anyone push their altus (m310) to a 36t rear cog?

[Michael Baquerizo]

bought a 11-36t cassette for my new appa and already have some altus' that i'd like to use ( i guess i have back up shimano rear in case they dont) but i realized it's supposed to be 34t max. anyone get it past that?  tried looking elsewhere to no avail.

keep seeing altus' on riv builds and it's growing on me aesthetically, in a riv sort of way. my back up is an m952 xtr rear. not a huge fan of the charcoal color so i'm not super excited to use it, but i guess i can get over that pretty quickly

[Jared Wilson]

We have two bikes successfully set up with Altus rear with Microsoft 9 speed 11-42 cassettes using the Sunrace derailleur extenders available HERE on Rivendell's website. I think you'd be fine without one on a 36 but that's the next move if you aren't able to swing it.

[dougP]

I have an 11-36 9 speed cassette shifted by an Altus on my Atlantis.  Works fine.  I had a 34 big cog before & didn't change a thing when I replaced with the 36. 

dougP

On Sunday, June 20, 2021 at 6:20:31 PM UTC-7 Michael Baquerizo wrote:

[Joe Bernard]

What Doug said, it should be fine, Shimano rear derailers are usually good for pushing a couple teeth bigger than listed. I believe - this is math stuff I don't fully understand - some of the concern comes from if you're running a wide-range triple crank and a big cassette..at some point in there things get screwy. But most of us don't run triples that way and you may not even have a big ring, just guard-middle-small. I say give it a whirl! 

Joe Bernard

On Sunday, June 20, 2021 at 6:20:31 PM UTC-7 Michael Baquerizo wrote:

[Bill Schairer]

I ran an Altus on my Atlantis with a 12-36 9 speed cassette and a 42/34/19 triple for a week on the GDMBR and had no troubles other than being laughed at by another cyclist for my selection of a rear derailleur.  What can I say - it worked.  I decided to switch to the Altus for that ride because I had it and it has amazing chain wrap, which I thought would be desirable with that 19t granny.  It has been two years now and it is still on the bike.

Bill S

San Diego

[dougP]

Same here.  My Atlantis has a 24/34/44 triple, and the Altus handles it fine.  IIRC, the Altus is less than $30 at Rivendell (if they have them to sell).

dougP

[Lefebeaver]

My Atlantis is set up with an Altus, 24-34-44 up front, and 11-34 8-spd in back. I set up the chain length according to guidelines I got from Riv, but my Altus grinds on the second biggest gear in back when shifting to the innermost one - it scrapes on the gear on its way up and makes a horrendous noise, and although it'll run in that second gear, it's clunky so I rarely use it, but the biggest gear works fine once you get up there. I'm wondering if anyone else has had this issue - should I add some more links to the chain? I ultimately wish to go bigger in back - was on a loaded dirt road tour in Brazil where there were some hills I didn't have a low enough gear to climb and I had to walk it up, while my companions on mountain bikes just went grinding up in their 1X setups. Thinking I need to get a goat link for that next step to a larger cassette in back; what is the guidance for choosing chain length with a link?

[lconley]

Sound like the chain is too long, and/or the B screw (body angle screw) needs to be turned in. Turning the B screw in (clockwise) increases the distance between the derailleur and the cogs.

Laing

Delray Beach FL

[dougP]

Lefebeaver:

Is your Atlantis one of the newer ones with longer chainstays?  Mine is an '03 with IIRC 45 cm chainstays.  I always install chains as they come, with no length adjustment.  The longer stays where you have to add chain may require some care. 

dougP

[Joe Bernard]

Lefebeaver, I'll add to the chain questions with a shifter one: Are you using friction or index? Your problem on the second-biggest rear cog sounds like the pulley wheels are landing slightly off-center and towards the biggest cog, which would create that crunchy sound. Like you're going to get that crunch when shifting to the big cog, and the chain is already halfway there and crunching before you start the shift. 

I've had this exact issue with an Altus and indexing, it's not a terribly precise derailleur for clicky-shifting. This theory is moot if you use friction and can't trim that sound out. 

Joe Bernard

[Lefebeaver]

I’m running silver shifters, so it’s not an indexing issue. The upper part of the pulley cage actually makes metal to metal contact with the cassette as it passes between 3rd and 1st. When runnng in the middle ring up front and second in the back, it just touches the innermost gear on the cassette.  It is a newer Atlantis 59cm with very long chain stays, so I had to buy two chains and add a section to get a long enough chain. I’ve played with the B screw in the past, just checked it now and it’s all the way in - but the slack in the spring of the derailleur still allows it to swing forward directly under the cassette. With the chain length I’m currently running, the Altus gets pretty stretched out in a max to max stretch, so it seems like the only place to go is a bit longer on the chain... or maybe it’s time to add a goat link?