MidlandSpinner

Evening. I have a SRAM Rival 1 x 11, 42T, 11-42 cassette (on a Planet X Full Monty SL if that makes any difference). I want to change the chain ring for a smaller one for my 26 mile round trip commute along the undulating Cornish coast with loaded panniers. So a few queries if that’s ok:

1. Is this possible?
2. Are there non-SRAM rings I can use which are cheaper than the proper jobbies?
3. Do I need to shorten the chain?
4. Do I need special tools? Do I need to remove the crankset?
5. What size ring would really make a difference?
6. Have I missed anything?

Thank you

msu2001la

Should be pretty straightforward.

SRAM 1x setups use a narrow/wide chain, so you need to make sure whatever chainring you buy is narrow/wide. There are some different bolt diameters and patterns for different cranks, so you may need to measure your current setup to find out what it runs. It might be marked on your current chainring. (My setup uses a 110 BCD 5-bolt, for example)

You haven't told us how much smaller you're planning to go, so hard to say if you'll need to shorten your chain or not. The only tools you'll need are an allen key. You will probably want to remove the chain, but I suppose it might be possible to do this without even doing that. Literally just unscrew the old chain ring and bolt the new one on.

You can get an idea of how much a new chainring will change your gearing by plugging info into a bike gearing calculator like this:
https://www.bikecalc.com/speed_at_cadence

msu2001la

For a reference point on chainring sizes, consider that a typical road double crank uses a 39T small ring. A "compact" double will run a 34T. Triple cranks usually have a 30T inner. If you've ever rode a bike with 2x or 3x gearing, you probably have a good idea of what those small ring sizes feel like.

I don't know how steep the hills are on the Cornish coast (sounds awesome, by the way), but if it were me I would probably try a 36T, which would still get you some reasonable top-speed gearing (around 26mph at 100rpm cadence) but also give you a really low 36x42 combo to get up steep hills.

It just depends on how low you want to go, and how much you're willing to give up on the top end.

MidlandSpinner

That is all really useful, thank you. So if I went for a 36t would the chain need to be shortened? Or, teach a man to fish, how would I work that out?

The hills are bleddy steep and I’m well out of practice! Thank you.

xroadcharlie

The stock 42T chain ring will give you about 27 gear inches and just 5 mph @ 60 rpm cadence in the lowest gear. That's pretty low. I would do a test run with that first. If you want lower, It looks like they have a 38T that should work well for you. Chain will likely need shortening. You might need a tool to remove the links. Don"t know about removing a crank arm.

I see you have steep hills, So yes, Go low. I see 38T options, Or 36 as suggested above.

markjenn

I bet your crank is 110 BCD which limits you to 38t as the smallest chainring you can run. To go smaller, you have to go to a MTB crank.

- Mark

msu2001la

Here's a good guide on chain length and how to size a chain and remove links: https://www.parktool.com/blog/repair...-length-sizing

Your SRAM chain likely uses the masterlink style of connectors. You can usually undo and reconnect these with some small needle-nose pliers (the Park Tool noted in the guide is way easier to use), but to remove links and shorten the chain you'll also need a regular chain tool.

My guess is that you will if you are going down to a 36t or even a 38t chainring, you'll need to shorten it. Hard to say without seeing it in person.

msu2001la

I'm not sure what kind of crank the thread starter has, but Wolf Tooth makes 36t and 34t rings that they say are compatible with 110 BCD 5 arm cranksets:
https://www.wolftoothcomponents.com/...oss-chainrings

EDIT: I see that SRAM Rival 1x crank specs list 38t as the smallest chainring. (And this crank is 110 BCD 5 arm)
I don't know if that is because the smaller rings from Wolf don't actually fit, or if SRAM just doesn't make a 5 bolt 110 BCD ring smaller than 38t. https://www.sram.com/en/sram/models/fc-riv-1-a1

MidlandSpinner

Just got the tape measure out and you are correct, it is 110 BCD which does seem to limit me to 38T on the SRAM website.

However, there do seem to be alternative brand 110 BCD 5 bolt narrow-wide 34T rings available. There is a Hope one on Chain Reaction but this website wont let me post a URL!

markjenn

Probably the latter. I was thinking of the 38t limitation with road 130bcd cranks, but I think you can physically go down to something like 30t on 110.

I bet 38t would be a good compromise, however. Going lower really starts hampering you high gear in a 1x with an 11t cog.

- Mark

MidlandSpinner

Thanks everyone for your help. I've done lots more reading and decided to try a Hope Retainer 110 BCD Narrow Wide ring - seems like it should do the job.

I'm getting 34T to start with - low and slow! Looking at the ratios it doesn't look like it will limit the top end too much (at my current fitness level) but I'll have to wait and see. Only £30 so can always upsize as I get faster.

Cheers

dsaul

If you have the current SRAM Rival 1 crankset, it has a removeable spider that can be replaced with a SRAM compatible direct mount chainring.

xroadcharlie

It's not a matter of limiting you max speed in the highest gear, It's the chain angle that is at its max in the highest and lowest 2 gears on an 11 speed cassette. It is best to avoid them for normal cruising. Not a problem in a pinch though.

A 34T chainring will only give you about 70 gear inches in 10'th, which is already near max chain angle. Even this 63 year old recreational rider on a slow comfort bike often uses my 78 gear inch sprockets with a light tailwind, never mind downhill.

That's why I suggest going with the 38T chainring. That still goes down to 24.4 gear inches when you need it and will keep the chain angle reasonable at normal cruising speeds also going down hill you're much better off with the 38T.

Russ Roth

110 seems to be limited to 33t unless its an irregular spider, my FSA goes down to a 32t which is hard to find.
From my experience pulling a trailer loaded with stuff on a tour (kids are too small to deal with their own equipment and wife had to learn what is really necessary) along with panniers so quite the load I had a 36 11/32. The 36/11 wasn't as fast as I'd have liked when the roads sloped a little or even cruising with the wind at my back, often found myself once the momentum was going cruising in the 46/13 or even 12 on the longer downhills; a 10t with a 36 chainring would have done it. I did end up walking a couple of hills with the 36/32 and as a result my bike now sports a 46/34 and 11/36 which I think should be more then sufficient to get me up any hills. If you run a 36t at 36/39 which your 42t skips over you'd be easier then my 34/36. I'd suspect a 36t might be a better ring to try out for an allrounder that will have ok speed and decent climbing.

MidlandSpinner

Thanks everyone, your wisdom has changed my mind. Just ordered 36 and will return the 34 for a refund. Hope it bleddy fits now!

martianone

At the time when the 9 speed 12-36 cassette was introduced, i set up a 1x9 commuter/utility bike with the 12-36 cassette and 38 t chainring. Since then, I've ridden the bike around 25000 km over all sorts of terrain, often with a pannier or two of stuff- including a couple 5 day tours. It is pretty hilly where I live. That gearing combination has served me well.

Toadmeister

How did this turn out? I'm thinking about doing the same for my wife's bike.

MidlandSpinner

It turned out a treat. I have a SRAM S350 1x crankset which is 110mm BCD. The Hope retainer ring fitted fine. Hardest part was getting the bolts undone. Only thing to note is that due to the shape of the ring it sits a few mm further outboard than the factory fitted ring, so the chain line is altered slightly but no big deal for me.

The 36T is good, based on gear inches it gives me roughly one gear lower than i had before. It's noticeably easier for climbing and i don't miss the top end speed.

Toadmeister

thanks! I ordered the 36t for my wife’s bike to replace the 40t

nayr497

Similar question, thought I'd avoid starting an entirely new thread. Not training & racing as much as I used to on my cx bike, using it for commuting some days as well, would like to lower the gearing.

Setup:
SRAM Force Crankset (double/road), 130 bcd, 172.5 with 46/39 gearing
Cassette = 11x28

I think on a medium length/range SRAM Force RD 11/28 is the lowest they recommend you go (I know others have made it work, would rather stick to their guidelines and not do any after-market solutions).

I'm pretty sure 46 is the smallest outer ring you can use, as anything smaller hits the back of the crank arm. Can I go below 38 on the inner ring? A one tooth switch wouldn't gain me much, would be nice to go to a 36 or 34, if possible.

Thanks for any advice!

woodcraft

The crankset would have to change to 110 BCD to use 46/34 chainrings, which would effectively give one gear lower. If It's Force22, just the crank spider and rings can be changed.

Switching to an 11/34 cassette with long cage RD or Roadlink would give about 1 1/2 gears lower, and 11/36 would get about 2 gears lower.

Change both the rings and the cassette to go lower still.

nayr497

This is a very helpful reply, so thank you! Ooof, as I was hoping wasn't the case, looks like there isn't an inexpensive solution to my problem. Pretty sure this is a plain early 2010s Force crankset, not the 22.

Looks like my best option is to get my legs back in racing shape and push the gears I have

Thanks again! I appeciate your time and knowledge!

woodcraft

~$60 for a name brand cassette, ~$20 for the Roadlink bit, & ~$30 for a chain

nayr497

Good point, not exactly breaking the bank! And, I have a cassette and chain already on hand.

In looking around at the Wolf Tooth tech docs and the SRAM info, trying to see if this would work. Looks like the max cog is a 28, as per SRAM. Wolf Tooth talks about capacity

https://www.wolftoothcomponents.com/...cc5a2a90&_ss=r

I'm at: (46-39) + (28-11) = 24
@ 11/36 I'd be at: (46-39) + (36-11) = 32
@ 11/34 I'd be at (46-39) + (34-11) = 30

I'm not clear on if this is recommended or okay. I'd be above the 28 tooth rear cog limit, but I'd be below the 32 tooth capacity. This thread seems to say both things...28 tooth cog is the highest you can go on a regular SRAM RD...but the total capacity is 33, so I'd be below that.

https://www.bikeforums.net/bicycle-m...-capacity.html

woodcraft

There's two things- what's the biggest cassette that the RD will clear, and how much chain slack can the RD take up.

The take-up capacity is not critical in practice- at worst, the chain goes slack in the small/small combination, which doesn't really get used anyway, but sounds like not an issue here.

The Roadlink drops the RD down so that 11/36 or larger can be used with a road RD. It may need a few strokes with a file to fit SRAM hanger as it is optimized for Shimano.

I have the set up on two bikes and did it once for a friend.