best O ring material for holding lights

[youngoldbloke]

The O ring holding my rear light to the seatpost has just failed - in the house fortunately. Looking on line for a replacement I see they come in various materials. Which is best for this job, or does it matter? I assume they are not really designed for this purpose anyway.

 

[Profpointy]

I shouldn't worry unduly. I guess a fairly stretchy material is best, but as you say, they are really for sealing gases or fluids at pressure not meant as rubber bands. The material is often chosen on the basis of the chemicals they are being used with, so hardly relevant here

 

[Ihatehills]

Nitrile is the most common o ring material, and probably the most suitable for your purpose imo

 

[shouldbeinbed]

Could you more permanently fix the light on with a zip tie?

 

[Yellow Saddle]

The most common O-ring material is nitrile but unfortunately it is not the best material for a stretch application. It performs poorly when stretched as opposed to compressed. You'll see that it quickly cracks (perishes) and breaks. I would try any other type, like Viton, if you have a choice. I haven't yet figured out which type performs best, perhaps someone can enlighten us. But I do know that nitrile is rubbish in that application.
If you are confronted with a range of hardness, go for something between 60 and 70 Shore. 90 will be way too hard and stiff.

 

[I like Skol]

I have a definitive answer.

I knew I had seen this somewhere so after 5 minutes searching for the box my recently purchased Garmin came in I have this>

 

[Profpointy]

Could you more permanently fix the light on with a zip tie?

Id you do this when you have to cut it off at some point, and when you've carefully checked so as not to cut the wire - don't then go and cut the wire anyway because it's really annoying.

 

[youngoldbloke]

Thanks everyone - very helpful. Just ordered a couple of EPDM o-rings from Sealforce on e-bay. No, I couldn't use a zip tie, and an o-ring is much neater anyway.

 

[PeteXXX]

I was looking around for some of the bands for a Cateye Nima rear light. They're priced at £1.50 for two (different sizes). The instruction leaflet doesn't say what the bands are made of just that they supply 22mm & 32mm in the box.
If I buy some new ones they'll probably snap as well!

 

[youngoldbloke]

I needed 44+ mm ID , just under 3mm dia. thickness

 

[PeteXXX]

I've saved that link. It seems like a handy place for retaining bands

 

[Yellow Saddle]

I have a definitive answer.

I knew I had seen this somewhere so after 5 minutes searching for the box my recently purchased Garmin came in I have this>

View attachment 146765

Try and say that when you're drunk...ethylene alcohol monopolywhasshisname.

I wonder if that stuff has a commercial name like....rubber or something. I also wonder why anything else would harm the fragile little Garmin.

 

[I like Skol]

I wonder if that stuff has a commercial name like....rubber

I remember when my loft conversion was done the architect specified an EPDM roof, the big seller is Firestone and they call it.............. Rubbercover

 

[youngoldbloke]

Try and say that when you're drunk...ethylene alcohol monopolywhasshisname.

I wonder if that stuff has a commercial name like....rubber or something. I also wonder why anything else would harm the fragile little Garmin.

- maybe the idea is that these o-rings don't break so readily, so avoiding damage from unintended road contact?

 

[themosquitoking]

- maybe the idea is that these o-rings don't break so readily, so avoiding damage from unintended road contact?

This was my immediate thought quickly followed by another about warranty voidage.