If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
Depends somewhat on your derailleur hanger and the distance between the axle centre and derailleur mounting bolt. This is not a constant on all frames. The limiting factor is going to be whether the top jockey pulley fouls the largest cog on the cassette.
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If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
I've used a 30t with a Campag Medium mech and some contributors to rec.bicycles.tech have used 32t (though I can't remember whether that was with long or medium versions).
But it's not good enough just to /intend/ avoiding large-large. You have to never select it by mistake if your chain is too short for it otherwise nasty things can happen to your mech and hanger. So you should have the chain long enough just in case.
11-32 cassette is nasty on a road bike anyway if you've been used to a narrower range. I bet you'd be happier with a compact or triple chainset.
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
This is not a good idea on two counts. The first is, even though you do not plan to use the big-big combinations, when you are tired and desperate for a lower gear, you might shift into one by mistake. If your chain is too short (so that you can use too wide a cassette), you can break something important doing this.
The second problem is that the upper idler wheel will rub against the big sprockets, and you probably won't have enough adjustment to avoid that.
You can either get a derailleur made for mountain biking, which will have both better clearance and more capacity, or you can get "compact" cranks which allow a smaller chaining in front. The first is cheaper, the second option is more versatile.
"David L. Johnson" <[email hidden]> wrote in message news:[email hidden]...
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Quoted message said:
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
This is not a good idea on two counts. The first is, even though you do not plan to use the big-big combinations, when you are tired and desperate for a lower gear, you might shift into one by mistake. If your chain is too short (so that you can use too wide a cassette), you can break something important doing this.
On a road double that's rather less likely than you may think - if you're that knackered, you'll be in the small ring anyway!
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You can either get a derailleur made for mountain biking, which will have both better clearance and more capacity
Check out what the OP is using - campag, so no MTB rear mechs. Mirage triple mech has more chain capacity (solving the big/big problem), but still specced at 29t max. 32 _might_ go - I'd suck it and see, but then I've got a suitable sprocket lying around to do this sort of thing. Sorry, that's not really much help :-(
"David L. Johnson" <[email hidden]> wrote in message news:[email hidden]...
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Quoted message said:
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
This is not a good idea on two counts. The first is, even though you do not plan to use the big-big combinations, when you are tired and desperate for a lower gear, you might shift into one by mistake. If your chain is too short (so that you can use too wide a cassette), you can break something important doing this.
On a road double that's rather less likely than you may think - if you're that knackered, you'll be in the small ring anyway!
Not necessarily. I've seen the results when people shifted into the big-big combination after setting up their chain too short to allow for this. Not a pretty picture.
If the issue were chain take up capacity it would be better to size the chain to allow for the big-big combination and avoid use of the smaller cogs when on the small ring. That way if you accidentally do still shift into small-small the only result is that the chain droops down and you may get some skipping - much better than the damage that can result from accidental use of big-big with too short a chain.
But in this case the problem *isn't* take-up capacity but rather the actual size of the largest rear cog. I've found this can frequently be pushed a bit past the official specs but the only way to tell for sure is to try it on your bike and see.
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
I've done that, use a 11-32 on an old Racing triple RD, the same cage length as the modern medium cage. If you get as large as a 34, a long cage is a better idea.
If I have a 52-39 double chainset and a mirage medium cage rear der what is the largest cog I can get away with at the back. The der specifies 29 as the largest with either a double or triple up front but could I go larger than this provided I avoid going large-large? I rarely go below cog 5 on the back when I am in the big ring on the front so it isn't a lot for me to give up. Could I go to a 11-32 cassette (note I am running a shimano cassette). Anyone with any practical experience of exceeding the der spec like this?
This is not a good idea on two counts. The first is, even though you do not plan to use the big-big combinations, when you are tired and desperate for a lower gear, you might shift into one by mistake. If your chain is too short (so that you can use too wide a cassette), you can break something important doing this.
The second problem is that the upper idler wheel will rub against the big sprockets, and you probably won't have enough adjustment to avoid that.
You can either get a derailleur made for mountain biking, which will have both better clearance and more capacity, or you can get "compact" cranks which allow a smaller chaining in front. The first is cheaper, the second option is more versatile.
Remember that the long cage Campagnolo rear der is really long, the same length as shimano MTB long cage rear ders, but not a 'MTB' rear deraulleur.
Dans le message de news:[email hidden], peter <[email hidden]> a réfléchi, et puis a déclaré :
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Clive George said:
"David L. Johnson" <[email hidden]> wrote in message news:[email hidden]...
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[email hidden] wrote: > If I have a 52-39 double chainset and a mirage medium cage rear der > what is the largest cog I can get away with at the back. The der > specifies 29 as the largest with either a double or triple up > front but could I go larger than this provided I avoid going > large-large? I rarely go below cog 5 on the back when I am in the > big ring on the front so it isn't a lot for me to give up. Could > I go to a 11-32 cassette (note I am running a shimano cassette). > Anyone with any practical experience of exceeding the der spec > like this?
This is not a good idea on two counts. The first is, even though you do not plan to use the big-big combinations, when you are tired and desperate for a lower gear, you might shift into one by mistake. If your chain is too short (so that you can use too wide a cassette), you can break something important doing this.
On a road double that's rather less likely than you may think - if you're that knackered, you'll be in the small ring anyway!
Not necessarily. I've seen the results when people shifted into the big-big combination after setting up their chain too short to allow for this. Not a pretty picture.
If the issue were chain take up capacity [snip]
It's not the issue ! The issue is learning how to use equipment properly. Simple, really. Don't do stupid things. End of lesson. -- Sandy -- Ce message, issu de l'agriculture biologique, a été rédigé avec des électrons recyclés. En conséquence, il est possible que des fautes d'orthographes s'y soient malencontreusement glissées.
