diverguy

I have a Cannondale Synapse 5 that is my travel bike. It's great. Love it. It has a FSA Gossamer 50/39/34 on the front and a 10 speed Shimano 12x25 on the rear. I like the 10 speed. It works fine. But last summer's trip through the Rockies was tough. The 34 x 25 combination wasn't enough for some of the steeper, longer grades and next summer I'm planning to do the hills around San Francisco.

I've heard of... but know nothing about... a 48/38/28 chainset. Any idea who makes it, if it comes in a 10 speed variety, and if it would work with an FSA Mega-Exo bb6000 bottom bracket (bb68 English)?

Or... can you recommend a smaller, like maybe for a mountain bike, chainset that would better tackle the mountains better, will work with my existing 10 speed set up, and will fit my current bottom bracket?

Thanks for any suggestions.

John

bradtx

John, I don't know about FSA cranksets, but see if you can replace the inner 34T chainring for a smaller, lower tooth unit. It will depend on the bolt circle diameter (BCD) as to how much smaller you can go. Another option is to replace the cassette with one that has a lower ratio bottom gear. Third option is to combine both.

Brad

frantik

yeah, i'll echo bradtx.. you only need a smaller granny ring and/or the biggest gear(s) on the cassette need to be bigger. the easiest is to just get a smaller granny ring (if possible). you will need a crank puller to remove it though.

50/39/34 seems a bit odd honestly.. not much difference between the middle and granny rings. 50/39/30 or 50/34/26 or something would make more sense and give you a wider range.

is this the crankset you have? https://www.nashbar.com/bikes/Product...23&cagpspn=pla it was speced wit 50/39/30.. did you buy the crankset brand new with 50/39/34?

jon c. 

That is an odd crankset, but it's easy and relatively inexpensive to switch out the lower ring.

acidfast7

shimano FC-TXXX series

T=touring

bud16415

Here is your data in a calculator, just click the link below.

I think the smallest 74 mm BCD granny that will fit your crank is 24t. You can also find 26t 28t and 30t easily. If you went 24t your climbing gear lowest would go from 36 to 26 gear inch. That’s a big improvement. You call it your travel bike if you are touring on it with some load 26 GI may or may not be low enough. For touring many people like to be down around 20GI or even lower. That depends on the weight and strength of the rider. I didn’t look to see what FD you have but you will have to check on the range there. Going to a small granny makes for a harder shift also and most people going to a real small granny add something called a chain minder to make sure the chain doesn’t miss the granny when dropping down.

https://home.earthlink.net/~mike.sherman/shift.html?R0=34&R1=39&R2=50&C0=12&C1=13&C2=14&C3=15&C4=16&C5=17&C6=19&C7=21&C8=23&C9=25&C10=999&CAS =101&WI=8&CR=170&RT=1&ST=0&RPM=90&SRT=0&lRPM=80&hRMP=100&G=show&S=no&TITLE=&HL=1
.

ultraman6970

Isn't better just train more??? you look very young to me.

34 x 30 will bring almost to a 1:1 gear that is just ridiculously light gear (just using that as expression ok?)... What I would do if I was you is just dump the triple, get a compact crankset, get a long cage RD and add a 30 in the back and do it all with 34x30 and tiny longer cranks. Like half of the triple is basically gears that are repeated anyways, thats the reason never liked triples.

The other thing is that since you are in FL even an overpass will feel like a darn climb, specially in the area where you are that is fairly flat. That links with my initial statement. Many try to fix the problem climbing adding bigger cogs and even smaller chainrings but w/o training no matter how low or light the gear is, the guy will suck anyways, telling you that by experience. I live in va and have done the darn skyline here and I would love to have money to get a compact crankset but i know that with the 500 miles I pedal every year there is nothing much to blame to the gear setting I have, i dont train and like ex tracker I just suck climbing... You can't mask a problem when the issue is just another one. Just my opinion ok?

Not a climber here just in case, just being practical.

Good luck with your choice

diverguy

Some good advice here. Thanks for everyone's input. Makes sense to just change the granny ring, instead of the whole chainset. The 50/39/34 that's on there came with the bike from the factory just like the 12x25 on the rear. The bolt pattern is a 74mm 5 bolt. After reading the suggestions and doing some internet research, it seems like a good choice might be the 26t Salsa. Plenty of people have written that they're running it on a 10 speed with no problem. Then swap out the cassette for a 12x28. A 26x28 combination should be able to handle most any of the slopes I might run into better than what I have now.

cplager

My triple crank came as as 48/38/28 and I dropped the granny to a 22 (so now 48/38/22). I like it a lot and recommend this setup, but:

I almost always stay in the middle or big ring up front. When I do drop to the granny gear, I need to simultaneously move the rear derailleur up 3 gears so that I don't spin out (it's worth practicing this a few times to get it down). I've pretty much perfected this technique so I very much prefer the wide range it gives me. I did add an N-Gear Jump Stop; before I would occasionally drop the chain.

In your case, since the difference between 34 and 30 is so small, I'm willing to believe that you don't use your granny very much at all. Dropping the 30 to a 26 will give you a lot more range and won't really impact how you currently ride, so I think this really will be a win for you.

Cheers,
Charles

10 Wheels

All you need is a 24T Small Chain Ring in place of the 34T.
I have that on my triple and it works fine.

bud16415

My similar bike came 52,42,30 although with a wide spaced cassette from the factory. When I first wanted lower gears for the hills I swapped the 30t for a 26t as you mentioned, also because I had read many had done that. I was worried about going less than 26t with the shift up to 42t. I later found it wasn’t any harder going from a 24t to 42t. You are starting with a 39t center ring so I wouldn’t be worried to go to a 24t if you think you need that bump. Might save you changing the cassette and won’t have any effect on your rides around home on the flats.

HillRider

+1 on changing just the granny ring to a 26T or 24T. One thing to keep in mind is that you will probably exceed the "wrap capacity" of your rear derailleur so you will have to avoid using the new granny ring with the smallest 2 or 3 cogs or the chain will go slack. It won't cause any damage but will be noisy and unusable.

Also +1 on the N-Gear Jump Stop or a Third Eye Chain Watcher. These are very useful to keep the chain from overriding the granny ring on a fast downshift. Cheap insurance and peace of mind.

contango 

A friend of mine runs a 48/38/28 chainset. I run a FSA 50/39/30 on my 2009 Tricross, coupled with a 9-speed 11-32 cassette. The 30/32 granny gear is low enough for me to do most hills. If I lost some of my excess weight I imagine it would be low enough for me to do just about anything on regular tarmac.

If you want to keep the 12-25 cassette and reduce gearing with just the chainrings you could put a smaller granny ring on it. You'll need to consider the limits of the FD - if I recall they have a minimum tooth difference between the outer and middle rings and a maximum difference between the outer and inner rings. So if you want to drop below a 30t inner ring you may need to put a smaller outer ring on it.

If you want to go really low you can get a 48/36/26 set or take something off a mountain bike like a 44/32/22 set. A 22/25 granny gear should get you up most things. My wife's Rockhopper has an Octalink spline BB (68x118mm) and takes a triple 44/32/22 chainring, if that's any help. Truth be told unless your bottom bracket is particularly expensive you might find it's just as easy to buy a new bottom bracket, relative to the cost of the chainrings it's likely to be cheap. A replacement BB for my wife's Rockhopper is barely over $20 (£12.99 at chainreactioncycles)

HillRider

This can be a problem if the small granny causes the chain to drag on the front derailleur's cage tail. However, if you avoid the granny-smallest few cogs combinations this isn't usually an issue. I have a 10-speed Campy Chorus triple crank and matching front derailleur on one bike and the OEM gearing was 53/42/30 and is now 53/42/26. The chain drags on the fd's cage in anything smaller than the 17T cog but this is no problem as there is no need for the granny if I can use the 17T cog with it since a 42x27 gives the same gear.

ThermionicScott 

I would recount the teeth on that 34t granny -- it's rare that a person would want one bigger than 32t, so they're kind of a specialty item. While 26/28 will definitely get you up most hills, I wonder if you're doing mostly seated climbing. It would be a good exercise to start climbing more hills out of the saddle.

HillRider

It struck several of us as an odd size too. The only 34T "granny" I've come across was on an old Suguino 110 mm BCD crank that had all three chainrings (52/42/34) mounted using one set of long chainring bolts and spacers.

frantik

yeah a 34t gear with 74bcd seemed odd to me. i googled and the only good match that that comes up for 50/39/34 is this thread

cplager

One last comment:

If you add a granny gear, you need to make sure your rear derailleur can handle it. You may find that if you are in or close to small-small, the rear derailleur you have can't handle the extra chain.

Cheers,
Charles

bud16415

Just one more thought as long as you may be pulling your crank and downsizing your granny. As some have posted you will have to watch your chain length and maybe going slack if you cross too far. Also the issue of the FD overall ring differences with a smaller granny. The FD height is pretty much set off your center ring and the clearance to the back shift plate.

In my case I looked at how little I rode on my big ring in the 3 smallest cogs. In your case those GI come out to be 110, 102, 95. For me 95GI would be high enough and to put it in perspective 95GI at 100RPM = 28 MPH @90RPM , 25MPH @80RPM, 23MPH given 700c wheels. What I did was at the same time was reduce my big ring also moving some of the gears I do use over so that I had a straighter chain line on my big ring. Depending on how fast you spin etc. you may want to look at a smaller big ring for those benefits 43t or 44t maybe. That would let you shorten your chain and get rid of the slack problem. In my case I found going to a smaller big ring I was able to lower my FD some and that helped with covering the smaller granny. The big plus was the shift center to big is super smooth now, so smooth I don’t even hardly hear it. It’s only an idea and no one knows how another rider rides.

HillRider

This has already been mentioned a couple of times. It is highly likely he will exceed the rd's wrap capacity with a smaller granny but all that does is eliminate small-small from the useful gears and they aren't of any necessity anyway.

ksisler

Fully agree with your pain on trying to up a steep hill in current gearing. Might want to consider adding a touring bike to your stable as gearing out a road bike to make it do touring duty can result in a bike not really perfect for either purpose.

cplager

I looked for it and missed it - sure enough, you did mention it.

It's not as bad as having the chain too short to go into big big and trying, but it's my understanding that if you do shift into a gear where there is too much slack, you can damage your rear derailleur/drive train. Is this not true? (I'm really asking, I'm not trying to be a smart-alek).

Cheers,
Charles

volosong

Another option is that Tiagra and Ultegra have a 12-30 cassette. (You'll need to check your chain length and if the RD is mid or long cage.)

ThermionicScott 

I don't know about long-term damage, but it sure doesn't sound good when the rear derailleur has retracted all the way and the lower run of chain has to grind on the jockey pulley to get to the tension pulley. I learned that unhappy lesson when trying to run a triple with a short-cage derailleur.

contango 

Had to think about what you were describing there for a minute, but when I got the picture in my head I realised you're right.