rubber/plastic caps on wheel nuts?

[Alex728]

one of these caps on the rear wheel nuts of my Salisbury has fallen off somewhere (probably along the B1113, and thus could be anywhere between Ipswich, Stowmarket and Finningham or beyond!!)

What is the actual purpose of these things? I notice the Wisper 905 also appears to have them, but I have not seen them on normal pushbikes.

Are they merely for show or do they serve some purpose?

 

[frank9755]

Mainly the former - make it look a bit tidier. A bit like valve caps; nice to have but no big deal if you lose one.

Normal bikes nowadays tend to have quick release or skewers, which these would not be compatible with. Nutted wheels which these would fit are fairly rare - only on the cheaper non-electric bikes. However i have to say that I have never seen one on a non-electric with a nutted wheel.

 

[flecc]

However i have to say that I have never seen one on a non-electric with a nutted wheel.

That I think is the key to the answer Frank. Hub motors tend to have fairly long spindles to copes with various mountings, e.g. with or without torque plates. The plastic caps are to protect any protuding thread area against burring damage, rather than the nut itself. The non-motorised wheel is usually treated to them as well for appearances sake.
.

 

[Barnowl]

Hi Alex,

Same thing happened to me on the front wheel. I though the bike looked tidier with both caps on. I searched the internet but couldn't find any. In the end I got one off the supplier of my bike who just popped one in the post for me.