Gearing questions
 

Hello gang.

I recently acquired a Specialized Tricross Comp that I am really enjoying.

​​​​​​IT is currently running Shimano 105/Ultegra mix (105 front/Ultegra rear);48/34 12-30 and I was wondering what I would need to change to make my rear mech 8nto a more appropriate set up for a cyclocross/gravel range for a 62 yr old newbie gravel rider and non climber....me.

Would I need to change my entire drivetrain or is it just a matter of a new chain and a long cage rear derailleur or MTB derailleur?

This bike is totally new to me, having come from a road bike and I am unfamiliar with the nuances of cross/gravel riding.

I do not plan on doing the work myself but I want to have some idea what I'm in for.

Thanks in advance.

​​​​​​Brian J.

I think only you can answer the question regarding how much lower gearing you need (if any) because it largely depends on the gravel conditions are you riding.

In my local area, there are many paved multi-use paths with adjacent gravel trails, such that the elevation differences between the two are minimal. I have a road bike and a gravel bike which weigh within a pound of each other, each with a 2x11 drive train. The road bike is 50/34 and 12-28. The gravel bike is 48/31 and 11-34, although I don't think I have used the < 1:1 gear ratio. And I only ride gravel when it is dry (to minimize bike cleaning); if the conditions are more than a little damp, I ride my gravel bike on paved roads.

But you may ride steeper gravel than paved routes.

congrats on the new bike ...

not famil with the bike - what components including crank and RD are installed ? (model #)

34t small ring might be the smallest ring you can install on the current crank (?)

you can go to a cassette with 32t big cog - possibly 34t ... (36 t ?) ... depending on your RD ... some of the mid/long cage 105 and Ultegra RD’s were rated to 32t max (5800, 6800 GS for example) ... later models are rated for 34t max (7000, 8000)

(note: you can sometimes go greater than the designed max)

so you could possibly go to a cassette with 34t big cog ... with your current RD or a newer 7000 or 8000 RD ... current chain / chain length could be sufficient - but with a new cassette you should use a new chain

if 34/34 combo not low enough - a crank swap might be an option ... crank with 46-30 or 48-31 or similar ... many of these cranks can require a different FD (due to chain line difference)

Ahhh...thank you. This is what I was looking for

Much appreciated!!

Gravel gearing preferences are usually based on how much climbing is involved. If most of your gravel riding is relatively flat, your current gearing is probably fine.
If you're saying "non climber" in the sense that you'll still be doing climbing, but want low gears to make it easier - then your first step would be to max out the rear cassette size (which as noted above is either 32 or 34T) to see if that provides you with enough range. For most people, 34x34 or even 34x32 is enough range, but there's a wide spectrum of "gravel" out there, and for someone doing extended climbs with a fully loaded bike over rough terrain, this might not be enough.

Cyclocross is a different story - it's a circuit race, and generally if a climb is steep enough to require 1:1 gearing to get up, it's not very long and therefore probably faster to dismount and run. For CX racing I run a 1x11 setup with 40T front ring and an 11-32 rear. 99% of my time on a CX race course is smack in the middle of that range.

Bike gearing calculators can give you a good idea of how the different combos might work. I like to look at "speed at cadence" as a basis of comparison, knowing that I can easily maintain 80rpm for climbing, and 90-100rpm for fast sprints - I can use this calculator to get a pretty good idea of what my gearing is capable of: BikeCalc.com - Bicycle Gear Speed Chart

Absolute Black makes smaller rings that will fit your crank, I'm running their 46/30 setup on my 105 crank. They aren't cheap though so it might make more sense to just go GRX.

Thanks so much. This is really helpful

2x or 3x!?
 

Wait a minute; Specialized's website for its most recent (2012) Tricross Comp says it came with a Shimano FCR triple crankset.

Tricross Comp | Specialized.com

OP says the current chain rings are 48/34. So what crank is on there?

But it appears that the 2009 model had 48/34 chainrings. The OP probably has an older model.

https://www.specialized.com/us/en/tr...or=30806-22438

To the OP: From my experience, the gearing you have on that bike is quite reasonable for most riding. I'm 69, and have ridden bikes with similar gearing for the last 10 years. The only issue you might have is if you need to climb a fairly steep hill. Then you might be walking...... :)

Roger

Added by edit: I saw the OP's bike in the "Post Your Bike" thread. It's a 2010 model. COOL bike...... :)

The crank is 48/34 double 10 speed rear, 12-30.

It was modified by the previous owner who wanted a more racy set up than a triple.

That gearing should be good for anything other than really serious hills.

Roger

I don't know about that. I have 50/34 and 12-28 for the road, so 34:28 is my rarely used bailout gear.

34:30 is a little bit lower but hard to say whether that is sufficient for gravel. As I mentioned above, it mostly depends on the terrain.

Since you are running 10 speed road 9 speed mountain bike RDs should work perfectly fine and allow you to run a bigger cassette. Works for Shimano that way at least.
https://brainybiker.com/can-you-use-...and-cassettes/

1- don't listen to people that tell you your gearing should be fine. If you have ridden the bike and want more gear range, then so be it.

2- if your rear derailleur is a long cafe( or medium cage called 'gs') then just buy a wider range cassette and toss it on. See if your current chain is still properly sized(YouTube for easy visual ways to know) and swap the chain if needed then call it good.
11-34 or even 11-36 are options for cassette range and medium or long cage 10sp rear derailleur should handle either.

3- if you still want lower gearing, buy a new crankset. There are multiple 46/30 crankset from shimano, fsa, and others. These will do the same effective thing as getting bigger cogs in the cassette- give you easier gearing for when you climb.

4- gravel gearing isn't typically the same as road gearing because larger tires affect the formula. A 34-28 bailout gear ratio with a 28mm tire is lower(easier) than the same gear ratio with a 45mm tire. Therefore, bikes with larger tires need wider range gearing to give the same effective bailout ratio as bikes with narrow tires.
Just something to keep in mind when you see road bike gearing directly compared to gravel bike gearing.

I have bikes that have 50/34 and 11-34. What I've found is that I "run out of leg" before I get to using the 34-34 combo on a steep hill, and end up walking it. Other riders' experience can, and probably will, vary. At 69, I can not climb like I used to.

All of the above discussion about what the OP can change is good and valid. But my take is that he is asking for opinion if he needs to do the changes before he starts riding, and I don't see that he is in a bad place to start with, with a 34-30 lowest combo.

I encourage him to take that beautiful bike and have at it.

Thank you. Actually I am riding the bike and I do enjoy it very much but I am thinking of switching to easier gearing due to a few factors...aging, bad (very) feet and the thicker heavier tires. I also want to start riding some of our beautiful unpaved trails here.

terrain, and fitness, and rider weight, and power output...

The OP is a bigger guy...

A chain, long(er) cage rear derailleur and a pie plate cassette can be installed for a few hundred bucks. A 34/42 combo will get you up just about anything.

Would recommend switching to 46/30 or 48/32 crankset at minimum. If you have sustained 10%+ grades you may appreicate a larger cassette.

We need to know not just the number of teeth on the chain rings (48/34) but also what cranks and what bottom bracket are currently installed to advise on what modifications may be feasible to achieve lower gearing. Does the crank look like the one on Specialized's website for this bike?

Tricross Comp | Specialized.com

Or if you are OK with starting with a BB replacement, you can measure the bottom bracket shell width, which will likely be 68 mm.

You need to spend some time riding the bike to be able to answer it for yourself. My last bike came with a 11-speed 11-42t cassette and after riding it a few months I switched it to a 11-34t one. I would have gone with a 11-32t but none were available when I made the change. I went to a deraileur with a shorter cage at the same time.

Cranks are FSA Gossamer. I'm not sure of the BB. The bike was modified by its previous owner and I don't have all of the specifics such as the BB type.

I am not a mechanic, just a rider so I was not aware that I'd need to supply that info.

Thanks for the tips.

I have been riding it almost daily since I got ir 2 weeks ago and I'm pretty sure that I'd like a lower gear than I've got.

Actually I was considering changing from a 48/36, 12-30 to a 48/34 11-34 if that would not take too much work

I love the bike now as it is but there have been a few times that I wished I had a lower gear.

I thought the chain rings are already 48T and 34T!?

How much work is needed is determined by your existing crankset and rear derailleur ("RD"). You have two non-mutually exclusive options, i.e., it should be possible to do both:

1. Like Canker said above, your best bet might to be install a 9-speed MTB RD (which has the same pull ratio as a 10-speed road STI shifter) and a 10-speed MTB cassette.
2. Post a picture of your Gossamer crank; does it have 4 bolts or 5? Older Gossamer 2x cranks have a 5-bolt 110 BCD. Current Gossamer Pro 2x cranks have a 4-bolt 120/90 BCD.
2. Just saw a picture of your bike here: Bike Forums - View Single Post - Post your gravel bike. Looks like the crank has 5 bolts. If it has a 110 BCD spider, then a 34T is the smallest chain ring that would fit, and you may have to switch cranks to install a smaller chain ring, which may entail installing a new bottom bracket, depending on what the existing bottom bracket is.

Pros and Cons:

Option #1 (larger cassette) increases the gaps between adjacent gear ratios.
Option #2 (smaller chain rings) may lower your highest gear ratio.

Thank you. Actually I only want to change the cassette from a 12-30 to an 11-34 or close to it

don't forget the chain.
If I were you, I would consider this cassette Shimano CS-HG50 10 Speed Cassette 11-36T