Road Bike, Cycling Forums banner
1 - 20 of 36 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter · #1 ·
Hi guys,

I'm new to cycling so please forgive my ignorance :)
I struggling trying to figure out how I can achieve the correct gear ratio for my son's bike. He joined the local club but as a Peewee, there are some gear ratio limitations for competition. His bike is a 49 Specialized Allez with a 8-Speed Claris Compact Groupset: 50/34 front and 11/32 back.

8th32
7th28
6th24
5th21
4th18
3rd15
2nd13
1st11

<colgroup><col><col></colgroup><tbody>
</tbody>

According to the rules the max ratio for his class is 2.875 or a (46/16). Looking at some videos on youtube I tried to limit the rear derailleur so that we would not go the lower gears (11,13,15) but I can only manage to stop at the 3rd cog (15). 50/15 = 3.333 which is higher than what he can go. If there was a way to limit the derailleur to stop at the 4th cog (18), 50/18 = 2.777, he would be fine. The Hi-Limit screw in the rear derailleur is already all the way in. Is there another way to limit?

I also thought of changing the rear cassette but all Claris Cassetes have their 3rd last cog as 15 which would not help me in this case. Is it possible to mix and match cogs from different Cassetes within the same groupset? I mean, could I have something like this:

8th32
7th28
6th24
5th21
4th19
3rd18
2nd15
1st13

<colgroup><col><col></colgroup><tbody>
</tbody>

Shimano Cassettes: 2017-2018 SHIMANO Product Information Web

Thanks in advance for all your help :)

Alex
 

·
Registered
Joined
·
7,492 Posts
If you bought one of these - 12-13-15-17-19-21-23-25

Combined with your existing cassette you could get 12 (not used), 18-19-21-23-25-28-32

Which gets you 7 useable gears with a good spread.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #3 ·
Wow! That would be great, so there is no problem mixing and matching cogs from within the same groupset :)
I was worried that would not be possible. Does the 1st cog need to be either the 11 or the 12 teeth or could I have the 15 as the first? even if he will not be using that in competition but could possible use for regular rides. I guess the first cog is a special one right?

Thanks again!
 

·
Registered
Joined
·
7,492 Posts
I feel pretty safe in saying that you can mix cogs within the same family. I'm not familiar with Shimano cassettes but I suspect the first cog is specific. Someone else will confirm I'm sure.
 

·
Banned Sock Puppet
Joined
·
14,409 Posts
Do you know for sure that this is not a one-piece cassette with all the cogs riveted together? This would be a show stopper.
 

·
Registered
Joined
·
7,492 Posts
redacted
 

·
Banned Sock Puppet
Joined
·
14,409 Posts
Actually I don't know that. I was assuming the cogs were always seperate :/
Nope. Some are one piece. Others have a few of the larger cogs riveted together and the smaller cogs separate. You won't know until you remove it from the freehub.
 

·
Registered
Joined
·
7,492 Posts
My searching indicates that people wanting customization are drilling out the rivets. Then the sprockets are all individual.

Last time I messed with a Shimano cassette it was loose cog, so I'm out of date.
 

·
Banned Sock Puppet
Joined
·
14,409 Posts
Another idea would be to just disable the front shifter cable, and have the front in the small 34 ring all the time. If you do that, I believe you may only have to disable the 11T cog in back.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #11 ·
Since I don't have the tools to remove the cassette, I'll have to bring the bike to a LBS or wait for someone with access to a Claris Cassete, maybe someone who works in a Bike shop, to clarify that for us.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #13 ·
I went to a LBS and the 8-Spd Cassete only have the first 2 cogs free, smallest ones, the others are riveted together.
 

·
Banned Sock Puppet
Joined
·
14,409 Posts
I went to a LBS and the 8-Spd Cassete only have the first 2 cogs free, smallest ones, the others are riveted together.

I was afraid of that.

As I said, make the front a single 34. Problem solved!
 

·
a real member's member
Joined
·
3,880 Posts
disable the front shifter cable, and have the front in the small 34 ring all the time, [and] disable the 11T cog in back.
you can get very close to the max gear allowed by doing the above, changing the small ring to a 36t, and prohibiting the rear derailleur from 11t small cog access. see the gear calc below:

Mike Sherman's Bicycle Gear Calculator
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #17 ·
the 16-23 would be perfect. I could also change his outer chainring to a 46T and get him to use all his gears. I'll try to buy the cassette.
 

·
Registered
Joined
·
760 Posts
the 16-23 would be perfect. I could also change his outer chainring to a 46T and get him to use all his gears. I'll try to buy the cassette.
While you are at it, you could pick up a chain whip and lock ring tool to swap it yourself (think you said you needed LBS to swap?) also a 46T chain ring if feeling inclined to try that too.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #20 ·
I've received the 16-23 Cassette from Bike24.com and bought a FSA 46T Chainring.
Text Font Material property Paper Advertising Undergarment
I've installed the Cassette myself but I couldn't find that special too to hold the back screws of the chainring so I had to bring the bike to a LBS to have it replaced. Anyway, my son raced this weekend at the Preston Street Crit Race here in Ottawa and finished in 2nd Place :)

Thanks everyone for your help in finding this perfect solution, I really appreciate :)
 
1 - 20 of 36 Posts
Top