Twin to triple..
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Discussion

s.m.h.

Original Poster:

5,733 posts

244 months

Friday 30th July 2010
quotequote all
Any Shimano experts out there?

Bike I just bought has a twin front gearset (34/50) though the lever is for a triple.
Ive rode it a few times and although I can manage to get up the hills near me, I'd like to see if its an easy/cheap upgrade to a triple.

Now Ive done a little looking and there is a Sora triple (which I think is 30/42/50) which comes in 2 flavours. 1 has what looks like the same tapered crank as is in the bike (Fuji Roubaix 3 18speed) the other, looks like 2 piece with 1 one crank held on with pinch bolts.

Would I be wrong to assume that the tapered gearset would fit straight on - with a little adjustment of the front derailleur so the Sora lever selects 3 (not 2 as present)??

Alternatively is there a way of fitting additional chainwheels instead of replacing the front gearset?
The bcd is 110 which look like a no-go, though the price of replacement chain wheels is pretty close to a new gearset!

Before anyone shouts UPGRADE, I'd like to stick to a budget of under £80 if possible, so if theres any alternatives that may work.....

AnotherClarkey

3,698 posts

218 months

Friday 30th July 2010
quotequote all
Have a look at the back of the crank arms - there might already be fitments for a granny ring. I bought a new single speed once and it came with triple-ring cranks converted by the simple expedient of only putting one ring on.

s.m.h.

Original Poster:

5,733 posts

244 months

Friday 30th July 2010
quotequote all
contango said:
You say you are running a compact 50/34 crankset up front.....if you use a cassette with a 28 on the back you should be able to get up anything, less weight and complication than a triple...Should cost less if you don't already run a 28 and less to go wrong or out of adjustment.
Think (from the specs) its got a HG50 11-25t 9speed.
So basically change the cassette to one with 11-28t and it will make a difference on steep hills.

Looking further into it, I now cant find a 9 speed front gearset with taper, so assume I'd need a new bb as well...

s.m.h.

Original Poster:

5,733 posts

244 months

Friday 30th July 2010
quotequote all
I was looking at it as the sora levers are already triple and because you can (inadvertantly) shift up 2 rings with one movement meaning its 2 clicks to drop to the granny ring.

Would I be looking at HG50 cassettes or is it any 9 speed shimano will fit?
Sorry for the daft questions but its been 30 years since I rode a road bike and things have changed quite a bit! Just like my neck which was stiff as a board after the climb home!

b2hbm

1,301 posts

251 months

Saturday 31st July 2010
quotequote all
s.m.h. said:
Think (from the specs) its got a HG50 11-25t 9speed.
So basically change the cassette to one with 11-28t and it will make a difference on steep hills.

Looking further into it, I now cant find a 9 speed front gearset with taper, so assume I'd need a new bb as well...
If you're already running a compact with a 25t bottom gear then personally I wouldn't bother moving to a triple. Using a 30t chainring on your existing cassette will give you a lower set of gears, but not by much. As an explanation without getting too geeky, gear ratios are measured in "gear inches", but don't worry about what it means and just look at the numbers;

34t x 25 is about 36 gear inches.
34t x 28 is about 32 gear inches. That's not a lot but you would notice it on your legs - my own view is that 5" is a good spacing, 10" is a serious jump.

move to a triple and

30t x 25 is about 31 gear inches. As far as your legs are concerned, that's the same as the 34x28 combo.
30t x 28 is about 28 gear inches. But that means changing both rear cassette and also the front rings - very expensive for comparatively little benefit.

When I fitted a triple I needed the c/set (obviously ! ) and a new BB axle because the chain line moves outwards slightly to accommodate the granny ring. Sometimes you need a new front changer as well to pick up the chain but I was lucky & retained the old one. Shift lever (campag) was ok as well. So as a minimum, budget for a new BB & the triple chainset.

Changing the rear cassette to one with a 28t bottom is much cheaper - you only need a new cassette. If the old cassette/chain is really worn then you might need a new chain as well, but even so it will be the cheaper option. And as you can see from the numbers, getting a 28t rear sprocket will be the same as fitting a triple with your existing cassette.

s.m.h.

Original Poster:

5,733 posts

244 months

Saturday 31st July 2010
quotequote all
b2hbm said:
s.m.h. said:
Think (from the specs) its got a HG50 11-25t 9speed.
So basically change the cassette to one with 11-28t and it will make a difference on steep hills.

Looking further into it, I now cant find a 9 speed front gearset with taper, so assume I'd need a new bb as well...
If you're already running a compact with a 25t bottom gear then personally I wouldn't bother moving to a triple. Using a 30t chainring on your existing cassette will give you a lower set of gears, but not by much. As an explanation without getting too geeky, gear ratios are measured in "gear inches", but don't worry about what it means and just look at the numbers;

34t x 25 is about 36 gear inches.
34t x 28 is about 32 gear inches. That's not a lot but you would notice it on your legs - my own view is that 5" is a good spacing, 10" is a serious jump.

move to a triple and

30t x 25 is about 31 gear inches. As far as your legs are concerned, that's the same as the 34x28 combo.
30t x 28 is about 28 gear inches. But that means changing both rear cassette and also the front rings - very expensive for comparatively little benefit.

When I fitted a triple I needed the c/set (obviously ! ) and a new BB axle because the chain line moves outwards slightly to accommodate the granny ring. Sometimes you need a new front changer as well to pick up the chain but I was lucky & retained the old one. Shift lever (campag) was ok as well. So as a minimum, budget for a new BB & the triple chainset.

Changing the rear cassette to one with a 28t bottom is much cheaper - you only need a new cassette. If the old cassette/chain is really worn then you might need a new chain as well, but even so it will be the cheaper option. And as you can see from the numbers, getting a 28t rear sprocket will be the same as fitting a triple with your existing cassette.
Thanks for that, I sort of understand gear ratios a little - I used to look after gearboxes in LMP cars smile but always good to confirm with someone thats done it!
So are all cassette's compatible with the shimano hub?( Ive read campag. dont fit) Ive seen HG80,SRAM etc with the ratios but as Im new to swapping bits over what may seem obvious to those in the know..

b2hbm

1,301 posts

251 months

Saturday 31st July 2010
quotequote all
s.m.h. said:
Thanks for that, I sort of understand gear ratios a little - I used to look after gearboxes in LMP cars smile but always good to confirm with someone thats done it!
So are all cassette's compatible with the shimano hub?( Ive read campag. dont fit) Ive seen HG80,SRAM etc with the ratios but as Im new to swapping bits over what may seem obvious to those in the know..
I don't know if SRAM fit shimano hubs, campag certainly don't.

My advice would be to stay with shimano stuff because generally speaking it's interchangeable. Ok, not as in 6sp moving to a 10sp, but the low end cassettes will fit the high end hubs - Tigra fitting Ultegra for example.

I tend to buy Tigra/Sora (HG50 IIRC) for winter bikes and either 105 or Ultegra for summer bikes. Quite honestly, apart from the minor weight savings, I can't tell any difference in change quality but I suppose the Ultegra ones look nicer !

Stuart

11,639 posts

280 months

Sunday 1st August 2010
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SRAM fit the Shimano hubs perfectly. Your LBS should be able to advise but there are a number of non OEM manufacturers of cassettes to fit both Shim and Campag. You just need to tell them if you're running a Shim 9 or 10spd cassette, and they should sort you out.

I'd echo what has been said about changing the rear cassette. When I built my road bike I originally specced an 11-23 ( I think) and it was a huge mistake. Swapping for a 12-24 made a tremendous difference to my hill climbing ability, with negligible loss at the bottom end.

s.m.h.

Original Poster:

5,733 posts

244 months

Sunday 1st August 2010
quotequote all
Ok, so i have now ordered a SRAM 9 speed 11-28 cassette. Was £23 so not too bad!
As my fitness improves I have the option of re-fitting the 11-25, though I havent been up the steepest hills round here yet.. Hopefully be here early next week so will report back on the difference.
Thanks for the pointers, as I was almost ready to spend another £xxx on a triple.

Rocksteadyeddie

7,971 posts

256 months

Sunday 1st August 2010
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swerni said:
Right I've just been through all of this and the bike is now working and brilliant.

Here is what I've done.

Purchased a brand new 10 speed Shimano shifter from ebay circa £38
New SRAM Apex rear cassette with 11-32 ratio circa £50
Shimano Ultegra long cage rear dérailleur circa £60 (am sending the sram dérailleur back as its never going to work with my set up).
10 speed chain cica £35

I put a 12-28 sram cassette on the bike previously but it sacrificed some top end and didn't give me the climbing ability I have with my triple.

I've been out this afternoon on it and the gear changing is brilliant, no big jumps and it feels like I could ride up a cliff on it.

It's now got a wider range than my triple has.

so for sub £200 my bike is now perfect for my requirements.
This. Just done this for a friend of mine to get her up the Alpe D'Huez. Works a treat and a big weight saving over a triple.

Obiwonkeyblokey

5,400 posts

269 months

Monday 2nd August 2010
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im also look at options on this subject as I have problems with my left knee and am concerned about buying a new bike with a double chainring as I live in a reasonably hilly area.

The option isnt really there to spec a three ring set up from new as the bikes are in stock, so maybe I'll talk to them about changing the rear cassette if its straighforward enough and will give me the "granny gears" I need for some of the hills around me. the spec is shimano 105 with 34/50 on the front and 12/25 on the rear.

Reading this thread and being newbie to cycling it seems that if I were to change the rear to a 28 or 30 I could do away with the requirement for a three ring set up. correct?

Rocksteadyeddie

7,971 posts

256 months

Monday 2nd August 2010
quotequote all
Obiwonkeyblokey said:
im also look at options on this subject as I have problems with my left knee and am concerned about buying a new bike with a double chainring as I live in a reasonably hilly area.

The option isnt really there to spec a three ring set up from new as the bikes are in stock, so maybe I'll talk to them about changing the rear cassette if its straighforward enough and will give me the "granny gears" I need for some of the hills around me. the spec is shimano 105 with 34/50 on the front and 12/25 on the rear.

Reading this thread and being newbie to cycling it seems that if I were to change the rear to a 28 or 30 I could do away with the requirement for a three ring set up. correct?
Short answer, Yes. It's a 5 minute job at worst. You should certainly be able to go to 28 with no problem. 30 may depend on the length of chain and rear mech cage. The supplying dealer should be able to advise.

pdV6

16,442 posts

290 months

Tuesday 3rd August 2010
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Obiwonkeyblokey said:
The option isnt really there to spec a three ring set up from new as the bikes are in stock
The option's always there Owen - you're spending cash with them for a new bike and most decent bike shops will let you swap out parts at cost (i.e. just charge you any difference between the parts you don't want and the ones you spec).

Having said that, just swapping the cassette rather than the chainset/BB etc. will probably get you the climbing ability you need for the least hassle.

s.m.h.

Original Poster:

5,733 posts

244 months

Tuesday 3rd August 2010
quotequote all
Changed the rear cassette, all seems good but didnt have the time to go out for a proper ride so will test it tomorrow evening on the way home. A quick whiz around the workshop and it feels rather different from the 25!

s.m.h.

Original Poster:

5,733 posts

244 months

Monday 9th August 2010
quotequote all
Finally the weather was good enough to try out the new bits, the 1 1/2 mile climb home was much easier - still an effort but just what was needed.
Glad I didnt go for the triple and it still keeps the 50/11 top so still zooms down hills!