Changing Cassettes

DHC

I am new to road bikes and finding the gear ratios different from my hybrid and moutain bikes. Basically, hills that I can climb with ease on my hybrid, I struggle up on my road bike. Question is, can I change the cassette to one that would normally be fitted to a mountain bike/hybrid. Current setup is as follows:



Shifters – Shimano Tiagra 9 speed STI

Rear Mech – Shimano 105

Front Mech – Shimano Tiagra

Cassette – Shimano HG 50 9 speed 12-25

Chain – Shimano HG73 narrow

Chainset – Truvativ Elita 2.1 Compact 50/36T

Bottom Bracket – Truvativ GXP



Hope is that I can change the cassette to either of the following:



11-32 or even 11-34.

http://www.cyclesportsuk.co.uk/product_ ... cts_id=903



Any comments or advice would be appreciated.

whyamihere

You may well need an MTB rear mech to take that size of cassette, road ones tend to be for more closely spaced cassettes. 29 teeth is around the limit of the medium cage road mechs, 32 might work, but is unlikely, 34 almost definitely won't.

DHC

Thanks for the reply.

topdude

You will have problems with a cassette of that size as mentioned above.
Either fit a 34/50 compact chainset and 12/27 cassette, probably cost about £50 or so.
Or fit a triple chainset and a longer cage rear mech for about the same cost.

DHC

My first choice was to fit a triple chainset, but I was informed by the local bike shop that this would involve changoing the shifters as well, which would push the cost up to approx £150. Hence the change of tact and looking at changing the cassette instead. Is the bigger cassette (12-32) just not an option?

Peasoup

casette is an option, as mentioned above, but will require new mtb rear mech (long cage)
to cope

try shimano deore or similar with hg50 11-34t cassette.

andrewgturnbull

Ah, I think you must have MTB legs - you need to upgrade them to roadie ones!

;-)

Cheers, Andy

andy_wrx

You already have a compact, but 50/36, and 12-25 cassette.
For little expense you can change the 36 ring to a 34 and fit a 12-27 cassette, so you'll gain two lower gears-worth
But this won't get you low as your MTB

I think Tiagra shifters will handle double or triple - anyone know better ?

John Stevenson

Current model Tiagra shifters - ST-4500 - are double/triple compatible, according to the 2008 Shimano sales & support manual (it's on p201 you need to quote chapter and verse to your local bike shop)

A triple is therefore an option, though you'll need an FD-4503 front derailleur to go with it.

You might also still need a long-cage rear derailleur to wrap the extra chain slack generated by the triple.

leonlikestrees

I'm not sure if it's bad form to try and peddle kit on a thread like this, but I actually have an unused 34t compact ring for sale (came off a SRAM Rival crankset), and also a brand new 11-34 XT cassette.

I run an 11-34 on my cross bike for the 3 Peaks, and for that I have to fit a long cage MTB mech to work. You'll also need a longer chain too.

PM me if interested in the bits.

Leon

DHC

Thanks for all the valuable input. If I am correct, I can summarise it as follows:

OPTION 1 - change cassette to 11-32 or 11-34.

* Requires a longer MTB read derailleur/mech.
* Existing Shimano Tiagra 9 speed STI shifters can be used.
* Downside is bigger jump, not as smooth transition between gears.

or

OPTION 2 - Change to a triple chainset.

* May require a longer MTB read derailleur/mech.
* Requires a new front derailleur, such as FD4503.
* Existing Shimano Tiagra 9 speed STI shifters can be used.

If the above is correct, then next step is to estimate likely costs of both options.

Mettan

DHC wrote:

Thanks for all the valuable input. If I am correct, I can summarise it as follows:

OPTION 1 - change cassette to 11-32 or 11-34.

* Requires a longer MTB read derailleur/mech.
* Existing Shimano Tiagra 9 speed STI shifters can be used.
* Downside is bigger jump, not as smooth transition between gears.

or

OPTION 2 - Change to a triple chainset.

* May require a longer MTB read derailleur/mech.
* Requires a new front derailleur, such as FD4503.
* Existing Shimano Tiagra 9 speed STI shifters can be used.

If the above is correct, then next step is to estimate likely costs of both options.

On my 8-speed Road bike, I currently run:

Shimano - 11-32 cassette
Shimano - 50/34 Compact
Shimano - Altus Rear mech

To summarise - it works well - it's very cushy, particularly going uphill - it's ok on the flat (prefered the 53/39 on the flat tbh). So it can be done - and the 34/32 certainly came in handy on the Cheshire Cat last week

peanut

I find it amazing that you should require the same gearing on a lightweight road bike as you had on a heavy MTB with wider tyres.?

What tyres are you using on your road bike ? anything larger than 23c is too big unless you intend on using grave/mud l tracks Stick 120 lbs in them so there is less drag you should really fly on a road bike.
:?

As an ordinary club rider I used to use a 52/38 with a 11-25 and climb porlock hill and cheddar gorge etc without problem. Either you have some serious mountainous geography in your locale or you need to do some more hill climbing to build some cardio vascular fitness.

if you want to go the triple route you can buy pair of
9 speed Sora Levers3400 STi lever for £58.00 Ribble
a Shimano Sora Triple 3403 9 Spd Chainset for £27.00 Ribble cycles
Shimano Sora 3403 9 Triple Front Gear £11.56 Ribble

Tiagra 9 speed are only £83.00 at Ribble RRP is £150 which is what you'll pay at the lbs :evil:

turkeytickler

DHC - what sort of terrain are you riding on? Assuming its not 20%s up and down for your whole route can I suggest you stick with the original casette? You will soon get used to the effort - you can try sitting further back in the saddle to use your climbing muscles etc.... and a widely spaced cassette will be very annoying on the flat esp if you ride in a group as you will find the gaps between the gears very big. Road casettes give you a nice gradual progression up and down.... if you really must change then I agree use a compact or triple - but dont change the casette.

tt

beverick

I'm running a 11-34 on a 105 rear mech without trouble. It's all 105 except the chainwhieel which is a Truvativ GXP triple (50/39/30 I seem to remember).

Bob

DHC

I am going to France and plan on cycling 1200k over a week, with a of the tour hill climbs thrown in, just for the hell of it. Hence, my concern over my ability to get up the hills.

Thanks for all the advice. I may stick with it, and delay doing anything as yet.