Absolute black sub compact advice needed

[Holio cornolio]

I'm planning an ascent of Ventoux in the summer next year and since I live in Essex and am currently, ahem, not at peak fitness, I'm thinking of putting a subcompact on my bike for the trip. I don't particularly want to buy a new chainset but the options for aftermarket subcompact rings are limited. The bike is a look 785rs and has a compact ultegra chainset. Obviously it's a 'braze on' (integrated? Fixed?) Front mech hanger and the mech is about as low as it goes on the hanger so I'm a bit frightened that I won't be able to set the mech up with 46/30 chainrings. I couldn't give a flying toss about oval or carbon rings, I just want something my weedy legs can turn on a 2 hour ascent.
This is a 2 part question. Part 2 is could I just change the inner ring for a 30 tooth and leave the 50 on the outer ring or is that too big a jump for the mech?

[Tigerbiten]

Put the chain small/small and measure the gap between the chain and the bottom of the front derailleur cage.
The chain will move down by 2mm per small chainring tooth shrink.
This will let you know by how much you can shrink the inner chainring by and not rub the cage.
But going over a 16t gap will make the shifts worse.

The other option is to use something like a "Front Derailleur Dropper".
There one here -> https://southerndistributors.co.uk/prod ... n-adaptor/
One of these will move the whole derailleur down by around 8mm-16mm for an overall 4-8t smaller double chainring.
So a compact 50/34 to a sub-compact 46/30 is possible if your spider will take the smaller chainrings.
Or even a 42/26 if you want to really want to shrink the rings.

You need to know your BCD so you can work out the minimum chainring size that will fit your cranks.
See here -> https://www.sheldonbrown.com/cribsheet-bcd.html if you need to work it out.
Most compact doubles are 110mm BCD and a 34t chainring is the smallest that will fit.

Luck .......

[PT1029]

There was a whole thread on sub compact chain rings recently viewtopic.php?t=153478
Have you thought about looking at the other end, larger capacity rear gear +/- gear hanger extender with a wider cassette? Keeps your chain rings Essex compatible! You could always put your existing cassette/chain back on when back in the flat(ish) earth world of Essex.
Moving your chainring sizes/gap away from Mr Shimano's recommended sizes sometimes works/sometimes doesn't/sometimes works until things get a bit worn.
If you use none indexed levers (bar end levers) you have a lot more flexibility in going off spec.

[Holio cornolio]

Cheers for the guidance and pointing me to the subcompact thread which was an interesting and helpful read.

[NickJP]

You can get adapters to allow braze-on FDs to be lowered further than the postiion of the braze-on on the frame allows. Wickwerks and Sugino both make them. I haven't used the Wickwerks adapter, but here is one of the Sugino adapters that I that I used on one of my wife's bikes to set the derailleur at the correct height for a crankset with 39/26 chainrings:

[Jupestar]

If it only for one trip. Put 1x chainrings on, easier to find them. Put it in the small ring going up. And manually swap to the big ring coming back down. Then went your back in Essex put the original chain rings back on again.

[gxaustin]

I ride with someone who has a 50/30 set up using an Absolute Black inner. He says it works.
I use 46t outer chain wheels and the front derailer is about 10mm above the 46t ring. It changes OK. I searched for a derailer dropper and couldn't find one anywhere on th enet - so thanks for your links to these devices.

[Holio cornolio]

Thanks for that. I might have found a second hand absolute black subcompact set. If that doesn't work out I will try switching just the inner ring for an AB one.

[SimonCelsa]

I had a pal who was quite fond of Absolute Black stuff.
I have no experience of their products so cannot really comment.
However I stumbled across this you tube clip which 'reviews' one of their products. Quite revealing.
https://www.youtube.com/watch?v=50aGgDvqglI
Hambini for sure is not to everyones taste, but he seems to say it as it is.