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chain ring question

Old 11-15-16, 12:15 PM
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chain ring question

We've got some serious hills here in San Antonio (I know-hard to believe) would I benefit from changing to a 38T front chain ring from my current 42T? I believe my spacing is 130mm.
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Old 11-15-16, 12:23 PM
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There is about a 10.5% difference between a 38T front chain ring and 42T front chain ring. Courtesy of Sheldon Brown's gear calculator.
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Old 11-15-16, 12:27 PM
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The Torpado's BCD looks to be 144mm. Smallest inner which can be fitted is 41T. Options are to make a change on the back or use a different chainset.

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Old 11-15-16, 12:40 PM
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Originally Posted by juvela View Post
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The Torpado's BCD looks to be 144mm. Smallest inner which can be fitted is 41T. Options are to make a change on the back or use a different chainset.

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Or add a triplizer ring


(Red Clover Components - Red Clover Components - Bicycle Triplizers and Chainrings)


although that might be a more elaborate solution than you want.
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Old 11-15-16, 12:43 PM
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Originally Posted by jonwvara View Post
Or add a triplizer ring


(Red Clover Components - Red Clover Components - Bicycle Triplizers and Chainrings)


although that might be a more elaborate solution than you want.
Now where on earth I wonder would a person be able to find such and item?
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Old 11-15-16, 01:45 PM
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Sounds like I just need to suck it up and live with it! Ha--story of my life.
Thanks guys
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Old 11-15-16, 02:04 PM
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Move to Houston I don't use my small chainring or front derailleur unless I go to San Antonio!
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Old 11-15-16, 02:43 PM
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Originally Posted by LouB View Post
Sounds like I just need to suck it up and live with it! Ha--story of my life.
Thanks guys
All joshing aside.

If gearing not to your needs do not hesitate to make a change.

A bike which is not geared correctly for you is a disincentive to ride.

BTW Sig. Torresini's front mech looks to be one of the seldom seen Nuovo Valentinos. Is that correct?
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Old 11-15-16, 02:54 PM
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I live in Buvlerde, to get home from Cibolo Creek is a 400' climb including 14% grade, and here's what I did - a cyclotouriste triple with half-steps and a granny ring (26T)



This also required changing the bottom bracket to 121mm asymmetric, which I did with SKF and 2.5mm spacer (if you try this, get a 4mm spacer, too, and use which one works best - tightest clearance is the chainring stack bolt heads against the chainstay).


here's the chainline on the little ring (and 18t middle rear cog)
A cyclotouriste is so narrow, it works best with road double FD

I did this originally on my '77 Grand Prix, which I rode this way for about 5 years, and I'm moving the whole drivetrain over to an International frame.
I have another cyclotouriste stack and arms around here, but I think a friend has already claimed it.

and yes, if all else fails, take the 10%.

Last edited by bulldog1935; 11-15-16 at 03:25 PM.
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Old 11-15-16, 03:03 PM
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Now that's getting it sorted!

Thanks for this fine post.


-----
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Old 11-15-16, 03:27 PM
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So I'm assuming they dont (and never have) made a 38t ring with a BCD of 144mm. That sure sounds like an easy fix. Wouldnt want to loose the pantographed big ring. Damn, I might just have to move to Houston.....
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Old 11-15-16, 03:31 PM
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smallest chainring for 144 BCD is 41t, which TA makes (I may have one here). SJS and most UK/EU vendors sell it - search Campagnolo Strada chainrings to find it.
https://www.sjscycles.co.uk/chainrin...nring/?geoc=US

I ran half-steps with 46/41T and 13-28t rear for a few years before I sprung for the cyclotouriste.


never mind, i checked - I have the 46T - the 41T went with the Strada-clone crank to my daughter's go-fast.

Last edited by bulldog1935; 11-15-16 at 03:37 PM.
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Old 11-15-16, 03:41 PM
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Originally Posted by LouB View Post
So I'm assuming they dont (and never have) made a 38t ring with a BCD of 144mm. That sure sounds like an easy fix. Wouldnt want to loose the pantographed big ring. Damn, I might just have to move to Houston.....
41T is a physical limit with the 144mm BCD.

Ironically, the maker of your chainset, OFMEGA, was the first manufacturer to offer a 41T c/w for the 144BCD. Prior to that 42T was the smallest. Also well known in the U.S. as Avocet brand.

Last edited by juvela; 11-15-16 at 04:05 PM. Reason: addition
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Old 11-15-16, 03:42 PM
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Originally Posted by juvela View Post
All joshing aside.

If gearing not to your needs do not hesitate to make a change.

A bike which is not geared correctly for you is a disincentive to ride.

BTW Sig. Torresini's front mech looks to be one of the seldom seen Nuovo Valentinos. Is that correct?
Here's a closer shot of the front DR. From what I've read Valentino's are not highly thought of, though it works fine for me.
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Last edited by LouB; 11-15-16 at 03:51 PM. Reason: spelling
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Old 11-15-16, 03:56 PM
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Originally Posted by LouB View Post
Here's a closer shot of the front DR. From what I've read Valentino's are not highly though of, though it works fine for me.
Thank you.

Can see the winged wheel logo on the cage in this new photo. It was not discernable due glare/reflection in the earlier picture.

Have one of these on a Bianchi model 980 from ~1979-80.

There is the Valentino (pushrod) and the Nuovo Valentino (parallelogram).

VeloBase.com - Component: Campagnolo 2050, Valentino

VeloBase.com - Component: Campagnolo Nuovo Valentino

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Old 11-15-16, 03:59 PM
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Originally Posted by bulldog1935 View Post
If you put some pedals on that bike you'd get more power to the ground. Then you might not need the triple.

FWIW, a 47T-42T ring pair makes a nice half-step crossover with a 14-34T 6-spd FW.

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Old 11-15-16, 04:00 PM
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Still waiting on my seatpost - if I stand the whole time, I don't need the triple.

and yes, those are nice half-steps

47T TA Pro5Vis outer rings are hen's teeth - they haven't made them since the 80s - I actually have one on the other ring stack,
47/42/26T.

Last edited by bulldog1935; 11-15-16 at 04:04 PM.
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Old 11-15-16, 04:07 PM
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Pedaling without a seat post is a WHOLE lot more comfortable than pedaling with a seat post and without a seat.

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Old 11-15-16, 04:25 PM
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Originally Posted by LouB View Post
So I'm assuming they dont (and never have) made a 38t ring with a BCD of 144mm. That sure sounds like an easy fix.
It's not possible. A 144 mm BCD is simply too big for a chainring that size. The chainring bolts of a 144 mm BCD crankset would be sitting in the teeth of a 38-tooth chainring and getting in the way of the chain.
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Old 11-15-16, 04:38 PM
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Originally Posted by SkyDog75 View Post
It's not possible. A 144 mm BCD is simply too big for a chainring that size. The chainring bolts of a 144 mm BCD crankset would be sitting in the teeth of a 38-tooth chainring and getting in the way of the chain.
Makes sense.
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Old 11-15-16, 04:48 PM
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so another option would be to keep the 52/42t front and swap out the free wheel for one with a larger big ring.
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Old 11-15-16, 04:54 PM
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Originally Posted by LouB View Post
so another option would be to keep the 52/42t front and swap out the free wheel for one with a larger big ring.
What you got in the back now?

A 28 was about as large as derailleurs of that day could handle, but if you have something smaller, a 14-28 was a very common cog range. You could get more going to a long cage RD though.
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Old 11-15-16, 04:55 PM
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Originally Posted by juvela View Post
Now where on earth I wonder would a person be able to find such and item?

I know, shameless of me--couldn't help myself.
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Old 11-15-16, 05:07 PM
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Originally Posted by jonwvara View Post
I know, shameless of me--couldn't help myself.
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Old 11-15-16, 05:15 PM
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Originally Posted by juvela View Post
-----

Pedaling without a seat post is a WHOLE lot more comfortable than pedaling with a seat post and without a seat.

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Especially with no pedals.
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