Need suntour derailleur replacement

[Ba_50]

My sensation crossroads cruz needs a rear derailleur. I need to verify which shimano part and shifter will work.
Thanks
Bob

[Painkiller]

(03-05-2026, 08:27 AM)Ba_50 Wrote:  My sensation crossroads cruz needs a rear derailleur. I need to verify which shimano part and shifter will work.
Thanks
Bob

Do y

[ReapThaWhirlwind]

Count the number of gears you have in the back cassette.

That's the speed rear derailleur you need.

Likely, it's a 7/8 Speed rear derailleur, medium cage.

[froze]

I'm not 100% sure but I thought those bikes first came out as a 6 speed and then later became 7 speed, and as far as I can remember they were never 8 speed. I thought those came out with Shimano Tourney derailleurs, but your title says Suntour, which when I researched that I couldn't find any Crossroads Cruz that came with Suntour derailleurs, not saying they didn't absolutely not come that way, but I can't find any record of that; if by chance it did come that way it had to be an SR Suntour since Suntour was out of business by the time that bike model came out.

But I admit I know next to nothing about those bikes, so take what I'm going to say with a grain of salt.

I don't know what year your bike is, and online specs are a bit sketchy, so if it’s a 7-speed 14–34T freewheel, I’d go with a long-cage Shimano Tourney RD-TY300-SGS derailleur, these are easy to find. A better option is to go with a Shimano Altus RD-M310, this is a better derailleur without costing a lot, and I wouldn't spend a lot for an even better derailleur, the Altus is as far up the food chain as I would go with that bike.

Not sure how old your chain is but you might want to consider getting a new chain since you'll be paying for the labor to remove the chain to put on the derailleur, so the labor is covered, so get a new chain.

That Altus is less than $30 so it's not an expensive item, the Tourney is $20, but for $10 more you're getting a better derailleur.

Unless I missed the boat somewhere due to the Suntour thing I think the recommendations are good, but double check that stuff.

[SPINMAN]

Not familiar with the defunked Suntour, but I came across an old forum post from 2014. Maybe this will help if you haven't solved the problem yet, or for those with a similar issue.

-Please allow me to barge in here as an owner of a 1994 Trek T50, originally equipped with a Suntour 12-30 7 speed cassette and Shimano derailleurs and indexed shifters.

The Suntour cassettes mounting is not compatible with Shimano or Campy. The Suntour cassette 7 speed spacing is the same as Shimano.

On our T50; the rear rim cracked, and I used that as an opportunity to build up new wheels with Velocity Dyad rims, Wheelmaster 40H hubs and Wheelsmith spokes.

As Jef notes; you need a new chain with your new cassette, and possibly new shifters if you choose to go to 8 or 9 speed.

As noted, you need a new hub. A new rim is probably called for due brake track wear. A new wheel is probably the best solution.

[Jesper]

@froze why do you need to remove the chain to replace the derailleur? I have never needed to before.

Author asked about a derailleur and now it is recommended that the hub, cassette, rim, chain, etc. be replaced

Why did no one ask what problem with the derailleur is? Aside from accident damage, the only wear would be in the pulleys (common issue, easy and inexpensive to replace), pivot points and/or springs. If already dealing with a 'worn out' mech than I certainly do not recommend buying a used one to replace it as it might have similar wear, unless you get a guarantee from the seller that there is no play, springs are good, and pulleys are essentially new.

Replace other parts as needed if worn, you will not have to deal with compatibility issues if you use the same style derailleur as you are not changing speed capacity on the hub. A photo of the bike and components would be helpful. I would at least check the chain for wear so you may need a shop to do that if you do not have a chain wear gauge (if chain is worn most likely chainring(s), if alloy, is also worn and both should be replaced).