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

TimJSharpe

Wrt chain length I get it now - was thinking that the bigger cog would mean longer chain...

Rear derailleur is SRAM Rival - looks like this one:
http://www.sram.com/sram/road/products/ ... erm-id/148

I'd be going from: 11-26: 11-12-13-14-15-17-19-21-23 -26
To: 11-32: 11-12-13-15-17-19-22-25-28-32

In theory the new cassette should work with the derailleur as it's all SRAM Rival kit.

drlodge

Got this from Amazon:

The SRAM Rival Rear Derailleur is available with two cage length options -- Medium and Short. The Medium has a maximum 37t chain wrap capacity and can handle up to a 32t cog. The Short cage version has a 33t chain wrap capacity and can handle a 28t cog

So is yours a short or medium cage? The medium will work fine, the short will struggle.

TimJSharpe

Interesting.
Checking out the SRAM site it looks like the WiFLi version is the medium cage (it actually says it'll deal with 32T) whereas the plain, non-WiFLi version is probably short. It doesn't rule out the 32T cassette but...

I'm pretty sure mine's the short cage. Will stop by the garage on the way out to work...but...a bit of a PITA.

drlodge

There's two separate issues with smaller derailleurs:
- maximum sprocket size e.g. 28 or 32T. Most racing deraileurs are advertised as max 28T, but in my experience they can handle more especially if you fiddle with the "B" screw. Its possible yours may stretch to 32T but shifting might not be optimum on the odd occasion you need that bottom gear. Some fettling will be required to see if yours can physically move enough to accomodate the larger gear - if it will, then its more a question of whether it will then shift into bottom gear when on the road.
- take up of chain slack. This is where the cage length comes in. However as I mentioned earlier, you should never be in the large-large chainwheel-sprocket combination, so effectively your largest sprocket for chain slack take up is the second to bottom gear e.g. 28T on a 32T cassette.

John.T

No. Effectively the gear is big/big. I know you should not use it but one day you will. We all do, often by mistake or plain bad planning. It must change into that gear safely or you will end up with a big bill and a long walk.

drlodge

I agree its not sensible to have a RD and chain that's not long enough for big-big. As sure as eggs are eggs, one day you will change into it and it will create one big mess.

cgraley77

After deciding I want to tackle Holme Moss (the nearest 'big' climb to me) before I head back to uni, I've decided I most likely wont be able to do it on my 51/39 with 12-25 Shim 105. Now i've read that the highest a Shimano rear mech can handle is 12-27, but is there any tolerance? Can it do 12-28 without any damage?

Any helpful replies very much appreciated
C

drlodge

If the spec says 27T max, I'd put money on it being able to handle 28T. How steep if the hill? 27 or 28T will give you a little lower gear than 25, but going for a compact (34/50) chainwheel will give you a much lower gear, and a 34/28 should see you up all but the steepest of cliffs.

bazzer2

I don't do hills that often, but when I do, I'm royally slow and have to get off. This cannot continue, I've got Sportives to get round!
I've got a standard road setup, 42 and 52 on the front and an 8 speed HG50 13-26 at the back. With the help of this thread, I've identified that I can put a 38t ring on the front, and using the various gearing calculators available I've worked out it will only give me the difference between the existing two lowest gears more.

I'll try it and see if it's enough to help, but I don't imagine I'll be happy with this.

I think I'm going to have to move to a compact setup. But that's going to be an expensive change. As I'm on 8 speed, I don't know if you can safely fit an 8 speed chain (and cassette) to a 9 speed compact chainset. I'd have thought the chain would offer too much sideways play for it to shift properly and not drag etc? Thoughts on this are welcome, but I think I'd be looking at new shifters, re-dish (or new) rear wheel etc. And that's a big purchase.

John.T

9sp chainset would be fine. Even a 10sp would work. It is really only the outer width of the chain that is different. You may get a bit of chain rub on small/small but using a 9sp chain would help here.
Your 8sp wheel will take a 9sp or 10sp cassette with no trouble. Cheapest option would be the 38 ring and a new cassette with a 28 sprocket. A Tiagra mech would allow a 30 and may take a 32 with care on chain length. After that you are looking at a mtb mech that would take up to 34.

davidof

cgraley77 wrote:

After deciding I want to tackle Holme Moss (the nearest 'big' climb to me) before I head back to uni, I've decided I most likely wont be able to do it on my 51/39 with 12-25 Shim 105. Now i've read that the highest a Shimano rear mech can handle is 12-27, but is there any tolerance? Can it do 12-28 without any damage?

Any helpful replies very much appreciated
C

Which 105 do you have? The new 105 short cage derailleur will handle a 28T and I run it on a 30T rear and it changes perfectly, 32T would probably work. You may find the older 105 derailleur will also shift 30T. My B screw is right in so there is scope for a larger cog.

It depends on your hanger and frame.

davidof

John.T wrote:

9sp chainset would be fine. Even a 10sp would work. It is really only the outer width of the chain that is different. You may get a bit of chain rub on small/small but using a 9sp chain would help here.

As you say put a 9sp chain on at the same time, it will shift better than an 8sp chain.

drlodge

bazzer2 wrote:

I think I'm going to have to move to a compact setup. But that's going to be an expensive change.

I just changed to a compact Chainset on my 7 speed bike, fitted a Shimano Ultegra 6750 chainset which cost £135 from Ebay seller RoadBikeParts, using 9 speed chain and a mix of 9 speed sprockets on the back, with Dura Ace deraileurs, and Sora 8 speed Brifters. With 13-28 at the back, the gears area really quite low now.

cgraley77

davidof wrote:

cgraley77 wrote:

After deciding I want to tackle Holme Moss (the nearest 'big' climb to me) before I head back to uni, I've decided I most likely wont be able to do it on my 51/39 with 12-25 Shim 105. Now i've read that the highest a Shimano rear mech can handle is 12-27, but is there any tolerance? Can it do 12-28 without any damage?

Any helpful replies very much appreciated
C

Which 105 do you have? The new 105 short cage derailleur will handle a 28T and I run it on a 30T rear and it changes perfectly, 32T would probably work. You may find the older 105 derailleur will also shift 30T. My B screw is right in so there is scope for a larger cog.

It depends on your hanger and frame.

2008/2009 105 I think. Cheers, I'll look into it!

SPOC

davidof wrote:

cgraley77 wrote:

After deciding I want to tackle Holme Moss (the nearest 'big' climb to me) before I head back to uni, I've decided I most likely wont be able to do it on my 51/39 with 12-25 Shim 105. Now i've read that the highest a Shimano rear mech can handle is 12-27, but is there any tolerance? Can it do 12-28 without any damage?

Any helpful replies very much appreciated
C

Which 105 do you have? The new 105 short cage derailleur will handle a 28T and I run it on a 30T rear and it changes perfectly, 32T would probably work. You may find the older 105 derailleur will also shift 30T. My B screw is right in so there is scope for a larger cog.

It depends on your hanger and frame.

I'll echo the above.

Despite what Shimano say, I've got the older 105 short cage and a 30T works with my 34/50 compact. In the end it came off and went with a 28T to avoid the massive gearing gaps with a 9 speed. Been using the 28T cassette for about a month now with absolutely no problems whatsoever.

davidof

With the Tiagra 12x30 and a compact chainset you do end up with a gearing gap in the middle which requires frequent changes on the front. To a certain extent I'm better on my old 13x28 8 speed because the chain will run right across the rear cog set without rubbing anywhere.

cgraley77

davidof wrote:

With the Tiagra 12x30 and a compact chainset you do end up with a gearing gap in the middle which requires frequent changes on the front. To a certain extent I'm better on my old 13x28 8 speed because the chain will run right across the rear cog set without rubbing anywhere.

In the end I tried Holme Moss on my 39x25 today. A little slow going at one point but I made it, don't know how. Would like to try it on an 11-28 or maybe even a compact at some point tho.

davidof

cgraley77 wrote:

In the end I tried Holme Moss on my 39x25 today.

I used to ride on a 39x23 but those days are long behind me now.

drlodge

I've just changed from an old 42-52 chainset to a compact 34-50, with a 13-28 cassette. I'm finding I use the lower gears more than I thought I would, but my overall speed remains the same. Hence on the hills I'm able to keep my cadence up nearer the 90 mark rather than let it drop to around 60, and this saves my legs which is a big plus on long rides.

I did Combe Lane leading to Staple lane the other day, almost identical time but my heart rate was no where near as fast, and I was far less knackered at the top.

boileroo

Hey all

Another (no doubt annoying) gearing question for you all.

I've been riding for a few months now, absolutely loving it. However, I've just moved from Norfolk to Bath, and suffice to say I'm more than struggling with the hills!! I'm riding a spesh allez compact (50/34) with a 13-25 8 speed cassette. I feel as though I should be able to ride hills with this, but I'm really not very strong! Also, to my admittedly limited knowledge, it seems that a 12-25 cassette is fairly stupid?

Anyway my question: I'd love to change to a triple but can't afford to right now. My current plan is to change the cassette to something that'll help me in the climbs. I've been looking at the shimano 11-32 8 speeds with this in mind. What do I need to be aware of with this? Will any shimano 8 speed be compatible? Any tips would be hugely appreciated. Cheers all!

John.T

Fit a MTB mech and new chain with the 11/32 cassette. All this has been covered many times on here.

boileroo

Heya
-
So just to clarify, if I put on something like an alivio m410 rear mech I could use a cassette with anything up to 34 teeth? Only change would then likely be a new chain? Just wanting to clarify before I do anything!

drlodge

Basically:
- fit new cassette with gearing of your choice e.g. 12-34T
- find RD with "capacity" that suits. This comes in two forms (a) largest rear sprocket (needs to handle 34T in this case, most 32T max RDs would probably do it OK IMHO) and (b) total chain capacity, in this case its (50+34) - (34+12) i.e. 22 teeth (large front + large rear) - (small front + small rear).
- you'll likely need a new chain too as it'll need to be longer than the old one.

Pross

drlodge wrote:

Basically:
- fit new cassette with gearing of your choice e.g. 12-34T
- find RD with "capacity" that suits. This comes in two forms (a) largest rear sprocket (needs to handle 34T in this case, most 32T max RDs would probably do it OK IMHO) and (b) total chain capacity, in this case its (50+34) - (34+12) i.e. 22 teeth (large front + large rear) - (small front + small rear).- you'll likely need a new chain too as it'll need to be longer than the old one.

Are you sure that's correct? Shouldn't it be (large chainring - small chainring) + (largest cassette sprocket - smallest cassette sprocket) i.e. (50-34) + (34-12) = 38?

drlodge

Actually both equations are the same, just I got my calculation wrong. The right answer is 38, which is achieved via either method

(large front + large rear) - (small front + small rear) == (large front - small front) + (large rear - small rear)

gazhilla

Can I just say a massive thank you to the folks contributing to this thread, as an 18stone returning rider the advice has been great for someone who lives on the edge of the lake district

tenagadalam

thanks a lot. It's very useful

______________________________________
tenaga dalam | energi positif | tenaga dalam

sandwats

Me too - incredibly helpful. Only thing that could improve it would be for the world-weary types who complain "this has been covered so many times before" to save their breath!

chrisaonabike

Sorry if I'm repeating stuff that's been covered - I've been through most of this thread and I'm still not sure.

I have Tiagra, compact chainset (50/34), and a 12-28 10-speed cassette.

As others, I don't want to switch to a triple, but although it's early days, I am considering how to achieve a little more range at the back.

AIUI, there's no option for 30 or 32 instead of 28 without changing the rear mech and chain. Is this right?

drlodge

You need a RD with adequate capacity (36 links), so it depends on what your current RD is...?