(not so) Low gear on Bikepacking bikes

[Goodaches]

I'm trying to select a pair of bikes for multiple extended, self supported, off road, bikepacking trips including the Great Divide.

I was looking for bikes with 27.5+ size tires to get the foot print and compliance we need but I am finding the fixed forks and frame geometry that makes mission sense are built around 29+ tires. That's fine since it would gives us the 3" width I want with even better rollover. However, I am noticing that these tall wheeled bikes don't come with very low gearing.

With the 1x11 or 1x12 drive trains first gear is in the high 20s but even with the 2x_ drive trains 22" is common for first gear. I understand that the + size tires are a problem for 3x_ drive trains.

Since I'm pulling a BoB Ibex with most of the gear weight for two people I'd like first gear around 18" or less so I can stay on pedals for the steep grades. I am looking at bikes that are marketed for bikepacking so why aren't the gears lower?     

Input? Discussion? Clarification questions? I'm looking forwarded to finding out what's in everyone else's head on the topic.

Thanks, Gary

[RonK]

I am looking at bikes that are marketed for bikepacking so why aren't the gears lower?

Because the essential philosophy of bikepacking is to travel ultralight, so most bikepackers don't need the extra low gearing and there is little demand for it.

My sense is that off-the-shelf bikes that satisfy all your criteria will be hard to find. Most likely you will have to buy and modify a bike or build one to your specifications.

The 2017 Salsa Fargo frame would suit if you are prepared to build. It can accommodate 27.5+ wheels and the low gearing can be achieved using Sram 2x10 or 2x11 with either flat or drop bar shifters.

You would need to verify that the Fargo's alternator dropouts can take the Bob attachments, but if a trailer cannot be avoided I think an Extrawheel is a better choice.

Edit: The  Fargo GX 2x10 comes very close to your required gearing, which could be achieved with a simple change of inner chainring from 24t to 22t.

It is equipped with 29" wheels and has clearance for 29er+ size tyres.

[Goodaches]

Yeah, not blind to the ultra-light concepts. I just assumed other bikepackers were going on even more extreme trails than I would pull the BoB through and therefore still need the low gears.

I noticed at least one of these bikes had a 108" top gear - that's gearing I can only imagine using on a road bike carrying nothing more than a water bottle. My experience with off road bikepacking so far has been if I'm on a grade that I'd over rev my legs in an 80" gear then gravity is going to be all the power I need and I'm probably more concerned with braking for the curves rather than trying to go faster.
 
So you're also seeing that the combo of 3" tires, fixed forks, and packing frames with low inches is not in the marketplace. I was hoping I was merely that I was unaware the ideal bike.  I am a bit stubborn to the idea of having to throw a couple hundred  dollars at modifications on bikes that cost $2,100 to $5,000 each to begin with.   

We may stick with the matched pair of bikes that we have now with 27.5x2.1, suspension forks, and 3x9 drive trains (17.7" 1st gear). I was just wanting the 3" tires to enable the weight reduction of solid forks and having to walk less often in sandy or large gravel situations. We encounter waaaay more miles of packed surfaces with relentless climbs than we do of any grade on loose sand or large gravel. If I can't have it all then I'll compromise for the conditions we encounter most often.

[zzzz]

Hi:

I'm doing the GDMBR next year and needed an appropriate bike and I was looking for a bike w/ specs pretty similar to what you are. I've decided I'm going to have something built for me by my local frame builder but before I took that step the closest I got to finding it was the Co-Motion "Siskiyou". It's got the 650B wheels and a 20" low gear. Biggest tires it fits is 2" which is less than you wanted.

pm

[Haust]

Late to the party, but I have you considered a large tooth rear sprocket? That may help to get you to the gearing that you need, without a series of custom decisions. Specifically, Wolftooth, OneUp and a few others make 40t and 42t cogs, for the rear cassette. If you are interested, there is a ton of information about these options.

[Goodaches]

Hey, no, party's not over yet! 
I am only vaguely aware that some oversized cogs are available to swap out in 1st position. What I haven't seen or heard is do they create other problems. The couple of examples I've seen looked like a big climb for the chain from 2nd to 1st. Is it still a reliable shift? Do most derailleurs have enough range of motion to accommodate the big cog or does the idler arm or entire derailleur need to be replaced? Are most chains sold long enough or will I need to inventory some extra links?
Regards

[Haust]

As I understand it, the biggest issue is using a stock 10 speed derailleur and pedaling backwards. If achieving the required movement by adjusting your b screw, the chain may drop off of the 40t or 42t cog, to the next gear. The solution appears to be an 11 speed derailleur. There is a wealth of information on this subject, at the MTBR forums: 11-40T/42T conversion: OneUp vs. Wolf Tooth vs. Hope

Here is a link to an example of a complete cassette: Sunrace MX3 10 Speed Cassette