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_info.php?products_id=903

Any comments or advice would be appreciated.

 

[MichaelM]

That's a fair range for a 105 rear mech to handle, depends on whether or not it's a long cage or not. Try Sheldon Brown for info - though someone more knowledgeable may be along to clarify.........

 

[DHC]

Thanks for the reply.

 

[fosmaal]

The max rear sprocket capacity of a 105 rear mech is 27 teeth, so you will need to get a rear mech with a long cage, which wold mean getting a MTB one (I'm not sure if you can get a long cage road specific mech, unless somebody tells me different) this should allow you to go upto 34 on the rear. Luckly a MTB mech will work with you index shifters, unlike MTB front mechs.

Some of you questions are answered here.

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3808

 

[bonj2]

whack an 11-23 on there you girl. And use a triple chainset. Doubles are no good if you are having to grind up hills, and putting a MTB cassette on is not the answer! The main (only?) reason for having a double is to look hard. It kind of ruins it a bit if you then whack a dirty great 34 toother on the back

 

[bianco]

Why don't you use smaller tyres?

The decreased diameter will give you a lower gear!

 

[DHC]

whack an 11-23 on there you girl. And use a triple chainset. Doubles are no good if you are having to grind up hills, and putting a MTB cassette on is not the answer! The main (only?) reason for having a double is to look hard. It kind of ruins it a bit if you then whack a dirty great 34 toother on the back

.

I was informed that changing to a triple chainset would also involved changing the gear shifters and this was rasing the cost to an unacceptable level.

Perhaps the answer is get fit, save money.

 

[Chris James]

.

I was informed that changing to a triple chainset would also involved changing the gear shifters and this was rasing the cost to an unacceptable level.

Perhaps the answer is get fit, save money.

I think you have been misinformed. As far as I am aware Tiagra STIs work for both double and triples and have done so for some years.

 

[fossyant]

Perhaps the answer is get fit, save money.

That's the cheapest option.

Problem with having a wide ratio 11-27/32 or what ever, is you have big jumps between sprockets, so you'll not have the smoothest of transition between gears. I.e. spinning in one gear, then grinding a bit in the next.

My cassettes are always close ratio - either 1 tooth or two teeth at the bigger sprockets, I don't like any bigger jumps.

 

[Danny]

Personally I would go a wider range of gears, particularly if you cycle somewhere that is reasonably hilly. If you are struggling to get up hills you are not going to enjoy your cycling, and may even be deterred from going out regularly and thus getting fitter.

You can always go back to closer ratio gears in the future.

 

[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.

 

[DEWY]

hi DHC

it seems i'min excactly the same predicament as you. i have a boardman road comp with the same spec as your bike.

i'm very interested what you did in the end, cost, are you happy with it???

 

[Globalti]

I have fitted this bike with a Compact 34-50 front and a Shimano 11-32 8 speed rear, (not in the picture) using the old 105 short cage derailleur. It works fine, the gears change fine, the gaps between ratios are big but as somebody else wrote above, it being freehub I can easily change the cassette for something with a shallower slope.

If I was doing it again now from a fresh start I think I would go for a closer ratio cassette and a triple though.

 

[John the Monkey]

Sorry to sidetrack the thread a bit, but that really is a lovely looking bike RR, top job.

 

[Gerry Attrick]

Here here. Superb. It looks as though it has an incredibly short wheelbase, or is it the photo?