If I keep it in a single gear for a trainer ride, will the spacing be similar so I can put an old 7 speed shimano wheel on my 10 speed shimano-equipped cervelo? I’m too lazy to swap a cassette right now.
NO.
The hub is 5mm narrower, so you will have to flex the frame to fit the hub.
Your 10sp chain will never work with a 7sp cassette, even if you leave it in one gear.
Thanks
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No animosity intended, but there is incorrect information in your post.
A 10s chain will run fine on a 7s drivetrain, especially if it is left in one gear. The teeth pitch is identical and the internal dimension of the chains are the same–it is the external dimensions that differ, which is why a 7s chain will not run on a 10s cassette because it is too wide externally.
A picky point–Typical 7s hubs are 4mm narrower than current road, but can be respaced to 130mm.
No animosity intended, but there is incorrect information in your post.
A 10s chain will run fine on a 7s drivetrain, especially if it is left in one gear. The teeth pitch is identical and the internal dimension of the chains are the same–it is the external dimensions that differ, which is why a 7s chain will not run on a 10s cassette because it is too wide externally.
A picky point–Typical 7s hubs are 4mm narrower than current road, but can be respaced to 130mm.
Are you sure a 10-speed chain will work well (or at all) on a 7-speed drivetrain because the cog spacing on a 7-speed cassette is 5mm and the spacing on a 10-speed cassette is 3.95mm… so I’d think the narrower chain might jam on the wider-spaced cassette.
Early 7-speed hubs were 126mm but some later ones were 130mm. 8- 9-, and 10-speed road hubs are all 130mm and your Cervelo rear dropout spacing is 130mm. You should be able to put the 7-speed wheel in even if it is 126mm, but if it is 126mm, I would space it out to 130mm if it were going in an aluminum or carbon frame.
You won’t be able to put the 10-speed cassette on the 7-speed wheel, though. The 8-9-10-speed freehubs are about 4.5mm wider than 6-7-speed.
The narrower chain works–I’ve done it. It is not as good as a wider chain, but it does work. Front shifting with a narrow chain is sluggish as the FD needs to push farther to move the chain–requires an overshift and then compensation.
That 1.05 mm difference is too little to let the chain fall between the cogs. Remember that the 10s chains are about 6mm wide so the space between 7s cogs is still narrower than the chain.
I am not suggesting that one routinely run a 10s chain on a 7s drivetrain, but to address the original question of whether a 7s wheel could be run in a 10s drivetrain in a single gear, then absolutely yes.
Are you sure a 10-speed chain will work well (or at all) on a 7-speed drivetrain because the cog spacing on a 7-speed cassette is 5mm and the spacing on a 10-speed cassette is 3.95mm… so I’d think the narrower chain might jam on the wider-spaced cassette.
Yes, the 9- and 10-speed cogs are a bit thinner than 6-7-8-speed and the inner width of 9-10-speed chains are also narrower. But if he’s running just one gear, it will work. It would probably be a bit sluggish for shifting, though, since the chain might bind a bit as it moved sideways trying to get off the cog.
Sort of a thread hijack.
I have 7 speed Shimano RX-100 components on my 14 year old Bianchi. Are there any race wheels that would be compatible with this old stuff? Or would I be better off getting a rear wheel cover and only a front race wheel? Is there any way to go from the 52 big ring to a 53 or 54? It’s setup with a triple crank, but I almost never use the small ring - maybe only a couple times a year on some of the extremely steep Colorado hills I occasionally ride.
I’ve got many thousands of miles on this bike and everything is basically stock. Only non stock items are the seat and an original Scott aerobar. Still works as good as the day I bought it. Getting a new bike just isn’t a budget priority, but a couple hundred to improve speed could maybe be squeezed in.
Point of reference: I averaged just short of 28 mph in a 9 mile TT on this bike last fall and have gone as high as 56 in a tri on a good downhill. Did the Rockman HIM in 2:52 on almost zero training. I’ve won the overall at a duathlon and have some AG tri wins all on this bike as is. I think a few minor improvements would make me almost as fast as some people on much newer bikes.
Any suggestions?
You can put 7-speed cassettes on most new wheels. All you need is a 4.5mm cassette spacer behind the cassette. One exception that I know of is the Dura-ace 10-speed hub which will only accept 10-speed cassettes. There may be other exceptions so ask before buying.
An early 1990’s frame may already be spaced at 130mm (or the intermediate spacing of 128mm) so you may not need any changes to run a new wheel (which will be 130mm). If the frame is 126mm and is steel, you can just spread the stays out to 130mm to fit the new wheel. It’s not recommended to spread carbon fiber or aluminum stays, though (although I’ve ridden 130mm rear wheels in my 126mm alum bike a few times).
Yes, you can change your big ring. But IMO, you don’t gain much at all by doing so. If it were me, I’d make the change only if it was time to replace the ring because of wear.
FWIW I just rode on the trainer with a 7sp wheel on my 10-speed p2k. It worked just fine and it even shifted well in friction mode (I didn’t shift a lot though). I think this will be my new trainer wheel.
If your courses are flat to rolling, where the weight penalty would be minimal, then a rear wheel cover would be your best bang for the buck. I agree that changing the big ring isn’t necessary unless you routinely spin out of your 52.
If you want to build on what appears to be some baseline talent, then additional training would help more than any bike upgrade.
Did not see it mentioned above, but if your wheel is 126mm, a simple solution for you is to put two washers on the axle. You need to use a little care putting the wheel and axle in the frame, but when done, you don’t need to worry about squeezing your 130mm frame.