Different chain ring different feel. How?

[Desmond]

How big is the difference in feel on a 11-36 a 11-42 and a 11-50 chain ring on a bike with 9 gears and a Bosch Performance CX 2019 motor, when driving on steep tarmac hills?

I need to be able to climb hills (10 -20%) at 50-60 rpm cadence in a high gear.

 

[Zimmerframe]

Sadly, can't answer that bit for you, but I did try a couple of things yesterday based on your previous questions.

In reply to your other post, where you were worried about motor torque and the e8000 being no good at lower revs : I presently have a brose and previously an e8000. Despite the numbers on paper, there's not that much of a difference between the two, performance wise, in real world riding. I still have some, none technical, climb times from the e8000 bike that I can't beat with the brose bike.

I suspect for your needs, you'll find all the MTB orientated motors to be fairly similar (ballpark) and all much stronger than the activeline you have now.

My Kenevo came with a 32t front chainring, which I changed to a 36t as I felt I was disproportionately using the higher gears. The cassette is an 11 speed 11-42. Don't get hooked up on number of speeds though 8,9,10 are generally all fine when used in conjunction with a motor. That might help with your gear calculations ?! (or maybe not ) I'm presently back on the 32t as my 36t is wrecked. Switching back is quite interesting as on the whole the bike feels like it pulls more on lower assistance (eco) than it does with the 36t front ring.

So, yesterday you asked about running at low cadence , 50-60, I tried plodding up a reasonably steep hill (muddy and slippy), in turbo at 60 and it pulled fine. Not as hard as it pulls at 80, but not a problem.

I then slowed down and tried the same thing at 30 in Turbo (highest assistance on a brose). It still pulled me up without much physical effort. It was slow and I wasn't killing myself like I normally try to, but it took me up the hill no problem. (angle : 10% average, 16% peaks)

 

[Desmond]

Great info, thanks!
Which motor did you use for your experiment, i didnt get that?

So no point in trying out bikes with different chain rings, cause the performance CX (2019) will get me up those hills in high gear and with a low cadence fairly easy, as i understand it

 

[Jamy]

I have a 38t front and a 11-50 rear cassette and to be honest, unless I lost power and was riding the bike home under my own steam the top two rings are pretty much useless. Infact since moving to electric, I'm finding i'm changing gear alot less. I'm not sure if thats a good thing or a bad thing tho.
As for the 10-20% climbs, I recently hired an electric bike in Keswick and rode to whinlatter mtb park. On the ride there's a 15% tarmac road about a couple of mile long and the 9 speed electric made it without me getting out of breath, infact it easily made all the off road climbing once we where at the park

 

[Beekeeper]

Your cx front chain ring will probably be a T15 fitted.
You can change it for anything from T14 to T20 providing you have the space available for the very largest ones

 

[Zimmerframe]

Great info, thanks!
Which motor did you use for your experiment, i didnt get that?

So no point in trying out bikes with different chain rings, cause the performance CX (2019) will get me up those hills in high gear and with a low cadence fairly easy, as i understand it

Ha ha ... sorry, that didn't help did it Brose 1.3 (Specialized Kenevo) - so not the newer 2.1, but slightly more powerful than the 1.2 in the hardtails (on paper at least).

So no point in trying out bikes with different chain rings, cause the performance CX (2019) will get me up those hills in high gear and with a low cadence fairly easy, as i understand it

Basically yes, you should be fine, as confirmed by @Jamy's additional information. The steeper the hill the more important it will be to keep up in your 50-60 cadence zone. But assuming you're not trying to break any speed records, you shouldn't have any problems.

With your physical situation, probably start all the hills in the highest assistance level, as you won't want to risk stalling out and you'll be wanting to get your legs used to things. As you get more confident, you can drop the assistance level down. If you feel your cadence dropping, don't panic, just up the assistance level and it should pull you back upto your more efficient cadence range. Also, try to pick the gear you think you'll need at the start of the hill rather than trying to drop down the gears as you get slower and just keep a nice steady cadence through the whole climb.

As @Beekeeper says, if you really did struggle for any reason, you could drop your front chainring from a 15 to a 14, rather than change cassettes, or worry too much about what cassette was on the bike in the first place, and that would adjust the whole effective gearing range. As your muscles hopefully return, if for any reason you did decide you then wanted higher gearing again, you could just swap back to the 15 - though you'd probably not have needed to change anyway.

 

[Desmond]

Sounds good.
Crossing my fingers, and hope my legs will get stronger.
Thanks for helping me out brother.
I think i've got my bike list down to 2 candidates. Gonna try them out on monday.
Both with Bosch CX Performance 2019

 

[mark.ai]

I'm not sure if you are talking about cassettes or chain rings with the mixed description, but if it's the cassettes:

If you're in a high gear, then that's the smaller cogs on those cassettes, so they will be more similar to each other than on the larger cogs (which are very different).

If the cassettes are 11-36, 11-42 and 11-50, then so long as you are on a cog smaller than 36, then you should be able to get roughly the same gear (cog size) from any of the cassettes.

Only if you need a cog larger than 36 or 42 will you find you obviously can't have that on the smaller cassettes

If they all have 11 gears then you'll find the cassettes with the smaller range have gear ratios closer together, so you would probably be able to choose a gear to match your optimal cadence more closely (depending on your speed & slope etc).

 

[Desmond]

I saw this video, and he talks about chain rings.

The bike i want has SRAM PG1130 / 11-42 T casette and a FSA CK-310 / 170mm / 15T.

 

[mark.ai]

I saw this video, and he talks about chain rings.

The bike i want has SRAM PG1130 / 11-42 T casette and a FSA CK-310 / 170mm / 15T.

Aha yep so that is an 11-42 cassette and then the chainring has 15 teeth (in the video he also calls that a sprocket presumably as it is small). Those small chainrings are specially geared internally so they rotate faster than the pedals - I think maybe 2.5 times faster (?) So 15 teeth is equivalent to a normal one with about 38 teeth (15*2.5=37.5).

 

[Boris]

Great info, thanks!
Which motor did you use for your experiment, i didnt get that?

So no point in trying out bikes with different chain rings, cause the performance CX (2019) will get me up those hills in high gear and with a low cadence fairly easy, as i understand it

Yamaha pw-x is better at low cadence than Bosh cx

 

[Desmond]

Yeah, i heard this too

 

[Gary]

Less controlled assistance though.

As above fit low enough gears, take your time and you probably won't really need huge amounts of assistance

 

[outerlimits]

How big is the difference in feel on a 11-36 a 11-42 and a 11-50 chain ring on a bike with 9 gears and a Bosch Performance CX 2019 motor, when driving on steep tarmac hills?
.

If you run the 11-36, you will feel like people are looking at you as to why you don’t have a dinner plate on the rear. If you run the 11-42 you will feel like, kinda like, a normal Mtb rider. If you have the 11-50 you will feel like people are staring strangely at you as to why the feck, do you have such a big ring when you have a motor.
Affects on your body will be different and can be measured in ouch factor. The more ouche’s the worse you feel. It’s about getting the balance right. Below you will see examples of the gearing, with the corresponding amount of ouchie’s for your heart vs you muscles. Remember, it can take a few minutes for your heart to recover, however it takes a few days for your muscles to recover.

11-36, heart 2, muscles 6
11-42, heart 4, muscles 3
11-50, heart 6, muscles 1

As you can see the 11-42 set up is the most balanced in feel for both ouchies and your metal well being.

That’s SCIENCE Bitchs ?

 

[DrStupid]

Found this site useful for determining the effect of gearing changes. You'll need to nail down your chain ring to crank rotation multiplier, as mark.ai said above, but once have that, you can see effect of evey gear change at a given cadence on speed.


BikeCalc.com - Speed at all Cadences for any Gear and Wheel

 

[Desmond]

Its getting a bit too technical for me.
I'll try to decrypt all this new info the next couple of days

 

[Zimmerframe]

Its getting a bit too technical for me.
I'll try to decrypt all this new info the next couple of days

Don't over think it. You can spend hours determining what should be perfect and end up boxing yourself into a corner searching for, what is on paper, the only bike which will be right for you.

The reality is that they'll most likely all be fine and the fact you have some test rides set up give you a chance to see what they're actually like.

For most day to day riding like your doing, the Yamaha, either of the bosch's, the E8000 or the brose's should deliver enough torque lower down to accommodate your needs - most likely with whatever stock gearing the bike comes with.

When you do test ride one, if you're finding issues at that point, then you can just ask the shop to swap in some different gears/chainring at purchase time.

As @mark.ai says, the only one which might cause you any mental confusion is the 2018/2019 Bosch CX as the motor final drive has a weird internal gearing system which spins the chainring at 2.5 x the speed your cranks are going round. Hence why the Bosch has a tiny chainring/sprocket (15t) compared to everyone else. (definitely one to double check that it's turned off before you wash it and stick your fingers in there ! )

 

[Desmond]

So, i just tried a Scott E-ride Contessa 20 with a CX and a Scott E-ride aspect 20, also with a CX.

They felt completely different, even with the same motor.

Bought the Scott E-ride Aspect 20.
I can live with the sudden stop at 25 kmph. Perfect bike for me.

SRAM PG1230 / 11-50 T casette and FSA CK-745 / 170mm / 16T

 

[ckay76]

On the P1130 11-42 cassette, anyone know how many spacers are there?