SRAM 11-32 cassette on Super Record 2015

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mrgray
Posts: 775
Joined: Tue Mar 17, 2015 1:56 am

by mrgray

Hi there,
I apologise if this is elsewhere but as far as I know it is not.

Anyway, I initially started thinking about SRAM cassettes for the weight savings. ~175 g for a 11-28 versus 219 g for my 12-29 SR.

But after being told to become cadence obsessed, and with my liking for a hill, a 32 tooth ring started to sound good.

So i bought a 11-32 from our sponsor and got a shimano hub for my wheel (Dt240 SL) thinking I'd give it a shot.

Lo and behold it seems to work just fine. I didn't have to adjust anything, just stuck the wheel in, changed up and everything worked.

Anyway I couldn't find any similar experience when I was looking, it was all chat about getting a medium cage etc. Maybe I already have one but I thought my SR groupset was pretty stock so I don't think so (and I didn't get the impression you can have anything other than one length of SR cage).

I changed into big big and it looks like the RD is stretching for it but seemed to work. I won't be using that gear though as it does tend to create a bit of a racket via FD grind anyway. SRAM cassette doesn't seem to change down as readily as the SR however perhaps that will change once I am actually riding which does seem to slightly alter change characteristics versus the bike being on the stand.

Test ride tomorrow but right now, no reason it won't work as far as I can tell.

:beerchug:
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spdntrxi
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by spdntrxi

a lot of it depends on the frame was well... for instance I can use the 11-32 on my wife madone, but not my parlee z5 running DA9070...I could on the parlee but the 32 ring is kinda clunky to get on it and it look like my deraillier might rip off. The SRAM 11-30 works perfect on my Parlee.. so I use that for those real climbing days.
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russianbear
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Joined: Wed Apr 11, 2012 3:40 am

by russianbear

As graeme always points out, it really depends on the dimensions of the derailleur hanger (also to some extent chainstay length and drop outs). The upper pulley needs to be able to clear the cassette and of course the chain has to be long enough.

jimborello
Posts: 283
Joined: Sun May 31, 2009 5:07 am

by jimborello

I might be wrong but the tooth count on your chainring also has something to play in this equation, you migh add that uo to your question so that someone knowledgeable can give you a better answer

russianbear
Posts: 683
Joined: Wed Apr 11, 2012 3:40 am

by russianbear

That's chainwrap. The difference between the front chainrings is half of it, the other being the difference between the largest and smallest cog on the cassette (then you add the two numbers). The rear derailleur can only take up so much chainwrap, although you can usually fudge the 'official' recommendations by a tooth or two.

Valbrona
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Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

You can get an 11 speed Campagnolo compatible cassette with a 32t sprocket: http://www.interlocracing.com/cassettes ... d-cassette

highdraw

by highdraw

mrgray wrote:Hi there,
I apologise if this is elsewhere but as far as I know it is not.

Anyway, I initially started thinking about SRAM cassettes for the weight savings. ~175 g for a 11-28 versus 219 g for my 12-29 SR.

But after being told to become cadence obsessed, and with my liking for a hill, a 32 tooth ring started to sound good.

So i bought a 11-32 from our sponsor and got a shimano hub for my wheel (Dt240 SL) thinking I'd give it a shot.

Lo and behold it seems to work just fine. I didn't have to adjust anything, just stuck the wheel in, changed up and everything worked.

Anyway I couldn't find any similar experience when I was looking, it was all chat about getting a medium cage etc. Maybe I already have one but I thought my SR groupset was pretty stock so I don't think so (and I didn't get the impression you can have anything other than one length of SR cage).

I changed into big big and it looks like the RD is stretching for it but seemed to work. I won't be using that gear though as it does tend to create a bit of a racket via FD grind anyway. SRAM cassette doesn't seem to change down as readily as the SR however perhaps that will change once I am actually riding which does seem to slightly alter change characteristics versus the bike being on the stand.

Test ride tomorrow but right now, no reason it won't work as far as I can tell.

:beerchug:

MrGray,
With respect and based upon your post, I am quite sure you don't know why it would or wouldn't work.
I don't feel like explaining about chain wrap...biasing chain length per particular gearing...adjusting clearance between cage pully and largest cog...why cage length matters....why what chainring combo you are running matters etc. If you don't understand above relationships, you are even money to turn your SR bike into a heap of scrap metal by ripping the rear derailleur off. Take the bike to a shop to evaluate it and say yeah or nah. Typically a 32t cog with standard or compact crank with 55mm SR cage length is NOT a recommended combo...even with 'very careful' chain length selection.

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mrgray
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by mrgray

dear mr highdraw,
I do understand that I'm pushing it a bit with this setup and believe me I'm not 100% sure it'll work out well for me.

But if I hear you right besides "take it to a bike mechanic" you are saying even if i do have a decent gap between the rear derailleur and the 32 tooth sprocket (which i do to my surprise), and even if i keep it out of big big to avoid stretching the crap out of the RD, i risk failure of the rear derailleur? please do tell as i must admit two things worry me:
1. RD mech going into the spokes
2. chain failure due to the setup exacerbating wear

i did read about chain wrap and what i got from that was i could probably just squeeze the 32 in (right on margin).

i've gone from a chain wrap # of 34 (compact 11-29) to 37.
Bobo S&S Steel Bike - 7.5 kg
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Look 695 SR :D

russianbear
Posts: 683
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by russianbear

Officially, a short cage campy rear derailleur has a chainwrap of 33 teeth for pre 2015 groups and 34 for the revolution stuff.

Marin
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Location: Vienna Austria

by Marin

"Chain wrap", i.e. rear derailleur capacity, has nothing to do with the largest cog but with the ability to take up slack chain.

If there is a lot of difference between large-large and small-small chainring/cog combos, you need a derailleur with more chain capacity to prevent the chain going slack on small-small.

The chain going slack it not a big problem, and it's not dangerous.

The important thing is that the chain is long enough for large-large, if it's not, shifting to that combo can rip off the derailleur and the hanger and throw what's left into the spokes.

So, if you can shift to large-large easily, and the cage is not fully stretched forward, you're good to go.

russianbear
Posts: 683
Joined: Wed Apr 11, 2012 3:40 am

by russianbear

Chain wrap and the pulley being able to clear the largest cog are two separate issues that can cause problems if you're using a non officially recommended set up. I don't think anyone is conflating the two. It's easy to leave the chain long enough, it's harder to make yourself a custom derailleur hanger if yours doesn't work.

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mrgray
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by mrgray

limited empirical data is in. works like a dream. i am staying out of big big (and tend to as a matter of course to avoid chain wear) and my 34/32 combo is letting me keep the cadence up on even the steepest of grades on my commute. more like a take it easy gear that doesn't get used alot actually. the real intent is to save it for mountain specific stuff but i am in a proving period.

there was a bit of a rumble which was notable on rollers (haven't noticed it so much on road). i think this was just a brand new cassette and a 2,000 km chain.

so far so good!
Bobo S&S Steel Bike - 7.5 kg
Oltre XR2- 6.6 kg
Look 585 - 6.8 kg
Look 695 SR :D

highdraw

by highdraw

mrgray wrote:limited empirical data is in. works like a dream. i am staying out of big big (and tend to as a matter of course to avoid chain wear) and my 34/32 combo is letting me keep the cadence up on even the steepest of grades on my commute. more like a take it easy gear that doesn't get used alot actually. the real intent is to save it for mountain specific stuff but i am in a proving period.

there was a bit of a rumble which was notable on rollers (haven't noticed it so much on road). i think this was just a brand new cassette and a 2,000 km chain.

so far so good!

Don't mean to rain on your parade but building a bike where you 'could' shift to big/big and potentially rip the derailleur off due to too short a chain...provided your chain isn't too slack in small/small...I wouldn't own such a combo. Conscious thought to stay out of particular gear combos is a false boundary condition for most that ride bikes because the unintentional happens a lot when riding a road bike in a changing environment...when fatigued etc.
Just sharing my opinion...I wouldn't ride a short cage Campy rear derailleur with 32t cassette and a compact crank because of the lack of chain wrap and if you are riding a full size double, then you don't need the 32t cog size anyway.

If you aren't a strong rider and need a 32t rear cassette, why don't you sell your SR group and install an Athena Triple group and then you have the gear inches you need.
Or at least use an Athena triple rear derailleur which can handle the cable wrap and run it with a 50/34 crank...preferable UltraTorque and not PowerTorque. If you want you can combine with 2011-2014 Chorus UltraShifters which are compatible with long cage Athena rear derailleur and honestly they shift the same as any SR bike I've ridden.
Good luck...you will need it with your current config.

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glepore
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Joined: Thu Mar 28, 2013 4:42 pm
Location: Virginia USA

by glepore

One thing I'd like to see with electronic is the ability to program out cross chain. That would allow something like a 32 worry free.
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highdraw

by highdraw

Honestly there is a reason why this isn't part of a popular algorithm. If you think a bit deeper, what you suggest which maybe directionally correct to chainline, chain wear and even driveline noise, its isn't for riding in a competitive environment. The reason is anticipation. A computer algorithm can't anticipate...at least right now. Riders see a hill coming and/or anticipate a break away and a given cadence required and a clear decision is made as to what chainring to be in. This many times isn't consistent with best chainline. Good and top riders generally will cross chain in the big ring when slowing in a A group ride. This is because a shift to the small chainring is disruptive to energy application and time spent in the small ring will be fleeting. So a good rider will not want a needless shift to the small ring only to stay in the small ring for a few pedal strokes to shift back to the big ring based upon optimal chain line. Optimal chain line and most efficient shifting and speed on the bike aren't the same thing in summary. Hope that makes sense.
Last edited by Frankie - B on Wed Sep 30, 2015 7:25 am, edited 1 time in total.
Reason: removed the quote

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