Fitting 7 or 8 speed cassette onto 11 speed

[Col]

Hi all, I've got a 2019 boardman mtr 8.9 which has sram nx 11 speed currently.

I fitted a bafang HD motor 6 months or so ago, and gears are now starting to slip due to wear (these motors chew through them).

11 speed with this motor is pointless, so looking to stick a 7 speed cassette on, advantage of less gears and from what I understand a 7 speed chain should be stronger because it's thicker.

Big question is what's easiest and most cost efficient method?

I can use cassette spacers either side of the 7 speed, and my query which I have no experience of is to do with gear compatibility.

It has sram rear derailleur, in my mind I could use this with shimano cassette? As the derailleur just moves according to what the shifter does? Presumably if I go with shimano cassette I'd need to use shimano shifter, as I believe the movement amount of cable is different.

Any help much appreciated, don't need to go shimano, if it's easier just to put sram cassette and sram 7 speed shifter then happy to do that...

Cheers all

 

[Winford]

spacing is different between the cogs of a cassette for different sizes, and between Sram and Shimano, but some will cross over. I do have a Shimano mech and shifter with a Sram 12sp cassette. But getting down to something like a 7sp, id keep it the same brand for all components. Any deviation with that much power will chew through the parts much quicker.

 

[Col]

Thanks for that. Since it has sram derailleur I'm inclined to keep it all sram, otherwise I'll need to buy shimano shifter, cogs and derailleur, but shimano stuff seems more plentiful and affordable.
Reason for using spacers either side of cassette is so I can centre the cassette in line with chain line.... Because chain ring just skiffs chainstay so would enable me to centre this up. cheers

 

[Winford]

Reason for using spacers either side of cassette is so I can centre the cassette in line with chain line

Does not work like that. Most cassettes have spacing so the cassette fits one side to the other side of rim hub.

I got scammed on ebay by a guy selling a 9sp cassette, that was really a 10sp missing a cog, spacers made it bolt on, but it never would shift right.

Also spacers only mess up the chain line because they only fit behind the largest cogs, pushing the cassette the wrong way

 

[Col]

Does not work like that. Most cassettes have spacing so the cassette fits one side to the other side of rim hub.

I got scammed on ebay by a guy selling a 9sp cassette, that was really a 10sp missing a cog, spacers made it bolt on, but it never would shift right.

Also spacers only mess up the chain line because they only fit behind the largest cogs, pushing the cassette the wrong way

Thanks for the info. I assumed I'd be able to fit cassette spacers (or old cassette cogs) either side of the 8 speed cassette to centre it with chain line... And then set the high and low on derailleur to limit the movement? Am I missing something, fully open to any info as I've not done this before, but can't see why this won't work? Cheers

 

[Winford]

Am I missing something

Just that as an example, a 9sp cassette and a 10sp cassette are the same width. A 10 just has cogs that are closer together, and a chain that is more narrow. So dropping down to a thick chain and less cogs, does not leave room for a spacer.

 

[SaabaruAero]

You would have to look into how much movement is needed for the 7sp. The cable pull is different for different cassettes. 12sp pull is way different than 7sp. A 9sp shifter might work, but I cannot remember as I have not run 7sp since the mid90s.

 

[Winford]

You would have to look

You cannot cross shifters like that. Many derailleurs will not cross over. Nothing 12 to 9 interchanges other than using a 12sp chain on a 9 sp cassette. 7 is not a road I would even try to go down.

 

[Cris]

If you can live with the cost, a Wheeltop wireless derailleur can be configured to run anything from 3-12 speeds

 

[steve_sordy]

Don't SRAM sell an 8-speed cassette, mech, and shifter for an ebike? When I was looking for my first emtb back in 2018, I remember trying a top of the range bike that had an 8-speed gear. The next model down had a 12 speed! It was more expensive because it was stronger, so they told me. I just could not get on with it because I never felt to be in the right gear, always too high or too low.

 

[Cyclopath1000]

The sram ex1 is a 8 speed that uses 10 speed spacing and a spacer. They are very durable and very expensive if u can find one. The usual inexpensive way to go is to use a ten speed cassette, chain, derailier and shifter. The whole shebang is approx $200 if done right.

 

[Winford]

The whole shebang is approx $200 if done right.

Id be curious to their longevity, 35000 miles would only break even with Shimano 12 s set up. That would be a tough ask.

I get 1500 miles minimum out of Shimano 12sp Cassette and chain and that is about 100 bucks To get that kind of miles I use Molten speed wax every two or three rides. When I went to electronic shifting it doubled my cassette and chain life. I was getting 800-900 miles.

 

[Cyclopath1000]

Id be curious to their longevity, 35000 miles would only break even with Shimano 12 s set up. That would be a tough ask.

I get 1500 miles minimum out of Shimano 12sp Cassette and chain and that is about 100 bucks To get that kind of miles I use Molten speed wax every two or three rides. When I went to electronic shifting it doubled my cassette and chain life. I was getting 800-900 miles.

That’s a good question. I own several alternative 10 speed alternatives to
The ex1 set up on my 2019
Commencal meta power but ultimately bought an additional ex1 cassette ( $300 buckeroos). The alternatives are sitting in a box somewhere in my collection collecting dust. When push came to shove I stayed with the ex1 drivetrain primarily because it’s quite reliable. I’ve gotten approx 2k plus miles per cassette and a couple of chains. If you are buying sram stuff make sure the chains are manufactured in the old sachs plant in Portugal I believe not from Asia. I have gx1 t type on my trek exe and doesn’t seem to wear at 1500 miles. When I finally break that chain I’ll first do the chain and if the wear exceeds the spec that make this drivetrain so
Amazing, I’ll toss the entire drivetrain with the exception of the derailleur. Already own all the goodies.

If you have a functional 11 speed set up then buy a same brand (sram or Shimano …some have written about other smaller and cheaper brands) 10
Speed shifter cassette and whatever 10 speed chain but again I’d maybe buy a ex1 chain or similar 10 speed chain.

Going to 7 ,8, or 9 speed didn’t get traction in earlier methods. Unless the shifts are timed to the ramps ( gx1 t type) 12 speed cassette shifting under extreme load will quickly wear everything out and also break chains.

I still haven’t figured
Out if the new Shimano wireless is capable of timing to the ramps. If not then it’s the same as pre t type gx1 that my buddy Marty has on a year older exe.

 

[Winford]

I still haven’t figured
Out if the new Shimano wireless is capable of timing to the ramps

No. And the 11sp auto shift linkglide is not for those who can ride fast anyway.

alternatives

So far not one shifts as good as Shimano or Sram, and i run both hard.

I finally break that chain

Sram makes a stronger chain than Shimano, but im still getting 1500 ish out of the Shimano chains with good care.

Im about to go to a Sram electronic drivetrain and then ill have better stats on Sram.

I always carry a chain breaking tool and a link tool with extra master links, having a chain break 10 miles in a trail on a 100F day, is a bad day without tools.

 

[Col]

Thanks for all the replies, folks, very helpful.
Electronic shifting isn't in the budget, it's my commuter bike and main reasons for considering changing the setup to less gears is with the motor I have, I rarely end up going up or down one gear, 11 speed is just too many for commuting with a 1000w motor, and my other thoughts for attempting this was components will be stronger due to thicker chain.
Easiest option would just be to replace cassette and chain like for like, they've lasted 7 months, but keen to try less gears if it's not going to be a pita to do.
Cheers

 

[Spin]

10 speed Linkglide ? Cheap , durable. If a 43T first gear is useless for your commute , can you go a bigger chainring ?
I had a 40T chainring and ten speed 11 - 42 cassette on my old BBSHD bike

 

[Col]

Thanks, it was shimano HG I had on my last bafang HD conversion, with a 52t chain ring on front.
This current bike has the larger spacing at back, so chainstays prevent me fitting larger than the 46t it has, I already had to put washers behind the chain ring to space it out, so it now skiffs the chainstay with literally 1 or 2 mm clearance.
I tend to find on my commute I rarely if ever use gears 1 to 4 (roughly) and then once moving there's lots of frantic clicking up the gears to keep up/stay ahead of traffic.
Cheers

 

[Spin]

I think you've reached the point where a hub drive would be the right tool for the job

 

[Bontee]

Hi all, I've got a 2019 boardman mtr 8.9 which has sram nx 11 speed currently.

I fitted a bafang HD motor 6 months or so ago, and gears are now starting to slip due to wear (these motors chew through them).

11 speed with this motor is pointless, so looking to stick a 7 speed cassette on, advantage of less gears and from what I understand a 7 speed chain should be stronger because it's thicker.

Big question is what's easiest and most cost efficient method?

I can use cassette spacers either side of the 7 speed, and my query which I have no experience of is to do with gear compatibility.

It has sram rear derailleur, in my mind I could use this with shimano cassette? As the derailleur just moves according to what the shifter does? Presumably if I go with shimano cassette I'd need to use shimano shifter, as I believe the movement amount of cable is different.

Any help much appreciated, don't need to go shimano, if it's easier just to put sram cassette and sram 7 speed shifter then happy to do that...

Cheers all

Col,with respect just buy a steel 11 sppeed cassette and a new chain and go ride,You will encounter a number of problems going forom 11 speed down to seven,you will need new shifter derailleur cassette and maybe a new hub built onto your wheel ,or maybe just a whole new wheel,just buy the 11 speed cassette and chain and be done with it.

 

[Col]

I think you've reached the point where a hub drive would be the right tool for the job

Haha first conversion was a 1000w hub drive, and yes gears didn't matter much!

 

[Col]

Col,with respect just buy a steel 11 sppeed cassette and a new chain and go ride,You will encounter a number of problems going forom 11 speed down to seven,you will need new shifter derailleur cassette and maybe a new hub built onto your wheel ,or maybe just a whole new wheel,just buy the 11 speed cassette and chain and be done with it.

Yep thanks, that's certainly the simplest option. I could potentially set the high and low on derailleur to restrict the movement, and move cogs about to improve the chain line, which would give me less gears eg set it to only use 7 gears and have small 11t in a different place ... And not as you say, have all the messing about of new shifter etc. Cheers

 

[Col]

One thing I cant get my head around, and feel free to correct me, but the derailleur has no indexing unlike the shifter and the gears (with fixed space between them), but would assume from what I read about incompatibility that if you had shimano shifter, shimano cassette and sram derailleur the derailleur wouldn't move the correct amount to shift correctly.... Is that correct? Would need to be shimano derailleur?
If so I would assume the 2 makes of derailleur shift a different amount for an identical amount of cable pull.
Cheers

 

[Cyclopath1000]

Yes until you get to 12 speed. 12 speed are interchangeable. If your derailleur is in good shape the cheapest way is to stick with 11 speed changing the front chainring ,cassette and chain. Second cheapest is 10 speed with a new shifter. The 11 speed derailleur will most likely function quite well. Going below 10 speed is interesting and untried. Why bother. I’m sure if you were in serious financial shape anything can be mcivered even a single speed.

 

[Col]

Thanks.... Funny you mention single speed, I had thought about single cog on the back and 2 cogs on the front. Tbh with 1000w motor would probably do the job... But then you're into trying to jury rig 2 chain rings onto a bafang motor which is designed to have one( concave chain ring) ... Proprietary chain ring.... So probs even more messing about than with gears etc at the back. Cheers

 

[Cyclopath1000]

What’s the enemy of good??

Answer: better

 

[Winford]

12 speed are interchangeable.

They are but shifting is not perfect. I would not do it again. Ive got a 1000 miles on a sram 12sp cassette with a shimano 12sp mech and shifter. Their spacing is slightly different but it kinda works

 

[Winford]

derailleur has no indexing

Correct, but how far they move in relation to how far the cable pulls it, is different for different speed derailleurs that are the same make. 9sp and 10 are often compatible. Then you also have cage size to match the diameter of the largest cog.

 

[Bontee]

They are but shifting is not perfect. I would not do it again. Ive got a 1000 miles on a sram 12sp cassette with a shimano 12sp mech and shifter. Their spacing is slightly different but it kinda works

Strange that you experience that Winford,everyone I know who rides 12 speed trasmissions (really everyone)have run sram and shimano hybrid drivetrains for ever and no-one has had a problem in fact most of us prefer a mix.SRAM shifters and derailleurs work superbly on shimano cassettes ,this tends to be the favourite.Shimano shifters and derailleurs tend to be fractionally less quick to shift on sram cassettes but it is really only a millisecond due to a slightly different profile on the cassette teeth ,but they both work perfectly.
Please feel free to correct me but the spacing is the same on both.

 

[Winford]

SRAM shifters and derailleurs work superbly on shimano cassettes

slightly different profile on the cassette teeth

The width of cogs is slightly different as well, which causes the less than perfect shifting. I also use a Sram chain with the Sram cassette.

Glad it is working for you, and it works decent enough for me not to swap it out on my gravel bike, but perfect it is not.

 

[Bontee]

The width of cogs is slightly different as well, which causes the less than perfect shifting. I also use a Sram chain with the Sram cassette.

Glad it is working for you, and it works decent enough for me not to swap it out on my gravel bike, but perfect it is not.

It’s the same on mtb cassettes,both 1.8 mm ,I don’t know about road/gravel cassettes I don’t ride road or gravel bikes but mtb are interchangeable