Maestro

I've got a Novara Divano '08. Like it fairly well, but find the range too narrow for my fitness level and our hills around here. As a result, I find myself taking out my touring bike out most of the time.

I want to extend the range in a rear. Currently it has 12-25, and I probably want to go to all the way to 30/34, given that I have a road crankset in the front.

Is my assumption right that I have to replace the derailleur (Tiagra), and overall, I'm looking at new casette, derailleur and chain ? Would this be all ?

Thanks,
-MB

AEO

well, what chainrings up front do you have?
consider a triple?

can easily get a 26T 74BCD chainring.

the jumps in gear ratio really suck for 11-34 and 11-32 cassettes.

Al1943

+1
Mountain style cassettes are fine in the mountains but the large ratio jumps cause large cadence jumps and that sucks on high speed road rides, especially if you're trying to keep up with other riders.
Shimano mountain cassettes are 9-speed. If you have 10-speed shifters you'd need an IRD or some other aftermarket mountain cassette. How many cogs do you have in the back and what size chainrings?
It may be possible to convert your 12-25 cassette to a 13-28 if you can find the right parts. And a new 12-27 would be less expensive.

Al

Maestro

Sorry, I should've been more specific.

I already have a triple in the front, 50/39/30.
The bike is a 9 speed Tiagra, and I was actually thinking mountain style cassette.
I realize gear jumps will be bigger, but this is by far not a racing bike - nor is the intended use
I'm not sure that going from 25 to 27 will give me enough difference - I judge by difference in gear ration between my road(this) and my touring bikes - I have 11-34 on the touring (I do have smaller crank on it as well though - 48/38/28), and that setup works pretty fine for me.
The idea is that I would be able to do all those hills without hauling fenders and rack when I'm just out on a fitness ride around

The question still stands - do I have to replace rear mech ?(I'm almost positive). Also - will front derailleur handle bigger difference in the rear? (As far as I remember, it's Sora).

Thanks!

joejack951

Your front derailler won't notice the change in back though the rear will. It's possible that you could get away with running an 11-32 on a long cage Sora derailler but not likely. I had to turn the B-tension screw all the way just to use an 11-28 on my wife's bike. No way it would have cleared a 32 tooth cog. A 34 tooth cog is definitely out of the question for any road derailler though some here have had luck using 32 tooth cogs with road deraillers (Ultegra mainly, based on my observation).

What you will definitely want to do when you add the larger cassette is to lengthen your chain (or just replace it). You run the risk of severe damage if you ever shift into the big/big combo if your chain is sized for a 50/25 max and you are running a 50/32 or 34.

I use a 9 speed 11-32 cassette on my commuter bike and have done road rides with it. The jumps can feel a bit much towards the larger end of the cassette but it's nothing I couldn't deal with even when riding with others. The added bonus of the extra range make it worth it for me. I need a really steep or long hill to require shifting out of the middle ring. In the granny ring, I don't think there's a paved road that could stop me

AEO

shimano uses 130/74BCD, so I would just get a 24T or 26T chainring and be done with it. (I'd recommend sugino, since it's inner ring is shaped the same as shimano)

then if you really really need a lower gear, you can get a deore 11-34 and take the 26T and 30T from that. they would be replacing the 16T and 25T cogs from the 12-25 cassette.

which would give yourself a nice 12-13-14-15-17-21-23-26-30 cassette.

Chris_W

I expect that the top three gears on the 12-25 come as a one-piece unit and cannot be divided. My favorite large-range cassette is one that I put together using a 12-25 10-speed cassette, removing the 16T and putting a 28T on the end which came from an 11-32 9-speed cassette (I believe Deore and LX cassettes are suitable for this because they are separable, but with XT and XTR cassettes the top three rings are again one unit, so they cannot be used for this). I had to play around with a few different spacers between the 25 and 28 until I found a combo that worked. When I want even lower gearing, I remove the 14T and put the 32T on the end (and use an MTB rear derailleur).

rickowensis

As stated before, you will need a new chain without question. If you elect to choose a 30+ tooth on the rear cassete, choose a mountain bike rear derailleur such as a Deore or better quality. A nine speed mountain cassete with your preferred range should do the job.
I have changed gearing ranges on a few road bikes for the same reason.
Exceeding 32 teeth on the rear cassette shouldn't be necessary as the Divano is lighter than your touring bike. Good luck!

AEO

not for tiagra, they're just held together with 3 screws, but otherwise the cogs are all loose pieces.
https://bike.shimano.com/media/techdo...9830608763.pdf

even if they were, a deore 11-34 cassette offers a 23T.

getting a deore or deore LX cassette is necessary because those two are built with loose cogs, unlike the XT which is on a carrier spider. yes

Maestro

Coming back to this;

Thanks for all the advice, I'd probably go with front inner chainring replacement for now - haven't thought of that option before.

Would it be reasonable to go to 24 or should I stick with 26 ? Do I need to add a chain deflector?

And, would this:
https://www.ebikestop.com/sugino_26t_...ing-CR1151.php
or this:

https://www.ebikestop.com/sugino_24t_...ing-CR1150.php

work ?

Thanks.

clink83

Nevermind.

noglider 

Let me get this straight. You tried pedaling with the chain on the 30T chainring and the 25T rear sprocket, and the gear isn't low enough for you? That could be, but I believe it won't be long before you find that that low gear is so low you won't ever need it again. Unless perhaps I don't know how hilly your area is. I've been to Seattle and know it's very hilly, but what kind of hills are you on in Bellevue? How long is the longest one you typically ride?

Maestro

Well, if I feel I don't need it anymore, I'd put the old chainring back.

As for what kind of hills, the hill to my place (pretty much from anywhere), is a 1.5 miles 6-10% grade.
I'm not able to do it yet. But when I do, I doubt that I still won't need granny gear.

joejack951

I'm not sure how someone determines what gearing someone else needs through the internet. I so frequently hear "you'll never need a gear that low" that I'm beginning to think that maybe I'm missing something as I can't always tell someone what low gear they need when I'm out riding with them let alone meeting them in person. I've been out with very strong cyclists and seen them wishing for at least one more gear lower than a 30/25 so I know that plenty of cyclists out there could use something much lower.

Anyway, Maestro, those chainrings you linked to will work just fine. Any 74mm bolt circle chainring will do the job.

c_m_shooter

I have ran an 11-32 cassette with a Tiagra derailer on my Cross Check without any problems. Don't listen to the naysayers, you may need to add a couple links to your chain though.

noglider 

Sorry about my presumptuous tone. I didn't mean to sound like that.

Wordbiker

Don't listen to the people that call other people naysayers when they're running incompatible components with "no problems". They may not know the difference.

IK_biker

joejack951 wrote:
Not so. That's what I thought too, but then this fellow chimed in:
Poster: Deanster04, post #8587332.
After some PM exchange, I can tell you he knows his stuff pretty well.

I realise that RD hanger geometry, and frame interface (angle) to said hanger have impact on this, but don't be too quick to dismiss the thought only because it did not work on joejack951's wife's bike.

So much about the naysayers...

joejack951

In my defense, though I didn't state it, I was referring to Shimano products, given that the original poster has Shimano. Campy long cage rear deraillers are spec'd for a 29 tooth rear cog (as opposed to 27 for Shimano) so I'm not surprised that one can handle a 34 tooth cog with the right derailler hanger geometry. There might be a frame out there that lets a Shimano road derailler work with a 34 tooth cog but so far I have not heard of one.

Sluggo

I don't know the best way to make it work with your current hardware, but I have become more and more convinced in recent years that most bikes are over geared for those who want to maintain a reasonable cadence at an attainable power output. A low gear in the low 20 inches in not too low for someone in who is not an elite athlete and who doesn't live in the flat lands. The lower I get my low gears the more I find a need for low gears. And a top gear of 100 inches is probably too high, so ditch the 11's and 12's and probably 13's.

Harris has some good gearing options.

Maestro

So, I've got Sugino 24T inner ring - the one that I linked to above.
My crankset, apparently, is not Shimano - it's FSA Omega.

Anyway, after I got it off and removed inner chainring, it seemed not to be completely flat - mounting points are slightly out of plane with the chainring itself.

After I installed the Sugino one, everything appears to be working properly except for one thing -
I think that chain rubs very slightly on middle chainring ramps when on inner chainring.

How much of a problem this is? Did I have to order different chainring? Do I need some kind of a spacer?

Thank you,
-MB

Chris_W

This is a problem that normally occurs when changing the inner chainring on many Shimano cranksets, also. The solution is to get some thin washers from a hardware store and place them between the chainring and the mounting post. The only hard part is finding washers that have a whole in the middle that is large enough for the chainring bolt to go through, but at the same time are not too thick. The ones I've used successfully on several Shimano cranksets have a thickness of 0.8mm, but anything of around 1mm should also work, and an internal diameter of 8.5mm, but anything between 7-10mm should also work. The external diameter is not too important, as long as they are not stupidly big.