Help I need smaller gears - what can I do? A GUIDE

redddraggon

Generally bigger sprockets and smaller chainrings equals smaller gears.

Getting bigger sprockets is normally done by fitting a wider ranging cassette, 12-27 (shimano), 11-28 (SRAM), and 13-29 (Campag) are commonly available. If these are still too small a MTB cassette can be used (assuming you have 8-spd or 9-spd) which come in the ratios 11-32 or 11-34 - these normally require an MTB rear derailler to work suitably. MTB cassettes can also come in 11-30 and these may or may not work with road deraillers Changing the cassette is normally the cheapest option.

Assuming a standard double (53/39 etc) smaller chainrings can be achieved by fitting a compact (50/34, 50/36. 48/34), normally the current front mech will be fine for a compact along with the shifters.

To get even smaller chainrings at the front a triple can be fitted, these come in ratios similar to 50/40/30, 53/39/30 and 52/42/30 etc, "touring triples" are also available with slightly smaller chainrings eg 48/38/28.

A double to triple conversion is usually pretty costly, a new front mech, longer caged rear mech, and shifters (if only double compatible - Campagnolo and some shimano shifters are triple and double compatible).

(MTB triples (eg 44/32/22) can be fitted to road bikes, but road specific front mechs tend not to be able to cope with the very small chainrings)

gematkinson1

very useful... thanks!

fizz

dont forget a Shimano std double will take a 38 T inner ring so thats another option if you dont want to go the whole hog down to a compact.

woody-som

or even try the rotor Q ring on the inner of a normal double. will reduce the effective size of the ring on the hardest part of the circle. I ride them, and find I actually use a bigger gear at the back now, since the change from normal chainrings.

loz*

this is great, i've been wanting to ask questions about this for a while but didn't fancy starting a new thread just for it.

Can someone tell me, if I wanted to change from a double to a triple, would i need a new front derailleur? How would I be able to tell whether the shifters I have could cope with a triple? What is a longer caged rear mech?

thanks in advance!

grayo59

woody-som wrote:

or even try the rotor Q ring on the inner of a normal double. will reduce the effective size of the ring on the hardest part of the circle. I ride them, and find I actually use a bigger gear at the back now, since the change from normal chainrings.

Sorry? What does this mean in layman's terms please.

andrew_s

If you want a triple, rather than buy a new chainset, you can replace your inner chainring with a triple converter chainring (plus the 3rd chainring, another set of bolts and some spacers). The new small chainring then bolts to the new middle chainring rather than to the cranks direct.

You may or may not require a longer bottom bracket. It depends on the amount of clearance you have, and whether your front mech will swing in far enough to change onto the small ring without hitting the seat tube. Experimentation is in order.

andrew_s

For loz:

If changing to smaller chainrings, you may possibly require a new front mech for the following reasons.

1) The cage of the front mech is too short, so that when it's as low as it will go whilst clearing the big chainring, when in small/small the chain drags across the bottom end of the cage.
Try fitting a smaller large chainring so you can drop the front mech a little lower on the seat tube, or just avoid using the small half of the cassette with the small chainring. If this doesn't appeal or or doesn't work, then a look at a new mech.

2) The curve of the outer plate of the front mech is sized for a 53 chainring. If the large chainring is too much smaller than this, the bottom end of the cage will be well away from the chainring. The result is that you get poorer shifting between the middle and small chainrings and back up onto the large chainring, especially under power. Generally 48 is OK, smaller is where the problems start.

---

Longer cages on the rear mech.
The cage length is the distance between the upper jockey wheel and the lower one. Many rear mechs are available with different cage lengths (short/medium/long, or just short/long).
If you put the chain tight round small/small, you need less chain than when tight round large/large. The chain has to be long enough to go round large/large, and when you change gear the rear mech puts a zizzag in the chain to use up the spare and keep it tight. The amount of spare chain that you need to be able to wrap up in the zigzag depends on the sum of the differences between small and large chainrings and small and large sprockets. The amount of spare chain that can be used up the the zigzag depends on the cage length, and is expressed as having a capacity of so many teeth in the mech specifications.
So if you have a 52/42 chainset, and 12-23 cassette, your rear mech should have a capacity of 10+11 = 22 teeth or more
If you have a 30/40/50 chainset, and a, 13-29 cassette, your rear mech should have a capacity of 20 + 16 = 36 teeth.

In practice it doesn't matter if you exceed the rear mech capacity by a few teeth. What happens is that the cage comes up past the horizontal so the chain drags noisily across itself at the top jockey, and it's a bit slack so it will come off more easily if you hit a bump.
But you don't use small/small do you?

---

Do my shifters cope with triple?
Look up the specs for your shifters on the interweb.
Or you can count clicks and check whether the shifter pulls enough cable. One click is definitely double only, three or more is definitely OK for triple. If it's two, it may be double with trim or triple.
Back off the high and low gear limit screws on the front mech, then with the chain off, hold the mech cage positioned above the granny ring (or where it would be), and with the other hand take a grip on the inner cable where it emerges from the front of a cable stop (where "front" is towards the front of the bike). Then let the mech move to above the large ring whilst pulling on the cable by the stop. The distance the cable moves out from the stop tells you how much cable pull is needed to shift across 3 rings. To find out how much cable the shifter will pull, change to the large chainring end as far as the shifer will go, then grip the cable inner where it emerges from the rear of a cable stop, and keep it tight as you work the shifter as far as it goes towards the small chainring.
Don't expect too much accuracy, but it should tell you if the mech is well short of pulling enough cable.

loz*

wow, lots of info. thanks a lot for your effort!

Leedsblue

redddraggon wrote:

Assuming a standard double (53/39 etc)

What is the default size on a standard road bike (i.e non custom specced). My 42/52 13-23 seems rather restrictive in a hilly area and I seem to see more people having a 39/50 set up.


Secondly, if you have a Campag set up and decide to change the cassette to give a bigger gear is there any reason to stay with Campag or go with say the SRAM which offers a bigger range or whatever cassette is available cheaply at the time

Good thread, thanks for starting

woody-som

grayo59 wrote:

woody-som wrote:

or even try the rotor Q ring on the inner of a normal double. will reduce the effective size of the ring on the hardest part of the circle. I ride them, and find I actually use a bigger gear at the back now, since the change from normal chainrings.

Sorry? What does this mean in layman's terms please.

The rotor Q rings are not round. When your foot is at the top and bottom of the pedal stroke, you have less power in your legs to turn the gears, so the Q rings are smaller in this possition, and when your foot is at the 2-4 O'clock position, you have maximum power and the rings are actually bigger at this point than conventional rings.

I have both the small and large chainrings as Q rings, but you can just get the smaller one if you want.

loz*

Thanks again for the previous replies on this thread, they've been very useful.

I've decided that going triple will be too expensive (my sora shifters aren't triple compatible (model st-3300)).

Currently i've got 52/42 double chain rings and a 12-23 8 speed sora cassette. The front and rear derailleurs are also shimano sora.

The reason i'd like to get some easier gears is so i can use my older bike for some touring and i think i'd struggle to climb big hills day in , day out with the current setup.

So, my new plan is to get a Shimano HG50 8-speed cassette 11 - 32T
and a Shimano 3450 Sora 9-speed Compact chainset - 50 / 34T

Can anyone see a problem in this? I thought i'd wait and see if the rear derailleur works or not before getting another (i can't work out if my existing one is small/med/large!). Same logic with the chain, not sure if i'd need a different one so will just play it by ear. Guess I'll need tool for changing the cassette and chainrings too, any suggestions?

andrew_s

woody-som wrote:

The rotor Q rings are not round. When your foot is at the top and bottom of the pedal stroke, you have less power in your legs to turn the gears, so the Q rings are smaller in this possition, and when your foot is at the 2-4 O'clock position, you have maximum power and the rings are actually bigger at this point than conventional rings.

Q rings won't get you a lower gear as the smallest radius can't be any smaller than the smallest possible with a round chainring. The smallest Q ring that will fit on 130 bcd road cranks is 40T, and the smallest Q ring that will fit on 110 bcd compact cranks is 36T, comared to 38/34 for round rings
What they do is to allow you to use a slightly higher gear, without losing as much momentum when the cranks are at 6/12 o'clock as with round rings.

adeyboy

Assuming you change the cassette for one with bigger sprockets, will this then work OK straight away?
For instance I have a 12-26 SRAM 9 speed cassette, will any other 9 speed road cassette just slip in with the rest of the transmission system or will the rear mech need fiddling with etc? Seems a fairly simple job just to change cassette if that is all there is to it.

Went out on MTB today for first time since bought road bike 3 months ago, got to say that I tackle bigger hills on the road bike so a few more gears may help; the MTB granny ring is amazing! I'd forgotten really; I could sail up the Galibier on that!!!

The Shiny

Same question as above really, I have a Shimano 105 10spd 11-25 and I'm getting old.

Can I just change to a 12-27 and expect it to work without too much fiddling about?

redddraggon

The Shiny wrote:

Same question as above really, I have a Shimano 105 10spd 11-25 and I'm getting old.

Can I just change to a 12-27 and expect it to work without too much fiddling about?

The only thing likely to cause a problem would be chainlength - but it's normally worth getting a new chain with a new cassette anyway.

GavH

I have a 52/36 on the front and a 12-26 8 speed on the back. I have Shimano Sora 8 spd shifters. If I were to upgrade my square taper BB to a Hollowtech II and my front cranks to a 50/34 Compact to give me some extra breathing space on the bigger, longer hills, what other considerations do I need to take account of, or is it a straight swap out?
Thanks for any advice.

rickhotrod

I think you mean a 52/39 rather than a 52/36, otherwise you would already have a Compact.

Fitting a 50/34 would be a straight swap except for the need to lower the front mech a bit, and not using the two smallest sprockets with the 34 chainring if you have a short rear mech fitted.

Another option is to fit a 13-29 cassette with the 52/39. However, an 8-speed 13-29 cassette is not available off the shelf, so make it up using a 13-26 7-speed cassette and a 29 sprocket from a 14-34 7-speed cassette. Use the slightly thinner 8-speed spacers.

I have a 52/36 on the front and a 12-26 8 speed on the back. I have Shimano Sora 8 spd shifters. If I were to upgrade my square taper BB to a Hollowtech II and my front cranks to a 50/34 Compact to give me some extra breathing space on the bigger, longer hills, what other considerations do I need to take account of, or is it a straight swap out?

gbs

Leedsblue wrote:

redddraggon wrote:

Assuming a standard double (53/39 etc)

What is the default size on a standard road bike (i.e non custom specced). My 42/52 13-23 seems rather restrictive in a hilly area and I seem to see more people having a 39/50 set up.


Secondly, if you have a Campag set up and decide to change the cassette to give a bigger gear is there any reason to stay with Campag or go with say the SRAM which offers a bigger range or whatever cassette is available cheaply at the time

Good thread, thanks for starting

Did you get a response? I am struggling in the same way - lowest ratio available on my Campag setup is 39/23 = 1.7. I am hoping that x-27/29 cassette will solve the problem of 20% gradients.

Next issue: what are the tips for defeated, cleated riders forced to get off and walk? I do not want to fall again!

redddraggon

gbs

13-29 cassettes are available. I assume you have 10 speed Campag?

Whether or not it makes 20% doable is dependant on an individual's fitness.

I've got a similar 34-25 to the 39-29 on my good bike, it just requires me to stand up for the steeper bikes

On my Audax/Winter bike, I've got 50/34 with 13-29, that makes getting up hills easy

davidmiller

I asked this question last year and RD gave me some feedback - but I can't find the post now :oops: :oops:

So, I have a Trek 2000 with a standard Ultegra group set. Help - I need smaller gears -what can I do??? I understand it will be hard (read: expensive) to go to a triple so FTFAGoM. Should I go to a compact or get bigger cogs at the back????? I want the easiest gears at the lowest cost where I won't loose to much at the end.

I need easier gears because....

(a) I'm fat
(b) I'm slow
(c) I'm doing the Lakeland Loop on easter Sunday :!: :!: :!:
(d) I live in Cambridgeshire where I swear the biggest hill is the bridge over the A14!!!
(e) I'm slow - oh, sorry

John.T

DaveMiller. Compact chainset and 12/27 cassette will get you up most things. To go any lower would need a MTB cassette and rear mech. also a longer chain. Still cheaper than a triple.
Slow is not a problem. Fat is but can be rectified. Unfotunately we can not move a bit of the Lake District to Cambridge for you so you will have to find a way to get some hills in. Just having low gears does not make hills easy if you have not trained on them.

redddraggon

You can get 10speed SRAM 11-28 cassettes as an alternative to the Shimano 12-27 cassette.

John.T

That puts you 4 teeth beyond Shimano's recommended range. 50/34 with 12/27 works fine but I would not want to go much further. Also 1 tooth will not make much difference. You would need to go to a 30 for any real help.

davidmiller

Thanks guys. I'll start with the compact chainset and try that before doing the back. I plan to "downgrade" from ultegra to 105 because I'm tight and I don't think I'll notice the difference. Any probs with doing that????

Cheers,

DM

blorg

10sp 105 is completely compatible with 10sp Ultegra so you should be fine.

Grigio

I am buying a bicycle modified as follows, as proposed by my mechanic, he says it works perfectly and already tested many times. This should allow to go almost on every slope quite easily!

Shimano Ultegra compact
Front 50/34
Rear cassette modified 12/29, by eliminating the 15 gear and adding the29.

He says it is necessary to make the chain a bit shorter, I don't know if a spacer is also needed.

Ciao

John.T

You will be really pushing it there. I run 50/34 and 12/27 and that is 2 teeth more than Shimano recommend. The mech will only just take up the chain tension and setting chain length is rather critical. A Shimano road mech is designed for a max 27 tooth sprocket. You can get away with a 28 and some have done so with a 30 with a bit of 'B' screw fiddling. I think you would be going just a step too far for safety.
You would have to set the chain length so the lower run of chain is just clear of the small tab on the cage when you are in small/small gears.
If you are on Shimano wheels you would not need a spacer for 8 or 9sp. The 10sp cassette comes with a small spacer that you would have to use. If you have Mavic or other wheels you should use any spacers that came with them plus the 10sp one if 10sp.

185nick

Hi, I have posted this in the forum already but thought it might be better here. I'm new to road riding and bought myself a Pinnacle Lagerra 1.0 a few weeks ago:

http://www.evanscycles.com/products/pin ... gn=froogle

I love the bike and am hooked already. However, not being the fittest person at the moment and living in a hilly area I've been considering changes to my drive chain to get some lower gears. I'm not sure of the best way to do this so was hoping you guys could give me some advice please? At the moment by bike has an FSA Omega compact mega exo chainset with 34/50 chain rings and Shimano 105 11-25T 10 speed cassette.

I've thought of two choices, the first is to change the cassette, sticking with a 105 10spd cassette means 12-27T. I'm not sure how advantageous the 2 extra teeth will be and also will I have to change my chain to get some extra length? The chain is new so shouldn't have any issues caused by wear.

My second choice is to change the chainset from compact to triple. I read on this forum a couple of weeks ago about an adaptor to change a double chainset to triple:

http://www.spacycles.co.uk/products.php ... 0s149p1141

Do you think I could get a 39T adaptor then stick a 30T inner chainring to it without changing the BB? Would I need to change my front mech. A post by Andrew_s says that it could be possible to not change the front mech as long as the smaller half of the cassette is not run with the granny ring, which, coming from MTBing, I never do anyway. Do you think this would be possible in my case?

I live in SE Cornwall which is fairly hill, which option do you think would be most effective please? I know I'm probably asking a lot but any help would be fantastic.

Many Thanks
Nick

John.T

If the Omega crank has a step under the inner chainring, which I think it has you can not use this adaptor. It requires the back of the arm to be flat.
Changing to a triple would be expensive. You would need a new chainset, front mech, long cage rear mech, chain and probably shifters. The latter may work a triple but you would need to check. Some 105 do and some don't.
You would notice a bit of difference with a 27. It rather depends on how hard you find it at the moment. If you can nearly manage then it should be enough, especially as you get fitter. Wether you would need to change the chain depends on how long it is at the moment. If when you are on the big ring and small sprocket the lower jockey wheel is behind the top one you should be OK. If in front you need an extra link in it.
Another option would be to fit an MTB rear mech and a custom cassette. This would also need a longer chain.

185nick

Thank you very much John.T I forgot to say in my last post my shifters are already triple compatible. If I changed my cassette and needed an extra link in my chain could I get away with just adding a sram powerlink?