Which rear mech for 1x9 setup

ravey1981

I will soon be building a new bike up for all round off road riding and a bit of racing thrown in as well. I have decided on a 9 speed shimano setup for mud friendliness and crash replacement cheapness. I have been impressed with the Sora shifters (2014 spec) on my current cx/winter bike when comparing to ultegra on my road bike so will most probably use a set of those. I'm looking at running a 38t wide/narrow ring on the front, possibly on an XT mtb chainset to get a better chainline if the bb axel isn't too long for the cx frame, I'll need to check on that. With either an 11-30 or more likely 11-32 cassette.

Is anyone running a similar setup and will I need a short cage mech (again would prob stick sora on) or a medium cage (plenty of mtb mechs to choose from)

Cheers, and any other advice on running a 1x setup without a front chain guide or clutch mech, I'm hoping the n/w ring will be enough.

ugo.santalucia

Get a Shadow XT 9 speed and an inline adjuster to index it

ravey1981

Medium cage? Slx shadow mechs are a good bet too, cheaper, slightly heavier but just as good in function as XT ime

Ber Nard

You'd need a medium cage to run a 32t sprocket but you could get away with a short cage (though Tiagra and above) with a 30t. I've heard of people using NW chainrings without a clutch mech and not having any problems. Running a 30t sprocket and short cage would help reduce the chance of shipping the chain.

The XT crankset should work. The axle is longer so it works with 73mm shells but spacers are provided to fit 68mm shells. Were you thinking of fitting the ring as the middle of a triple? I wouldn't have thought it would make that much difference.

ugo.santalucia

Medium cage, yes

ravey1981

Yes ring in middle position on the chrankset, my thinking is that it will put the chainline more central on the cassette than with a road compact. I already have an XT crankset in the garage with worn rings so I will try both that and a road compact to see which works best.

One other thing, I notice hollowtech2 BB cups are marked either road or mountain, does that meant they are not interchangable?

devhads

I've successfully run both a 1x11 and 1x9 set up for racing this year without a clutch mech and without a chain guide.

Don't believe all the scare stories, a N/W chain ring is very good at it's job of keeping the chain on if your mech is set at it's highest spring tension and more importantly your chain is at the right length. I've not had one dropped chain in 20 odd races this year plus all the training rides. I wouldn't be worried if it did as without a guide or front mech it's very quick and easy to put back on.

I've also used a short cage mech with an 11-32 cassette with no problems. The quoted maximum sprocket size for mechs is assuming you are running a double and takes into account chain wrap capacity. All the different cage does is allow for extra chain when you are switching between small and big ring. I'm not saying all short cage mechs will go up to 32t but have at look at the mechs tech docs and note the part number for the parallelogram for short and medium cage mechs, if they are the same part number then they should fit as it's the parallelogram that determines if the mech will clear the biggest sprocket, not the cage. You will probably need to screw the b-screw right in though. I can confirm both Ultegra 6800 and 105 5800 short cage mechs both clear a 32t despite both quoting 28t max.

Ber Nard

ravey1981 wrote:

One other thing, I notice hollowtech2 BB cups are marked either road or mountain, does that meant they are not interchangable?

Only thing I can think of is perhaps the threaded sections are longer on MTB cups. The spacers I referred to earlier fit between the cups and the frame.

woolwich

The Bottom bracket shouldn't be too long but you might need to use the supplied spacers.

Don't get too hung up on perfect chainline. Yes its good to get it reasonably central but not critical.

As others have mentioned, I have messed about with short cage without issue up to 30t. I would definitely look to get an MTB part . I have no proof of this but my gut instinct is that MTB springs are much stronger. I have ruined two road mechs cx racing, both time the springs got tired and they stopped returning nicely. Even Deore mechs seem more durable.

Again as others have said, no issue without a clutch mech, Downhill MTB racing but not so far with other use. I tend to ensure the chain is as short as possible whilst still functioning properly.

ugo.santalucia

woolwich wrote:

As others have mentioned, I have messed about with short cage without issue up to 30t. I would definitely look to get an MTB part . I have no proof of this but my gut instinct is that MTB springs are much stronger. I have ruined two road mechs cx racing, both time the springs got tired and they stopped returning nicely. Even Deore mechs seem more durable.

Totally... the springs are much stronger, more positive shifting and they are easier to clean than road mechs

devhads

Shimano rear road mechs have two spring tension settings, factory default is the weaker one. It's about a 10 minute job to take the cage off and change the tension setting.

I was pretty sure 9 speed STIs like the OP has don't work with 9 speed MTB mechs with Shimano. I've never tried so I could be wrong. I always thought you needed 10 speed STIs with 9 speed MTB mechs.

ravey1981

Yes they do. Its 10 speed road with 10 speed mtb mechs that don't work due to cable pull issues. I've never heard of the spring change you are talking about, I will look it up, thanks.

jimwalsh

sram 10 speed clutch mechs play nicely with the road levers.

I have an x9 typeII with a right red shifter it works a treat

mattrixdesign2

Just to add to the clutch debate. I turned my XT hardtail to 1x10 with a NW upfront, the RD was Shadow, not Shadow+, but it worked brilliantly, never dropped a chain on Black Runs or on wild trails. However, last Sat I did a MTB race and the conditions were poor, i.e. sticky wet mud, leaves, twigs and I dropped my chain more than 10 times. I am now running an STX Clutch RD but not had chance to test it yet.

IMO if you are planning to race, and want the best possible position, make sure you have a clutch to keep things in place.

devhads

I'm sure the debate will continue to rage on. As I've said above, never dropped a chain in 20 races last season without a clutch mech.

I've decided to switch from 1x11 Ultegra to 1x10 Force due to wheel compatibility reasons and have got an X9 Type 2 mech so will see if that's any better next season, although I can't see how I can improve on zero dropped chains

mattrixdesign2

Hi

Off topic, but out of interest, how did you work out chain length for your 1x10? Big/Big + 2?

Like I said mine was perfect, even better than the previous triple+mech (which dropped one or twice), but this race in the mud just killed it, maybe the new clutch mech wouldn't even make a difference? I could have been unfortunate to get the RD contaminated with mud, twigs, foliage etc and that just kept throwing the chain.

devhads

Off topic, but out of interest, how did you work out chain length for your 1x10? Big/Big + 2?

Yes, exactly that. Cage ends up at about 45 degrees in big/big.

I could have been unfortunate to get the RD contaminated with mud, twigs, foliage etc and that just kept throwing the chain.

I did some proper muddy races, I ripped mechs off twice but it never caused a dropped chain. Was the Shadow a long cage? Long cage mechs, too long a chain and mud would all contribute to the problem.

mattrixdesign2

Chain was +2 links (as normal), not 100% sure on cage length, its an XT that was on a 3x10 setup (RD-M780). Front NW is Superstar.

Performed brilliantly, 100% reliably until that day :roll: - the chain was falling at very particular locations, thick mud, cruising/down hill ish (but not bumpy), each lap it was coming off in roughly the same places.

devhads

Back pedalling?? This reduces chain tension so could cause your chain to drop over a small bump. Seeing as you're cruising downhill it could be something you're doing unconsciously. It may only take a half turn back when you're getting in the ready position before an obstacle, maybe why it's happening the same place every time.

mattrixdesign2

Not consciously back pedalling, but possibly free wheeling, that could end up in a slight back turn to level the pedals?! Even if this was the case, mud made it worse, as not had the same problem riding elsewhere.