I just got a Kickr Core and I’m trying to install with a 7 speed cassette.
I put a 4.5mm spacer on and then the matching cassette so it’s the same as my bike. However, my gears are rubbing a bit on the front derailleur, and the chain doesn’t reach the smallest cog of my 7 speed cassette. The other 6 can be reached, and it doesn’t fall off the top either.
Did you only add a 4.5mm spacer? or also the 1.8mm that came with it? and if so… all before the cassette?
@NomadicVelo There is a sequence I went through to get this to fit. Here’s my suggestion to get the best shot at it fitting as well as possible. See the attached photo for what my setup looks like.
Before doing any of this, ensure you have a good chain. Measure your chain for stretch. If it is old and stretched it will never align well and you will just burn time being frustrated. If it is stretched beyond 0.5 on a measuring guage, replace it now. This hold for when on your wheel as well. Just standard bike maintenance.
Use the the shortest Kickr Core axle inserts provided. Your bike dropouts must slide onto the Core’s axle easily, just like sliding a wheel on. If you have to use force to spread your droupouts/rear triangle at all, the bike will not fit on there well as the rear derailleur will not span across the cassette because it is no longer in the correct location relative to your right dropout. I’ll assume your bike is dropping on there smoothly as mine did. Once you see it drops on smoothly, remove the bike to install the cassette.
start with a 4.5mm spacer. Cut 2 notches in it about 1/2 to 1 mm deep exactly aligned with the 2 rivets on the inside of the 7-speed cassette. See the photo above in one of my previous posts. If you have a dremel or grinder, that is great as it will cut the notches in seconds. Else you can use a hand file, just take a little more time. When you think you have the notches cut to the right depth, hold it u to the inside of the cassette and confirm the 2 rivets align cleanly in the notches so the rest of the space sits flat against the inside of the cassette. This is critical. If you need to cut the notches a little too deep or wide to have plenty of margin, go for it. This is not structural or life critical, you can make those things big.
Slide the 4.5mm spacer onto the Core’s splines. Align the 2 notches so they will perfectly fall under the cassette rivets and slide the cassette onto the hub splines. The spacer can rotate easily on there. As you slide the cassette onto the splines, ensure the rivets drop cleanly into the notches. When it all looks good, install the locking ring onto the Core’s hub.
Spin the cassette/hub and ensure it is sitting flat on the hub. There should be zero wobble as it spins. If there is wobble, either your rivets are not aligned in the slots or the cassette is not tight on the hub.
Grab the cassette and pull and push sideways to see if there is any play at all. Mine in initially felt tight so I finished the rest of the steps. I rode if to for a number of days and was very frustrated that it did not shift well and clicked all the time. I removed the bike and found after a little riding the cassette actually had a little play side to side. The cassette was sliding left and right a fraction of a mm on the hub under chain load. Thus I removed it all and added another 0.5 mm spacer. Your results may differ.
Put your bike on. You will need to adjust your rear derailleur. The Kickr Core will not have the cassette exactly aligned where your rear wheel does. Just a reality of kludging a 7-speed cassette on there. The axle spacers are designed for 9 and above. So simply use the barrel adjuster on the derailleur to move your derailleur left or right as needed to align as well as you can. Your right dropout is now referenced to the right axled spacer that you put into the Core’s axle. It should align pretty well but will not be the same as your wheel. If you have to move it more than a few mm, you will likely also have to adjust the low and high limit screws on the derailleur to let it get to the lowest (largest) and highest (smallest) cog. They will go in opposite directions. Since you are saying you can’t get in to your smallest cog, you will likely need to loosen the high limit screw to let the derailleur go further to the right. If so, then tighten the low limit screw to move that end of the derailleur motion right also. If you don’t do this, you will drop the chain when shifting to the lowest gear. Remember, never adjust the limit screw when the chain is in the low or high gear you are adjusting. Shift a couple gears away from that cog, adjust, check it, and repeat. Play with it until you get it as good as possible.
Shift through the range while pedalling and it should shift pretty well to all cogs. Optimize the adjustment in step 6 to run smoothly in the middle cogs. The smallest cogs may make noise, that’s the nature of this game.
Once you have the chain running well on the cassette you may find it rubs on the front derailleur when in either the smallest or largest cog in back. If you had to do a good bit of movement in the adjustment of the rear derailleur, this is expected. That says your cassette is not in exactly the same place in reference to the dropouts as it is on the wheel. Thus you can expect the chain angle is different than where it was on the wheel and thus it enters the front derailleur at a different angle, Now adjust your front derailleur cable to get it as quiet as possible. Go through the same kind of steps as in #6. Especially with the low and high limit screws. Remember, it is not good to cross up the chain, meaning largest cog in back and largest chainring in front, or vice-verse. If it is only rubbing in one of those configs, leave it be, you are likely not going to get rid of that, and you shouldn’t be riding in those configurations on a 7-speed system.
Now you should be good. Give it a few rides then check if there is an side-to-side motion in the cassette on the hub like I had.
If you are still having problems, DM me and we can talk about the specifics of what you are seeing.
You will need a 7 speed cassette as the derailleur/shifter pull ratio is specifically for that cassette. Good news is that 7 speed cassette should work on the Kickr freehub but I’m not 100% sure on the spacer required to avoid re-indexing. I think its ~ 6.35mm but a few cleverer folks that float around here likely know shite loads more than me and should be along shortly to provide wisdom.
Yes I tried putting it straight onto the 11 speed cassette and basically the chain “jumps” on the higher gears (4-6). Strangely enough it works well on gears 1-3 but I need more than 3 gears for an enjoyable Zwift experience!
I try to add small spacers until the cassette is positioned so that no derailleur adjustment is needed (trying to match the position of the cassette as it is on the rear wheel) then replace as many of the small spacers as I can using the thickest spacers in my drawer.
To remove the cassette you will need both a lockring tool and a chain whip. Sometimes they are sold together as a kit:
Navi, all the guidance people have given in replies to you is correct. Buy the tools Paul_Southworth suggests to swap the cassette or if you know an avid cyclist then likely have these tools and the knowledge of how to use them.
Read through all my posts in this forum thread, they give you all the info you need for spacers, where to grooves need to be made on one of the spacers, etc… The pictures I’ve posted should help you envision it all. It takes a little time to get it setup, but it does work. I’ve got many thousands of miles on my 7-speed setup.
If you run into difficulties, feel free to direct message me on the forum. I’ll gladly chat with you.
I don’t have much more to add, everyone’s giving good advice I also wouldn’t know which spacers to add off the top of my head, there are a number of factors that could make a difference, so just trying different options as Paul is saying would be the way I’d go.
I’d add that indexing a derailleur is a very good skill to have, and isn’t hard once you get the hang of it. So even if you can’t find just the right spacer, watching a Park Tool indexing vid and putting it to use would be a good time investment anyway. Grab a beer and turn on Calvin at Park Tool (chill guy with the big mustache) and learn a new skill
Oh, I guess I’ll add–you definitely can buy the cassette tools in sets. For example, Abbey Tools is offering a 10 yr anniversary titanium crombie, chain whip, and hanger tool combo in a commemorative walnut box. Only $650 US!
In all seriousness though, indexing is a good skill to have–the one that allows you to quickly help all your friends who complain about skipping and chatter from their cassettes. Usually need just a small Phillips head or Allen wrench.
Got everything working (or at least it seems), so I thought I’d put a full rundown of my experience here (for my own future benefit and for that of other folks who come to this forum). Apologies if I’m not using the right terminology - I’m literally Day 1 here.
Problem statement: How to get a 7-speed road bike onto a Wahoo Kickr (direct drive trainer)?
Short answer: Need a cassette removal tool + chain whip + wrench to remove the standard 11-speed cassette from the Kickr. Then need to install a 7-speed cassette + a couple of “spacers” which I picked up from my local bike shop, and luckily didn’t have to “file” anything.
Long answer:
Background: Brand new to cycling & Zwift. Just completed my first ever marathon but weather is getting quite hot in Australia, so looking for a new challenge and to add low-impact cross-training to supplement the running. A couple of my favourite running Youtubers use indoor cycling / Zwift, so that’s how I came across it all.
Picked up a Wahoo Kickr v4 secondhand for A$650 (about US$435 at current exchange rates) via Facebook marketplace. Pretty good condition and the guy was helpful with advice. As you all know, Kickr v4s come with an 11-speed cassette as standard.
Then picked up an entry-level road bike - a Decathlon Triban RC100 for A$459 (about US$305). Luckily I mentioned to the guy that I was using it for the Kickr v4 and he immediately pointed out that the bike has 7-speeds and may not play with the Kickr v4. So picked up a 7-speed cassette and a tool (which was actually for Freewheel removal tool)… and one of those shorts with the padding inside.
Googled what the hell to do in the situation and found this forum as one of the first hits. But, tried anyway to mount the 7-speed bike straight onto the Kickr v4 11-speed cassette. Obviously, this did not work - chains jumping all over the place as covered by earlier posts. But I got a good workout just trying to remove the tyres and mounting the bike. Also, noticed my behind was hurting just from sitting on the bike for a few minutes trying to get everything to work. Maybe I need a seat gel pad thing too?
Resigned myself to the fact that I need to replace the cassette, so I tried to use the tool from Decathlon. Discovered it was a Freewheel removal tool, so gave up for the evening.
This morning, I went to my local bike shop and described the situation. They (a) laughed out loud that I purchased a 7-speed bike to use on a Kickr v4 (b) strongly suggested I return the Decathlon bike and just get “a proper bike” (c) claimed Kickr v4s are not designed for 7-speed cassettes and that using spacers is a very n00b activity.
I immediately get reminded of why, especially as a runner, I kind of despise hardcore road cyclists - so elite and exclusionary. The opposite of runners, really, who are chill, welcoming and inclusive.
Another guy at the shop was a bit more chill. After making fun of my new bike purchase again, he dug up 3 spaces and the proper Cassette removal tool and I was off A$20 poorer.
With the Cassette removal tool in hand and a wrench, I tried to take the cassette off the Kickr v4. After grazing my hand and trying to use a tool to stabilise the cassette, I went back to Google. Ok, I need a “chain whip”, whatever.
Went back to the local bike shop and picked up a chain whip. This time the guys were a bit more chill. Maybe they haze all new cyclists? Another A$20 poorer, but this is small fry compared to what I already spent. Picked up a gel seat cover too - why not.
Went back home and finally swapped the cassettes, used only 2 of the 3 spacers they provided (because using the third meant I couldn’t put the last of the cassette gears in), and finally mounted the bike. All is apparently working. Didn’t have to “file” anything down but I noticed that the spacers that the bike shop gave me had three indents… so maybe they didn’t need any more filing.
Downloaded Zwift and played around - loving it so far! But despite wearing the shorts with the pads and putting the gel cover over the seat, am still finding my sit bone (or whatever it’s called) hurts after only a few minutes. Nevertheless pushed out a 20 minute beginner’s workout.
Other things I’ve already bought as a Day 1: a. Couple of fans from the hardware store; b. A sweat catcher thing; c. Lifeline trainer mat; d. Lifeline Turbo Trainer table (basically a cheap version of the Wahoo table); e. Chamois creme (apparently a “must”); f. a “bib” (basically one of those outfits that makes you look like a wrester).
You’ll need some miles to assess the saddle, but good bike shops offer return policies on saddles and will help you identify a model that suits your anatomy (spoiler: it’s personal). Some also offer demo saddles. The saddle pad should not be necessary and will impede your pedaling.
Bike shops that “haze” customers don’t know their business, which is creating long term happy customers at all levels of ability and experience.
Thanks - I’m hoping it’s just beginner’s discomfort and I’ll get used to it. It’s a cheap Decathlon bike so I think my options are to just buy a better saddle if it all doesn’t work out. Will give the standard one a go for a few weeks and then take it from there.
And agree on my local shop (not the Decathlon - just a local bike shop). It’s intimidating as it is to walk into a shop with $5,000-10,000 bikes when all I want is a couple of spacers and a cassette tool, but it was literally 9am in the morning and empty. Maybe they needed to have their morning coffees! Just playing right into the whole ‘angry cyclist’ thing!
Fantastic, glad you got it working. Impressive for a newbie to easily figure out how to use the chain whip and tools to replace the cassette, shim it properly, and index the deraileur. Well done.
As Paul mentions, it will take a week or two for your butt to get used to being on a saddle. No quantity of padding is going to change that. The pad will not be needed once you are broken in and actually it will hamper you. A good saddle properly fit to you is far better then trying to band-aid with padding. As your ride lengths increase, that padding can actually cause more irritation of the skin.
Since you did not notch the spacer that is directly against the cassette, it may or may not be fitting on there correctly. A typical 7-speed cassette has 2 rivets protruding through the back (behind largest cog). A flat spacer against those rivets, or if you don’t have the indents aligned with the rivets, will rock back and forth. This will hamper shifting sharpness and make some noise when in gear. Take a look at the photos in my post about the 13th post of this thread then about 9 below that. You’ll see what I’m referring to on the rivets and the notches created to solve it. Sit behind your kicker looking at the cassette while someone pedals it forward. You’ll see if your cassette is rocking a little or not. If not, you are golden. If so, you’ll want to notch the spacer to avoid those rivets and then the cassette will smooth out.
Enjoy your new Kickr ride and exploring the world of Zwift. Maybe we’ll see on the virtual road some time.
Putting this out there: saddle height, tilt, fore/aft, and cleat position (read: “Bike Fit”) will have more effect on saddle comfort than changing the saddle. It’s worth spending some time dialing those in first. (a lot of stock saddles are pretty good these days)
No need to spend a fortune on a saddle either - once fit is dialed in, just about any mid-range saddle will be fine.
Some videos if you want to go down that rabbit hole:
First, glad you got it sorted @Navi Cassette swapping isn’t hard in the spectrum of bike wrenching, but things like that can be daunting for a newcomer. Good job.
Second, I’m already irritated by your LBS (local bike shop) and I wasn’t even the one who had to talk to them. Elitism is a crappy attitude to have–and someone always has a better bike than the elitist jerk anyway. The best bike is one that fits you and you like to ride and does what you want it to do. You may find if you keep at it that you’ll want to upgrade your bike (for any number of reasons–components, or a whole new bike), but it’s silly to say you immediately need a different bike just because you didn’t spend a lot on it.
(I’d guess that they were more receptive the second time around because you were buying tools–you’re ‘part of the tribe’ at that point )
Third, on the topic of saddles, I agree with CJ above that saddle position will play a big role in a saddle feeling good–but imo position can’t help a saddle that’s not the right width for you. Your sit bones need to sit on the right parts of the saddle, and a saddle that’s much too wide or too narrow won’t allow that to happen. That’s when padding can get jammed up into places it doesn’t belong, cutting off blood flow while not supporting the sit bones it’s supposed to support.
It might help to measure your sit bones. If you have a set of carpeted stairs (or you can throw a sweater or something on a hard chair), put a sheet of aluminum foil down on the stair. Sit down on the foil, being careful not to crinkle it. Lean forward so you’re in approximately the position you’re in on your bike. Then stand up. You should see two clear indentations of where your sit bones are. Measure those, and then compare that measurement to your saddle–are the highest supporting parts of the saddle roughly the same spacing? If they’re a ways off, you might need a new saddle. (But they don’t have to be expensive.)
I also wouldn’t know which spacers to add off the top of my head, there are a number of factors that could make a difference, so just trying different options as Paul is saying would be the way I’d go.
