Road Bike, Cycling Forums banner

1 - 10 of 10 Posts

·
Parlee fan!
Joined
·
747 Posts
Discussion Starter #1
Hi Guys!

I have a friend who bought his first Time Trial bike (Trek Equinox). It is equipped with Shimano 105 9spd components and a standard crank (53/39) and cassette (12-25). He needs to change the his big chainring on his 105 crankset to a 55. There are a few brands that offer this option. He's looking at either the shimano DA 55t or the FSA 55t.

Will this modification work on the 105 9spd crankset?

Thanks in advance!!!!

Joe
 

·
NeoRetroGrouch
Joined
·
6,491 Posts
santosjep said:
Hi Guys!

I have a friend who bought his first Time Trial bike (Trek Equinox). It is equipped with Shimano 105 9spd components and a standard crank (53/39) and cassette (12-25). He needs to change the his big chainring on his 105 crankset to a 55. There are a few brands that offer this option. He's looking at either the shimano DA 55t or the FSA 55t.

Will this modification work on the 105 9spd crankset?

Thanks in advance!!!!

Joe
Any 130mm BCD ring will fit. There may be problems mounting the derailleur and shifting though. - TF
 

·
Parlee fan!
Joined
·
747 Posts
Discussion Starter #3
130 Bcd

TurboTurtle said:
Any 130mm BCD ring will fit. There may be problems mounting the derailleur and shifting though. - TF
Thanks TF!!!

I was corrected by my friend who owns the bike.. It's a 105 10spd. I researched and it appears that the crank is also a 130 BCD. I'll let him know your input!

Joe
 

·
Banned forever.....or not
Joined
·
24,406 Posts
Why would he even think that he might need a "55" ??????
If he is in the catagory of "damn fast", a 53X13 gives a pretty good chainline.
 

·
Parlee fan!
Joined
·
747 Posts
Discussion Starter #6
TT bike

MR_GRUMPY said:
Why would he even think that he might need a "55" ??????
If he is in the catagory of "damn fast", a 53X13 gives a pretty good chainline.
According to him, he's spinning off 53x12. So, the option was to either get an 11-23 cassette or get a 55t or 54t chainring. Last year, he placed in the state TT championship at 59 min 40K TT on his roadbike.

Joe
 

·
On your left!
Joined
·
1,299 Posts
59 for a 40k is fast...

santosjep said:
According to him, he's spinning off 53x12. So, the option was to either get an 11-23 cassette or get a 55t or 54t chainring. Last year, he placed in the state TT championship at 59 min 40K TT on his roadbike.

Joe
But there are several in the club I ride with who do much faster on 53X11.

So, I think a 55t will not drop his time as much as more work on the motor would. I'd recommend an 11 tooth cog first if he is running out of gears.
 

·
LOOK lover
Joined
·
616 Posts
santosjep said:
According to him, he's spinning off 53x12. So, the option was to either get an 11-23 cassette or get a 55t or 54t chainring. Last year, he placed in the state TT championship at 59 min 40K TT on his roadbike.

Joe
Maybe spinning off on the downhills! 59 min for a flat 40K is respectable, but certainly not blazing fast enough to spin out on a 53x12. I only go down to my 13-t cog if I've got some good tailwind assist.

Tell your friend to get a 11-23 cassette if that makes him feel better - then he can avoid the total fred embarrassment of showing up at a TT with a 55-t logo-emblazoned TT chainring and not even win.
 

·
Registered
Joined
·
21,509 Posts
Spun out?

santosjep said:
According to him, he's spinning off 53x12. So, the option was to either get an 11-23 cassette or get a 55t or 54t chainring. Last year, he placed in the state TT championship at 59 min 40K TT on his roadbike.
Assuming 700c, 90 rpm in a 53/12 is nearly 31 mph. If it's 650c, then it's over 28 mph. That's a long way from the 25 mph your friend did in the TT. 55/12 would give you less than a 4% increase in speed, or around 3 rpm at 90 rpm. Unless we're talking some bigger hills, this seems more of an ego quest than a need quest. :)
 

·
Parlee fan!
Joined
·
747 Posts
Discussion Starter #10
Thanks for your responses.

I shall relay the information to my friend.

Ride safely.

Joe
 
1 - 10 of 10 Posts
Top