Shimano Deore/105 compatibility queries

Hi,

I need to gear down as much as possible for a project later this year, so I am considering all the options, trying to minimise the number of parts to swap from current setup which is:

ST-5800 shifters
FD-5800 front mech
RD-5800 long cage
CS-5800 11-28 cassette
FC-5800 compact 50/34 cranks

The lowest gear being 34-28 at the moment.

I can easily change the cassette up to a 11-32 with the same derailleur. This is not going to be enough though (many long gravel climbs). I would like to keep the double gearing option, and at the same time avoid going for something expensive.

I was thinking of using a FC-M8000-2 crankset (probably 38/28 or 36/26).
This means either using the same FD or eventually changing it to a FD-M8025.

Does anyone know about FC-M8000 to FD-5800 compatibility? What about FD-M8025 to ST-5800 I would expect the same pull ratios more or less.

Cheers

What about getting a roadlink + mountain cassette ($)

or

tanpan+mountain RD+ mountain cassette ($$$)

I have a similar setup ( Ultegra 11speed ) and successfully put a 11-36 SRAM cassette on for hilly rides. Just needed to tighten the b screw to get the jockey wheel to clear the cassette. This may not be low enough for you though.

Are you able to lower the FD sufficiently to work with a smaller chainset. I believe there are compatibility issues using an MTB FD with road shifters, so sticking to a road FD is best .

Second vote for the goat link.
Used one on my CX bike for a bit - very easy to fit, and used an 11 speed Deore mtb cassette. About the lowest cost option

That would get me up to 36? So the smallest gear would be 34:36. Might be enough, given how cheap it is

Still would like to know if the compatibility is good

See here:

http://www.wolftoothcomponents.com/pages/1x-gravel-setup

Wolftooth claims a roadlink enables you to use 11-40, but some reviews say the shifting quality is a little bit worse.

Anyway, I would opt to get a tanpan + mtb RD if I want 11-42 cassette

This seems more reliable.
Are 11s MTB same width as 11s road ones? Meaning they work on the same freehub..

Hopefully I'm correct:

If you have 11spd road hub, you need a 2mm spacer to use 11spd mtb cassette

I was thinking of using a FC-M8000-2 crankset (probably 38/28 or 36/26).

I've done something similar, swapping out a 50/34 for an old Ultegra triple with the outer ring taken off, giving 42/30 on my Genesis CdA (Claris shifters and mechs). It's worked fine. A couple of friends have fitted XT chainsets (40/28) to both 9 speed Tiagra and 11 speed 105 set ups, without changing their front mechs either.

That's what I'd like to do as well, 38/26 XT on the front, with 11-32 at the back. @RichE73 I have a braze on FD, so I believe I can lower to suit it. Chainline should be roughly the same I am guessing. Probably need to remove some chain links.

On the other hand, if I keep the 50/34 crankset, and want a bigger sprocket at the back, I need the tanpan, wolftooth goatlink, mtb cassette, spacer, mtb rd, longer chain.

I think pricewise it's more or less there.

Option 1 (front drivetrain): 32/26=1.231
Option 2 (rear drivetrain): 40/34=1.176

Worse case I can use a triple fd, which is longer and should have the same pull

Still trying to decide on the subject.

Still thinking about changing the front crankset, now considering the cheaper option of a M7000-2

As far as I understand (very little) these typically have a 48.8mm chainline (based on a 73mm BB shell)

Would I be able to adjust the chainline to a 43.5mm (like I currently have) by mounting a MTB BB on a road 68mm shell or the length of the spindle of the cranks will prevent me from doing that?

Apologies if I am talking nonsense.

So if you put a mtb crank, you need spacers to fit it into a 68mm road BB.

My concern is that the chainline will be shifted 2.5mm, but I'm not sure because it depends on what rear hub you have. Anyway, it's not a single-speed setup, so a chainline is less crucial...so I guess... it's OK?

https://www.lfgss.com/conversations/299760/#comment13508617

I think I've settled for this option of roadlink + mtb cassette.

On wolftooth website they specify that an 11-40 is ok with a GS derailleur as long as the front teeth gap is less than 10, rather than my current 34/50 compact one, will it work anyway?