130 hub in a 135 disc frame...

[Broady]

For reference, I currently have a steel frame with 135 rear spacing / QR / disc brake. I'm thinking about converting it to rim brake by getting a new brake bridge fitted but am having some thoughts about the derailleur alignment etc.

In theory I could just space the hub out 2.5mm on each side and that should keep it central and not require any wheel dishing etc. The issue with doing this would be that the cassette would be 2.5mm inbound to its usual position. Would the derailleur be able to take up the slack with High / Low?

Second option would be a 5mm NDS spacer, but then I'd have to dish the wheel so it was centred for the rim brake. Should work in theory but not ideal if I want to swap wheels out.

Any thoughts?

[joejack951]

Would you consider to just leave the frame alone and run a mechanical disc brake in the back?

[Broady]

Nah, the frames due a respray / refresh and I need a new groupset so was planning on new Dura Ace rim (when it's available...). I have a really nice set of rim wheels spare too that would be great on it also.

[synchronicity]

It's really two issues then. Is it worth it?

[CampagYOLO]

Given it's a steel frame it could be cold set as it's only a 5mm difference. Usually cold setting is to spread a frame out but I don't see why it couldn't be done in reverse but have never tried it myself!

[Broady]

Yeah was thinking about getting my guy to cold set but then you'd likely have the issue of dropouts not being square, although I'm sure that's something that could be sorted when cold setting. Definitely an option to think about.

[joejack951]

Yeah was thinking about getting my guy to cold set but then you'd likely have the issue of dropouts not being square, although I'm sure that's something that could be sorted when cold setting. Definitely an option to think about.

I've crunched the numbers on going from 126 to 130mm (modernizing old frames with a newer rear wheel) and the dropout alignment is a non-issue. It was tenths of a degree even with short chainstays. Knowing how inaccurate frames can be, you are just as likely to improve the dropout alignment by squeezing them in as you are to make it worse. In fact, the 5mm change is so subtle that you might as well try installing the wheel without even cold setting the frame and see how it works. Worst case, you find out you need to cold-set because perhaps the stays don't deflect evenly, but best case you don't need to touch the rear end, other than adding your brake bosses.

[alcatraz]

If it's going to be permanent on rim brakes then maybe just bend the stays a tiny bit. Might need to check dropout alignment afterwards.

If you want to keep the disc brake door open then you could lace rim brake rims to some 100/135 hubs. Just don't mount the rotors.

Isn't your frame missing the cable stops for the rear brake? Gotta zip tie the housing along the entire top tube then, no?

[kode54]

If its DT Swiss, they make various end caps that may work out for you. I went the other way...135 down to 130.

[Broady]

If it's going to be permanent on rim brakes then maybe just bend the stays a tiny bit. Might need to check dropout alignment afterwards.

If you want to keep the disc brake door open then you could lace rim brake rims to some 100/135 hubs. Just don't mount the rotors.

Isn't your frame missing the cable stops for the rear brake? Gotta zip tie the housing along the entire top tube then, no?

I'd be getting the stops brazed on along with the brake bridge.

[Broady]

If its DT Swiss, they make various end caps that may work out for you. I went the other way...135 down to 130.

I was thinking about that, it is 240s I'd be using with the rim brake setup, the issue I was concerned about was whether the cassette being 2.5mm closer to the hub centre would be an issue with gear indexing / cross chaining etc.

I'm an engineer so could knock up some new end caps myself easily enough if it was a valid solution.

[kode54]

If its DT Swiss, they make various end caps that may work out for you. I went the other way...135 down to 130.

I was thinking about that, it is 240s I'd be using with the rim brake setup, the issue I was concerned about was whether the cassette being 2.5mm closer to the hub centre would be an issue with gear indexing / cross chaining etc.

I'm an engineer so could knock up some new end caps myself easily enough if it was a valid solution.

FYI...something like this. Early on, Road disc brake bikes were QR rather than thru axle. So by changing the end caps, you essentially use the 2.5mm thicker (each side) end caps from these, for example.

https://www.ebay.com/itm/193912929194?h ... SwVD9gNUvF

[Discodan]

Personally I would go down the path of the 5mm NDS spacer. Dishing it would be a one-time exercise and you've made no changes to the frame. If you later put a different wheelset (assumedly temporarily) in you won't have to change chainlines/RD as the cassette will be in the same position and 5mm of misalignment in the wheel will be impossible to see or notice on the bike

[WorkonSunday]

im not 100%, but i thought it wasnt simply adding 2.5mm each side, more like adding 5mm on rotor side while keeping the cassette in the same place? i had similar issues previously when my frame is 135mm and i ordered a 142mm wheels and only managed to change one side hub ends while the other is stucked. it was enough to mess with the chain line that it just didnt work (lower limit screw was all the way in and the uper limit screw even 100% out, the rear mech just can get tot the last cog).

[ooo]

Permamently increase left and right dropout thinkness by 1.25mm from internal side, so
you will have 132.5mm OLD steel frame, that will be compatible with both 130mm and 135mm wheels.

(Some manufacturers produce steel frame with this OLD and both disc mounts and rim brake mounts)
No need to redish wheels, no RD problems with indexing, you may need to use 135mm QR skewer.