[matt4x4]

Looking for a triple crank with 52T or better yet 54T large ring, and a low 20's small ring, with a rear of 11-38'ish ?

Priority would be hill climbing, so perhaps go down to 48T.

Also ideally I would not want to go to 10 speed as the price starts to jump up, but if I have to I would go 10 speed.

Front Der. Capacities.

Edit
I found this interesting website forum, which I found very informative....
https://www.cyclingforums.com/threads/max-tooth-capacity-on-a-front-derailleur.10250/

I dont mind using Grip Shifts, the Shimano 105 FD 52/42/26 is probably the way to go, but the Ultegra 50/36/24 might be a good option with Campy Centaur Ergo shifters.

 

[frdfandc]

Why going for road gearing when you want a hill climbing bike?

Not going to find a mountain crank with anything in a 50+. Largest I've seen is 44. Would have to go with a road crank, but the Q factor will be very narrow, more than likely the crank arms will hit the chain stays.

Front derailleur capacities max out at 16T IIRC.


If you want a hill climbing bike, go front single ring (maybe a 34T?) with a 11-42 in 10 speed. Give you most of the range you want.

 

[matt4x4]

Thanks for your input frdfrandc

I did just edit my first post, good info on there.

You make a valid point on the crank, gosh they are expensive! Its too bad I never purchased a road crank at the now closed community bike shop of used components. They had boxes full of Ultegra's.

I want both cruising on flats with a large crank ring, which I would be using most of the time, but there is the occasion where I'd be climbing hills. Nothing too long, but there are some steep sections that would be 10-15% and 100m.

Edit:
I am probably over thinking it, and going to extreme with the gearing.

 

[J.B. Weld]

I think Shimano lists the max tooth difference at 22t but it could probably be cheated a little.

Is this for a mtb? I think you'll have problems with chainring clearance if so.

 

[Sidewalk]

52 up front?

I just podiumed a ROAD RACE with a 50 up front.

 

[Harold]

Why going for road gearing when you want a hill climbing bike?

Not going to find a mountain crank with anything in a 50+. Largest I've seen is 44. Would have to go with a road crank, but the Q factor will be very narrow, more than likely the crank arms will hit the chain stays.

Front derailleur capacities max out at 16T IIRC.

If you want a hill climbing bike, go front single ring (maybe a 34T?) with a 11-42 in 10 speed. Give you most of the range you want.

Not only that, but the narrower spindles on most road cranks most likely will not fit a mtb bottom bracket width. There might be some with longer spindles, or that use older style cartridge bb's that might work.

I question why anyone who isn't a road/tri racer needs a chainring bigger than a 50t, as well. The VAST majority of road riders do fine with "compact double" gearing that maxes at 50t for the big ring. I have one on my commuter/touring/gravel bike and considering the weight of that bike and the speed that it gets ridden, 50t is too big even still.

And yeah, I don't think you're going to find a front derailleur that could handle that amount of range in chainring gearing.

Looking at Sora (current 3x9 capable drivetrain), you get a max large ring size of 50t, max difference between big and middle of 11t, and max total difference of 20t. That gives you, at best, the capability for a 50/39/30 gearing. Tiagra 3x10 basically gives you the same range options. You get 16t capacity between cogs if you look at 2x FD's, and capacity for larger chainrings from higher end groups, but that still doesn't get you what you want.

Seems to me that the easiest course of action here is to use a more modern Shimano mtb groupset (11spd xt, for example, will let you do 3x, and 10spd slx will also do 3x) and pair that with a wider range cassette with a bigger large cog to achieve the low range you want.

There are ways to combine road and mtb drivetrain parts but compatibilities are very specific and might require adapters and compromises. The other problem you'll encounter is the rear derailleur chain slack uptake capability. A long cage 10 spd mtb derailleur (M781 sgs) can do 43t max. Long cage 11spd (m8000 sgs) can do 47t. All the road derailleurs I'm seeing are GS cages with less capacity than that. M8000 sgs looks to have the largest uptake capacity of anything I'm seeing in that regard.