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« on: April 30, 2022, 11:53:01 am »
Joseph, welcome to the ACA Forums! Your post has a lot to unpack.
I have several bikes (too many my wife says). Our house has 5 bikes with a traditional derailleur system, two bikes with a Rohloff, and one bike with a Pinion P1.18 gearbox. One Rohloff and the Pinion have a belt, the only way to go I have discovered. All gear systems have their pros and cons.
NOTE: These are my opinions, take them for what you want. I will try to address them in the order of your post.
Congrats on the bike. I seriously considered getting one but wanted a Pinion which Koga does not offer unfortunately. Otherwise I would have gotten that wonderful bike. On my Rohloffs, I run the absolute lowest ratio I can get. Yes, a 50/19 combo would indeed give a very high gear, at least for me.
I am strongly in the "lower is better" group. I started touring in 1977 as a young teen. Only then when I was a very strong rider could I deal with anything with a lowest gear higher than 30 inches (sorry, I have yet to wrap my brain around anything other than inches) when touring but quickly learned lower is better. I am now a couple of years from turning 60 and don't have the strength I used to. However, the main reason I strongly prefer lower gears is I rarely spin out in my top (hardest) gear. I use a 42/22 (1.91 ratio) on my Rohloffs. This provides a low of 14.4" (using a 700x32 wheel), and high of only 75.6" for the high. However, with a cadence of around 85-90rpms early in the tour and going to around 100rpms after 6+ weeks of touring, my top speed at 100rpms in my highest gear is around 23mph. That is plenty fast with a loaded touring bike on flat ground! I have only done this a literal handful of times so it is rare indeed.
Also, I usually just gently pedal on major downhills just to keep the legs warm on downhills so I don't need a high high gear for that. Since I am rarely (couple of times a week maybe when on tour) in gear 14 I figure why waste the gear range on unused gears. The lower overall range of gears also allows closer spacing between the gears you mostly ride so that is better too. I personally use the lower gears 1-11 much more than 12-14 which supports my belief in lower is better. I actually wished Rohloff/Pinion would have a smaller range of gears so the gears would be even closer together.
BTW, your cadence will probably naturally speed up the more you ride on a daily basis and probably peak out between 90 & 105rpms if you are on a multi-month tour.
I would go lower than 1.9 ratio if I could but in reality, anytime I get below 2.5mph uphill, I have a hard time maintaining balance so therefore my low of 14.4 inches @ 60rpms just about does it. While you say you mostly do flats, the 30% of hills/mountains is definitely something to consider. Plus, if you go touring with gear a lower gear can't help assuming you prefer riding to walking.
As far as the belt life goes, a $100 belt lasting 15k+ miles is not that unreasonable. Plus there is the non-quantifiable aspects like the ease of maintenance or lack thereof compared to chains. The same goes for setting up your bike how YOU want it to be. If it costs an extra $300 initially to resize the gear system, but it gives you comfort and enjoyment over 10+ years, is that really a big deal?
I have learned that to extend the life of the belt, keep it looser than what Gates recommends. On my bikes with a Rohloff/Belt setup, the distance between the outer edges of the belt (top edge of "top" belt and bottom edge of "bottom" belt) measured halfway between the crank and the hub is just under 6" when just sitting there. The measurement when I use my hand to squeeze the belt together is about 4.25". It definitely is much looser than what the Gates App recommended but I noticed the belt lasts substantially longer (15k miles and no wear vs. 10k miles and the belt was done when tensioned "properly") plus it seems to be easier to pedal which I know is subjective but it really does seem easier. Plus I don't have the pedals rotating when I roll the bikes forward which drove me nuts. My tension is not factory approved but I have not noticed any downsides and have heard a lot of world tourists also use "loose" tension. Just don't make it so loose the belt slips on the rear cog. If that happens, you will need to tighten it a bit. I basically had the eccentric set for the loosest the belt could be.
I can't tell you what size belt, chainrings, or cogs to buy for your specific bike. I didn't get it right the first time I resized and had to sell my new unused belt on eBay at a small loss. I would maybe call/write Koga and ask them what can you do to get the lowest ratio. Surprised they offered the dedicated touring bike with such a high ratio. And honestly, I would go a little below Rohloff's required ratio if you need to if that is what is required to make it all work. However, if you had to go up a little from the 1.9 allowed ration, that would not be a deal breaker either.
Hope you have many enjoyable miles ahead of you! Tailwinds, John
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