Cassette range - 10-51t v 10-45t

[Nick314]

Guys,
So, I'm just looking at options and wondering if I'd miss the lower end range if I go with a 10-45T...strikes me that with the same number of actual cogs I'd get better options in the middle of the 'box'...opinions encouraged, please ;-)

 

[irie]

10-45: 10-12-14-16-18-21-24-28-32-36-40-45T
vs
10-51: 10-12-14-16-18-21-24-28-33-39-45-51T

So only the 4 lowest gears are different

 

[Nick314]

Thanks, thats really useful. I was just thinking I'm pretty sure I've never uses the 51T cog in any situation, so might well give this a go...

 

[mccoyman]

I would also go for the 45. The 50/51/52 contest from Sram and Shimano is pointless for Emtb's unless you do some extreme climbing.

 

[Nick314]

I would also go for the 45. The 50/51/52 contest from Sram and Shimano is pointless for Emtb's unless you do some extreme climbing.

I agree, a mate has a 45T SRAM and he doesn't complain. Same bike otherwise.

Can I lose a chain link or two as well do you think?

 

[mccoyman]

One link should be fine to reduce from stock, there is a big difference in diameter from 45 to 51, that you would not need to cover now

 

[rzr]

I would also go for the 45. The 50/51/52 contest from Sram and Shimano is pointless for Emtb's unless you do some extreme climbing.

or climbs with flat battery....
(personally I've upgraded my eagle drivetrain to 11-46 11s)
less unsprung mass - better working suspension ...
(what's the point of mounting heavy coil shocks (I see it's quite common on this forum if other things hold back your suspension)

 

[Alexbn921]

The jumps aren't that big and and someday you might want to drop the power down to do an epic ride. Go for the 51. It will be more versatile.

 

[Nick314]

One link should be fine to reduce from stock, there is a big difference in diameter from 45 to 51, that you would not need to cover now

Great, thanks for the advice, really useful

 

[irie]

The jumps aren't that big and and someday you might want to drop the power down to do an epic ride. Go for the 51. It will be more versatile.

Both are 12 cogs and almost identical weights, so better to keep the 51 just in case. Don't use my 51 very often but sometimes do in really tight nadgery stuff.

 

[steve_sordy]

You could consider the 10-51 as just an 11-speed with an emergency bail-out gear.

The periphery of the 51t gear is about 0.4" (1cm) closer to the ground than the 46t but that is all. Which means that the business parts of the mech are closer to the ground too, which may be critical to you. I haven't measured how much closer the mech is; just an estimate.

 

[irie]

You could consider the 10-51 as just an 11-speed with an emergency bail-out gear.

The periphery of the 51t gear is about 0.4" (1cm) closer to the ground than the 46t but that is all. Which means that the business parts of the mech are closer to the ground too, which may be critical to you. I haven't measured how much closer the mech is; just an estimate.

I think 51t is about about 0.4"/10mm closer to the ground than 46t.

 

[B1rdie]

I am happy with a 40t as lowest cog, the smaller, the lighter and cheaper, the better.
Now, I can't imagine why the distance to the ground should be significant? if it ever hits the ground, I would rather bail out and be far from the bike when this happens
The chain should be properly sized according to whatever the OP chooses, no guessing about how many links to cut, please.

 

[Jurassic]

I don't understand the standard gearing on my (and a lot of other) emtb. It came with a 36t chainring and 10-51 cassette. What possible use is a 36t ring on an ebike that cuts the power at around 15mph? Don't get me wrong I do use the bottom gear ratio on silly steep climbs but why not spec 10-45 and a 32t chainring as it has the advantage of tighter ratios, more ground clearance, slight weight saving and the option to use a shorter cage rear mech which is less vulnerable to damage (my first mech lasted three weeks before I ripped it off on a trailside log). I've already binned the 36t chainring in preference for a 34 and it's made a significant difference to the amount of times the chainring decks out on logs, rocks etc as the old 36t protruded below the level of the bottom of the motor and it's (admittedly pretty flimsy) bash guard. Slamming the chainring onto trail obstacles and the corresponding force that puts into the bearings in the motor can't be a good thing.

 

[BIG-DUKE-6]

You could consider the 10-51 as just an 11-speed with an emergency bail-out gear.

The periphery of the 51t gear is about 0.4" (1cm) closer to the ground than the 46t but that is all. Which means that the business parts of the mech are closer to the ground too, which may be critical to you. I haven't measured how much closer the mech is; just an estimate.

Absolutely this

 

[irie]

I am happy with a 40t as lowest cog, the smaller, the lighter and cheaper, the better.
Now, I can't imagine why the distance to the ground should be significant? if it ever hits the ground, I would rather bail out and be far from the bike when this happens
The chain should be properly sized according to whatever the OP chooses, no guessing about how many links to cut, please.

I calculated approx distances to the ground out of pure curiosity, starting with the fact that bike chains have 0.5" pitch.

 

[Planemo]

I don't understand the standard gearing on my (and a lot of other) emtb. It came with a 36t chainring and 10-51 cassette. What possible use is a 36t ring on an ebike that cuts the power at around 15mph?

I dunno, I absolutely love my stock setup (38t, 11-50). Being on the road a lot it helps keep me out of wearing the 11t into a washer every 300 miles (but there when I need it - I do pedal beyond 15mph even when the motor didn't) and the 50 gives me enough spread for knarly off-road. I honestly don't feel the need to change the gearing at all. Admittedly it's come into it's own now that it's been dongled but even prior to that I wouldn't have changed a thing. Horses for courses I guess, plus I don't really enjoy high cadences.

 

[MoabC&J]

The jumps aren't that big and and someday you might want to drop the power down to do an epic ride. Go for the 51. It will be more versatile.

I had an 11-46 on a da Vinci Symbiosis e-tandem and it worked good for everything...except the 16% climb we had to do everyday at the end or our rides. An 11-51 solved the problem and I didn't have to add any links to my drive chain. although we don't use the 51 much, it's always there...one gear left "in the bank".

 

[steve_sordy]

I think 51t is about about 0.4"/10mm closer to the ground than 46t.

That's what I said. Like you, I calculated it on the difference in diameter of the gears. I knew that difference was accurate. But what I didn't bother checking was how this affected how much closer to the ground the mech came. Was it the same distance lower or a little bit different?

 

[mike_kelly]

I have found the motor essentially adds a couple more gears.
But using the 11-51 does allow you to play with your high gears. In an up coming trip I need to connect with some dirt road sections. So for the first time i am thinking about the higher gears. With the 11-51 I can change the chainring to give a higher high gear, for road segments, and still maintain my previous low gears.

 

[irie]

That's what I said. Like you, I calculated it on the difference in diameter of the gears. I knew that difference was accurate. But what I didn't bother checking was how this affected how much closer to the ground the mech came. Was it the same distance lower or a little bit different?

Agreed, that is what you said.

But as I said: "I calculated approx distances to the ground out of pure curiosity, starting with the fact that bike chains have 0.5" pitch".

 

[BeBiker]

I would also go for the 45. The 50/51/52 contest from Sram and Shimano is pointless for Emtb's unless you...

... dont always ride in Turbo

 

[SwampNut]

I recently switched from an 11-42 to an 11-46. In a couple of situations that's been better. I rarely need that super climbing power, but when I do, I do. My primary riding buddy has 11-51 and he says he does use it, but also says that he's barely moving in that gear. We both think the 46 is probably an ideal compromise with a good motor.

 

[rzr]

not only this, Sram Eagle petrudes outside about 2cm more than Shimano 11s !

 

[Nick314]

So my conclusions after a few steep rides now is that the larger cogs are spot on. I've used them all, but not missed any. The chain is a link shorter to the mech looks fine in terms of clearance and generally I am happier with this as a set up as I seem to now have gears I use. This cassette is 260g lighter than the other as well.
Thanks for all the help/guidance/discussion