Tech Single front chain ring for road bike - Why not?

Apr 3, 2012
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Boso
#1
I've been messing around with Sheldon Brown's Gear Ratio Calculator and it occurred to me that you could get the exact same gear ratios with a single 46 tooth chain ring and an 11-36 "MTB" cassette as you can with a 50-34 compact chainset and a 12-26 cassette. I understand why this isn't adequate for racer types, but this seems like a pretty good option for your average Fred's road bike. It would be lighter and one less thing to keep tuned and maintained. What with 10 and 11 speed cassettes available now you could even get pretty close ratios. Is there any reason not to do this? I wouldn't, but that's just because I'm a proper wimp and need lower gears than 34-26.
 

Cactaur

Speeding Up
Feb 3, 2014
97
23
28
#8
I used to have a single chainring folding bike with a 9sp capreo on the back. There was a problem with the chain sometimes dropping off the chainring at the low end.
 

AlanW

Maximum Pace
Jan 30, 2007
1,214
435
103
Tokyo
#10
I wonder if it would be possible to use the XX1 or X1 setup in the back with the crankset from the CX1 group
You would need a 135mm spaced frame. You'd have to find a drop bar shifter that pulls the right amount of cable too. But 11-32 is quite feasible, 10 or 11 speed. You could use something like a deda dog fang to keep the chain from falling off the inside.
 

bloaker

Maximum Pace
Nov 14, 2011
1,533
1,197
433
Miura, Japan
#11
You would need a 135 to use a mountain hub, but not for using a mountain cassette - unless Sram changed something for the 11 speed stuff.


My off road touring bike has a 2x10 setup.

I run the following
Sram X9 rear derailleur (medium)
Shimano XT Cassette 11-36
Sram Apex Shifters.

Upfront I run an x9 gxp and fr Derailleur. - so that is where you can make your change.

The Cassette will fit on a road wheel - the width of the cassette is the same as a Sram 10 road cassette, you would just need to run a "wifli" or mountain Derailleur.
Unlike Shimano, Sram has kept the pull ratio on the 10 speed identical between mountain and road, so you can mix and match all day long.
 
Apr 3, 2012
338
276
93
Boso
#13
I went out for a quick ride on my rando / touring bike today using just my "big" chain ring (which since yesterday has 44 teeth in the front and 11 to 36 in the back). It was really more than adequate for going up or down any hill and the jumps weren't so bad. If I were carrying much weight the easy gears wouldn't be easy enough, but for unloaded road riding it's plenty. 44-11 is really a pretty big gear. Plenty for the likes of me.
If I ever get another bike just for speedy road rides I might try this. Might be nice on a cyclocross bike too.