jxpowers

Ok so i have a GT bike (aggressor 2), I crashed and I went to my independent bike shop to get it checked out,
He said the gears need adjusting which was about right, and he also said that the cassette and the rear dérailleur were not compatible because they are two different makes and he explained that the distance between each gear on a particular make would be different from another so he could keep on adjusting forever and ever but it would never be perfect

i had a sram 9 speed cassette with a shimano deore rear derailleur

now both are shinamo

did i just get tricked into buying a new cassette?
or was he telling the truth please let me know

bradtx

Often SRAM and Shimano are compatible WRT the cassettes and I am pretty sure that GT didn't make a mistake.

Brad

Spoonrobot 

Possible. GT did ship a bunch of bikes with a compatibility issue last year but they came with the correct cassette in a box that was to be swapped for the one actually installed on the wheel, by the shop mechanic when the bike was assembled.

Although, IIRC it was a Sunrace/Shimano swap?

Airburst

SRAM and Shimano cassettes use the same spacing for 7- and 8-speed (I'm using a SRAM 7-speed cassette with a Shimano derailleur and shifter on one bike and an 8-speed Shimano cassette with a SRAM derailleur and shifter on another). I'm 90 percent sure they're the same for 9-speed too - a guy I ride with runs a 9-speed SRAM cassette and a Shimano derailleur, and it's perfectly adjusted.

cyccommute 

Fixed it. There is no problem with using Sram cassettes with Shimano derailers or vice versa. You can't, however, use (most) Sram rear derailers with Shimano shifters...at least not mountain bike ones. They have a different cable pull ratio.

Don't know about Sram road stuff.

9-speed and 10-speed (not sure about Dynasys). I've used Sram cassettes with Shimano derailers on 7, 8, 9 and 10 speed systems. There's no problem with the spacing. Sram cassettes shift, in my opinion, better than Shimano.

LarDasse74

Sram and Shimano cassettes and chains for the same number of cogs are generally interchangeable. It is likely your LBS guy is inexperienced or otherwise ignorant and he wasn’t intentionally trying to trick you – furthermore, it is unlikely the tech in the LBS workshop has anything to gain by selling an unnecessary cassette.

If I were you I would call and tell the manager or owner of the shop that his staff may need more training or oversight. If the guy who told you of the ‘incompatibility’ was the owner or manager… find a different shop.

FBinNY 

Sram and Shimano cassette spacing is the same, so maybe you were tricked into buying a cassette you didn't need.

Possibly the mechanic was confused because while cassette spacing is the same, the cable response is different, so you cannot mix Shimano derailleurs and Sram levers.

There are also subtle differences in the cut of the teeth and shift gates between Shimano and Sram cassettes, but in any case Sram cassettes are commonly used with Shimano drive trains, both OEM and as replacements.

MNRon

Mechanic should have checked the der hanger, the cassette will work fine.

fietsbob

Was the seller a Bike Shop, or a big box store sporting goods section?

AlphaDogg

I'm pretty sure that only Performance Bikes sells GT.

fietsbob

if not one of their Brick and mortar Shops , Performance
does not ship an assembled bike , they ship the carton Un Opened
since closed in the contract factory way over there.

jxpowers

https://oi45.tinypic.com/10rpnyr.jpg
can anyone tell me what model this derailleur is

this is the cassette i had installed [h=1]Shimano Cassette CS-HG50 9[/h]
and i dont know what SRAM cassette it was but i think it was Sram PG950
not 100% sure

clarkbre

Looks like a 9 spd Shimano Deore to me. Model # may be "M591"

The shimano HG and Sram PG should be interechangable.

On the Shimano, the "9" after the "HG50" designates it as a 9 speed

And, on the Sram, the PG950 designates it as a 9 speed.

I was recently looking at HG50 8's and PG850s. Totally interchangable. The only difference is the gear ratios on each cassette.

I would go back to your LBS and atleast ask for a refund or exchange back on the cassette. The LBS told wrong information and it cost you money which then benefited the LBS.

mprelaw

My GTR has a SunRace cassette, a 2300 RD, and Microshift shifters. They all work well together, and I can keep it in tune myself.

Your shop hosed you. Find a new one. Write off the loss and move on. Before he tells you that you can only use a Shimano crank with your FD.

escarpment

for the most part Sram and Shimano cassettes have the same spacing and construction, especially your cassettes , unless there is something we dont know, you got hosed alright.

LesterOfPuppets

Oooh, man, I'd be wanting my old cassette and some money back.

I don't think I've ever bought a Shimano cassette and only one Shimano chain (back in the 90s), even though I have some of their shifters and derailers.

Medic Zero

IIRC REI does as well.

zacster

before you crashed, did you have problems shifting? Was it difficult to get the gears just right? If not, then there was no reason at all to put a new cassette on. Does it shift better now?

The big incompatibility is between Shimano and Campagnolo. Those 2 brands will NOT work together without some kind of add-on cable adjuster. You even need different freehubs on the wheel as the spline patterns are different.

onespeedbiker

It is very very common for manufactures like GT to spec a bike hoping for more bang for the buck. Along these lines SRAM rear cassettes are 1/3 cheaper (or more) than Shimano and generally there is not compatibility problem. It is unlikely you would have been able to tell the difference between the two as SRAM purposely uses the same spacing so they can under cut Shimano medium to low-end components..BTW, just because a guy wears a Park Tools apron does not automatically make him more knowledgeable about bicycles.

DiscTruckerMF

whoever works at your shop doesn't know jack. Everybody has to learn, potentially an honest mistake, but man. Even the most entry level of us know that a SRAM and SHimano cassete are interchangeable without issue. As others noted, the shifting mechanisms are different because of the amount of cable pulled in order to move the derailleurs the appropriate amount.

Airburst

Except for the SRAM shifters that are Shimano-compatible. Why these exist, I'm not sure, but I've seen several.

jxpowers

before i crashed there was a small problem shifting, there was noises like the chain was rubbing onto the next gear when i got it "fixed" by the guy that said what i have is not compatible it was fine, so i thought ok and left

then i crashed then it got worse i landed on the derailleur side and i there is a huge patch of paint missing i think i slid at least 10 meters on one side of the bike

*so i may have a slightly broken derailleur**********? *

now the cassette is completely brand new as is the chain and after about 20 miles the gears started to stop changing smoothly again which i thought was weird,

so i tried to fix it again and i got everything to run smoothly just now it wont change into the big gear at the back, as i fix one thing another thing breaks so i just stopped trying ( i dont even need the big gear at the back anyway )

jxpowers

Hey guys ive also noticed that when i was tuning my gears, they changed very smoothly

but when it comes to riding it is totally a different matter, they is at least a 1-2 second delay to when riding so when i change gears then peddle, theres a big clunk and my leg goes straight down like im in 0 gears

anybody know what i mean?

Airburst

It sounds like you're pedalling too hard when you shift. The trick is to ease up on the pedals for the shifts.

As for correctly adjusting it, https://www.parktool.com/blog/repair-...nts-derailleur

FBinNY 

Duh! Shimano is the dominant player with more derailleurs sold than everybody else combined. Sram was maker shifters long before they made their first derailleur, so it makes sense that Sram would make shifters compatible with Shimano.

Going back to the early years, Sram built the company supplying Sram twist Grips as OEM for Shimano equipped bikes.