How to tell what Casette you have?

benhben

Bought a scond hand Moda Stretto recently. Its a stunning bike and zips along the flats, however on the steeper hills the lowest gear on the stretto is definitely much harder and tougher than the lowest gear on my Raleigh Avanti Carbon Comp. Im now wondering if the Stretto has been deliberately geared for racing on the flats and not climbing. The stretto groupset is SRAM Force 10 and the Raleigh is Shimano 105

How can a rider with limited technical knowledge of bike mechanics (i.e me) find what cassette type is installed on my bike?

Is it an expensive job to change the gearing on a bike to include a easier bail out gear for the steep climbs?

Thanks

outcastjack

Each cog on the cassette will almost certainly have the number of teeth stamped on it somewhere. Expect 11/12/13 for the smallest one and somewhere between 22 and 32 for the biggest.

The chainrings at the front will also have the number of teeth, expect around 53 to 49 for the big one and 39 to 34 for the smaller one

The cheapest way to get a lower gear is just to swap out the rear cassette (take the wheel out, remove the cassette locking ring and swap them over)
something like this (the 11-36 one) would give you a very low bottom gear and costs just over £40 it is possible to spend three times that if you wish.
http://www.chainreactioncycles.com/Mode ... elID=51846

Shimano Cassettes will fit your wheel and may be cheaper, but i am not sure if they are compatible with Sram shifters/deraileurs.

MattC59

The Force cassette is available in loads of ranges:

http://www.wiggle.co.uk/sram-pg1070-10-speed-cassette-road/

Have a look at the back of the 105 cassette (taking the wheel out will make it easier) on one of the cassette arms, it will say something like 11-25 or 11-18. Just buy the Force cassette in the same range.

Check that your chain is long enough though and that your rear derailleur has enough capacity. Count the number of links on the raleigh chain, and make sure that the Moda chain has the same number (assuming that your chain rings and cassettes are now the same).

MattC59

outcastjack wrote:

Each cog on the cassette will almost certainly have the number of teeth stamped on it somewhere. Expect 11/12/13 for the smallest one and somewhere between 22 and 32 for the biggest.

The chainrings at the front will also have the number of teeth, expect around 53 to 49 for the big one and 39 to 34 for the smaller one

The cheapest way to get a lower gear is just to swap out the rear cassette (take the wheel out, remove the cassette locking ring and swap them over)
something like this (the 11-36 one) would give you a very low bottom gear and costs just over £40 it is possible to spend three times that if you wish.
http://www.chainreactioncycles.com/Mode ... elID=51846

Shimano Cassettes will fit your wheel and may be cheaper, but i am not sure if they are compatible with Sram shifters/deraileurs.

Be careful if you go for the 11-36 cassette, it's designed for the WiFli gears, which are essentially longer caged rear mechs. Your current rear mech may not have the capacity to cope with it.

benhben

MattC59 wrote:

The Force cassette is available in loads of ranges:

http://www.wiggle.co.uk/sram-pg1070-10-speed-cassette-road/

Have a look at the back of the 105 cassette (taking the wheel out will make it easier) on one of the cassette arms, it will say something like 11-25 or 11-18. Just buy the Force cassette in the same range.

Check that your chain is long enough though and that your rear derailleur has enough capacity. Count the number of links on the raleigh chain, and make sure that the Moda chain has the same number (assuming that your chain rings and cassettes are now the same).

#

Thanks for that. What sort of numbers will be a good blend between good speed on the flats and decents but having a bail out gear on the steeper hills?

smidsy

Simply count the number of teeth on the smallest cog and the biggest cog.

If you are in a hilly area then you will need something between 27 to 30 for the largest. Smallest look for somewhere between 11 to13. So maybe a 12/27 or 13/30?

If you do relatively flat rides and live in Norfolk then maybe go to an 12/25 or 11/23.

MattC59

I've got a triple on my Trek, chain rings are 52/39/30, at the back, there's a 12-27 cassette.

I rarely (4 times in 3 years !) use the 30T chain ring, but when used with the 27T sprocket on the back, it gives me the bail out gear if I really need it. This is a properly low gear that I can winch myslef up the steepest climbs with.

The 30, 27 combination gives me a gear ration of 1.11

I'm about to build a new bike with a compact double chain ring set up on the front. That's a 50/34 chain ring combination, but I wanted to keep a similar top gear and also maintain the bail out gear for nasty climbs. So:

For the top gear:
Old ratio = 52/12 = 4.33
New ration required is closest to 4.33.
new largest chain ring = 50T, therefore; 50/4.33 = number of teeth required = 11.5

For the bottom gear:
Old ration = 30/27 = 1.11
New ratio requires is closest to 1.11
New smallest chainring = 34T, therefore; 34/1.11 = number of teeth required = 30.6

The closest I can get is either 11-28 in Ultegra, or 11-28 or 12-27 in 105. I've gone for 11-28. which gives me these sprockets: 11-12-13-14-15-17-19-21-24-28, there are big jumps, but ony when I get to the bail out gears, not an issue as far as I'm concerned.

Find out what chain rings and cassette you have on your 105 equipped bike and do the above calculations. Then pick the nearest equivalent (assuming that you want something similar). The larger the sprocket, the lower the gear.

Hope this helps.
M

jonomc4

Just remember on the Force the largest rear cog you can have is 28. to go any bigger you need a long arm dérailleur (not available in Force).

t4tomo

......but 28 should be plenty big enough, if its not, it will be once you've got some miles in your legs

benhben

MattC59 wrote:

I've got a triple on my Trek, chain rings are 52/39/30, at the back, there's a 12-27 cassette.

I rarely (4 times in 3 years !) use the 30T chain ring, but when used with the 27T sprocket on the back, it gives me the bail out gear if I really need it. This is a properly low gear that I can winch myslef up the steepest climbs with.

The 30, 27 combination gives me a gear ration of 1.11

I'm about to build a new bike with a compact double chain ring set up on the front. That's a 50/34 chain ring combination, but I wanted to keep a similar top gear and also maintain the bail out gear for nasty climbs. So:

For the top gear:
Old ratio = 52/12 = 4.33
New ration required is closest to 4.33.
new largest chain ring = 50T, therefore; 50/4.33 = number of teeth required = 11.5

For the bottom gear:
Old ration = 30/27 = 1.11
New ratio requires is closest to 1.11
New smallest chainring = 34T, therefore; 34/1.11 = number of teeth required = 30.6

The closest I can get is either 11-28 in Ultegra, or 11-28 or 12-27 in 105. I've gone for 11-28. which gives me these sprockets: 11-12-13-14-15-17-19-21-24-28, there are big jumps, but ony when I get to the bail out gears, not an issue as far as I'm concerned.

Find out what chain rings and cassette you have on your 105 equipped bike and do the above calculations. Then pick the nearest equivalent (assuming that you want something similar). The larger the sprocket, the lower the gear.

Hope this helps.
M

Cant quite get my head around how to calculate what cassette I need to include an easier gear on my Stretto.

My Raleigh Avanti Comp has a gear ratio of:
Front: 52/39
Rear: 12/25

Stretto:
Front: 53/39
Rear: 11/25

Now does the fact that the front chain rings are different mean that to get a gearing better suited for steep climbing its not simply a case of buying a SRAM Force in the 12/25 ratio?

MattC59

benhben wrote:

MattC59 wrote:

I've got a triple on my Trek, chain rings are 52/39/30, at the back, there's a 12-27 cassette.

I rarely (4 times in 3 years !) use the 30T chain ring, but when used with the 27T sprocket on the back, it gives me the bail out gear if I really need it. This is a properly low gear that I can winch myslef up the steepest climbs with.

The 30, 27 combination gives me a gear ration of 1.11

I'm about to build a new bike with a compact double chain ring set up on the front. That's a 50/34 chain ring combination, but I wanted to keep a similar top gear and also maintain the bail out gear for nasty climbs. So:

For the top gear:
Old ratio = 52/12 = 4.33
New ration required is closest to 4.33.
new largest chain ring = 50T, therefore; 50/4.33 = number of teeth required = 11.5

For the bottom gear:
Old ration = 30/27 = 1.11
New ratio requires is closest to 1.11
New smallest chainring = 34T, therefore; 34/1.11 = number of teeth required = 30.6

The closest I can get is either 11-28 in Ultegra, or 11-28 or 12-27 in 105. I've gone for 11-28. which gives me these sprockets: 11-12-13-14-15-17-19-21-24-28, there are big jumps, but ony when I get to the bail out gears, not an issue as far as I'm concerned.

Find out what chain rings and cassette you have on your 105 equipped bike and do the above calculations. Then pick the nearest equivalent (assuming that you want something similar). The larger the sprocket, the lower the gear.

Hope this helps.
M

Cant quite get my head around how to calculate what cassette I need to include an easier gear on my Stretto.

My Raleigh Avanti Comp has a gear ratio of:
Front: 52/39
Rear: 12/25

Stretto:
Front: 53/39
Rear: 11/25

Now does the fact that the front chain rings are different mean that to get a gearing better suited for steep climbing its not simply a case of buying a SRAM Force in the 12/25 ratio?

The largerchain ring will only have an effect if you're using it. (not meaning to state the obvious ), so; the gears which will provide the lowest ratio are the smallest chain ring on the front, coupled with the largest sprocket on the back. So:
Raleigh: Smallest Front = 39: Largest rear = 25; Ratio = 39 divided by 25 = 1.56
Stretto : Smallest Front = 39: Largest rear = 25; Ratio = 39 divided by 25 = 1.56

You have the same bottom geat on each.

However, If you're using your large chain ring:
Raleigh: Largest Front = 52: Largest rear = 25; Ratio = 52 divided by 25 = 2.08
Stretto : Largest Front = 53: Largest rear = 25; Ratio = 53 divided by 25 = 2.12

If you're using the big ring, the Raleigh has the slightly lower gear when using the 25T sprocket.
If you're using the small ring, then they both have the same bottom gear.

oldwelshman

MattC59 wrote:

benhben wrote:

MattC59 wrote:

I've got a triple on my Trek, chain rings are 52/39/30, at the back, there's a 12-27 cassette.

I rarely (4 times in 3 years !) use the 30T chain ring, but when used with the 27T sprocket on the back, it gives me the bail out gear if I really need it. This is a properly low gear that I can winch myslef up the steepest climbs with.

The 30, 27 combination gives me a gear ration of 1.11

I'm about to build a new bike with a compact double chain ring set up on the front. That's a 50/34 chain ring combination, but I wanted to keep a similar top gear and also maintain the bail out gear for nasty climbs. So:

For the top gear:
Old ratio = 52/12 = 4.33
New ration required is closest to 4.33.
new largest chain ring = 50T, therefore; 50/4.33 = number of teeth required = 11.5

For the bottom gear:
Old ration = 30/27 = 1.11
New ratio requires is closest to 1.11
New smallest chainring = 34T, therefore; 34/1.11 = number of teeth required = 30.6

The closest I can get is either 11-28 in Ultegra, or 11-28 or 12-27 in 105. I've gone for 11-28. which gives me these sprockets: 11-12-13-14-15-17-19-21-24-28, there are big jumps, but ony when I get to the bail out gears, not an issue as far as I'm concerned.

Find out what chain rings and cassette you have on your 105 equipped bike and do the above calculations. Then pick the nearest equivalent (assuming that you want something similar). The larger the sprocket, the lower the gear.

Hope this helps.
M

Cant quite get my head around how to calculate what cassette I need to include an easier gear on my Stretto.

My Raleigh Avanti Comp has a gear ratio of:
Front: 52/39
Rear: 12/25

Stretto:
Front: 53/39
Rear: 11/25

Now does the fact that the front chain rings are different mean that to get a gearing better suited for steep climbing its not simply a case of buying a SRAM Force in the 12/25 ratio?

The largerchain ring will only have an effect if you're using it. (not meaning to state the obvious ), so; the gears which will provide the lowest ratio are the smallest chain ring on the front, coupled with the largest sprocket on the back. So:
Raleigh: Smallest Front = 39: Largest rear = 25; Ratio = 39 divided by 25 = 1.56
Stretto : Smallest Front = 39: Largest rear = 25; Ratio = 39 divided by 25 = 1.56

You have the same bottom geat on each.

However, If you're using your large chain ring:
Raleigh: Largest Front = 52: Largest rear = 25; Ratio = 52 divided by 25 = 2.08
Stretto : Largest Front = 53: Largest rear = 25; Ratio = 53 divided by 25 = 2.12

If you're using the big ring, the Raleigh has the slightly lower gear when using the 25T sprocket.
If you're using the small ring, then they both have the same bottom gear.

Which basically means no differene at all as you should not use the big fron big back due to chain deflection which will cause increase in wear of sprocket chainring and chain

jonomc4

to calculate ratios etc. use this website

http://www.sheldonbrown.com/gears/

simon_e

benhben wrote:

Cant quite get my head around how to calculate what cassette I need to include an easier gear on my Stretto.

My Raleigh Avanti Comp has a gear ratio of:
Front: 52/39
Rear: 12/25

Stretto:
Front: 53/39
Rear: 11/25

Now does the fact that the front chain rings are different mean that to get a gearing better suited for steep climbing its not simply a case of buying a SRAM Force in the 12/25 ratio?

Ignore the 52 v 53. Your smallest gear - 39 front & 25 rear - is the same on both bikes.

The Stretto's SRAM Force short cage rear derailleur won't work with a much larger (lower geared) cassette such as 32 tooth anyway. It should be OK with a cassette with 28 teeth on the lowest gear. If you do that you'll probably need a longer chain as you're asking it to wrap around 3 extra sprocket teeth.

An alternative is to fit a long cage derailleur with greater capacity e.g. SRAM Apex. Another solution would be to fit a compact chainset so you have a smaller front ring. Either will help on steep hills, the derailleur will be cheaper.

I suggest you go to a shop that can advise you properly (and fit the appropriate parts for you).

chiv30

Ideally you should be able to change your front rings from 53/39 to 50/34 ( if the front BCD is 110 then you're laughing ) and then swap ur rear cassette to something like a 12-28 or the SRAM equivalent , that way you shouldn't have to tweak chain length or indexing and theoretically should get up most hills/mountains the UK has to offer

chiv30

Also as its been mentioned previously in this thread , if you are running 39/25 on both bikes you have an identical bottom gear .... in this case the only reason I can see for it being harder to climb on one bike over the other would be weight differences between the bikes as the gear is identical , the rider is identical and I can only assume it was the same stretch of tarmac ....