Out of gears

#1
Hi guys,

I have a short and simple question: On flat road, with my gios aerolight, tiagra groupset (front gear must be a 50) i'm out of gear. This is my commuting bike. i'm byuing a new bmc slr01 for longer rides, but I would like to upgrade my gios as i can still push harder on it. :bike:

Can I just change the front gear for a bigger one, without changing the whole gearset ? any ideas ? I dont want to invest top dollar on that bike, since i already bleed out 600k yens for the slr01.

Thanks !
 

m o b

Speeding Up
Jun 22, 2008
341
23
38
Bremen
cyclitis.wordpress.com
#2
OK, out of gears in this sense means you want to ride faster, correct?

If you have a 50 front ring my guess would be that you are riding a compact crank combined with a 34 inner ring.
This one?

http://bike.shimano.com/publish/con...a/product.-code-FC-4550-S.-type-.fc_road.html

The chainrings are fixed to the crank by five bolts arranged in a circle of 110mm, this is the Shimano compact crank spec. I am not 100% sure but I guess it wil not be easy to get bigger chain rings for compact.

So you would need to exchange the whole crank to a standard one with 130mm circle bolt arrangement.

http://bike.shimano.com/publish/con...gra/product.-code-FC-4500.-type-.fc_road.html

with 52/39 chain rings. So 52/50 would give you perhaps 4% more gear range of speed. Hm, expensive and not so much more. In addition you would need a new, longer chain.

How about the rear casette sprocket? It would be less costly to buy a new (9 speed) cassette. Shimano standard is 11-25 , 11-30 ..... 14/25. So if your smallest sprocket is 14 now and you exchange the cassette with one where the smallest sprocke is 11, you would come from 50/14 ratio to 50/11 ratio which is much more than if you change the front chain ring. But if you have a 11 or 12 cog already it doesn't make much sense either.

If you change from 12,13 or 14 to 11, you will also need a new lockring which often is not supplied with the cassette.

http://bike.shimano.com/media/techd.../EV-CS-HG50-9-1880C_v1_m56577569830799948.pdf

More expensive solutions would be the combination of standard crank and new rear cassette, or new crank with chain rings from other makers up to 55T. The front derailleur can handle up to 16T difference between the inner and outer chain ringe so you could run 55/39 for exanple.

At a certain point you would also need a longer rear derailleur. Summarizing, new cassette plus chain plus lock ring would be the easiest way. Otherwise I don't see any necessisity to change any other component of the group set.
 

FarEast

Maximum Pace
May 25, 2009
5,528
538
193
Yokohama
#3
MOB is correct - you are limited to 50t on a 110PCD (Compact Crank Set) there are larger out there but people that have used them complain of flex - also due to the price it is going to be about the same price to buy a brand new Taigra 130 (Standard Crank) that has a 53t front.

You may also want to take a look at your rear cassette as you maybe running a minimum of 13t at the back and this could be replaced for a minimum or a 11t.

A new Taigra crank is only going to cost you 6,000 JPY

http://www.sagamicycle.com/shopping-home/シマノコンポグレード別/tiagra-4600シリーズ/

Or a new cassette with a tighter range will cost you 2,400 JPY (Same Page)

You will need specific tools to change the cassette over and a set of Allen keys to change over the cranks - however as you have been running a compact you will need to raise the height of the front derailleur to accommodate the larger diameter of the Chainrings.
 

FarEast

Maximum Pace
May 25, 2009
5,528
538
193
Yokohama
#8
Jayves - are you running a short cage or long cage rear derailleur with that?

Also now that Shimano Mtb has gone 10 speed you'll be able to run an XT or XTR rear cassette.
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#9
My q exactly. Even if I sacrifice a couple of cogs at the top... Interested in this for the HR. Having a 'refreshment gear' would be nice. Old school mechs could never handle this swing. But I've been trying a 11-28 combo and it's flawless , so, why not push the limit a bit more?? Only thing I'd be concerned with is maybe chain durability.

I'm currently using 38/53 crhainset which I really love. But experimented with 36/50 as well. I'm still partial to the larger front rings. But really like the spinning ease of the 36 / 28 on steeper grade of 15%+

Jayves - are you running a short cage or long cage rear derailleur with that?

Also now that Shimano Mtb has gone 10 speed you'll be able to run an XT or XTR rear cassette.
 

Jayves

Speeding Up
Nov 20, 2009
115
3
38
Yokohama
jayves-rando.blogspot.jp
#12
Also now that Shimano Mtb has gone 10 speed you'll be able to run an XT or XTR rear cassette.
Exactly, I currently have that setup using Shimano MTB DynaSys XT 10 spd 11-34 on ultegra long cage. Tiagra (RD-4600-GS) long cage work better with this setup as the 'official' max sprocket size is 30T compared with Ultegra 28T. Ultegra is kind of pushing the limit.
 
#14
Wow, great answers guys thanks a lot !

I can't identify exactly the cassette i'm using now, Looking all over the internet, I can't get the exact description of the groupset used on the 2009 airolight. So i simply counted the teeth and the smallest ring is 11T.

So I guess i have to change cassette and front rings, but for just 4% extra, it doesnt seems to worth it.

I'm worrying about my new bike choice now, the BMC slr01, I chosen the Ultegra di2 53T ... it wont be much more gears than the tiagra 50.

What options I have to get way more gears ? Triathlon bike ?
 

GSAstuto

Maximum Pace
Oct 11, 2009
945
242
103
tokyo
www.roadfixie.com
#20
I test rode the SLR01 a few months ago. I would have liked to take it on a longer, harder ride to determine more about their claim of enhanced comfort, etc. But overall, it was a nice bike with predictable response and performance for a roadbike priced at this level. In my opinion, there are really no 'bad bikes' anymore - especially with carbon framesets being so ubiqutous. It just comes down to how much you're willing to pay for styling details, finish quality and assumed performance tweaks based on blabble from the marketing departments of the Private Equity firms. Decent Frame + Proven Geometry + Good Groupset = Good Bike.