cause a lot of sharp corners are going to cause a lot of stress in a small area.

Could also help if i could see the frame woithout the rear triangle on it and where specifically the cracks are helping. 

snowy

Does this give you a better view? 


So you're saying just modify the existing gusset to meet the downtube at a less sharp angle, like this below?

image 43

1
earleb
Posts
155
Joined
3/23/2023
Location
North Vancouver, BC CA
Fantasy
225th
9/8/2024 1:54pm

On my current build I have used a set of plates to tie the bb/main pivot/shock mount all together with the downtube. So far it has worked well. The plates are probably a touch on the thin side, I had Send Cut Send do them and they have limited options in 4130. 

p4pb27085677
4
Biketechspert
Posts
36
Joined
8/19/2020
Location
Woodbridge, VA US
Fantasy
1409th
9/8/2024 2:00pm
if theres a way to do one smooth gusset, thats the move cause a lot of sharp corners are going to cause a lot of stress...

if theres a way to do one smooth gusset, thats the move cause a lot of sharp corners are going to cause a lot of stress in a small area.

Could also help if i could see the frame woithout the rear triangle on it and where specifically the cracks are helping. 

Does this give you a better view? So you're saying just modify the existing gusset to meet the downtube at a less sharp angle, like this below?
snowy

Does this give you a better view? 


So you're saying just modify the existing gusset to meet the downtube at a less sharp angle, like this below?

image 43

Mainly talking about where the gusset sections meet each other and the frame to make a sharp angle. That 4030 plate looks really cool!

1
Eae903
Posts
90
Joined
10/20/2023
Location
Laramie, WY US
9/11/2024 8:22am Edited Date/Time 9/11/2024 8:23am
I'm super frustrated, as this has happened to my previous design as well. My single pivots keep cracking right here, around the main pivot shell. I knew...

I'm super frustrated, as this has happened to my previous design as well. 

My single pivots keep cracking right here, around the main pivot shell. I knew this would be a high stress area so I even added a gusset here. My guess is that the angle between this gusset and the downtube is too acute and putting stress on the weld, causing the crack. 

What are people's recommendation? Add yet another gusset on top at a shallower angle? or just change the angle of the existing one? 

This is a short travel titanium single pivot that hasn't been hucked off anything more than probably 5 feet. 

20240906 143502 0v1.1-pviot-closeup3

What materials are you making your frame out of? Just the titanium or other materials too? 

9/11/2024 1:35pm
Eae903 wrote:

What materials are you making your frame out of? Just the titanium or other materials too? 

Titanium for now. 

I'm exploring steel for an ebike. 

buckoW
Posts
21
Joined
8/4/2009
Location
CH
9/11/2024 8:51pm
Does this give you a better view? So you're saying just modify the existing gusset to meet the downtube at a less sharp angle, like this below?
snowy

Does this give you a better view? 


So you're saying just modify the existing gusset to meet the downtube at a less sharp angle, like this below?

image 43

Maybe you could increase the wall thickness of the down tube in addition to the gusset with a shallower angle?

1

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