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Why 3 x 7 to 1 x 7/8/9/etc? Why not 3 x 7 to 3 x 1?

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Why 3 x 7 to 1 x 7/8/9/etc? Why not 3 x 7 to 3 x 1?

Old 05-04-21, 05:27 PM
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opusbike
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Why 3 x 7 to 1 x 7/8/9/etc? Why not 3 x 7 to 3 x 1?

In mountain biking, the 1 x 8/9/etc is becoming more popular. I am wondering why I haven't heard of anyone going to 3 x 1 (3 speed in front, one in rear). Can this be done? When I go biking with my kids, I usually don't touch the rear gear, I just change the front one. This avoids me having to keep on shifting.
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Old 05-04-21, 05:35 PM
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wgscott
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When you shift the front, the rear derailleur moves to take up the slack (or to provide it).

In general, rear shifting works better, so it is preferred. Also, you can get much smaller increments of change, which leads to smoother shifting. Fewer chainrings generally means fewer chain drops when shifting, and fewer stabbings when you aren't in the largest chainring. Also, SRAM doesn't know how to make front derailleurs.
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Old 05-04-21, 05:50 PM
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UCantTouchThis
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Hmm, the front derailleur on my bike is a bigger movement. Don't think that would be as smooth in my case vs shifting the rear. I rarely leave the small ring 39 I have. I can hold anything from 0 to 20 without leaving the 39. If I had little kids to ride with, that would work for me and the shifting would be much nicer working with smaller rings vs the front.
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Old 05-04-21, 06:02 PM
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Three gear choices vs 21? If you don't want many gears an IGH or single speed would be cool.
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Old 05-04-21, 08:15 PM
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Paul Price of Paul Components fame did a 3x1 bike at the shop to test out his Melvin Chain Tensioner you could ask him but it was probably just a silly shop project he thought up at Sierra Nevada over a couple of their brewskis.

I wouldn't want a 3x1 personally I do most of my shifting at the rear like probably 99% of the bike riding population that has gears. The front does quite a big shift and is not really what I want often enough and when I do it is usually preceded by some rear shifts.
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Old 05-04-21, 08:30 PM
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It takes a Pinion gearbox in order to make doing away with the rear derailleur make sense:

https://pinion.eu/en/
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Old 05-04-21, 09:19 PM
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Originally Posted by opusbike View Post
In mountain biking, the 1 x 8/9/etc is becoming more popular. I am wondering why I haven't heard of anyone going to 3 x 1 (3 speed in front, one in rear). Can this be done? When I go biking with my kids, I usually don't touch the rear gear, I just change the front one. This avoids me having to keep on shifting.
1- for MTB, a smaller front ring leads to less interference when rolling over rocks, stumps, etc.

2- a 1x10 system gives you 10 options to match the cadence you want for the terrain you happen to be riding at the moment(up hill, down hill, etc). A 3x1 system would give you only 3 options to match the cadence you want to the terrain you happen to be riding.

3- why do you only change the front derailleur when riding?...the rear allows for smaller changes. I can't remember the last time I was in 50-18 and thought to myself that I need to be in 34-18 immediately.
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Old 05-05-21, 02:06 AM
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Because shifting the rear is so much easier to trim or shift.
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Old 05-05-21, 05:50 AM
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This sounds awful, especially for mountain biking.
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Old 05-05-21, 03:53 PM
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As mentioned above, I think that a SRAM i-Motion 3 speed IGH would accomplish almost the same thing but maintain the chain line throughout all the gears.
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Old 05-05-21, 03:55 PM
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You could also go the other direction as per the late, great Sheldon Brown. https://www.sheldonbrown.com/org/otb.html
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Old 05-05-21, 04:05 PM
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njkayaker
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Originally Posted by opusbike View Post
In mountain biking, the 1 x 8/9/etc is becoming more popular. I am wondering why I haven't heard of anyone going to 3 x 1 (3 speed in front, one in rear). Can this be done?
Rear shifts are much faster and tolerate shifts under power much better than front shifts. Rear shifts tend to be mechanically more reliable.

You also need some sort of thing to take up chain slack. Which means you'd have something "springy" in the rear even if there was no rear shifting.

Originally Posted by opusbike View Post
When I go biking with my kids, I usually don't touch the rear gear, I just change the front one. This avoids me having to keep on shifting.
You aren't really avoiding shifting.

The "best" practice is to minimize front shifts. And to shift the front with large changes in speed.

You should be able to pick a front chain ring and just use the rear.

Last edited by njkayaker; 05-05-21 at 04:09 PM.
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Old 05-05-21, 06:58 PM
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I've got an old Schwinn LeTour set up as a 2x1. The rear wheel is a single speed and the RD acts as a tensioner. I've got a few small hills on my way to work and the drop from 52T to 34T makes it easy. Also nice to go down to the 34T for just cruising along.

But I'm usually the oddball in any group. YMMV
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