lower gearing

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subandean
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lower gearing

Postby subandean » 9 Sep 2017, 5:46pm

Looking for advice on how best to lower the gearing on a bike running 8 spd Campag Racing T (52-42-30) with 13-26 cassette.
Thanks

Brucey
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Re: lower gearing

Postby Brucey » 9 Sep 2017, 6:22pm

if you get a cassette with a 29T #1 sprocket you will get lower gearing. ~28T or 29T is the largest sprocket that an 8s mech will cope with (in theory).

However 8s cassettes are not so easy to find these days. You may find that you can use the sprockets from a Miche, Bianchi (or I think Ambrosio) cassette with the campag 8s spacers to make a custom cassette. IIRC these types carried on using the 8s spline for some 8s, 9s, 10s cassettes, whereas campag changed to a different spline.

There is a nice set of pictures on the Branford bikes website which shows the different splines.

IIRC you can modify campag 10s sprockets to fit an 8s spline. Thus with 8s spacers (and the 8s lockring, and some of the 8s sprockets) you may be able to make (say) a 15-29 custom 8s cassette by starting with a 10s one that goes 12-29T or something. Or you could use marchesio sprockets.

A worry is that the 10s sprockets are slightly thinner than 8s ones; you may need to use some coke can shims with these to avoid a cassette spacing problem.

cheers
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fatboy
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Re: lower gearing

Postby fatboy » 9 Sep 2017, 8:04pm

I would look to reduce the chain rings. I run 24t on most of my bikes with either 39 or 38 as the middle. Now the jump from 42 to 24 would be too much but 28 could work which would make more of a difference than a slightly bigger cassette.

Your mileage may vary of course!
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Brucey
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Re: lower gearing

Postby Brucey » 9 Sep 2017, 8:39pm

a campag 8s 13-26 cassette usually goes 13,14,15,17,18,21,23,26.

Probably you don't need the 13 and the 14 so one can go, to be replaced by a 29T sprocket.

BTW whether it is a smaller chainring or a larger sprocket, you will use up derailleur capacity. Do be sure that you have some to spare. A benefit to the smaller chainring approach is that you won't need a new/longer chain (unless it is already worn).

cheers
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Debs
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Re: lower gearing

Postby Debs » 9 Sep 2017, 10:13pm

I successfully lowered the gearing on a Shimano Tiagra triple from 52-42-30 to 48-38-30 using French TA

The lowest gear isn't a concern to me but nothing to stop you changing it too if you wish.

The front mech from a 52 ring will need to adjust down quite a bit to fit a 48, no problem with band mech but one will need to hope a braze-on front mech has enough adjustment available...

IMO 48-38-30 is the perfect winter run about gearing. The 9 speed rear block i use is 13-25

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Tigerbiten
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Re: lower gearing

Postby Tigerbiten » 10 Sep 2017, 12:09am

subandean wrote:Looking for advice on how best to lower the gearing on a bike running 8 spd Campag Racing T (52-42-30) with 13-26 cassette.
Thanks

How far do you want to step it down by ??
If by only about 1 gear (10%) then .....
Either drop the 13 sprocket and fit a 29 tooth sprocket.
Or change the crank to a 110 BCD and fit a 48-38-26 triple.
Both give very similar results.
If you want to go lower then a 110 BCD and a 44-34-22 triple will give you the lowest gears without changing the cassette. But you may need a MTB front derailleur to cope with the very small chainrings, which may mess up the front shifting.

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Mick F
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Re: lower gearing

Postby Mick F » 10 Sep 2017, 6:06am

I have a Campag triple and swapped my 30t inner for a 28t and I could have gone to 26t. Not sure if it would take a 24t, but I willing to bet that it would.

That is the simplest way of lowering the gearing.
Mick F. Cornwall

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foxyrider
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Re: lower gearing

Postby foxyrider » 10 Sep 2017, 9:35am

Mick F wrote:I have a Campag triple and swapped my 30t inner for a 28t and I could have gone to 26t. Not sure if it would take a 24t, but I willing to bet that it would.

That is the simplest way of lowering the gearing.


I have a Xenon triple set up with 52/39/26 rings - it would take a 24 if I wanted to be really silly. The braze on mech means it sits a bit high meaning dropping into the 26 requires a bit of juggling although it changes up ok.

It originally ran with 8 speed but now has 10 at the back (11-29 custom build) to play with using the same 8sp Veloce long arm mech. I do have to run the chain slightly short to stop flapping but I can get the extremes - not that 52x29 is something i'd expect to use! Overall it's an 84” gear spread, I did use the 26 to get up the ferry ramp at Europoort last weekend!

With a 24 front it would work with a 30 rear.
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subandean
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Re: lower gearing

Postby subandean » 10 Sep 2017, 1:52pm

Mick F wrote:I have a Campag triple and swapped my 30t inner for a 28t and I could have gone to 26t. Not sure if it would take a 24t, but I willing to bet that it would.

That is the simplest way of lowering the gearing.


Thanks Mick, simplest solution, I willl swap the 30 chain ring for a 28

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Mick F
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Re: lower gearing

Postby Mick F » 10 Sep 2017, 2:20pm

Mick F. Cornwall

De Sisti
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Re: lower gearing

Postby De Sisti » 10 Sep 2017, 3:50pm

Debs wrote:IMO 48-38-30 is the perfect winter run about gearing for me. The 9 speed rear block i use is 13-25

FTFY :wink:

tatanab
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Re: lower gearing

Postby tatanab » 10 Sep 2017, 4:10pm

Mick F wrote:I have a Campag triple and swapped my 30t inner for a 28t and I could have gone to 26t. Not sure if it would take a 24t, but I willing to bet that it would.

That is the simplest way of lowering the gearing.
Yes it takes a 24 no problems. That is the smallest that is supposed to run on that PCD, but there is a cheap steel 22T available which will also fit but puts the chain so close to the end of the crank spider that it touches it. So, 24 T is the practical smallest and one I've been running for over12 years.

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subandean
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Re: lower gearing

Postby subandean » 22 Sep 2017, 9:23pm

Thanks for all the advice.
I plan to run a 50-39(TA rings)-26(Spa).