Building a lightweight touring bike....

[PAFARMBOY]

I’d like to try my hand at building my own sub-20 pound touring bike (similar to what adventure cycling did: https://www.adventurecycling.org/adventure-cyclist/online-features/exploring-packing-possibilities/ with a jamis renegade elite) but to be quite honest, I have no idea where to start.  I can wrench adequately but have no idea how to go about getting the correct parts.  I am hoping for:

Frame that is touring friendly
Single crank with 12 cog cassette ideally with at least 500% gearing range
Granny gear more important than top speed gear
Butterfly handlebars
Electronic shifting -does this save weight or add to it?
Hydraulic or disc brakes- which ones are lighter? Better?
No panniers 
Saddle bags and handlebar bag only (total gear weight is around 12 pounds)

Would like to keep cost under 3.5k and bike weight under 20 pounds.  Is this even possible?  Can you merge all these components together?  I can get a brand new renegade elite 2017 model for $2750. Should I scoop on that and forget about my mishmash of wants?  Any help would be appreciated.  Thanks.

[DaveB]

The only way you are going to get your desired 500% gearing range with a single chainring is with a 10x50 (SRAM gx Eagle or SRAM xg1295 Eagle group) or 10x51 (Shimano XTR) cassette.  Using a compact double MTB double crank would open up many more options to getting that gearing range. 

[paddleboy17]

I am a little confused about what you are trying to do.  A bike packer and a touring bike are two different animals -- they are designed to do different things. 

My touring kit weighs 60 pounds, and  provides a comfortable level of food and shelter in four panniers.  Sure a loaded touring bike is not nimble, but it rides well under a lot of road conditions (wash boarded dirt roads really suck).

I bought a Salsa Cutthroat a year ago, and I got talked into a bike packing trip in early May.  My last frame bag gets delivered today, but it will be at least a week before I can practice packing my gear in these new bags.  Sure it will be a more nimble and faster ride than my touring rig, but I think for most of my trips I will miss the comforts of my  heavier and less nimble touring bike.  I ride for the spiritual experience, so speed is not super important to me.  I bought the Cutthroat because I live in Michigan and we do not have nice black top roads any more, and probably never will.  So I don't have nearly as many opportunities to ride my criterium bike anymore.  The Cutthroat is almost as fast as my criterium bike, and does not care what kind of  road, path, trail it is on.  The Cutthroat has all the mount points for bike packing, and I have adventurous friends.   Ask me how I feel about bike packing after my trip...

A Salsa Cutthroat equipped with Rival 1 components is in the same price range as a Janus Renegade Elite, and it comes equipped with a single ring crank already.  If you do the tubeless conversion, the weights should be about the same.  I was wait listed when I ordered my Cutthroat, and agreed to take a Rival or Apex bike, if one could be found (the annual Cutthroat production run sells out quickly).  I ended up with an Apex grouping, but the frames are all the same (except for color), and Apex has proven to be an amazing group.  I also did the tubeless conversion and that was really impressive.

[keithmisegades]

Though this answer probably blows your budget, here's how I achieved a lightweight touring rig.

A few years ago I had Kent Eriksen build me a lightweight titanium touring frame.  I use an FSA 30/44 Adventure double crankset with a SRAM red 22 setup and a 32 tooth rear cog.  I use 4, 8 liter dry bags strapped onto my own custom made plates.  I also use an Arkel trunk bag and a Giles Berthoud bag on a decaleur.  With all this, I can do multiple week tours if you don't have long steep mountains to get over and you are in the warmer time of the year.  Due to the lack of space, it's very hard to carry warm weather gear with this somewhat minimal setup. 

Total weight of bike and gear come in around 45 lbs.  The image shows my setup during last years double RAGBRAI crossing where I rode this both ways carrying what you see.

[brianmcgloin]

What do you mean by "Hydraulic or disc brakes?"

Discs can be cable-actuated or hydraulic. Both will stop you in all sorts of conditions just fine. Cable-actuated brakes can be less expensive and use traditional MTB brake levers and cables; whereas hydraulic brakes use complete hydraulic systems.

[brianmcgloin]

If you went with a 1x drivetrain you may not get the 500% you wish, but should be able to get a granny-granny (as in pedaling quickly to go sub-walking speed) gear while having decent cruising gears. SRAM Eagle or Shimano XT (XTR?) will work just fine.

Electronic shifting generally weighs the same as cable-actuated shifting, I think, but may be more with the battery. The benefit of electronic shifting isn't weight, it's simplicity while riding.

Revelate has (had?) a new line of ultra-light handlebar harnesses and seat bags. If you can't find them, then really any of the Revelate or other high-quality arrangements will work. You may consider a frame bag also, to make use of that space. If you don't want panniers then any frame is "touring friendly." IF you stick with titanium or carbon fiber handlebars, stem, rims, cranks and whatever else you can do, you'll find it easier to get your bike lighter. Carbon fiber is lightweight, super strong (DON'T BUY CHINESE KNOCK-OFFS OR GENERIC!) and can be easily field repaired, but it's expensive.

Keep in mind each liter of water weighs a kilo.

I'm curious why you want to put so much emphasis on light weight?

[paddleboy17]

I am a little confused about what you are trying to do.  A bike packer and a touring bike are two different animals -- they are designed to do different things. 

My touring kit weighs 60 pounds, and  provides a comfortable level of food and shelter in four panniers.  Sure a loaded touring bike is not nimble, but it rides well under a lot of road conditions (wash boarded dirt roads really suck).

I bought a Salsa Cutthroat a year ago, and I got talked into a bike packing trip in early May.  My last frame bag gets delivered today, but it will be at least a week before I can practice packing my gear in these new bags.  Sure it will be a more nimble and faster ride than my touring rig, but I think for most of my trips I will miss the comforts of my  heavier and less nimble touring bike.  I ride for the spiritual experience, so speed is not super important to me.  I bought the Cutthroat because I live in Michigan and we do not have nice black top roads any more, and probably never will.  So I don't have nearly as many opportunities to ride my criterium bike anymore.  The Cutthroat is almost as fast as my criterium bike, and does not care what kind of  road, path, trail it is on.  The Cutthroat has all the mount points for bike packing, and I have adventurous friends.   Ask me how I feel about bike packing after my trip...

A Salsa Cutthroat equipped with Rival 1 components is in the same price range as a Janus Renegade Elite, and it comes equipped with a single ring crank already.  If you do the tubeless conversion, the weights should be about the same.  I was wait listed when I ordered my Cutthroat, and agreed to take a Rival or Apex bike, if one could be found (the annual Cutthroat production run sells out quickly).  I ended up with an Apex grouping, but the frames are all the same (except for color), and Apex has proven to be an amazing group.  I also did the tubeless conversion and that was really impressive.

Having finished my bike packing trip, I feel better qualified to talk about bike packing vs bike touring. 

I am not going to retire my heavy touring bike and live out my days with just my gravel bike.  The trip I was on was explicitly designed to be too nasty to do on a touring bike.  Several of the attendees made remarks about how easy I had it this year.  The nasty part was fine loose gravel over crushed limestone.  Missing from last year (which I did not attend), was snow, ice, and standing water.  The fine loose gravel would have made the course too difficult to do on my heavy touring bike with 35MM wide tires.  It was still difficult with my 2.2" wide tires on the gravel bike. 

My Salsa Cutthroat and gear weighed in at 56 pounds.  I used everything except for an extra pair of smart wool socks and an extra pair of shorts.  I had to contend with some rain, and temps that ranged from 30F to 70F.  I figure my kit weighed 31 pounds, and that includes 5 or 6 pounds for a CPAP machine (I have sleep apnea).  I ate my meals in restaurants and I don't know where I would have put cookware or food in my kit.

So I think I would bike pack off road or on really crappy roads.  I can probably rethink what I take on my touring bike to keep the weight down.