janvo

hi, I am building a fast touring bike.
I like to do credit card tours (cycling from lodge to lodge)

road gears are just too high, I don't use the outer chainring (50T) unless going downhill
trekking gears are just too low (26T front + 32T rear) and doesnt allow the fine cadence selection found in road gears

Will the following combination work ?

• Shimano Deore XT FC-T781 10 speed trekking crankset with 48-36-26 chainrings
• Shimano 105 CN-5701 10 speed chain
• Shimano 105 CS-5700 10 speed cassette 12-27 (I already have this component and an Ultegra rear derailleur long cage, these are spares from my previous bike)

The Deore XT chainring 48T has "HG-X CHAIN ONLY" printed on it.
But Shimano is known to say these things so you would buy stuff that they want you to buy.

HillRider

Another possibility is an FC-5703 crank, the 105 triple. It comes 50/39/30 but the 30T granny is easily replaced with a 26T chainring and it will use any Shimano (or KMC or Wipermann or SRAM) 10-speed chain. If the 50T is too big, I expect 48T won't help either. Also, the 105 has a correct road bike chainline while the trekking cranks have a wider chainline.

Barrettscv 

I run a 105 FC-5603 triple with a 26t small chainring in combination on two bikes with either a 12-30 cassette or an 11-32, it runs great. Avoid the newer FC-5703 crankset, it will not take a 26t chainring. You can fit a 26t chainring to a 10-speed Tiagra FC-4603 triple crankset.

I also run a 9-speed Deore Trekking crankset with 48, 36 and a 22 along with a road derailleur. Getting the road derailleur to shift the to the large chainring was just possible, the wider chainline on the Deore cranksets required careful adjustment and use of all the travel the derailleur can provide. Both of these drivetrains avoid the issues of mixing modern 10-speed XT and Road chains, cassettes and Cranksets

janvo

I understand that you are sceptical about 48T making a difference if 50T is too big.

However, I have just finished a 1200km ride through England on a Trek 7.5FX 2008 with 48T. Just before I started that tour, my Trek 7.9FX 2010 (which had an FC-5603 crank with 50/39/30) was stolen. During that tour through England, I noticed that I was using the 48T a lot more often, and not just for downhill.

So if I can use a Trekking chainset with a road cassette, I am absolutely sure that is my sweet spot.

bikemig 

I'm curious, why not? The FC-5703 is a 130/74 mm bcd right?

bikemig 

Old school with a square taper but very nice quality: sugino xd 600 triple crankset. Personally I like a 110 mm/74 mm crankset and I have no issue with square taper BBs; YMMV.

Barrettscv 

Yes, I think it has a 130/9X bcd like the Dura Ace Cranks. The current Tiagra crank is just as nice as the 105 cranks.

You might be fine with the HG-X chain and a modern Cassette. Shimano went to a unidirectional chain on the most modern road and Deore drivetrains.

janvo

Just for the record, I am not looking to use a 26T chainring.

I have cycled up Mont Ventoux, El Teide, Carson pass, Monarch pass and other big mountains... with a 30T front and 27T rear... a lower gear would be nice but that is not what I am aiming at.

I am just looking for the following setup :
48/36/26 Deore XT trekkeing chainset
12-27 105 cassette (which I already have from spare parts for my previous bike)

janvo

You think a HG-X chain like HG94 can work on a 105 cassette ?

Barrettscv 

It will work, the question is: Will it work as well as it should or will performance suffer in any way? I'm doing a little research...

Barrettscv 

This might help: https://www.bikeforums.net/bicycle-me...-casettes.html

janvo

I have found a Shimano Line-Up chart for Deore XT trekking.

This chart tells me that the following setup should line up :

• Deore XT Trekking FC-T780 48/36/26
• CN-HG95 10 speed chain
• CS-6700, a 10 speed Ultegra cassette

looks like i found it !

Barrettscv 

Great! I would expect that the unidirectional chain design is compatible to both road and MTB products, it looks like is.

HillRider

That's not correct and you have it backwards. The 5703 does have a separate 74 mm bcd for the granny. I have two of them so I'm certain about this.

Also the Tiagra 4603 does indeed have the 130/9X bcd and the granny is bolted to the middle chainring like the current Ultegra triple. The previous 4503 did have the separate 74 mm granny bcd but not the current 4603

Road Fan

I can't comment on the "HG-X chain only" thing, you need a real Shimano expert for that. I'd not ignore it before I understood it.

I don't see any pitfalls with the Deore crankset, unless you can't get the Q you like, or the front derailleur is somehow not compatible with the chainring set, or it needs special BB that you can't get anymore. Assuming none of these things are true, I think you have a decent strategy. At first I thought you could make-do with a different set of chainrings, but then you explained how you understand the experience of riding with the chainrings you are seeking.

Again, I don't see a problem.

1speeder

So, the whole Shimano 10 speed thing has got my head spinning (yes, I am a Sram guy ;-). Will the Shimano XT FC-T781 10 speed crank set work ok with the old and true shimano 9 speed road bike components? I would be using the Tiagra 9 speed shifters with the IRD front derailleur with the Shimano XT 9 speed rear derailleur and 9 speed chain. Rear cassette, something between the 11-30 to 11-32 or 11-34. I too am looking for something lower than the 30/42/52 chain ring combo and would love slightly lower gears.

Thanks, Mike