Consequences of chain ring size changes on my Creo

[kahn]

I've got the Aluminum Creo. I believe it is stock with a 42 inch chain ring. It is that WAVE Tech that needs the chain links to be aligned with inner/outer tooth pattern. Since I've had chain jumping off issues recently I decided it might finally be time to dump that "technology". Since I had purchased Wolf chainrings in 38 and 40 TEETH a number of months ago which have sat idle maybe they should replace the WAVE-thingies.

I'm long since divorced from gear inch conversions so I'm looking for the more practical aspects of moving to one or the other of the 38 or 40 chainrings. Obviously not necessarily a great change but I don't want to throw off my already poor cadence too much. Opinions are solicited. And would this "chainge" also necessitate a CHAIN change? Actually, a chain change might be warranted anyway. But when I purchased those "spare parts" I was looking for a bit easier hill climbing gears and I still am looking for that. I don't know how much this would affect level pedaling but I can probably deal with that. Besides, in Seattle there ain't much level anyway.

Have at it, fine friends.

 

[Stefan Mikes]

And would this "chainge" also necessitate a CHAIN change?

If you swap your 42T ring for the 40T one, you cannot do anything with the chain length: your existing chain will be more loose, which is not good for you (as you have already complained on the chain dropping). You might remove two chain links, that's the option. With the 42 -> 38T swap, you should remove 2 links.

 

[kahn]

If you swap your 42T ring for the 40T one, you cannot do anything with the chain length: your existing chain will be more loose, which is not good for you (as you have already complained on the chain dropping). You might remove two chain links, that's the option. With the 42 -> 38T swap, you should remove 2 links.

Thanks for the reply.

Oh, so a move to the 40 would be too close to the 42 and no chain length adjustment would be possible. Whereas going to the 38 would allow links to be removed to tighten the chain????

 

[Saratoga Dave]

I am in the same boat as you, just on the proper side of the country

I’m planning on a visit to my friends at the LBS on Monday to have them get me either a 40 or a 38 for my SL Creo also, after a year with the 42:42 setup. It’s normally fine, but I would like a little more leeway on the steeper and grittier stuff, which I seem to be doing more of. I used to leave the real hills to my Toughroad E+, but I find I grab the Creo almost all the time this year just because it’s so all around great.

Obviously the 38 would be more impactful, and therefore logical, but it almost seems sacreligious to the Bike Gods to put a 38 on what is essentially a road bike. But I don’t go all that fast most of the time anyhow and I doubt I’d spin it out based on my 3000 plus miles so far. 40 a safe bet all around, but that 38 would be a nice security blanket going up the four mile escarpment hill west of Albany on a 95 degree day for sure. We get a lot of those around here the last several years.

 

[kahn]

I am in the same boat as you, just on the proper side of the country

I’m planning on a visit to my friends at the LBS on Monday to have them get me either a 40 or a 38 for my SL Creo also, after a year with the 42:42 setup. It’s normally fine, but I would like a little more leeway on the steeper and grittier stuff, which I seem to be doing more of. I used to leave the real hills to my Toughroad E+, but I find I grab the Creo almost all the time this year just because it’s so all around great.

Obviously the 38 would be more impactful, and therefore logical, but it almost seems sacreligious to the Bike Gods to put a 38 on what is essentially a road bike. But I don’t go all that fast most of the time anyhow and I doubt I’d spin it out based on my 3000 plus miles so far. 40 a safe bet all around, but that 38 would be a nice security blanket going up the four mile escarpment hill west of Albany on a 95 degree day for sure. We get a lot of those around here the last several years.

Are you sure about that - what with stinky water - I remember it after MANY, MANY decades away from that side of the country...

Ignore the last image in this collage which Google tossed in with the local shots - the last image is Iceland!

But back to hill climbing... Yes, that's why I turned to this group for some practical input into the ideas. I already have those two rings but I'm not sure that I'm up to the replacement myself and then the possible doctoring of the chain.

 

[bobf]

Going from 42 to 40 on the chain ring is only a 5% change in gears. That is less than any one step on your cassette. On my Creo I went from 46 to 42, and that worked out well, not a huge change but enough to give me a little more range for climbing. I've never experienced a chain drop (knock on wood). Changing the ring yourself probably isn't hard. I was able to do it by taking out the bolts on the spider, no need to remove the crank arm. But I have a 4-arm spider and I think you have 5 arms, which might possibly make a difference. Be sure to have the correct side of the new ring facing outward, and tighten the bolts to the correct torque.

Chain length is something of a judgement call. It doesn't have to be perfect, but it needs to be fairly close. IMO if you are already close there isn't much point in changing it to prevent dropping. Are you dropping when the chain is loosest (shifting to/from the highest gear)? If not, I don't see that shortening the chain will help.

It's true that you must only add or remove 2 links at a time, regardless of whether you have wide/narrow teeth on the chain ring. There has to be an even number of links (removable included, if used) so that inner link meets outer link where the chain comes together. Also, the chain wraps only 1/2 of the front ring, so a change of 2 teeth in the ring corresponds to 1 link of chain. If you go from 42 to 40 teeth you will have to leave the chain alone, which leaves it slightly more loose, or take out 2 links, which will make the chain slightly tighter. That probably won't affect anything enough to notice. If you go from 42 to 38 teeth, removing two links will leave the chain just as tight or loose as it was before, to within a slight effect from smaller chain ring diameter.

A SRAM chain and cassette user's manual has recommendations on chain length. The SRAM recommendation comes out a little longer than the chain that shipped on my bike, so I didn't take out any links when I changed the front ring. If you really want to shorten the chain to make it tighter, check first to see if the derailleur can handle it. Shift to the lowest gear and see if the derailleur is maxed out. Different people have different definitions of "maxed out", so you might have to do some research.

Last, if you change the front ring, and your chain has more than 10 or 15 hundred miles on it, I'd put on a new one. Some chains are available with different numbers of links. Get the the number you need or larger, so you can shorten to fit.

Enough. Apologies if I just told you a bunch of stuff you already know.

 

[kahn]

Going from 42 to 40 on the chain ring is only a 5% change in gears. That is less than any one step on your cassette. On my Creo I went from 46 to 42, and that worked out well, not a huge change but enough to give me a little more range for climbing. I've never experienced a chain drop (knock on wood). Changing the ring yourself probably isn't hard. I was able to do it by taking out the bolts on the spider, no need to remove the crank arm. But I have a 4-arm spider and I think you have 5 arms, which might possibly make a difference. Be sure to have the correct side of the new ring facing outward, and tighten the bolts to the correct torque.

Chain length is something of a judgement call. It doesn't have to be perfect, but it needs to be fairly close. IMO if you are already close there isn't much point in changing it to prevent dropping. Are you dropping when the chain is loosest (shifting to/from the highest gear)? If not, I don't see that shortening the chain will help.

It's true that you must only add or remove 2 links at a time, regardless of whether you have wide/narrow teeth on the chain ring. There has to be an even number of links (removable included, if used) so that inner link meets outer link where the chain comes together. Also, the chain wraps only 1/2 of the front ring, so a change of 2 teeth in the ring corresponds to 1 link of chain. If you go from 42 to 40 teeth you will have to leave the chain alone, which leaves it slightly more loose, or take out 2 links, which will make the chain slightly tighter. That probably won't affect anything enough to notice. If you go from 42 to 38 teeth, removing two links will leave the chain just as tight or loose as it was before, to within a slight effect from smaller chain ring diameter.

A SRAM chain and cassette user's manual has recommendations on chain length. The SRAM recommendation comes out a little longer than the chain that shipped on my bike, so I didn't take out any links when I changed the front ring. If you really want to shorten the chain to make it tighter, check first to see if the derailleur can handle it. Shift to the lowest gear and see if the derailleur is maxed out. Different people have different definitions of "maxed out", so you might have to do some research.

Last, if you change the front ring, and your chain has more than 10 or 15 hundred miles on it, I'd put on a new one. Some chains are available with different numbers of links. Get the the number you need or larger, so you can shorten to fit.

Enough. Apologies if I just told you a bunch of stuff you already know.

Thanks
And, no, you did not provide too much info. I've changed flats. Much beyond that is left to the nuclear engineers

 

[Stefan Mikes]

In my experience, the chain is of the correct length if the derailleur cage is in the 5 o'clock position in the largest cassette cog.

 

[Saratoga Dave]

Thanks Bob, all good stuff. I’m going to go with the 38 and will report back once it gets installed and I go find some awful hill to ride it up.

 

[kahn]

Mine is in the shop as we "type!"

Going with the 38 and a new chain. Yah - no more Wave Tech to match chain links and teeth position. While there they are replacing some cables and will be updating firmware on the bike, main battery and two range extenders. They also claim I never had a full workup in the two years. I think they missed something entering data.

 

[Stefan Mikes]

If the new chainring is Narrow Wide then you have to match the links and teeth position, too

 

[kahn]

If the new chainring is Narrow Wide then you have to match the links and teeth position, too

IT IS NOT, you evil villain, you.

Now I'm heading to the store to buy the fixings for Oxtail Stew to comfort me on this predicted rainy weekend. Of course, no one has seen an Ox since Babe the Blue Ox. But cow will do!

 

[Stefan Mikes]

IT IS NOT, you evil villain, you.

Sorry, it is. When you do the alignment on the Narrow Wide chainring, look at the chain and the ring from the top. It becomes instantly clear how the alignment is to be done.

 

[Rás Cnoic]

Just to chime in on the replacing chainring/shorten chain debate. I went from the stock Praxis 44 to a Raceface 38 on the Vado SL. Took 5 mins. No chain snipping needed. Has run fine for 2 years like this. I'm guessing you might have issues, drops, noises etc if the chain is worn or already loose, but in my case it was a new bike, new parts (couple months riding) and it worked perfectly. Again zero problems with the chain. I am keeping a close eye on the chainring after a couple thousand miles as it's alloy and so teeth will wear down quicker. Will need a new one soon, but they are pretty cheap.

Anyway my advice is always try first without resorting to buying loads of new expensive parts and see if a simple chainring swap works!

_ one caveat I just thought of is that the rear mech and chain etc might have finer tolerances with road bikes like the Creo. The Deore mech on the Vado Sl, being an MTB one is tough and designed for mud etc so tolerances are probably more forgiving.

 

[Stefan Mikes]

Just to chime in on the replacing chainring/shorten chain debate. I went from the stock Praxis 44 to a Raceface 38 on the Vado SL. Took 5 mins. No chain snipping needed. Has run fine for 2 years like this. I'm guessing you might have issues, drops, noises etc if the chain is worn or already loose, but in my case it was a new bike, new parts (couple months riding) and it worked perfectly. Again zero problems with the chain. I am keeping a close eye on the chainring after a couple thousand miles as it's alloy and so teeth will wear down quicker. Will need a new one soon, but they are pretty cheap.

Anyway my advice is always try first without resorting to buying loads of new expensive parts and see if a simple chainring swap works!

_ one caveat I just thought of is that the rear mech and chain etc might have finer tolerances with road bikes like the Creo. The Deore mech on the Vado Sl, being an MTB one is tough and designed for mud etc so tolerances are probably more forgiving.

Ras, kahn had his chain dropping. I really recommend proper shortening of the chain to ensure its proper tension!

 

[Rás Cnoic]

Good point. Missed that. Though I'd check the chain for wear. Must be a cause for the chain dropping.

 

[Dazmanturbo]

When I got my Creo, I was looking at way to make it lighter and went for 38 front and e13 9 to 34 on rear. I used an on-line Gear Ratio checker ( BikeCalc.Com ) to see what I getting. Like you, I wanted a lower climbing gear, so have now swapped to 42 (Garbaruk) and 10 to 42 in rear (SRAM XXO). This has now given me my perfect gears. Good high speed and 1 to 1 climbing, all with weight far lower than the standard equipment.

 

[Kenmnz]

Please excuse me putting my nose into this conversation, as I know nothing about all these different chain sizes and systems. However ,on my home converted trike I was having the chain regularly come off, and eventually found it was due to the frame flexing slightly under power [ Cyclone 1800 /3000 watt motor on 48 volts ]
As a result I have purchased a shop built trike which I can ride while I make fairly drastic modifications to my home build.

 

[Stefan Mikes]

We do not discuss custom builds here
It's a Specialized forum.
FYI, Specialized e-bikes offer from 240 to 565 W max mechanical power assistance, require pedalling, and have no throttle. All these are production e-bikes.
Some of us climbed 19% grades on Specialized motors such as 2.2 (new) with 565 W or 1.3/1.2s (older) with 520 W max power and with proper gearing, that's to address your comments you needed a 750 W Bafang motor.
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As I think I explained elsewhere, you are applying motorcycle-grade stresses to a cheap bicycle drivetrain and are surprised it becomes damaged?