Suitable Cassette/Chainring ratios for Bikepacking/GDMBR?

[Calshot]

Hello all,

A question for bikepacking veterans out there: what kind of cassette and chainring ratios are you running? Specifically, if any TD or GDMBR vets have any advice, I'd be interested to hear their feedback on the gearing they used for that route.

I'm thinking of running a 22t & 36t chainring and an 11t-32t cassette as a standard bikepacking set up. I run a double chainring set up normally when riding unloaded (currently running 24t & 36t with 11t-28t cassette) and prefer a 'double' over a 'triple', which is why I've considered 22/36 x 11-32 for bikepacking.

I don't know if a 22 chainring x 32 sprocket low ratio is too big for a 'classic' bikepacking route like the GDMBR, though, so any advice is really appreciated - as I know gearing choice is often a well kept secret.

Cheers.....

[jimfab]

IMO= If i had to choose from 2 fronts i would go with a 20/30 in the front and the 12/36 in the back. If you cant get the 20/30 to work then the normal 22/32 will work fine also. On my short attempt at the TD last year i used every gear i had at least twice and i had a 23/30/40 with the 12/36 in back (29er). Most of my time was spent in the 1/1 ratio, but later in the day's i used the 20/36 a bunch. Never wished i had a taller gear.

Best o luck

[Calshot]

Thanks for the reply Jim.

So what you're saying is that the GDMBR has a load of super-steep climbs, right?  I know that there is a lot of climbing on the route, but it was my mistaken impression that the majority of climbs were long and kind of gradual: about 5-7% grades. That's excepting the famously hard climbs like Fleecer's etc., which I know is steep.

If you're recommending a 16 and a half inch gear (20t ring x 36t sprocket) it suggests massively steep gradients quite frequently, which I did'nt know was the case, so I will do a bit more gear calculation.

I absolutely agree with you that the really tall gears you can get on most normal MTB cassette/chainring combinations are largely superfluous, though. I have no idea when or where I would ever use a 115" top gear (44t x 11t) which is why I use a 'double' now-a-days.

Cheers....

[jimfab]

Hey

I can only tell you about the canadian section. I was also under the impression that most of the climbs were quite tame. I was mistaken. That 5-7% is just an average. there are many shorter grunts all over the place that dont show on the profile, and a few power line roads, Snow, Mud, rain. At about mile 70 there is a wicked power line climb that is steep all by itself, add in the sponge like ground that did everything it could to prevent your wheel from spinning, and all your gear. All that with 100+ miles in your legs.  I have no idea how the SS guys do it. IMO lower is better. I never had the need for the tall gears because my plan was to coast as much as i could, whenever i could. If you are non human like Matt and Kurt then go with the taller gears. If you are indeed human, i would give yourself the option.

good luck!

[Calshot]

Thanks Jim,

Excellent advice, I'm most grateful. I have to admit, I get a bit obsessed about correct gear ranges before any big trips and feedback from vets is always the best way to get an understanding of the terrain. Last time I did a long trip, I likewise found myself using the lowest gear much more frequently than I thought I would, but the route was'nt anything like the GDMBR, of which I really have no knowledge at this stage.

Cheers.... 

[harryonaspot]

I ran a 22 32 44 triple up front and a 12 36 out back. I used all my gears and climbed in 22 36 often . I also used the 44 up front and wouldn't want to be geared too low. While there is a LOT of climbing, anything you go up you are coming down. Being geared too low would make you too slow. There are many areas where you just want to go.

[Calshot]

Thanks Harry,

Also good advice about the descents and gearing needed to 'motor' down them. I might do a bit of gearing revision, I think.....

Cheers...!