buzp

I have shimano 2300 3x8 components on my road bike (specialized secteur). Can I change to a 10 speed gear set and use the same crank set and bottom bracket, or will I need an entire new groupset? If I only need new shifters, this would be a good upgrade for me as I ride a lot of hills and more gears would be nice, but an entire group set might not be worth the money.

demoncyclist

Simply having more gears isn't an upgrade if you don't have the right gears. Maybe changing the cassette to one with lower gears would be a better answer...

MRT2

Are you using your small chainring on climbs?

buzp

Yes. 30 tooth chainring, 26 tooth cog.

fietsbob

Do the Ratio Math... what size , (tooth count) are you lacking? you can resolve that, perhaps, without the large expense of replacing the drivetrain.

MRT2

Maybe see if you can go down to a 26 tooth chainring. I have been using a 26-36-48 triple chainring with a 12-25 cassette for the last 2 1/2 years and it provides a nice range of gears. There are times where I think an extra climbing gear in the back would be nice, but so far I am sticking with this setup.

HillRider

The answer to your question is that the current crank will work sort-of. The chainring spacing is greater than 9 or 10-speed cranks and you may have problems with the thinner 10-speed chain getting caught between the chainrings if you shift under load. If you are careful it can be acceptable.

At a minimum you will need new shifters, a new cassette and a new chain and possibly a new front derailleur A Tiagra 10-speed crank (FC-4600 double or FC-4603 triple) and matching bottom bracket would be the lowest cost replacement crank and will certainly work.

cycle_maven

Sure, you can use your 8-speed crank with 10-speed rest of the group. It won't be perfect, and it will possibly exhibit more episodes of chain suck and skating over the teeth when shifting with a 10-speed chain, but it will mostly work OK. But do you want MORE gears or LOWER gears? I know that some folks upgraded to 10-speed to get that elusive 15 cog in their otherwise acceptable cassette span. But that's the only reason I can see to change a perfectly fine 8-speed system to 10 speed.

If you want lower gears, my suggestion is to get a new cassette, maybe 12-32 rather than 12-26, and a 8 or 9-speed mountain bike derailleur (and a new chain of course). You'll get out for under $100, and have perfect shifting and the lower gears you want. Upgrading to 10-speed will cost two to three benjamins and the supply of low geared cassettes is poor.

HillRider

15T cogs are very common. The really "elusive" cog is the 16T and is the reason I changed a perfectly fine 9-speed 12x27 cassette to a 10-speed 12x27. If Shimano sold a 13x27 9-speed cassette I would still use 9-speed.

buzp

Doh! Looks like a simple change in the gear set is all I need. Don't know why I was trying to do it the hard way.

Slash5

The crank may or may not work. I recently upgraded to 10 speed and found I couldn't get reliable shifts on the front. Most of the time the chain would sit on the top of the large ring and not drop down onto the teeth. I went through my stack of chainrings and found one that appeared to have less offset. I installed that and had reliable shifting.
However, the limit to larger gears would likely be your present rear derailleur. If it has a limit of 28 then 10 speed isn't going to help.
You could try a 8 speed 30T cassette - even if your derailleur is rated for 28 it will probably handle a 30T cog if you adjust the B-screw.

Bike Gremlin

More gears are worse - more sensitive to tune, and more expensive to buy chains and cassettes.

You could get a nice MTB rear derailleur (Shimano Acera, or better) and do a straight swap with your current rear derailleur (up to 9 speed MTB ders should be compatible). That will allow you to use a 32, or even a 34 biggest tooth at the rear. Plenty of range for steep hills.

buzp

Thanks for the responses. Looks like I'll try a new gear set and new rear derailleur if necessary.

Bill Kapaun

I've upgraded 2 bikes to 9 speed.
The first had friction shifters and I picked up a used 8/9 speed Free hub wheel at a garage sale for $5, so it was pretty inexpensive. Just a chain & cassette.
I then did N+1.
On my Globe, it was originally 8 speed and that involved new ST Brake/Shifters, chain & cassette. Noticeably more $, but not too bad since I waited until the various parts were on sale.

The bad part was my former EXCELLENT friction shifting skills went down the tube when I got the 2nd bike with trigger shifters, so I ended up getting them for bike N.

Since you are going to get a new cassette anyway, you'll probably get a new chain.
It just might be time to make the switch to 9 speed.
I just ordered a set of ST-EF 65 shifters from Amazon for $42 delivered. (my Globe was stolen and I got it back somewhat stripped)
What I like about 9 speed vs 8 is the much wider variety of cassettes available.

Drew Eckhardt 

Acceptable spacing on 8 speed road cassettes limits you to a 21, 19, or 18 big cog depending on whether you started with a 13, 12, or 11 cog.

cny-bikeman

Acceptable spacing is 10% jump or less on the same cog? That's uncalled for - I certainly welcome the smaller jumps made available by more cogs (though I find anything beyond 9 silly when they start at a next to useless 11 tooth) but somehow we managed to survive back when the standard for racing was 5 cogs to get from 14-21. I have an 8 speed 13-28 and I don't find the jumps to be inefficient or uncomfortable, and have a few on the alternate chainrings to fill in gaps where I most often ride.

MRT2

Consider switching out the small chainring first. I did this with my wife's bike to give her a more useful 39 tooth chainring instead of the stock 42 tooth one. In her case, she found for moderate efforts, the middle chainring was a bit too big, while the small 30 tooth chainring was too small. It turned out to be an easier and cheaper way to go than to switch out the back cassette and derailleur.

As I have said, my bike comes equipped with a 12-25 road cassette but more a touring triple 26-36-48, which provides a decent range of climbing gears good enough to handle most of the tough climbs in my neck of the woods. If I lived somewhere more mountainous, I might switch to a mountain cassette and rear derailleur.

LastKraftWagen

I have a SecTour for use in the trainer, and when one of the 8spd shifters went FUBAR I "upgraded" (spare shifters laying around) to older Ultegra 3x9spd. Installed 9spd cassette (again laying around), and while I didn't count all the teeth, I know the low gear is 32T, and worked with the original RD without B-screw adjustment. My FD however seems to have an incapitable pull ratio as even with 9spd chainrings shifts are moo poo. Couldn't tell you if I have the same group, just my experience.

a77impala

I have a road bike 8 speed triple gearing 52/42/30 chainrings, 12/25 cassette. I regeared 50/39/30 with an 11/30 cassette, all I had to do was add two links in the chain, put on a new chain. I had the chainrings so my total out of pocket was less than $30. With 1-1 gear can climb anything.
All you need is cassette and chain, no need to change crankset.

GeorgeBMac

If you haven't already, Sheldon has a nice calculator to tell you what you will get with a new cassette or chain ring with different gearing...