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Okay to remove small & large chainrings & front derailleur?

Old_Dude

Monkey
I'm finding I never use the smallest chainring & rarely use the larger chainring. By removing them and the front derailleur, would any problems arise?

I would like to do this, but I'm concerned about using the largest & smallest cogs on my freewheel. By using only the middle chainring, will this create too much "diagonal stress" on my chain? Will it damage either the chainring or the cogs? Would it help to go to a 7 cog cassette? Should I adjust the rear derailleur to stop at the 2nd & 7th cog? Would removing the two chainrings & f-derailleur really lighten the bike significantly? Can I get spacers for the largest & smallest cogs? Does the moon really create the tide?

This time I did a search first - except for the tide question.

Thanks,

OD
 

Toshi

Harbinger of Doom
Oct 23, 2001
27,804
2,306
I had my old bike set up this way, but I wouldn't recommend it. The chain was very prone to hopping off the middle chainring when at either end of the cogset. To solve this, you could run a chain guide (such as an Evil Bikes Security guide), but it's so much easier and cheaper to keep your chainrings and derailleur on the bike, assuming you don't race dual slalom or downhill and have no real need for a guide.

Old bike:

 

bomberz1qr20

Turbo Monkey
Nov 19, 2001
1,007
0
OK with running only the middle ring (I assume it's a 32 to 34 tooth).

This is the reason dh and slalom bikes have chain guides:

the most important factor is the chain hopping off, so if it doesn't bother you, leave the front derailleur ON, and adjust the bottom (low) limit screw till the cage is centered on the ring. It helps maybe to lower it as far down on the seat tube as possible. Because it's not shifting anything or moving at this point, it only needs enough clearance to prevent the chain rubbing. Now you can ditch the front shifter for more real estate on your bars.

One other thing that helps is a rear derailleur with a strong pulley spring, SRAM springs are ape strong, and XTR's have an extra adjust screw to increase tension.

Additionally an added tension device like a Kore chain reactor can help, but with possible sacrifices in shifting smoothness.

Keep in mind none of this might work, so ride wih CAUTION at first. A skipped chain in a sprint gave my a busted collarbone once!

As far as cross chaining and wear, the middle ring is usually ok to use with every rear cog, ( all dh and slalom bike do this) provided the chainline on your bike was correct in the first place. If you have a stock setup from the factory, they probably spec'd it pretty close. You want the middle chainring lined up dead center on the rear cassette. That means on an 8 speed setup, the chainline on the middle cog would be centered BETWEEN the 4th and 5th rear cogs, and dead center on the 5th cog in a 9 speed setup.

I'm getting long winded here.

All this centering helps your shifting if you were to leave the front rings on by the way.
 

madbiker

Chimp
Jul 6, 2001
55
0
Nor Cal
This can also be done using any 2 rockrings (blackspire, raceface, truvativ etc.) and a Truvativ Hussefelt I. Then replace the Truvativ rollers with MRP rollers (like 9 bucks a throw) and you've got an MRP for less and with Raceface bashrings (like 1/4" thick) you can really bash on them hard.