HTupolev

For solo riding, I agree that tight spacing in the ultra high gears - and to a large degree having the ultra high gears at all - isn't terribly important. Group riding can be another matter, though.

The issue comes to a head for me on my gravel bike.

One of the most enjoyable rides I ever had was in January of last year. I wanted to do my usual Saturday morning group ride, but a friend was starting a gravel ride a couple hours later. I wasn't going to be able to finish one and get to the other, but, the road ride passed near where the gravel ride started, and the timing looked good. So I just did the road ride on my gravel bike.
It wasn't a slow road ride, at least not by my standards. A couple cat3 guys where there, and right at the very start, we were cruising at 24-25mph across the flat valley floor. When we got into the hills, people were pushing the descents pretty hard, so having some gears in the high-end was useful.
I was pretty blown up by the time I bailed out to do the gravel ride, about 50 miles in, so thankfully that was a slower and less-competitive pack. But, all the more reason to want some looooooow end for the foothills double-track.

In the case of this gravel bike - which is also a pretty cheap build - I've basically "solved" this with a 3x8 1.5-step-plus-granny arrangement. It's a bit whacky, but it would be tricky to replicate all of its strengths without making any compromises on a double, even with a 12-speed cassette.



If I was doing a similar build for only solo riding, or as a gravel-only thing without pavement in mind, I'd probably be happy with something like a 42-26 double.

banerjek

This is one of the reasons I've never been clear on the demise of the triple which gives superior range, selectivity, and overlap around key ratios.

For 20 in, 20 back, and one mile of steep, I'd be tempted to go with a 50/34 compact with a 12-27 since it would get a reasonable low gear for a steep climb that's not too long and decent midrange selectivity for the flats which could be handy when you're working against wind.

HTupolev

With smaller jumps between chainrings, the smaller shifts can also resolve faster, and require less double-shifting to compensate for the changes in front ratio. It can make front shifts considerably less disruptive.

They've always been unfashionable, and most modern road triples have pointlessly huge q-factors.

This is the steep spot (from a different route that only included gravel roads in the foothills):



As it's very steep and unpaved, grinding out of the saddle isn't much of an option.

If I was strong enough to handle that comfortably on a 34-27, the whole matter of gearing would be less of an issue: the faster the rider, the narrower their speed range for a given assortment of terrain (fast racers are way faster on climbs but only a little faster on flats and descents), and huge gearing is readily-available for top-level racers.

woodcraft

Do you really do this- 122rpm at 40 mph?

For me, it's possible, but what's the point?

HTupolev

Depends on how I'm feeling and whether I'm trying to hang onto a wheel or not.

Plenty of people can drill out 40+mph on shallow enough downhills that coasting in the draft isn't good enough.

122rpm isn't really that high, especially if it doesn't go on for very long. Occasionally I'll go higher than that intentionally, even when I've got higher gears available.

rm -rf

I was trying to hang on fast group rides around 20 mph and still climb steeper hills.
So I want low end gearing and close shifts, if possible, from 18-24 mph.

~~~~~

My Di2 bike came with 50/34 and 11-28. Calc link
At my typical flat road cadences. I wanted lower gearing than 34-28.
This does show the advantage of an 11 tooth cog. I could stay in the 34-13 up to 20 mph, and use the 34-12 (with a bit of cross-chain rubbing noise).


~~~~~~~

So I switched to a 11-32. I kept the same derailleur. This is way out of spec, but it works perfectly. The top pulley looks like it's way too close to the 32 cog, but the shifting works great. It probably depends on the exact frame-dropout geometry, I think.

50/34 and 11-32 calc link.
Better low end, but the 20 mph range has big gaps. On a fast group ride, I'd be shifting the rear one gear easier--too fast cadence, then back--too slow cadence.



~~~~~~~~~~~~

So, from a BF thread, I made a custom 14-32 from the 11-32 and a junior racing 14-28. calc link.
It's got the same low gearing, and nice close shifts in the 20 mph range.
It spins out around 29-30 mph, so I'm coasting downhills a bit sooner. A good tradeoff.
I'm shifting the front more often, since the 34 doesn't have the top end range. And shifting the front needs 4 or 5 shifts in the back. That's easy and fast with my Di2. It's likely annoying with mechanical shifting.
When I head to rides, like the Blue Ridge Parkway, that have very long downhills, I switch back to 11-32. I like to soft pedal instead of coast on those very long descents.

This won't appeal to every rider, but it's perfect for me.

Note the different mph scale on this chart.

kingston 

This is exactly what I want (although my range is probably 1-2 mph lower for solo rides), and seems like what a lot of people would want, so I've never understood why is basically unavailable with standard components.

banerjek

I don't. I probably stop pedaling close to that speed and I'm not sure if I've ever turned the pedals at over 45.

The kinds of places that have pitches that allow you to go much over 40 tend to be all about aero and handling with significant effort only to quickly accelerate at the beginning and after sharp turns.

Sure, a taller gear would sometimes be nice, but it ultimately doesn't provide nearly the benefit of better low and mid range selection.

If you don't have the top gear you want, it will cost you a few seconds. If your mid is too wide, you'll lose more time and get more tired. If you don't have the low end you need, you're in for a world of hurt.

rm -rf

Yes, my speeds are lower for solo, too. I always wondered why gearing was designed so that many riders were right at the low gearing limit.

Before the virus, I was zooming down hills, sitting in the draft right on a wheel at 20+ mph, etc. Now I still go ride -- country roads are very quiet now. But I'm way more careful -- no ER visits please! I wonder why I thought the risks were reasonable before! I'm liking this style of riding, immersed in the scenic countryside, not feeling that I need to keep my training load high.

Some riders are going to 30/46 chainrings. I think that makes a lot of sense for many riders:

30/46 front, 11-28 rear. calc link.
Note that this is Sram's 11-28. It's different than Shimano's 11-28. It's grouped closer together at the smaller cogs, perfect for this setup. Sram's 11-28 is great for fast riders on a 50/34 too.
A nice 30-28 lowest gear. And close shifts at faster flat road speeds. The tradeoff is a few mph lower at the top end, and the 30 chainring tops out around 17-18 mph, maybe needing more front chainring shifts?

kingston 

Yes, randonneurs have been using these setups for years for good reason, but there have been very few standard options until the recent gravel craze. It's just always puzzled me that I'm sort of an average recreational cyclists, not too fast or too slow, I ride my bike a few hundred miles a week in the summer, but I still don't have enough power to push a compact crank and a narrow cassette without cross-chaining most of the time and mashing up hills in a too-high low gear. I've just always thought that was odd. I've come to the conclusion that most people don't care about narrow spacing and have no problem using a wide-ratio cassette to get low gears.

Racing Dan

The reality is, that at the speeds many recreational riders actually go, there is little to no difference between a 11-34 and a 11-28. As noted before the 11-34 is actually better, or the same, up to about 25 mph assuming standard road tyres and a 50/34 or 52/36 and about 90 rpm.

Bicycle Gear Calculator

Im sure thats the reason very few complain about the supposed vide gear spacing of a 11-34 - Its not noticeable unless you are very fast and often ride 52/14 or above.

DaveSSS 

Keep in mind that even a 48 big ring won't work on many bikes because the FD can't drop low enough. There is a lowering adapter made, but I've never tried one. I can just barely get my FD low enough to use a 48/32.

Pedaling at speeds much over 30 mph for long periods is rarely needed, unless you're drafting a very fast group, or there's a modest down slope or strong tail wind. I ride hills where I regularly hit 50 mph, while coasting. I wind the 48/11 up to 38 mph quickly, then coast on up to 50.

I find the cog spacing on the new Campy 12 speed 11-34 to work well. The new SRAM AXS 12 speed 10-33 is similarly spaced, but their 46/33 crank gives up some range, so I have a little lower 32/34 low gear.

kingston 

Your example uses cassettes with 2 teeth steps, which is not narrow spacing, and if I spend most my time in the 15-20 mph range, I'm cross-chained the whole time. Apparently most people don't care about either of those things.

Racing Dan

The cassette shown is a standard shimano 11s 11-28 and a shimano 11s 11-34. Very few is complaining the 11s 11-28 has too wide gear spacing and all im saying is the 11-34 in no worse, unless you venture in to the very high gears. Only then the 11-28 is tighter.

If you spend most of your time in the 15-20 mph range the 11-34 is BETTER than the 11-28 if you, like most, have a 50/34 crank. ppl refuse to believe this and always make the knee jerk remark that the 11-34 has too wide gear spacing. - Except it doesn't :-)

kingston 

I wouldn't run either one of those cassettes because neither one has narrow spacing, which is why I can't use a normal compact crank.

HTupolev

Loads of people complain that the Shimano 11-28 is too wide because of the missing 16T cog. The 15-17 jump is over 13% and happens at speeds which a lot of people spend a lot of time at. Even the 17-19 jump isn't terribly small.

If you spend most of your time in the 15-20mph range, one solution is to stay in the small ring and use the 11-15 straight block on the 11-28 cassette. This is what kingston is talking about with being "cross chained" on a compact with an 11-28: at those speeds, you're either in a wide-spaced part of the big ring or cross-chained in the small ring.
An 11-34 cassette doesn't fix the situation, it takes away one of your least-inconvenient options for tight spacing.

DaveSSS 

I ran a gear and speed chart for my 48/32 and 11-34 12 speed cassette and 85-100 rpm range. It will easily work in the 15-34 mph range, using only the big ring. Cogs 11-19 all are one tooth shifts, except the 17-19. The 17-19 is the largest percentage change at 10.5%, but it's a better option than having a ridiculously small percentage shift by including an 18. The little ring is too small for this range.

I previously had a 50/34 with a 12-32 11 speed (Campy. I definitely stay in the big ring longer with this setup and don't find myself shifting to the little ring until I get to a hill. I have very few modest hills to climb, so the little ring is used frequently.

kingston 

DaveSSS I don't think the new campy 12s cassettes are much better than anything else. That missing 18T cog is a pretty big miss. With a 48T crank it's 70 inches which for me at least is THE most important gear. I could make those cassettes work with a 42T big ring, but those aren't easy to find, and I'm not sure would even work with most frames.

DaveSSS 

No one puts an 18 tooth on a cassette, these days, unless it's got a very narrow range and/or the largest sprocket isn't very large. 70 gear inches is a 2.6/1 gear ratio, which is a 48/18.5. You're getting pretty picky when a 48/19 (68 inches) isn't close enough. Actually a 50/19 is a 2.63 ratio or 71 inches.

kingston 

Yes. I'm very picky. What's surprising to me is that most people don't seem to be.

HTupolev

You're juggling rollout assumptions. The relevant aspect is that 19/17 is an 11.8% change that sits within kingston's cruising speeds.

woodcraft

I marvel at how folks can be so picky about two tooth gaps, but also ride a fixed gear, or something like this:

Racing Dan

You are completely missing the point of the post you are replying to. All im saying is that within the usual speed range of many a recreational cyclist, the 11-34 is better spaced than the 11-28 when combined with a 50/34, even if many will knee jerk claim the opposite.

If you absolutely must have 1t spacing in the midrange speeds, get a triple, a really small big ring + 11-25, a 14-28 youth cassette or whatever. lots of options.

DaveSSS 

No I am not. There is more than one way to figure the percentage of change. 19/17 = 1.12, or 12%. 17/19 = .895. 1-.895 =.105 or 10.5%. Both are legitimate calculations and neither involves rollout, which would mean a change in tire diameter. Gear inches is a meaningless number that is just the gear ratio times 27. A 48/19 is a decent gear ratio for 15 mph riding.

kingston 

I can ride anything, but my preference is to have a top gear of around 100" narrow spacing around 70" and a low of around 30" or lower. It's not difficult to put that together. It's just not standard, which I've never understood because it doesn't seem like it's that unique of a preference.