Cycling UK Forum

Hiya All,

Many thanks to the guys for the techy info on this!

For ease of reference, I've edited this OP, to close off this post in one go
This is just a summary in the OP - see the replies below for the growing Q&A solutions and thought process!


Costing up Changing Double Front Chainset into a Triple:
Not economical really - think about new rear cassette with wider gearing range, or think carefully before buying that next bike!


Parts breakdown - Cost summary:
In order to achieve lower gearing by changing to a triple at the front you will also need to make other changes, probably :-
0) £64 Shimano Claris 2403 Triple chainset
1) £20 change the front dérailleur from a double to a triple
2) £22 change the rear dérailleur from short cage (SS) to a mid/long cage (GS)
3) £83 change the left hand shifter from a double to a triple
4) £21 probably a new bottom bracket (Advised 68mm X121mm)
5) £?? New longer chain? TBC
--------------
£215 approx





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Original Post

Hi All,


Can I Change my Double Front Chainset into a Triple?


The more I ride it, the more I'm actually getting to like my entry level road bike!
Happy to convert into a commuter at some point, when i finally upgrade to a more expensive leisure road bike.

One issue though is the up hills going home, The 16 speed Claris set up seems to be missing the low low gears of my hybrid

One idea, is in the off season, to get a compatable triple in the sales.


Would this fit my bike?:
http://www.evanscycles.com/products/shi ... Tg#answers


My bike details:
http://www.gtbicycles.com/gbr_en/2014/b ... -gts-sport


Summary of bike:
Chain: KMC 8spd
Crankset Chainwheel: Sun Race 8spd 12-25
Crank: FSA Tempo Compact 50/35
Bottom Bracket: Sealed Cartridge
Pedals: Low Profile Nylon w/ Toe Clips
Front Derailleur: Shimano 2400 Claris
Rear Derailleur: Shimano 2400 Claris 8spd
Shifters: Shimano 2400 Claris Sti


If the above won't work, if there another way to do this?

Regards
Martin

cheapest and simplest to fit a different cassette and a new rear mech if needs be; that ought to get you lower gears, maybe not enough lower but that is for you to decide.

You could fit a triple chainset, but you will need a different BB, different STIs ( check by all means but I think your present front shifter won't run a triple) and you may still need a different cassette anyway.

cheers

In order to achieve lower gearing by changing to a triple at the front you will also need to make other changes, probably :-
1) change the front dérailleur from a double to a triple
2) change the rear dérailleur from short cage (SS) to a mid/long cage (GS)
3) change the left hand shifter from a double to a triple
40 probably a new bottom bracket
This is likely to be quite expensive.

Another way of getting lower gearing is to change the rear cassette to one with a greater range with probably a new chain to allow for the greater large-large combination. This is likely to be a considerably cheaper option particularly if you replacing you cassette and or chain anyway as part of maintenance for wear and tare.

The triple you are looking at has an inner ring with 30 teeth compared with the 34 of your current chainset, a percentage change of 34/30 = 1.13 = +13%. If you change the rear cassette to one with say a 28 tooth largest cog, you will get a slightly lower change in ration 28/25 = 1.12 = +12% at a considerably lower cost all be it at the expense of larger steps between individual gears. Depending on the capabilities of your rear dérailleur you may be able to go to a cassette with an even larger rear but again with the penally of larger steps between gears. It is worth looking at the cassette from both Shimano and SRAM as for the same overall range they sometimes have different combinations of intermediate cogs giving different steps between intermediate gears.

markfh wrote:In order to achieve lower gearing by changing to a triple at the front you will also need to make other changes, probably :-
1) change the front dérailleur from a double to a triple
2) change the rear dérailleur from short cage (SS) to a mid/long cage (GS)
3) change the left hand shifter from a double to a triple
40 probably a new bottom bracket
This is likely to be quite expensive.

Another way of getting lower gearing is to change the rear cassette to one with a greater range with probably a new chain to allow for the greater large-large combination. This is likely to be a considerably cheaper option particularly if you replacing you cassette and or chain anyway as part of maintenance for wear and tare.

The triple you are looking at has an inner ring with 30 teeth compared with the 34 of your current chainset, a percentage change of 34/30 = 1.13 = +13%. If you change the rear cassette to one with say a 28 tooth largest cog, you will get a slightly lower change in ration 28/25 = 1.12 = +12% at a considerably lower cost all be it at the expense of larger steps between individual gears. Depending on the capabilities of your rear dérailleur you may be able to go to a cassette with an even larger rear but again with the penally of larger steps between gears. It is worth looking at the cassette from both Shimano and SRAM as for the same overall range they sometimes have different combinations of intermediate cogs giving different steps between intermediate gears.

Ouch!

Thanks for the info guys!

Will look into changing the rear cassette then.
No rush on this one really, at this rate, be at the end of 2016, in the (alleged) sales

Regards
Martin

Hiya All,


Summary:
OCD Martin here, I looked into the conversion parts as suggested - before moving on
£130 in parts alone, as per breakdown, before any labour, Gosh. (The prices are the current off season sales prices! 20% 10% off etc)


What to do next?:
... It would be great to run the bike into the ground, with a view to upgrading as per the below parts list
... But realistically - How long would it take for an average joe to wear out the parts below on a road bike?!

Realistically, am I looking at simply leaving the current bike alone, and using as a sportive on the flats - and simply using the cash on the next bike, and using that bike instead to commute up the hills?!

Or are the costings realistic in the big scheme of things, to get a nice commuter bike from upgrading a quality old bike with quality new parts? Compared to buying a new replacement commuter?


Parts breakdown - Cost summary:
In order to achieve lower gearing by changing to a triple at the front you will also need to make other changes, probably :-
0) £64 Shimano Claris 2403 Triple
1) £20 change the front dérailleur from a double to a triple
2) £22 change the rear dérailleur from short cage (SS) to a mid/long cage (GS)
3) £ 0 change the left hand shifter from a double to a triple £0 (I believe My existing Shifter already has this)
4) £21 probably a new bottom bracket (Advised 68mm X121mm)
5) £?? New longer chain? TBC
--------------
£130 approx


-----------------------------------------------------------
-----------------------------------------------------------
Parts breakdown - Costs In-depth:
Full web links:
1) change the front dérailleur from a double to a triple
£20
http://www.evanscycles.com/products/shi ... 97#answers

2) change the rear dérailleur from short cage (SS) to a mid/long cage (GS)
£22
http://www.evanscycles.com/products/shi ... -A#answers


3) change the left hand shifter from a double to a triple
I believe My existing Shifter already has this. (Has it on the top indicator, and clicks for it when I try - Dosen't click into any 3rd though, as no extra cog upfront)

4) probably a new bottom bracket
Below link on same FSA Compact 50/34:
http://answers.chainreactioncycles.com/ ... stions.htm
BB advised for:
£21
(68mm X121mm)
http://www.chainreactioncycles.com/shim ... nt=Default

Lower gearing....I did this a couple of years ago....

From memory...New cassette (11-32) New Shimano Deore mech' and a new chain....All in, 50 quid ish.

Easy job and it worked really well...

RideToWorky wrote:
3) £ 0 change the left hand shifter from a double to a triple £0 (I believe My existing Shifter already has this)

not unless you have SL-2403 model shifters, SL-2400 (as indicated) are double-specific.

ker-ching!

cheers

Meanwhile a new cassette is a tenner.

According to shimano the short cage rd is 37t total capacity so in theory an, eg, 11-32t would work with a 34/50 compact though the gaps would be largish. Is your hybrid 8spd? If so could move the cassette over from that for testing purposes. You still might need a new chain though, still under 20 quid total.

Brucey wrote:

RideToWorky wrote:
3) £ 0 change the left hand shifter from a double to a triple £0 (I believe My existing Shifter already has this)

not unless you have SL-2403 model shifters, SL-2400 (as indicated) are double-specific.

ker-ching!

cheers

oh maaaann!
Another £83
http://www.wiggle.co.uk/shimano-st-2400 ... rs-triple/

tonight - I'm having a look at the hoods!
.... hoping - against hope - that they say "Triple" and not "8 speed"....

If need replace STIs, then just not economical I reckon!

Stevek76 wrote:Meanwhile a new cassette is a tenner.

According to shimano the short cage rd is 37t total capacity so in theory an, eg, 11-32t would work with a 34/50 compact though the gaps would be largish. Is your hybrid 8spd? If so could move the cassette over from that for testing purposes. You still might need a new chain though, still under 20 quid total.

Hiya,

yup, going back to the 1st suggestion from the guys!

Are we talking about, 8 speed rear still, using the same STI Levers, and just "spacing" out the gearing on the rear cogs? (Apolgoies for the non tecnical descriptions!)


Regards
Martin

Yes, you'll just have larger jumps between gears. Your current cassette is 12.13.15.17.19.21.23.25. The standard 11-32 8spd hg50 shimano is, iirc, 11.13.15.18.21.24.28.32.

Whether this bothers you largely depends on how much you like to pedal at a specific cadence.

Obviously other cassette options are available, your current 'short cage' (not as short as they used to be it would appear) rd can handle a largest sprocket of 32t and a total capacity of 37t (the chainset uses 16 of this). http://cycle.shimano-eu.com/content/seh-bike/en/home/components1/road/claris/rd-2400-ss.html. You may have no use for a 11t small sprocket but if you're looking at 28t+ for the largest there isn't much choice as these cassettes tend to be aimed at the 'trekking' market with smaller chainrings.

Another possibility is to change the double chainset to a smaller (super compact?) double as here http://forum.ctc.org.uk/viewtopic.php?f=5&t=103107&hilit=chainset&start=15.
This lets you lower all the gears (including lower top gear, which doesn't inconvenience me) keeping small differences between gears.

RideToWorky wrote:

Brucey wrote:

RideToWorky wrote:
3) £ 0 change the left hand shifter from a double to a triple £0 (I believe My existing Shifter already has this)

not unless you have SL-2403 model shifters, SL-2400 (as indicated) are double-specific.

ker-ching!

cheers

oh maaaann!
Another £83
http://www.wiggle.co.uk/shimano-st-2400 ... rs-triple/

tonight - I'm having a look at the hoods!
.... hoping - against hope - that they say "Triple" and not "8 speed"....

If need replace STIs, then just not economical I reckon!

damn damn damn... its a double! ....oh well.... dreaming over

Changing the rear cassette is a nice cheap option but it will only reduce the gearing so far.

What if that still isnt enough? You may still have to go for the triple after all but you will already have the rear derailleur to cope and a cassette that will let you go super-low with a triple.

The lowest front chainring on your double is 34, the standard triple is 30 or 28 but can go to 26 or 24 on many chainsets.