going from 40t to 42t

[ruffruff]

I want to swap out my rear cassette. I have a sunrace 11-40 on now.

If I go to 11-42 I get a whole lot more options especially in the Shimano and SRAM line.

Would my current chain fit? What other issues do I need to consider?

 

[Art Deco]

I want to swap out my rear cassette. I have a sunrace 11-40 on now.

If I go to 11-42 I get a whole lot more options especially in the Shimano and SRAM line.

Would my current chain fit? What other issues do I need to consider?

Someone who knows your bike will be able to answer. But it really depends on your bike. Specialized is a challenge to swap, others not a problem. I am looking to swap down to a 40 from a 48 ...a big jump but a 44 may not fit.

 

[ruffruff]

It's a BH Rebel with Deore derailleur.

 

[ruffruff]

come to find out, it was a 11-42 originally. I swapped in a 11-40. Can't tell any difference.

 

[Browneye]

I doubt you would notice 2-teeth on the lowest gear unless you were really fighting a very steep hill.

What exactly are you trying to accomplish anyway?

 

[ruffruff]

Smooth shifting! Seems some of these BH bikes don't shift so well out of the box.

I ride a lot of single track and nothing worse than in the middle of a climb your derailuer decides it likes the next lowest gear.
Feels like your whole rear end is going to get ripped off!

 

[Browneye]

That's derailleur adjustment.

My Trance has Shimano XT and I have to tweak it about every third ride or so. After a quick spritz with the hose, a trip around the block to dry it off, I turn it upside down, clean and lube the chain, adjust the shifter, and dry everything off.

I don't know what the technical term is for the distance between the top idler and the largest cassette ring, but that distance is critical for smooth shifting. Too close and it will grind, too far and it won't shift up reliably.
And everything needs to line up with the chain on each gear.

I thought the ParkTools vid was pretty good. I've developed an eye for it, looking at all the alignments and adjusting for reliable shifting.

 

[ruffruff]

That's derailleur adjustment.

My Trance has Shimano XT and I have to tweak it about every third ride or so. After a quick spritz with the hose, a trip around the block to dry it off, I turn it upside down, clean and lube the chain, adjust the shifter, and dry everything off.

I don't know what the technical term is for the distance between the top idler and the largest cassette ring, but that distance is critical for smooth shifting. Too close and it will grind, too far and it won't shift up reliably.
And everything needs to line up with the chain on each gear.

I thought the ParkTools vid was pretty good. I've developed an eye for it, looking at all the alignments and adjusting for reliable shifting.

One would think! But after hours of trying to get it to shift right I was ready to throw up my hands. The ultimate give up....take it in.
So I figured for the LBS charge of around $50 I'd try a new cassette and start over.

I'm not the only one that couldn't get these bikes to shift right with adjustments.

 

[penserv]

Someone who knows your bike will be able to answer. But it really depends on your bike. Specialized is a challenge to swap, others not a problem. I am looking to swap down to a 40 from a 48 ...a big jump but a 44 may not fit.

That's interesting, because I just went the other way and changed out a 42T front for a 48T and I love the bigger ring on the front. With the 42T, I was only using 3 or 4 of the smaller gears on the back (10 ring, 11-36T). With the 48T, I use 7 or 8 gears and only the 36T and the next smaller ring don't get used. That's what the power and the hub motor is for. With the 48T front, when I'm pedaling hard going over the top of a hill and on the down slope, I never get pedaling so fast that I feel like I'll lose my balance, something that happened frequently with the 42T front.

 

[Art Deco]

That's interesting, because I just went the other way and changed out a 42T front for a 48T and I love the bigger ring on the front. With the 42T, I was only using 3 or 4 of the smaller gears on the back (10 ring, 11-36T). With the 48T, I use 7 or 8 gears and only the 36T and the next smaller ring don't get used. That's what the power and the hub motor is for. With the 48T front, when I'm pedaling hard going over the top of a hill and on the down slope, I never get pedaling so fast that I feel like I'll lose my balance, something that happened frequently with the 42T front.

I never made the swap, but I still should. I never even use high gear over here it's always either uphill or coasting down

 

[FlyingScot]

That's interesting, because I just went the other way and changed out a 42T front for a 48T and I love the bigger ring on the front. With the 42T, I was only using 3 or 4 of the smaller gears on the back (10 ring, 11-36T). With the 48T, I use 7 or 8 gears and only the 36T and the next smaller ring don't get used. That's what the power and the hub motor is for. With the 48T front, when I'm pedaling hard going over the top of a hill and on the down slope, I never get pedaling so fast that I feel like I'll lose my balance, something that happened frequently with the 42T front.

How did you manage the chain ring to chain stay clearance I have a 34T and find I am spinning out and only using the bottom three gears and would love to put a 48T on it but will start with a Spider on the CX GEN 4 DU, so I can swap chain rings without major hassle and I WILL probably start with a 36T or 38T and hope to get to a 40T or 42T, a 48T would be awesome, but I suspect I don't have the chain stay clearance for that unless I can move the front chain ring out a bit

 

[penserv]

You probably cannot go much larger when you use individual rings. I was able to go 42T front but ran into problems at 44T with a chainring that bolts onto the crankset. The trick is to buy an integrated crank arm and chainring set. The advantage of the integrated set is that the chainring is offset towards the crankarm and you will get a bit more clearance on the chainstay. The major disadvantage is that you will no longer be able to easily swap out chainrings, but if you get the combo that works well, then it's not such a big disadvantage. The one I bought was a dual chainguard. I had to throw away the rear chainguard and then I just had a mm or 2 clearance on the chainstay from the chainring. Now that I have a 48T front, I'd love to go to 52T or 54T, but I would have to change the frame completely. Maybe that would be a good project for this winter, but not right now.