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

velogee

Guys,

I have an Allez with a 9 speed 12-25 casette, and I am finding moderate hills a total killer.

Would it be worth changing to a larger casette or should I stick with 12-25 and up my performance

I can get up the hills, but my worry is that if I did a hilly sportive I would become unstuck

cheers

Barbarossa

scarthie99 wrote:

could put this on my super six 105 so i climb hill better Shimano Zee Rear Derailleur Shadow+ 10sp M640+Shimano XT M771 10 Speed Cassette 11-32 i know i need new chain.cheers

You need a 9 speed rear mech. I just set up my road bike (Ultegra) with a Deore T661 rear mech, and SRAM PG-1050 11-32 cassette. Works well.

scarthie99

i got 10 speed shifts on my super six 105 the rear mech 105 short cage max rear sproctet is 30 t

John.T

scarthie99 wrote:

i got 10 speed shifts on my super six 105 the rear mech 105 short cage max rear sproctet is 30 t

Not sure what you are asking. Most Shimano rear mechs will work with your shifters (early DA and 10sp MTB will not). Current 105 has a recommended max sprocket of 28 teeth. It will handle 30 but Shimano are rather conservative in their recommendations. If you want a larger cassette then fit a 9sp MTB mech and longer chain. It will work fine.

Paulj700

Hi Folks.

I have a Campag Veloce 10sp. The 50/34 compact is made by FSA, and the 12-25 cassette is Miche on a Miche hub.

I prefer a higher cadence and find I need a lower gear. I know I can get a 13/29 campag mech and I just wanted to know how much difference I would actually notice moving from 25 to 29 tooth small cog?

Also would there be any issues putting a Campag Cassette on a Miche Hub?

Also, do I have any other options here? Could I for instance get a 11 or 12 tooth small cog and a 28+ big cog if I were to use other compatible Cassettes?

Thanks

Paul

Manc33

Its exponential. For example...

39F/15R = 2.6
39F/20R = 1.95 (difference of -0.65)
39F/25R = 1.56 (difference of -0.39)

Then again if you had a gear thats 1.5 turns of the wheel and a gear thats 1 turn, it is a massive difference, but between say 2 turns and 1.5 turns, its nothing like as big of a jump in gearing even though the back wheel is only moving at the same rate less, half a turn.

Most seem to cope with a 39F/28R but I am far weaker and need an 11-32T on with a triple 30/42/50. Even then I am in the lowest gear on long hills and could probably do with one gear lower even than a 30F/32R. Thats on a full road bike with 700c x 23's on it @ 115psi. Yes I am that pathetic, but, that is what is spurring me on to up the ante!

drlodge

Quick question on swapping my chainset.

Its an old road bike with Shimano 600EX chainset (42/52, square taper axle), with 126mm rear axle running a 7 speed cassette (13-28) and SRAM PC870 chain.

Would I have any issues fitting a Shimano Ultegra Double 6750 10Spd Chainset (34/50)? I know I need a new bottom bracket, but any issues with the 8 speed PC870 chain, or alignment issues?

John.T

The 10sp rings are mounted closer together than 7sp ones so you may get some chain rub on the smaller sprockets and small ring. The 8sp chain will help and you may be able to use a 9sp one which will be fine with the rings. Not sure about on 7sp sprockets. You should be OK unless you have a IG cassette which has 2.35mm thick sprockets. HG 7sp, 8sp and 9sp are 1.85mm, 1.8mm and 1.75mm respectively so near as makes no difference.

drlodge

Thanks for the reply, I hadn't thought of using a 9 speed chain, which MAY work since the cassette is actually made up using cogs from a 9 speed HG61 cassette with 7 speed spacers (which gives roughly 8 speed spaced gears for my 8 speed Sora brifters). However the 2 smallest cogs (13T and 14T) are the original 7 speed Dura Ace cogs (others from the HG61 cassette are 16-18-21-24-28). I rarely use the 13T or 14T cogs, and hardly ever use the smaller cogs with the small chain ring due to the chain cross over angle. I can get the Ultegra 34/50 chainset for £145, also with 172.5mm cranks which would then be the same as the new bike on order. Food for thought.

John.T

I think if the cassette uses a lockring you will be all right. The earlier cassettes used the top sprocket to hold it all on. I have used 7sp top 2 sprockets on 9sp with no trouble. I had to let the high limit screw out a little as the top spacing is different. No problem there as this gear is non indexed anyway.

drlodge

John.T wrote:

I think if the cassette uses a lockring you will be all right. The earlier cassettes used the top sprocket to hold it all on. I have used 7sp top 2 sprockets on 9sp with no trouble. I had to let the high limit screw out a little as the top spacing is different. No problem there as this gear is non indexed anyway.

That's what I'm doing - using the 7sp smallest 2 spockets to hold the other 5 in place (actually its just the smallest that's threaded but the 2nd smallest is also needed due to the way the freehub slots are formed and the 2nd smallest sprocket has an integral spacer). The only potential issue is if these two sprockets are too wide for a 9 speed chain, but as you posted earlier, there's very little difference in sprocket width.

Manc33

I got 30/39/50 on the front and 11-32T on the back and still need the front chainrings about 2 teeth smaller on each. I am weak, but all that seems to do now is make me push harder. :twisted: I guess this is what stopping smoking does for you. 2 years ago I was unable to do 5 miles without it nearly killing me. Now I can do 25 with the same effort.

s1mon

Hi,

I've got a standard 39/53 Ultegra chain set and a 12/25 Ultegra cassette. I've normaly had a compact on my other road bikes so I'm now struggling on the hills how much difference will a 11/28 cassette make or will it be better to buy some compact chainrings ?

Thanks.

John.T

Either option will give about the same lower gear. 34/25 is 36.7" and 39/28 is 37.6". You would not notice a difference this small. Your choice should take account the rest of the gear range and your normal riding.
Check gear ratios here. http://sheldonbrown.com/gears/ Change the gear units to 'gear inches' or 'meters development' as preferred. Crank length is irrelevant in these settings.

drlodge

s1mon wrote:

Hi,

I've got a standard 39/53 Ultegra chain set and a 12/25 Ultegra cassette. I've normaly had a compact on my other road bikes so I'm now struggling on the hills how much difference will a 11/28 cassette make or will it be better to buy some compact chainrings ?

Thanks.

Depends how much you're struggling, but actually there is not that much difference wither way. Moving from 25 to 28 will kinda give you "one more gear" on the back ( ratio difference is 28/25 or 1.12). Moving from 39 to 34 will give you more the feel of "2" more gears although the ratio difference is only 1.15. Can you get a cheap 12/28 cassette and give that a try?

s1mon

Thanks, would I need to lengthen my chain if I just changed the cassette ?

drlodge

It depends...probably not. What's the chain length like when on the smallest chainring and cog?

John.T

Big/big is more important. Too short and the mech is in the wheel. And you will go there sometime.

photomcbeth

I assume it's not possible to just replace the inner chainring with a smaller one and keep the standard outer one. Front mechanism issue?

John.T

PhotoMcbeth wrote:

I assume it's not possible to just replace the inner chainring with a smaller one and keep the standard outer one. Front mechanism issue?

No. Smallest ring that will fit a 'standard' Shimano is a 38. With Campag it is 39.

photomcbeth

So my only option is to fit a whole new compact chainset?

John.T

Yes. Or a bigger cassette and mech to suit.

federalski

Anyone please tell me if this lot would work ok?

Ultegra 6700 10 speed shifters
50/34 Rival chainset
Ultegra 6700 front mech
Shimano XT M771 9sp Rear Mech (medium cage)
SRAM PG1050 10 Speed Cassette 11-32

And would the mtb rear mech handle a tighter road cassette like 12-25?

Thanks.

John.T

Should all work fine including with the 12/25. You may have to reset the B screw but that is all.

federalski

Brilliant. Can now press 'buy' on a couple of items a whole heap more confident.
Thanks for the quick response, you deserve a forum knighthood for services to noobs

carrock

John.T wrote:

Should all work fine including with the 12/25. You may have to reset the B screw but that is all.

are you sure a 9 speed rear derailleur will work with 10 speed cassette and shifters?

John.T

carrock wrote:

John.T wrote:

Should all work fine including with the 12/25. You may have to reset the B screw but that is all.

are you sure a 9 speed rear derailleur will work with 10 speed cassette and shifters?

Yes. The mech can not count. It is the shifter that decides how far it moves. All Shimano rear mechs, except some early Dura-Ace ones and the new 10sp mtb ones have the same cable pull ratio. I used a 9sp Ultegra mech on 10sp for several years. It worked just fine.

carrock

ah well I have learnt something.

TimJSharpe

This is a great thread. Reckon I have a problem that lot's of people do.

Currently I've got:

Rival 50-34 compact chainset
PG1050 11-26 cassette 10spd
PC1051 chain

Simply put, I find the 26 a bit too hard when the gradient gets up beyond 18% - particularly later in the ride when fatigued.

So, the plan is simple; replace the cassette with a PG1070 11-32 10 spd.

All I can think is that I might need a longer chain?

Was going to get LBS to do it (Evans) but might...in the spirit of self-improvement might do it myself. Actually I won't. I don't have a clue.

drlodge

TimJSharpe wrote:

So, the plan is simple; replace the cassette with a PG1070 11-32 10 spd.

All I can think is that I might need a longer chain?

You won't need a longer chain as you still have 34-11 as your longest chain-length gear. You may (and I think its likely) need a new rear derailleur as the chain length-difference has increased by 6 links. (50+26-11-34) which is 31 difference to (50+32-11-34) which is 37 difference. What rear deraileur have your got?

If you're careful you might get away with it, since you should never be in the 50-32 or 34-11 combination. If the second largest cog is 28T then you more likely have 50-28 and 34-12 which gives 32 difference, which most normal rear derraileurs can cope with albeit with some adjustment of the "B" screw.