Q for the mechanics. 1x shifting problems

Triathlon Forum
1

New Force 1 derailleur (replaced an Apex 1), new cable. Bike has less than 500km on it. So the cassette, chain are good as well.

Adjusteded my limit screws.
Adjusted the B screw to get the pulleys as close as possible.
The problem seems to be the cable tension.
I can get it to shift relatively well in either the top gear, or the low gears, but not both.
I adjust the tension for one end and other end shifts poorly or skips gears.

My best guess (and I’m a mediocre mechanic), is that the housing from the chain stay to the derailleur is too short causing the cable tension problems?
The rest of the routing from the shifter to the chain stay is very clean with no major bends.
My other other Force 1 bike has always shifted like a dream and it’s housing is probably 2 inches longer.

Ideas?

2

Check rear derailleur alignment?

3

Check rear derailleur alignment?

The hanger? Checked and it’s straight.
Derailleur is new out of the box from SRAM and looks straight as well.

4

the housing from the chain stay to the derailleur is too short causing the cable tension problems?

Picture??

Is the cable run to the correct side of the fixing bolt?

5

Yes, cable is on the correct side of the fixing bolt.

derailleur3.jpg

6

SRAM (road) needs a much longer loop going into the RD than Shimano. That’s quite short there.

7

Is chain sized correctly (big-big + 2 inner + 2 outer)?

Also, you say your b-gap is ‘getting the pulleys as close as possible’ - B-gap should be 15mm to large cog.

8

15mm? Park tool recommends 4-5mm unless we are talking about different things:

https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

9

Is chain sized correctly (big-big + 2 inner + 2 outer)?

Also, you say your b-gap is ‘getting the pulleys as close as possible’ - B-gap should be 15mm to large cog.

Chain size is one thing I am assuming is correct because it was done by a bike shop that sets up a lot of 1x bikes.
I’m not completely confident because this bike shifts terribly.
I’d remove the quick link but I don’t have the tool.

10

https://i.imgur.com/VZGmSZo.png
.

11

where is that from? Shimano’s R9100 manual also says to get “as close as possible”

https://i.imgur.com/pjuc2ZI.jpg

12

Also, you say your b-gap is ‘getting the pulleys as close as possible’ - B-gap should be 15mm to large cog.

Unsure if this is your problem, but I’ve heard the same from a SRAM employee as well.

13

SRAM/Shimano = Apples/Oranges

OP has SRAM Force 1x and that is for Shimano
.

14

SRAM/Shimano = Apples/Oranges

OP has SRAM Force 1x and that is for Shimano

Was not aware of the different guidelines. Thanks.

15

add 2 links and call me in the morning :wink:

Everytime i’ve seen a problem with the shifting on a 1x bike, its been because it was set up like a standard derailleur. These don’t pivot around the top pulley wheel, and running the chain a bit longer allows that top pulley to remain closer to the cassette as you shift to the smaller cogs.

16

SRAM/Shimano = Apples/Oranges

OP has SRAM Force 1x and that is for Shimano
+1. Chain length and B-screw adjustment are very different for sram cx1 and shimano 2x

17

add 2 links and call me in the morning :wink:

Everytime i’ve seen a problem with the shifting on a 1x bike, its been because it was set up like a standard derailleur. These don’t pivot around the top pulley wheel, and running the chain a bit longer allows that top pulley to remain closer to the cassette as you shift to the smaller cogs.

Nailed it. Chain too short. Added a couple links.

18

Also, you say your b-gap is ‘getting the pulleys as close as possible’ - B-gap should be 15mm to large cog.

Unsure if this is your problem, but I’ve heard the same from a SRAM employee as well.

Grosso27 is a SRAM employee. And a good cx racer!