changing compact chainset

Daz1214

hi

im currently running an FSA velo compact 50/39 chainset and find myself spinning out in the top gear. If i wanted to fit a 52-53/39 chainset, what else would i need to change?

Thanks

Beasty

You only need to move the front derailleur up a bit. Hopefully your chain will be OK as you are just adding a couple of cogs. What's your smallest sprocket on the cassette? If it's not an 11 you might want to try changing cassette first

Daz1214

the cassette on it is a 12-25 so what should i put on it instead?

Beasty

11-25 or 11-23 if you don't need the 25 on the hills

Moving from a 12 to an 11 increases your gearing by 9%

Moving the chainring from a 50 to a 53 increases it by 6%

ktz84

You'd need to check the bcd of the current chainset as if it is a compact it is likely to have a 110mm bcd and a standard chainset tends to have a 130mm bcd. There are 110mm standard bcd chainsets out there so you just need to be careful about ordering the right ones.

However as Beasty says an 11 may be the best and cheapest move and an 50x11, I think I'm right in saying, is actually a taller gear than 53x12 so you shouldn't have any probs running out of gears on this one.

Daz1214

my bike is running an 8 speed set up and ive found a SRAM 8speed cassette in either 11-28, 11-30 or 11-32...any of those any good?

531

That sounds like MTB cassettes to me. If it's fast road use, look for the likes of 11-21 or 11-23. Should be available in 8 speed. If I am correct, shimano cassettes would also fit and they are easily available.

Daz1214

they were listed under road cassettes .the only shimano 8 speed cassette i can find is the sora hg-50 which is whats on the bike already and is 12-23 or 12-25 only

Beasty

I think your best option is probably 11-28, although the gaps between gears will be a bit more significant. That's always going to be a bt of a problem with an 8-speed on a double though

You can revert to the plan of changing to a 52 or 53, but it will not actually give you that much of an increase in gearing. Presumably though you are only spinning out on descents? Is it really that much of an issue?

Daz1214

the bike is used for triathlons and where ive found the problem is on any courses with downhill sections and i havent been able to squeeze any more speed out of the bike

Lumen

Upgrade to 10sp or get more aerodynamic.

kenmc

Lumen wrote: »

Upgrade to 10sp or get more aerodynamic.

I vote for a new bike or 2

Keep_Her_Lit

Daz1214 wrote: »

the bike is used for triathlons and where ive found the problem is on any courses with downhill sections and i havent been able to squeeze any more speed out of the bike

So how much speed are you squeezing out of the bike? What does your speedo/computer read when you top out? Just wondering what your pedaling cadence is like.

At a cadence of 120rpm, a 50/12 top gear driving a 700-23 rear wheel gets you about 63km/h. With a little practice, you should be able to hold 120-130rpm for short periods without any problem.

Descents of 70km/h or faster tend to be very short, in Ireland at least, and are often tackled in an aero tuck position, without pedaling.

In summary, with a little work on your cadence, you may well be able to squeeze that elusive last bit of speed out of your existing set up.

Daz1214

Lumen wrote: »

Upgrade to 10sp or get more aerodynamic.

would love to upgrade but not in a position to at the moment...my aero position isnt the problem, just the short gearing

Daz1214

Keep_Her_Lit wrote: »

So how much speed are you squeezing out of the bike? What does your speedo/computer read when you top out? Just wondering what your pedaling cadence is like.

At a cadence of 120rpm, a 50/12 top gear driving a 700-23 rear wheel gets you about 63km/h. With a little practice, you should be able to hold 120-130rpm for short periods without any problem.

Descents of 70km/h or faster tend to be very short, in Ireland at least, and are often tackled in an aero tuck position, without pedaling.

In summary, with a little work on your cadence, you may well be able to squeeze that elusive last bit of speed out of your existing set up.

Im getting about 60kph on the decents on average...as it turns out, my cassette started slipping this morning on the club spin so will need replacing now

Raymzor

i was faced with similar situation-i have a 9 speed, compact 50-34 and 12-25. i decided to go for cassette 11-25-it hasnt arrived yet! when it comes to the gear ratios adding an eleven is a 9% step up from the 12. a 52 is a 4% step from 50 and a 54 is an 8% step up. the 110mm bcd on a standard compact makes it awkward to upgrade

kenmc

No matter the percentage upgrades by going from a 12 to an 11 or a 50 to a 53, what no-one has yet mentioned is the gearing gained by going from a 34 to a 39. I rode a compact for 2 years or so, and was ALWAYS in the big ring, and even then was spinning out. By moving to a standard 53/39 at the start of the year, I found myself using the small ring a lot more, even on the flats. I'm converted now.

Tonyandthewhale

http://www.ebay.ie/itm/8-Speed-Sunrace-Road-Bike-Cassette-Shimano-Sram-Compatible-11-23-/150743933544?pt=AU_Sport_Cycling_Parts&hash=item231909e268 8 speed cassette there in a 11-23.

Daz1214

seems to be the only option out there, question is whether or not its of good quality

mp31

kenmc wrote: »

No matter the percentage upgrades by going from a 12 to an 11 or a 50 to a 53, what no-one has yet mentioned is the gearing gained by going from a 34 to a 39. I rode a compact for 2 years or so, and was ALWAYS in the big ring, and even then was spinning out. By moving to a standard 53/39 at the start of the year, I found myself using the small ring a lot more, even on the flats. I'm converted now.

What did you have before changing to the 53/39 set?

kenmc

50/34