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Old 10-19-05, 03:54 AM   #1
johncap
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sora 8 speed

Hi,
i am riding a new Giant ocr 3 , fitted with sora shifters, triple chain ring and 8 sprocket rear cassette.
My question is:-
Should i be able to go thruogh all 8 sprockets whilst on the middle chain ring, without getting serious rubbing on the de-railer?

The current set up of the bike is as follows:-
( I don't use small chain ring,granny gear, so that is irrelevant for now.)
Middle chain ring- 1st Gear(largest rear sprocket) slight rubbing on de-railer.
From here i can shift through the next 3 gears before rubbing
starts agin in 5th gear.Past this point rubbing on the de-railer
becomes serious.

So, when riding, i use the middle chain ring with the 4 larger rear sprockets. This allows me to cleanly select low gears while climbing. ( i live in a hilly area.)When i get to 4th gear i swich to large chain ring, and select higher gears from there.

Does this sound reasonable?
I have noticed friends(With different drive chains) seem able to select all gears from 1 chain ring without any serious rubbing.

Thanks for any help

Cheers from the Goldcoast

John
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Old 10-19-05, 04:19 AM   #2
The Seldom Kill
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Presuming that you're talking about the front derailleur, the answer to that question is no.

I use the middle ring in conjunction with gears 2-7 without any rubbing. The indexing took me about 30 minutes to set up though an I haven't been able to get it any better than that.

Normally if I'm dropping below middle-3 then I shift to granny-5 and work down from that as necessary. Climbing above middle-7 is straight to large-6.

The shifters have a built in step option that allows you to move the front derailluer a little to prevent rubbing, but this only seems to be on the upshift and not the downshift. Maybe I'm not doing it right.

I would question your step-up to large ring timing as I, personally, find that a good range of cadence can be achieved on the middle-5to7 range for a cruise speed of 16-22mph on the flat. Of course what ever is comfortable to you is most important but how is your cadencing?
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Old 10-19-05, 04:52 AM   #3
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Thanks for the reply
Yes it was the front de-railer(oops)
I agree with you about timing of big ring, i only up-shift at that time to aviod rubbing on de-railer.
i might have to try granny gear and look at some adjustments.

p.s. with more expensive running gear is it still the case that you can't access all gears from 1 chain ring?
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Old 10-19-05, 05:02 AM   #4
The Seldom Kill
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I would say more so.

Basically the anticipation is that the more you spend on a bike, and therefore shifters, the more proficient you are at riding in harmony with your bike. Therefore they don't think that you're likely to consider that kind of range of gearing on one ring which affects the life of the chain and chainrings (3D sharkfining). Given that it's also easier and more accurate to set up a tight front derailleur they simply won't expend time and money on trying to produce a less reliable product for minority audience.
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Old 10-19-05, 05:06 AM   #5
The Seldom Kill
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You say that you live in a hilly area. I'd advise more use of the granny ring and faster pedalling. It'll do your knees a lot less harm and get you up the hills faster. Just remember to change down before you lose much cadence. Anticipatory shifting is difficult to start with but you'll get better with a bit of practice.
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Old 10-19-05, 05:18 AM   #6
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My Sora triple only rubs when I try to use either the largest or smallest rear cogs while on the middle chainring. I hardly ever do that though since I try to keep the chain line as straight as possible. I would probably have shifted to either the 52 or the 30 by the time I would have been looking for a ratio on either extreme of the cassette. Keeping the chain straight will help all the components last longer. For regular riding I like to keep the cassette plus or minus 3-4 cogs to the chainring in use...eg if I'm using the 52, I can select the top 4 cogs (the smallest 4) and if on the 30, I can select the bottom 4 (the biggest 4). On the 42 I can use the middle 6. Clear as mud?
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Old 10-20-05, 01:56 AM   #7
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thanks Seldom Kill and jbrians.
you have both been a great help
cheers
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Old 10-20-05, 05:04 AM   #8
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It is possible, through some careful tweeking, to be able to use all 8 rear cogs when in the middle ring on a Sora triple. My Sequoia is adjusted this way. While it's not exactly recommended, I do use all 8 cogs pretty frequently as I find the 42 ring to offer a great range of speeds.

Sora shifters have no intermediate shifts (trim). Start by making sure your high and low stops are set correctly then use tension adjustments to set the derailleur so that it does not rub when in the middle ring. Make sure the deraileur cage is set parallel to the frame before doing any of this.
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Old 10-20-05, 07:10 AM   #9
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Quote:
Originally Posted by The Seldom Kill
Presuming that you're talking about the front derailleur, the answer to that question is no.

I use the middle ring in conjunction with gears 2-7 without any rubbing. The indexing took me about 30 minutes to set up though an I haven't been able to get it any better than that.

Normally if I'm dropping below middle-3 then I shift to granny-5 and work down from that as necessary. Climbing above middle-7 is straight to large-6.

The shifters have a built in step option that allows you to move the front derailluer a little to prevent rubbing, but this only seems to be on the upshift and not the downshift. Maybe I'm not doing it right.

I would question your step-up to large ring timing as I, personally, find that a good range of cadence can be achieved on the middle-5to7 range for a cruise speed of 16-22mph on the flat. Of course what ever is comfortable to you is most important but how is your cadencing?
Actually, the answer is .. 'it depends'. Short chainstays provide less latitude among other variables.... A sora triple front shifter has trim only for the granny ring, IIRC.
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Old 10-20-05, 08:45 AM   #10
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I forgot about chainstay length. That does make a big difference. The stays on my Sequoia are I think 16.5" which is quite long (at least compared to my other road bike at 15.25"). That length is most likely the reason why I can use the whole cassette so easily.
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Old 10-20-05, 08:49 AM   #11
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Quote:
Originally Posted by joejack951
It is possible, through some careful tweeking, to be able to use all 8 rear cogs when in the middle ring on a Sora triple. My Sequoia is adjusted this way. While it's not exactly recommended, I do use all 8 cogs pretty frequently as I find the 42 ring to offer a great range of speeds.

Sora shifters have no intermediate shifts (trim). Start by making sure your high and low stops are set correctly then use tension adjustments to set the derailleur so that it does not rub when in the middle ring. Make sure the deraileur cage is set parallel to the frame before doing any of this.
Yes they do.. Trim for the big ring on a double and trim for the granny on a triple, IIRC.
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Old 10-20-05, 10:50 AM   #12
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I should have mentioned I have a small Giant kronos frame so the stays are shorter than others might. Thanks Sydney for mentioning that.

Small Giant? Military intelligence?
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