Wanted Hope Bulb 135x12mm rear end cap dimensions for machining


Orange 🍊 Fan
Hi all,

As it's looking increasingly unlikely that I will find a set of end caps for my 135x12mm bolt through rear bulb, I'm thinking of getting a set machined up.

Only this means I need some dimensions...would anyone here have a rear 135x12mm Hope Bulb hub they'd be able to accurately measure the end caps of?

Many thanks...hopefully someone can help out🤞🏻

Would anyone be able to confirm if this is a Bulb 12mm end cap?

May have found one...



  • Screenshot_20240413-190932~2.png
    661.4 KB · Views: 2
Have a number of 12mm end caps
Not sure how to identify


  • image.jpg
    496.4 KB · Views: 5
  • image.jpg
    533.3 KB · Views: 5
This is another photo of the possible Bulb end cap, but just need confirmation before I pay £30 on a job lot just for to get this spacer


  • received_441461561701180.jpeg
    183.8 KB · Views: 4
Is this for a 6 bolt or 5 bolt hub, and is it the drive or disc side (or both?)?

I'll be honest that the end cap in your post there doesn't look like any Bulb spacer I can remember. The disc side was loose and black anodised but with only a 0.5mm or so step to preload the bearing, nothing like that one, and that was the same for the 5 bolt and 6 bolt variants. It also never had any serrations on the frame end. The drive side spacer was always silver, but much shorter than that one and had a similar very small step to preload the inner bearing race. This I believe differed between 5 and 6 bolt variants, but I can provide measurements of the 5 bolt one if you need it.

It's for 6 bolt non-drive side. The internal dimensions are 15mm reducing down to 12 at the end, so does fit nicely over the axle.

I have just received in the post a 150mm wide bulb that has the drive side end cap...so my plan is to make a franken hub that uses the 150mm axle, cut down on non drive side to accept the knurled spacer. That may need cutting down also to give the 135mm overall width, but would allow for preloading of the bearings.

Ok, it may not be exactly correct, but sometimes an "engineered" approach to adapt and overcome needs to be applied...