Help I need smaller gears - what can I do? A GUIDE
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Your SL will take the 28 OK. You may need to adjust the B screw.
A standard SS short cage mech will take 50/34 with 12/27 easily (11/28 with luck and carefull set up) so will handle your 52/39 and 11/28 with no trouble.
I set the chain length for the largest cassette I will use and leave it at that. Currently riding 52/38 with 12/27, 12/23 and 11/21 on various wheels with the same chain.
You should have a chain splitter in your tool kit but I use joining links so I can take the chain off should I need to.0 -
Great, thanks for the speedy advice, I've been meaning to expand my tool kit for a while now so this is a good excuse!
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@ John.T - Great thread, I hope you're getting paid for this stuff
I've read the whole thread and I haven't seen any references to Dura-ace 7900. I'm just wondering what my options are - does dura-ace offer any additional gearing flexibility in terms of chainset or cassette over lower spec Shimano gear? I've got a new bike coming with 7900 on it. Im upgrading from my old bike which was Ultegra to which I fitted a compact chainring and a 27 at the back. I really really liked it on the hills, but found it a bit frustrating on rolling undulating stuff, where I was constantly jumping between chainrings at the front.
I'd like to know what your recommendation would be - there's lots of hilly stuff around where I live and I like to spin a hummingbird cadence and constantly work the gears.0 -
http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/products/road/di2.html#/site/product/7900/road
Full 7900 range here.
Cassettes go to 28 but only chainset options are 50/34 compact or a range of standard ones. It looks as if you will still have to jump between rings if you want low gears.
Not getting paid but am constantly learning in the hope of not making too many mistakes.
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John.T wrote:http://cycle.shimano-eu.com/publish/content/global_cycle/en/nl/index/products/road/di2.html#/site/product/7900/road
Full 7900 range here.
Cassettes go to 28 but only chainset options are 50/34 compact or a range of standard ones. It looks as if you will still have to jump between rings if you want low gears.
Not getting paid but am constantly learning in the hope of not making too many mistakes.
Cheers man. -If I kept the front regular (53/39, I think) and went for a 28 on the back over my old 27. How close would my new lowest gear (39/28) then be to my old (34/27)...0 -
As you want to work the gears, single tooth spacing to at least the 17 sprocket is essential. So stick to the 10 speed 12-27 (12,13,14,15,16,17,19,21,24,27) cassette.aogan wrote:I'd like to know what rickhotrod's recommendation would be - there's lots of hilly stuff around where I live and I like to spin a hummingbird cadence and constantly work the gears.
You could use 42-34 rings. This would allow you to go up rolling hills in the big ring and would work brilliantly most of the time. The downside is the rather low top gear. 120 rpm is 32.9 mph. That might be enough if you just tuck in once up to that speed going down hill.
48/39 would be better. 120 rpm is 37.6 mph. 48/39 will give a simple front shift sequence when you shift between the 17 and 21 sprockets as you only need one click on the right shifter.
53/39 isn't so easy with the 12-27 cassette when a double shift is made. For example:
(a) Changing down from the 53 ring to the 39 ring when initially on the 21 sprocket requires two clicks on the right shifter. (ie. you go from the 21 sprocket to the 17 sprocket.)
(b) Changing down from the 53 ring to the 39 ring when initially on the 19 sprocket requires three clicks on the right shifter. (ie. you go from the 19 sprocket to the 15 sprocket.)0 -
Just to add another option to the list for triple users. I was riding yesterday with a chap who had fitted a Stronglite 26 74BCD granny ring to his 105 triple. It worked fine. I had not mentioned this possibility before as I was not sure if it worked. He was running 50/36/26. It is beyond the recomended number of teeth for the front mech but worked well.0
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I converted my triple to a 28 at the front from a 30. Works ok and really good for just spinning away and it beats walking.
Only problem I have is it does seem to drop off the chain at the front when I change between gears now. I've always had a few shifting issues ever since I got the bike but hope to get these sorted at the next service0 -
Hello
I have a 2008 Specialized Allez Double which I’m finding hard to get up steep hills. Its front chain ring is 50-34 and rear cassette is a 9 speed 11-28. Hence the lowest gear is 34/28 which gives a ratio of 1.21.
I’d just about convinced myself that I needed to swallow my pride and get a 2010 Allez Triple but I’m not convinced this will help. The front chain ring on this bike is 50-39-30 and the rear cassette is a 9 speed 12 -25. Hence the lowest gear is 30/25 which gives a ratio of 1.2.
I have limited understanding of gears. So am I right that there’s a negligible difference between the lowest gears on both bikes (and hence I’d find the triple just as hard to get up the hill !) or is there something I don’t understand (i.e. the smaller front chain ring makes a difference).
Thanks in advance
John0 -
I don't understand your ratios. I am a gear inches man from way back and am not going to change.
I put your options into Sheldon Brown's gear calculator and it show that the 34/28 and 30/25 are almost exactly the same ratio at 32.8" and 32.4". You could use the 11/28 cassette with the 30 on the triple which would give you 28.9" which is an improvement but not a lot. The triple will take a 26 tooth granny ring which would give 28.9" or 25.1" which is more worth while. This range is outside of Shimano specs but works well. The change on and off the granny ring is not as sweet but that is all.
Have a play with the calculator and also read Sheldon on gears.
http://sheldonbrown.com/gears/
Explanation of 'gear inches' is just below the calculator.0 -
jacroz wrote:Hello
I have a 2008 Specialized Allez Double which I’m finding hard to get up steep hills. Its front chain ring is 50-34 and rear cassette is a 9 speed 11-28. Hence the lowest gear is 34/28 which gives a ratio of 1.21.
I’d just about convinced myself that I needed to swallow my pride and get a 2010 Allez Triple but I’m not convinced this will help. The front chain ring on this bike is 50-39-30 and the rear cassette is a 9 speed 12 -25. Hence the lowest gear is 30/25 which gives a ratio of 1.2.
I have limited understanding of gears. So am I right that there’s a negligible difference between the lowest gears on both bikes (and hence I’d find the triple just as hard to get up the hill !) or is there something I don’t understand (i.e. the smaller front chain ring makes a difference).
Thanks in advance
John
The key figure you need is the gear inch. First find the diameter of the rear wheel in inches (D), then calculate the gear inch as <D> times the number of the cogs on front ring divided by the cogs on the rear cassette. For example, if your wheel has a diameter of 27", the front cog count is 34 and the rear cassette cog count is 28, then the gear inch is 27*34/28 or 32.8 inches. This is typically of the sort of low value you need for steep hills. Likewise, if you use the 50 cog front ring and 11 cog rear, then the gear inch is 122 inches which is great for fast downhill descents. A good gear for fast descents needs to be >110 inches.
A triple doesn't always give a lower gear inch. For example, a Campag setup with a 29 cog rear cassette on a 34 cog front ring results in a 31.6 gear inch which is smaller than a triple with a 30 cog front ring and 25 cog rear sprocket (giving a 32.4 inch gear).
Finally, assuming you are using a Shimano setup, do they not make a wide-range rear cassette using a rear cog of 32? If you use that, you'll be able to get up anything that is cyclable.
Hope this helps.0 -
Whoops, John beat me to it 0
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John.T wrote:I don't understand your ratios.
Seems pretty straight forward to me, and is how I work out my gearing.
Front divided by back is a fine way of working out gearing if the wheel/tyre size remains constant.
Calculating gearing by inches seems like a load of extra work to me if you are always going to use 700c + 23/25mm tyres.0 -
Thanks all for your quick & helpful replies.0
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If the OP had said 1.2:1 and 1.21:1 I would have understood. They are ratios. The ones quoted are just numbers. Pedantic I know but I had to take a second look to understand them as I never use them.redddraggon wrote:
Seems pretty straight forward to me, and is how I work out my gearing.John.T wrote:I don't understand your ratios.
Front divided by back is a fine way of working out gearing if the wheel/tyre size remains constant.
Calculating gearing by inches seems like a load of extra work to me if you are always going to use 700c + 23/25mm tyres.
I don't calculate gear ratios Red. I use tables or Sheldon's calculator. I have all my options in a few minutes. I stick with 'gear inches' because I have used them for 50 odd years and know exactly what say a 69" gear feels like. Also very easy to check overlap on doubles and triples. Any system that you understand and find easy to use is good.0 -
one option to consider is that Shimano are now converting their MTB gearing to 10 speed and they already have 9 speed which you are using. This means you can get a larger cassette at the back to lower the gearing maybe an 11-32 or 11-34.
I know some people don't like triples and say just train harder but I was struggling for ages getting up hills and ended up doing far too much walking. I lowered my triple to a 28 at the front and could then get up more hills, which meant I could get more strength in the legs rather than walking and am now lookng to go back to a standard triple setup0 -
As with some other posters my nice (but now aging) bike came as stock with 53/39 and 12/23. I have always found it a struggle to get up the modest hills around here (Berkshire) and would undoubtedly fail on longer/steeper stuff. It is an Ultegra 9 speed (dates from 2001) double –so I understand that means it likely has an Octalink BB.
I believe that I can fit an Ultegra 12/27 cassette as a straight swap and 27 is the biggest possible without changing rear mech. Will that likely make a big difference on its own? I assume this is the best bet as a first step.
Next step I guess would be to convert to a Compact setup. From reading here and elsewhere I don’t think I could fit a smaller than 39T inner ring on my current chainset, so I would need a replacement chainset, which starts to sound pricey.
I found this (I’m not worried about the slightly smaller big ring)
http://www.ribblecycles.co.uk/showPart. ... R460&bike=
I realize it is not compatible with my Octalink BB, but is it possible to convert? What would I need to achieve that ?
Or are there other compatible chainset options I should look at?
Thanks,
Ian0 -
The 12/27 will fit straight on but you may need a longer chain. You should fit a new one anyway if the current one has done many miles (1000 max).
The smallest chain ring you can fit to 130 mm BCD cranks is 38 teeth.
The Tiagra chainset will fit. You need to get the HT2 BB as well and should get your BB shell faced. This is a bike shop job.
Any 110 BCD compact chainset can be used along with the relevent BB unit.0 -
John, Many Thanks!
No problem with the chain. I take that as a given with a new cassette.
To be clear, is this below all I need for the BB?
http://www.ribblecycles.co.uk/sp/road-t ... HIMBTBR710
How much roughly are we looking at for the LBS to face the shell (not sure what that really means..)?
Are you aware of an alternative compatible compact chainset that would not require a new BB?
Cheers
Ian0 -
That BB is fine.
Facing the shell is making sure that the end faces of the BB shell are parallel. The outboard BBs butt up on these faces and any mal-alignment will reduce bearing life. Not a problem with square taper and Octalink BBs as they just screw in. Not sure how much it would cost. I had a bare frame done for less than a tenner but I am well known there.
As far as I know there are no Oktalink compatable compacts chainsets.0 -
Not sure if this will help anyone or if it would be approved of by a "proper" mechanic but for what it's worth this is my story;
Having come back from 2 trips to Pyrenees/Alps on a mountain bike with a 24 front /28 rear as my lowest ratio I decided I needed a proper road bike but knowing how often I got down to a 1:1 ratio on some of the longer climbs was worried about not having the ratios I would need.
Therefore once I had chosen my new toy/bike (Scott CR-1 with Shimano 105) I bargained with the bike shop to swap the standard double crank on it for a triple 50/40/30. In the end they paid my half the value for the double crank sold me a triple and fitted the new one free.
First point was that this worked fine with all the existing shifters/mechs etc and gave me 30/25 as my lowest gear.
This is plenty for 99% of the time but I was still short of the 1:1 ratio I had hoped for so I then swapped out the 30 tooth granny ring for a 26 tooth and now I have a 26/25 gear which will take me up anything.
The downside is that I have to be careful which ratios I use but then in mountain biking using large/large and small/small was a big no no anyway. On the big front ring I can still get all but the biggest cog on the back and on the granny ring I never really go below 4th biggest anyway.
The granny ring is used sparingly and strictly for the steepest/longest climbs and will go weeks unused sometimes.
The advantage of this set up as I see it is that I have a serious bail out ratio when I really need it yet for the majority of the time (on 40 or 50 front ring) I still have a fairly close ratio'ed rear cassette (12-25) so no nasty jumps between ratios, something I had not appreciated the benefit of until I started on read bikes.
As I said this may be considered "wrong" but it works for me.
Damian.0 -
I use a similar setup of a 28 on the front and a 27 on the back. There really is no right or wrong just what works best for you. I was doing far too much walking up steep hills and now with a 28 I can still get up them which means I can improve and get more training in. I'm now at the stage where I am looking to go back to a standard setup of 30-39-53.0
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soveda wrote:Just to check, I have a tiagra short rear mech, can I keep that to go from a 50/34+12-15 to 50/34+12-27?
I know I may have to lengthen the chain but the 17% hills are a bit too much for me with a 34-25!
Just a quick update, I can report (confirm) that Tiagra 9 speed works well with a compact and a 12-27 ultegra cassette. All gear combinations are usable, even the ones with an unwise chainline!0 -
This is a superb thread! I've just changed from 36/50 to a 34/50(34 in the post), and if that's not enough will try the method of dismantling the 12/25 and putting in a 28T in place of the 14T rather than buying an 11/28 (will rob the 28 from my mtb turbo wheel cassette it's never been used and put in the spare 14 so 2 side by side?)
I'm assuming the reason 7 of the 9 gears in the cassette are riveted together is for keeping peoples sanity, and not some mechanical reason,or is it?! :?
It's a pity I couldn't just ditch the 12 instead of the 14 but doesn't look at all feasible?0 -
Hi folks,
I've currently got the Chorus groupset on my TCR with 53/39 and the alpine cassette 13/29.
I've got a medium cage rear mech.
Looking to go compact and I've been reliably informed that the only thing I need to change would be the chainset and the BB cups?
I was looking at the cheap option of the Veloce ultra torque 50/34.
I was told that this will still work with my alpine cassette without having to alter the chain length etc. My 2nd lowest gear is a 26 tooth.
This is in preparation for a trip to the Pyrenees and would be good news as I was expecting to have to change other parts like front mech etc.
Thanks 0 -
Thanks John,
Nice to have good news!!0 -
I've had my road bike for a couple of weeks now with 50/34 compact on front and 12/25 rear. It's 10 speed Campag centaur. Whilst i'm still getting really fit I'd like to fit the BBB 12/27 rear cassette to help when i'm riding the south shropshire hills.
Can I do this swap and still keep the sort rear mech or will I have to get a medium?0
