Changing from triple to compact

Cubic

Hi,

I've been thinking about my cycling and I think my current gearing setup isn't particularly compatible with me. I've got a triple(54/39/30), but I don't think I use it very well. I seem to spend most of my time in the middle cog, going uphill and on the flats. I tend to get a bit fatiged using the big ring on the flats and I don't use the granny ring at all - mainly pride but it also feels so slow!
So, I'm thinking a compact is the way to go. I think a 50/34 would help me on the hills (my weakest point) and give me more speed on the flats.

I was hoping to get the opinions of some more experienced people though, so any advice would be appreciated!

Also, if I was to convert to a compact, could I just change the chain rings on my current chainset or would I need to buy a new chainset altogether? I guess I'd need a new front derailleur too, anything else?

Thanks.

simon_e

Don't rush it.

If you use the 39T front most of the time I'd be inclined to suggest that it's fine as it is. Is this "a solution in search of a problem"? I use my SCR's middle ring virtually the whole time at the moment but am happy to have the 30T to hand for the really steep hills. The 52T will get used for faster rides in good weather.

The big downside I see of the compact - as well as the big jump when moving between the two chainrings - is that it doesn't really fit the gear range I like. 50T is close to the big ring while 34 is not much higher than the granny. If you want to know what the 30T ring is for by all means come to Shropshire and ride some of the hills.

I have uploaded a graph comparing the ratio spread, based on a 9 speed 12-25 tooth cassette. Solid lines = triple, dashed lines are the compact.

Take a look at the sticky thread titled "Help I need smaller gears" in this forum if you haven't done so already.

volvine

sorry for sounding stupid but are all front chain rings with 2 rings called compacts and the ones with three called tripples or is there a standard two ring and a compact??????

laurensdad

3 chainrings = triple
2 chainrings 50/34 or similar = compact
2 chainrings 53/39 are considered 'standard'

You are likely to need a new frot mech and also check the compatibilty of your l/h sti....

Hope that helps

Phil

John.T

Minimum would be just a chainset. You could use your current rear mech but it would look neater with a short cage one. Your current LH shifter should be OK with a double. You should be able to use the front mech but occasionaly there are issues. Suck it and see, if it works then fine.
If you are not on the later outboard BB then you would need to change the BB to one the correct length for your chainset. If on outboard then no problem.

wolleur

Can i suggest instead of shelling out on a compact chainset, swap in a 50t chainring (easy job and a lot cheaper) then you retain the flexibility of a triple but you'll feel better on it.

Compact doesn't really offer any advantages over triple, apart from weight as far as I can see? Play around with your ratios a bit until you find something you like, chainrings are relatively inexpensive compared to going the full monty.

BeaconRuth

wolleur wrote:

Can i suggest instead of shelling out on a compact chainset, swap in a 50t chainring (easy job and a lot cheaper) then you retain the flexibility of a triple but you'll feel better on it.

Good idea, wolleur.

Personally I'm a bit mystified why anyone would want to ride with compact gears. It would be a nightmare - such a lousy choice of gears on the flat, it would drive me nuts. OK, there's some nice low gears but surely if you want low gears like that, you're far far better off with a triple? I'm at a complete loss to understand why compacts are so popular. What am I missing?

Ruth

roger_merriman

BeaconRuth wrote:

wolleur wrote:

Can i suggest instead of shelling out on a compact chainset, swap in a 50t chainring (easy job and a lot cheaper) then you retain the flexibility of a triple but you'll feel better on it.

Good idea, wolleur.

Personally I'm a bit mystified why anyone would want to ride with compact gears. It would be a nightmare - such a lousy choice of gears on the flat, it would drive me nuts. OK, there's some nice low gears but surely if you want low gears like that, you're far far better off with a triple? I'm at a complete loss to understand why compacts are so popular. What am I missing?

Ruth

it's the range of gears it gives, with a 12-27 cassette and 34/50 chainrings your unlikely to spin out, and very few hills are too steep, plus for rolling land your not having to bother with 3 chainrings, like a lot of things there is fair lump of hype with it, but for some folk it's a good gear selection.

jrab

I have a triple with gearing pretty close to the graph posted earlier. On the flat I tend to run the middle ring and middle of the sprocket, between 60-80 inch gear - this gives a speed range of 16-21mph at 90rpm which is reasonable on the flat. to go faster I still have two more smaller sprockets, or can go to big ring and step back just one sprocket to get 90-inch gear (25mph) and then carry on up the block.

On a 50/34 compact, the same spread of ratios puts you on the smallest sprockets on the 34 ring, or the biggest sprockets on the 50 ring. Either way a change of gradient means you have to shift the front and then up or down 3-4 sprockets at the back, which is just annoying!

Triple gives you one set of close-ratio gears for downhill and tailwind flat (big ring), one set of ratios for flat, headwind and normal hills (middle), and one set of ratios for big hills (granny).

On a compact I would be riding all the time on the boundary between the rings, would probably end up shifting the front more than the back, which can't be right.

The best solution for a compact would be a 50/36 with 11-25, but only when you're fit enough to run the 50 on the flat and get up any hill on the 36.

Richard.

John.T

I tried a 53/42/32 triple and it was a pain. Spent most of my time in the 42 and had to keep messing around with the granny when things got steep. Changing to a 39 improved things but the 32 became almost redundant. Then went 53/39 and 13/27 This was OK but I was short of low gears in the Alps, Pyrenees and Yorks Dales. Also had to be a home made custom cassette as Shimano did not make 13/27 in 9sp and I wanted my 16 cog so out went the 12 and in went a 16. I finaly fitted a 50/34 Gran Fondo ('compact' was still on the marketing table) for a trip to the Pyrenees and have not looked back. Now running 50/34 on 3 bikes, including my race one. I just use the cassette best suited for what I am doing. 11/21 for TTs, 12/23 for hilly races and 12/27 for general riding. Most flat riding is done on 34/13 or 14 or on 50/19 or 21. Moving down from the 34/14 gives a good range of climbing gears. I seldom have a problem with the 16 tooth gap on the rings. Just get on the right one early. It does I think work better with 10sp than 9, I get my 16 cog back.
I have just returned from a 60 mile ride and have only changed rings twice, on to the 50 soon after setting out and back to the 34 for the rather hilly last few miles home. The rest of the day was spent in 50/21 and occasionally 19. My average speed was 15.1 mph. If I lived in Lincolnshire or similar I would probably have 53/39 but a triple, bin there, done that.
I would still recomend a triple to a novice living in hill country or intending to visit one but not for me now..

roger_merriman

i did find when i first had the bike i was swapping the front too much, but no any more, if it's just a minor lump then i can use some of the bigger cogs while on the 50t with out having too nasty a chainline, i'm fairly tolrent of gearing, and likewise down a hill if its a short and i can see or know i'm going back up shortly then there is little point changing up front.

works for me millage as ever varies.

wolleur

I'm not sure of the advantages of a compact, my bike came with one and I'm really happy with the bike. It might sound wierd but I prefer standards/compacts from an aesthetic view, that said i can't see it when I'm sat on it pedalling!

I've swapped my small ring from 34 to a 38 as changing from the 34 to 50 felt too big a step, so I'm somewhere between a compact and a standard. The main influence on the gearing I use is the local geography, fairly frequent but small bumps so no real need for a 'granny'. I've seen my strength and fitness improve incrementally since getting my bike, so hopefully the time will come when I can turn a standard chainset, maybe in 1000 miles or so....

nmcgann

wolleur wrote:

I'm not sure of the advantages of a compact, my bike came with one and I'm really happy with the bike. It might sound wierd but I prefer standards/compacts from an aesthetic view, that said i can't see it when I'm sat on it pedalling!

I've swapped my small ring from 34 to a 38 as changing from the 34 to 50 felt too big a step, so I'm somewhere between a compact and a standard. The main influence on the gearing I use is the local geography, fairly frequent but small bumps so no real need for a 'granny'. I've seen my strength and fitness improve incrementally since getting my bike, so hopefully the time will come when I can turn a standard chainset, maybe in 1000 miles or so....

My summer bike is a 38/50 and it's a combination I really like for general riding about. I just change the cassette to suit the terrain, 12-27 for (uk) hills and 12-23 or 12-21 for general use.

I can't get on with a compact for general riding - that 34 ring is just too small and the double shifting all the time drove me nuts. If I was off to the alps I'd fit one though as the cheapest change that would give me a low gear.

If I was after one bike to do it all though I'd definately go for a triple. My winter bike has a 30/40/50 chainset and it's useable anywhere with no compromise in gearing. The shifting isn't as slick as my summer bike with a double though.

Neil