kalli

hey! 1st time poster here.

I'm a mechanic by trade (cars), so I know my way around bolts, but I'm not an expert when it comes to bikes. this one has me stumped
if I open both limit screws in rear derailleur, put the rear selector gear into 7 (numerical highest, it has distinct clicks and its definetly 7), hook up the cable, adjust the cable so it's in 7th but just to go into 6 (noisy already), then if I go from there towards first it goes only up to 3rd.
with a lot of patience and indexing I got it so it can even go from 7 (noisy, nearly 6) all the way up to 2nd (just about). but no way into 1st
if I put it in 7th I can very easily switch all gears (7 to 1 to 7) by pulling on the cable at the frame, it goes all up all down.
it behaves as if the gear selector ratio is wrong. 1 click is only 3/4 movement at the bottom. so every about 3rd or 4th gear it doesnt jump and needs 2 clicks instead.

i bought the bike with hardgoing/broken gear selector. Bought a Shimano shimano gear selector to fix it (good looking my boy loved it) but realized its a SRAM-X3 at the bottom and that would be the problem. the rear says 1:1 ratio, so i got myself a sram x3 1:1 grip shift. the problem is identical ?! there is no play in the back, all screws are tight

what am I missing?

DorkDisk

The limit screws shouldn't be fully "open," they should limit the extremes of the motion the derailleur would be required to move to cover all the cogs.

kalli

agreed, I only did this for troublshooting to make sure it's not the limit screws causing the problem. I have them adjusted where they should be again, but just to isolate the problem making sure its not a limkited travel range at rear

Iride01 

Original equipment that all worked correctly once upon a time? Oops, missed the last part of your OP. Yeah, someone else will have to tell you about whether SRAM X3 and Shimano shifters play well together. Which model Shimano *****r?

Assuming this is a derailleur equipped bike, and it just started happening then I'd think you might need to have your DR checked for a bent hanger.

Sometimes a binding or frayed cable inside the cable housing can cause issues too.

Did you change out or fix anything prior to this happening?

thook

sounds like either you don't proper cable tension or there's obstruction somewhere along the cable path. housings and ferrules all in proper order?

thook

looks like the censor doesn't like something you meant to write? did you miss the F?..lol

Iride01 

I think I wrote shifter. Maybe I did misspell it and missed the "f" key. Too late now. The curse word bot makes actual changes.

ClydeClydeson

If you just leave out the F it is a misspelling of the word that is commonly used in place of 'toilet' or 'outhouse'. The word should be spelled like 'hitter' but with an S. If we were to swap the F back in for one of the Ts, we can make a sentence like, "I'll be right back, I gotta go to the shifter"

Bill Kapaun

The censor is fooled by the device that you use to change gears.

Bill Kapaun

Are you sure you have the correct front shifter?
Shimano has (I think) a 1.7 pull ratio.
Sounds like it's shifting about 60% of the travel, so the math adds up for a mismatch.

kalli

i know its confusing - sorry if it was not clear:
when I got bike used (alum frame kids bike for cheap, i thought i just quickly change all brakes and that s****er and would be good to go )
it was: sram x3 in back with what I think was correct grip shifter, but it didn't work well -- (it was very stiff)
so got a flashy Shimano grips shift (Revo) the junior liked but had this problem. so I went and got a not-so good-looking sram x3 grip shift that seemed to be like original replacement but still the same issue
cable and housing is new. no derailleur to bike. the only thing I can think off is that the chain too worn (it is widened in places).
I was also thinking tension, but if I put more tension on it, then the effect is that I can only switch from 6-> 1 and not from 7->2 anymore. I get max 6 gears out of this

i checked again, derailleur clearly says 1:1 and shifter is: SRAM 3.0 SHIFTER - GRIP SHIFT - 7 SPEED REAR 1:1

Hondo6

This source says the SRAM Gripshift 3.0 was produced in two versions: a 1:1 version and a Shimano-compatible "2:1" version (SRAM's term; actual pull ratio is the Shimano 1.7:1 pull ratio).

https://en.wikibooks.org/wiki/Bicycl...le_Replacement

If that's the shifter you ordered (your link didn't come through since you have <10 total posts here), it might be worth double-checking to ensure that the one you received is actually the 1:1 version for SRAM 1:1 drivetrains. The linked article says if that particular shifter is marked "MRX" or "Centera", it's the Shimano-compatible version.

Link is to a Wikibooks article, so caveat emptor. However, that link in turn points to the old SRAM archive, so you may be able to find more info and/or authoritative confirmation of what the article says there:

https://www.servicearchive.sram.com/service

viperocco

I recently had a similar issue and it turned out that I had routed the cable on the RD clamping mount incorrectly. Once rerouted and re-clamped full range shifting was available.