tomhaegler

I'm wondering if I could use a Shimano XT FC-M730 triple crankset (110/74) as double (inner two chainrings only) on my touring bike. Previous crankset was a STX-RC triple. Recommended BB is 122mm, I think - but I would use something narrower to have a lower q-factor. Have to check clearance though. Any experiences with this crankset? It looks nice - and it's not easy to find a classic, nice looking 110/74 crankset. Sugino XD copies are easy to get though...T.A. and Rene Herse are too expensive for this build. And using Hollowtech triples to get 110/74 might be a chainline mess? Need 110/74 because I want to run 46/30 or 44/28.

Oldsteeler

Shimano FC-M730 triple as 2x? BB?
hi tomhaegler , yes it works .
You can also use this crank M730 with only two chainrings.
I myself have mounted the M730 crank on three of my bikes with 50/36 and 48/34.
However, you should mount the chainrings on the outside and in the middle and dismantle the inner one.
Then you can also use a shorter bottom bracket.

tomhaegler

Thanks! But then I cannot make use of the 74mm inner - I need 46/30 or 44/28...

Oldsteeler

Yes, technically you can also ride 2x with the smallest chainring on the inside at 74mm and with 46 or 48 at 110mm in the middle.
But ...... it looks like ....... sh.. with the outer chainring missing .

Then it's better to mount 3x on the M730 crank, for example 48-36-28.
But , for this, you need a triple shifter on the handlebars.
Why not?

Dylansbob 

Uhh, just run the same chainline as the triple. If it's the correct one, your inner 110 ring should be in the middle of the cassette/freewheel.

Or just trial and error. It pays to have a dozen or so to try....


Edit: I checked, I have a m730 crank set up with a 44/28 with a non-shimano BB, 115mm spindle, on my Benotto.

tomhaegler

Thanks! Sounds good, I'll give it a try then.

Soody

I have 44/28 on my marin. It's as you plan, a triple with the middle ring deleted, and shorter chainring bolts. It shifts really well. I only did it though, because the middle ring was worn. I would rather have the middle ring too.
I think for this kind of setup you much rather have a friction shifter, so you can shift without dropping the chain, and trim, in which case, why not just run the triple? The whole super wide range double thing is slightly bizarre to me. It's just a triple with a hole in the range. Ostensibly it's for people who want to run 1x but with hill gears too, but you can ride a triple like that. And you end up trimming anyway. I think the niche which might make sense is if you really want to make it work with an indexed STI road lever but that might not even work so good.
Again, just why? Triples aren't cool? They are.
That FC-M730 is a very nice crank too btw.
As for spindle length, I try to get it as narrow as possible. Experiment. Buy a few bbs if you have to. You don't want to be pressing the crank on and off but you can put it on loosely and eyeball it going on a bit further.


This is only because the middle ring was toast.

rccardr 

Easiest way to do a wide range double like a 46/30, 48/28, etc. is with an 86bcd crankset and rings. SR Apex is my fave, but Stronglight made them as well.
There are lots of problems sorting out using the two inner rings of a crank as a double, wish someone just made a 110/74 square taper crankset that wasn’t weird.

tomhaegler

SR Apex looks nice! But I never came across one here...and you're right about 110/74 non-weird 2x square taper options...I did quite some research...seems like there is no perfect solution. I still have a FSA Omega Adventure Crankset (46/30) plus BSA BB from another modern gravel bike. But it just doesn't feel right putting this on a 1990ies steel frame...but if my XT Solution does not work out, I might have to...

C9H13N 

Look for a bash guard to put in the outer 110 position, it will look better than having exposed spider tabs with only an inner ring mounted.

You won’t be able to use a narrower BB spindle without wrecking your chainline. The 74 ring is already further inboard than the inner ring of a double, and if you want to be able to use it with most of your rear cluster you can’t move it further in.