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

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DavidMiller
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Postby DavidMiller » Fri Jan 23, 2009 20:55 pm

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

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John.T
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Postby John.T » Wed Jan 28, 2009 15:32 pm

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.

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redddraggon
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Postby redddraggon » Wed Jan 28, 2009 15:44 pm

You can get 10speed SRAM 11-28 cassettes as an alternative to the Shimano 12-27 cassette.
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John.T
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Postby John.T » Wed Jan 28, 2009 15:54 pm

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
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Postby DavidMiller » Wed Jan 28, 2009 20:35 pm

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

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blorg
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Postby blorg » Fri Feb 06, 2009 10:28 am

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

Grigio
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Postby Grigio » Mon Mar 02, 2009 17:56 pm

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

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John.T
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Postby John.T » Mon Mar 02, 2009 20:24 pm

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
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Postby 185nick » Sat Mar 07, 2009 11:47 am

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

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John.T
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Postby John.T » Sat Mar 07, 2009 12:06 pm

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
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Postby 185nick » Sat Mar 07, 2009 12:20 pm

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?

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John.T
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Postby John.T » Sat Mar 07, 2009 13:04 pm

You can extend the chain using a powerlink but you would still need the other half of the link. I used to change between a compact and a standard chainset by having 2 shortish lengths of chain and 2 powerlinks. I just fitted the relevent bit of chain. I would not recommend having 2 powerlinks together. It may be fine but it just seems wrong to me.

185nick
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Postby 185nick » Sat Mar 07, 2009 14:44 pm

Thanks John, great help I agree with your theory about having 2 powerlinks together. Think I'm going for the cassette option

joeyp101
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Lower T's

Postby joeyp101 » Thu Mar 19, 2009 02:48 am

has anyone considered the opposite?

can you get a sprocket lower than 11T? ie a cassette like 10-23 or 9-23?

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John.T
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Postby John.T » Thu Mar 19, 2009 10:14 am

Not in any normal set up.

Lunty
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Postby Lunty » Tue Jul 21, 2009 18:20 pm

I'm currently running a Shimano 105 double front end with 53/39 tooth chainrings. Looking to convert (at least temporarily for attempting the Hardknott with some friends) to a compact-type set up. Could I simply buy a 34T ring, stick it on and expect everything to run smoothly?

What do I need to consider regarding 104/110/130 measurements?
From some basic searching there doesn't seem to be a 105 34T ring, could I just stick a Sora (or other model) on? (would be switching back to my 39 after the Hardknott so durability isn't much of a concern).
Rear cassette is 9 speed (Dura Ace), what impact does this have to the front end set up?

Preferably (cost wise) I wouldn't be replacing the 53T, would this cause any problems with the front derailleur?

Any other points I should consider are welcome.

Thanks!

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John.T
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Postby John.T » Tue Jul 21, 2009 19:42 pm

Your current cranks have a 130mm bolt circle diameter (BCD). The smallest ring you can fit on them is 38 teeth. Compact cranksets have a BCD of 110mm which will take rings down to 33 teeth.
Tha maximum gap in the rings for a double front mech is 16 teeth so keeping the 53 would be a non starter anyway.
Your cheapest options are either a cheapish compact chainset that will fit your current BB with a 12/27 cassette, or a larger cassette, say 12/32 or similar with an MTB rear mech. You would also need a new chain. The latter would give rather large gaps between gears and probably cost more.

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Surf-Matt
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Postby Surf-Matt » Wed Jul 22, 2009 10:04 am

Or just pedal harder...
1994 British Eagle Strike - ratty bike
1997 Specialized Stumpjumper - still fun
2007 Stumpjumper Comp with upgrades - main bike
2008 Rockhopper Disk - for the wife
2010 Allez Elite - for goin faaaast

http://www.cornwallmtb.kk5.org

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John.T
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Postby John.T » Wed Jul 22, 2009 13:29 pm

Surf. Can we please try to keep these stickies factual. Plenty of room for levity in the rest of the forum. You are right though.

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blorg
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Postby blorg » Wed Jul 22, 2009 13:46 pm

@Surf- there are good reasons for wanting lower gears, griding away in a difficult one is generally not the most efficient way to climb a hill. If you can sustain a high cadence on 39-23 going up an extended climb then you should probably consider turning pro...

Unless you can ride up a mountain at the pace a pro does in the Tour why would you choose the same gearing as them? Just back from the Marmotte where triples were rather more common than you see in Irish sportives, and the guys riding them were not slow going up hills... I was on 34-27 and I needed it, not so much on the first climb but sure did on the Galibier and the Alpe d'Huez.


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