NOTE: I think the past owner downgraded from an 8spd to 7spd because the cassette looks almost new. Also picture 1 is with the B screw mostly out. The rest of the pictures are from the B screw mostly in
Now here are the specs
Rear derailleur: Shimano Deore Xt RD-M739 8 speed
Old cassette: 7 speed 12-32T
New cassette: 9 speed 11-36T
Front big ring: 44T
Front small ring: 22T
With the current b screw setting, halfway in, the chain rubs on itself on the smallest gear to smallest ring as seen in picture 3
If I pull the b screw out it will avoid that but then the chain becomes way too slack on small gear small ring. Should I play around with the B screw or remove a link?
The old 7 speed chain was 107 links
Using the calculator method with the new gears it suggested 8 links which the new chain is currently at
by Foxcookies
9 Comments
You’re kind of stretching that derailleur waayyy beyond its limits. Shimano has it specc’d at 38 tooth capacity and with your current setup (44-22)+(36-11)=47. Shimano gives a little wiggle room, but not that much wiggle room. You need a rear derailleur with a longer cage, or to switch it to a double in the front.
Send it as is, you shouldn’t ever need to use the smaller end of the cassette while in the granny ring
Max for that derailleur is 32t. There isn’t a perfect anymore so your on your own.
Wind the b screw in a bunch to get some of the slack out in little gears, then go for a pedal and see if it works.
You’ll never be in big/big or little/little anyway.
Remove the entire drivetrain and go to a 1×10. These old bikes are perfect for it. Shimano Deore Linkglide RD with an 11-42 10spd deore cassette and a linkglide right shifter. Up front go to a GRX crank with a 40t front ring. GRX already comes stock as a narrow-wide ring. Plenty of gears to go uphill and downhill with zero doubling. You’ll also get to lose your left shifter. All of this is around $300-400 bucks and will double the lifespan of your bike. I have same setup on an old specialized that is so fun to ride now.
Don’t combine the smallest chainring with the smallest cog. Or you get that…
You’re in the NO NO gears. your big cassette gears are good to your middle and granny gear. Your big ring is for the middle and low of your cassette. Never Big Big and Small Small.
Did you put a 9 speed cassette on an 8 speed drivetrain?! (Check the shifter)
If it was me id buy a $2 aliExpress/temu/Amazon derailleur extender, that will increase the derailleur capacity for you. I have been known to replace b tension screw with a longer one, might help. Had you tried the Shimano chain length guild? Chain on big cog at back & on big chainring without going thru rear derailleur plus one link & magic link.
https://bike.shimano.com/stories/article/determine-chain-length.html
Lastly you should never cross ur chain like that in real life, u will hear the transmission growling. Never low-low or high-high!
Just get a nice kit from microshift.