Cassette sizing
Discussion
On my Scott S30 Speedster I have a 12-30 cassette and as I am new to road cycling occasionly find it quite difficult on steep hills. It has been suggested to me to swap out the cassette with another unit with more suitable ratios but I am a little confused as to what sizing to go for.
This is the bike spec:
Shimano Tiagra ST-4600 new Dual control 20 speed shifters, Shimano Tiagra FD-4600 new front mech, Shimano Tiagra RD-4600 27 Speed rear mech, Shimano Tiagra Compact new, FC-4650, Hollowtech II chainset with 50/34 tooth chainrings, Shimano Tiagra CS-4600 new 10 speed 12-30 tooth cassette, 20 gears
The other options in this range are 12-28 and 11-25. How much difference does 2 or 5 teeth make to the low gears?
This is the bike spec:
Shimano Tiagra ST-4600 new Dual control 20 speed shifters, Shimano Tiagra FD-4600 new front mech, Shimano Tiagra RD-4600 27 Speed rear mech, Shimano Tiagra Compact new, FC-4650, Hollowtech II chainset with 50/34 tooth chainrings, Shimano Tiagra CS-4600 new 10 speed 12-30 tooth cassette, 20 gears
The other options in this range are 12-28 and 11-25. How much difference does 2 or 5 teeth make to the low gears?
When you say difficult on steep hills , is it a case you find it hard to push down on the pedals (need to stand up) or you find you are having to spin the pedals at a uncomfortable fast pace to keep going. As said above 30 is about the largest cassette ring you can get (apex do a cassette with a 32)
A triple (again as suggested above) would add a small ring at the front (probably a 29 or 30) this would then give you a 30 at the front and 30 at the back - which i imagine is as low as you can go on a road bike.
Also how steep are the hills and how long you been ridding ? i'v been riding for a while and mainly in the peaks, the hills never get any easier you just can a little faster. I am now up to a whopping 6mph on the steep ones and I have a 32 ring cassette.
A triple (again as suggested above) would add a small ring at the front (probably a 29 or 30) this would then give you a 30 at the front and 30 at the back - which i imagine is as low as you can go on a road bike.
Also how steep are the hills and how long you been ridding ? i'v been riding for a while and mainly in the peaks, the hills never get any easier you just can a little faster. I am now up to a whopping 6mph on the steep ones and I have a 32 ring cassette.
Ive only been riding properly since October and more seriously now I have my road bike. I suppose coming from a mtb with extremely low gearing I will need some time to get used to it. Living in Sussex there are quite a lot of hills and couple of weeks ago I had to get off and push going up the hill from East Dean (nr Beachy Head) to Friston.
Unfortunatly the weather has gone against me this morning which is a shame as the route I had planned to do and have completed a couple of times on the mtb included Ditchling Beacon which I have done comfortably.
I wanted to avoid the granny ring which is one of the reasons I chose a bike without it. Should I be training on the flat with higher speeds or on hilly rides to increase leg strength. I dont have the opportunity to cycle during the week due to work so Sundays are my only day.
Unfortunatly the weather has gone against me this morning which is a shame as the route I had planned to do and have completed a couple of times on the mtb included Ditchling Beacon which I have done comfortably.
I wanted to avoid the granny ring which is one of the reasons I chose a bike without it. Should I be training on the flat with higher speeds or on hilly rides to increase leg strength. I dont have the opportunity to cycle during the week due to work so Sundays are my only day.
You won't benefit from a triple chainset and you would need to replace your double shifters. 34x30 is already a very low gear but if you really want lower then fit a long cage rear mech and an 11-32 rear cassette. You may well need to lengthen your chain. My advice is to ride more hills and your fitness will improve
30 should have you wizzing up most of the stuff down south. High cadence is great but you also maybe need to try pulling a big gear on the flat and ride standing to help improve leg strength.
Just changed the 12/25 to an 11/28 on Sophies bike to help her with the hills I've been pushing her up
and its made a huge difference.
Something I'm doing is just riding up and down the same hill for hours atm
Just changed the 12/25 to an 11/28 on Sophies bike to help her with the hills I've been pushing her up
and its made a huge difference.Something I'm doing is just riding up and down the same hill for hours atm
Edited by crisisjez on Sunday 4th March 12:59
swerni said:
Why wouldn't he benefit from a tripple
Standard triple is 30-40-50. 30x30 would give 26.3 gear inches. He would need triple chainset, new front mech and new front left shifter (assuming you can find a single shifter and not have to buy a pair. Staying with 34-50 and using a 32 rear cassette would give 27.9 gear inches so very close to the same ratio. He would need only need new casette and rear mech, plus a couple of extra links in the chain. This is a much cheaper option.
Gary Fisher Triton, 48 x 18 fixed/free and Halo wheels. Lovely, lovely thing 
BPC7 said:
On my Scott S30 Speedster I have a 12-30 cassette and as I am new to road cycling occasionly find it quite difficult on steep hills. It has been suggested to me to swap out the cassette with another unit with more suitable ratios but I am a little confused as to what sizing to go for.
This is the bike spec:
Shimano Tiagra ST-4600 new Dual control 20 speed shifters, Shimano Tiagra FD-4600 new front mech, Shimano Tiagra RD-4600 27 Speed rear mech, Shimano Tiagra Compact new, FC-4650, Hollowtech II chainset with 50/34 tooth chainrings, Shimano Tiagra CS-4600 new 10 speed 12-30 tooth cassette, 20 gears
The other options in this range are 12-28 and 11-25. How much difference does 2 or 5 teeth make to the low gears?
Could someone stop me if I'm missing something here, but if you've got a 10 speed cassette with a 27 speed rear mech, how are you managing to use all 10 gears on the cassette?This is the bike spec:
Shimano Tiagra ST-4600 new Dual control 20 speed shifters, Shimano Tiagra FD-4600 new front mech, Shimano Tiagra RD-4600 27 Speed rear mech, Shimano Tiagra Compact new, FC-4650, Hollowtech II chainset with 50/34 tooth chainrings, Shimano Tiagra CS-4600 new 10 speed 12-30 tooth cassette, 20 gears
The other options in this range are 12-28 and 11-25. How much difference does 2 or 5 teeth make to the low gears?
Wouldn't a 27 speed rear mech be limiting you to just 9 of the gears? If so, might this mean you're not actually using that 30 you've currently got?
Kermit power said:
Could someone stop me if I'm missing something here, but if you've got a 10 speed cassette with a 27 speed rear mech, how are you managing to use all 10 gears on the cassette?
Wouldn't a 27 speed rear mech be limiting you to just 9 of the gears? If so, might this mean you're not actually using that 30 you've currently got?
Reading the blurb I posted it is a typo on the 27Wouldn't a 27 speed rear mech be limiting you to just 9 of the gears? If so, might this mean you're not actually using that 30 you've currently got?
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