Noob Spacing on Spacer Combination
 

I have read and tried to make sense of the multiple posts regarding this issue but am not comprehending for some reason. Your help is appreciated after the LBS told me this is just too dangerous and I need to buy an 8/9/10 cassette...

Here is the scenario:

Putting a 7-speed Shimano cassette on an Aksium wheel.

The wheel came with a 2mm spacer.

What combination of spacers should I use to make this work?

Super noob = the spacers go on the axle closest to the spokes, correct?

Thank you in advance.

There's nothing dangerous about fitting a 7-speed cassette to an Aksium wheel - assuming it has the appropriate Shimano compatible freehub body. But the spacer goes on the body, not the axle. And yes, it should sit on the insideof the cassette.
A 2 mm spacer probably isn't enough. Depending on cassette/body, you may need either 3 mm, or 4 mm to stick a 7-speed cassette on a 8/9/10-speed body.

adamjmeek, My daughter's bike required a 4.5 mm spacer (between the cassette and hub closest to the spokes) in order to use a 7S cassette on a freehub meant for 8S+.

Brad

http://www.google.com/#q=4.5mm+shima...w=1280&bih=610

4.5mm is what normally I use. What you need to be sure of is that the cassette lockring bottoms out on the cassette and not the hub; the spacer needs to be wide enough to make sure that the cassette protrudes beyond the hub shoulder and is securely clamped. Don't forget to put grease or preferably antisieze on the lockring threads and to torque it properly.

Why would a shop consider this dangerous?

Thank you for your fast replies, I appreciate them all.

So it sounds like 4.5mm is the way to go; is there any way of combining the current Mavic 2mm spacer with a Shimano cassette spacer in order to achieve this 4.5mm thickness?

If so, how can I do this?

Thanks again.

Because they want to scare you into buying stuff from them?

I'd be wary of an LBS that did this - don't boycott them just yet, but be on your guard...

Because if the RD is the slightest bit out of adjustment the chain can get caught behind the last cog and get jammed agains tthe spokes adn cause damage to derailleur, frame and wheel.

I hadn't thought of that, but in all honesty, it's not hard to adjust derailleur limit screws precisely. I wouldn't call it dangerous.

... which can, and does happen just as easily even if you run a "matched" cassette on the freehub body....

Alright, so now that we have determined that it can be dangerous and why...

Any input regarding a combination of spacers using a Mavic 2mm and Shimano 7 speed cassette in order to achieve 4.5mm?

Can I simply sandwich two spacers together without worrying..?

I am living in Qingdao, China so ordering/obtaining the 4.5mm spacer is pretty much out of the question.

Thanks again in advance for any input involving the combination of spacers.

If you can't order a 4.5 mm spacer you can see if a machine shop can make a 6.5 mm spacer using the Mavic spacer as a guide.

Brad

I say you can.

One of "my" webshops lists two different spacers for use together with Shimano 7-speed cassettes on 8/9/10-speed bodies, one is listed as 3 mm and one as 1 mm.
According to them, sometimes you get away with only the 3 mm (I did), sometimes you need both. From that source 4.5 mm isn't even mentioned.
I've once improvised a spacer by making a thin coil of steel wire and placing it over the body before putting the cassette back on. It worked just as well as the real thing, so I left it there. Took a few tries to get the diameter right though.

But if you're set on shooting for 4.5mm, then your current 2 mm spacer + a spacer scrounged from a disassembled Shimano 9/10-speed should get you really darn close.

Working with standard off-the-shelf parts, you can stack Shimano 10spd cassette spacers. They are 2.35mm and combined with the 2.0mm Mavic spacer will give you 4.35mm. Darn close enough to 4.5mm. If the end of the freehub body still protrudes past the last cog, then use 2x 2.35mm 10spd spacers for 4.7mm thickness.

Do a test and make sure you have at least two threads engaged with the lockring.

4.5MM spacers are a "standard".
Many later 7 speed bikes used the 8/9 speed body with the spacer added.

http://www.lmgtfy.com/?q=4.5mm+spacer

Thank you for all of your input. So I was able to obtain a 2mm spacer that I can sandwich with the 2.5mm mavic spacer. One question: the 2mm spacer doesn't have any "teeth" or rivets/grooves, it is simply smooth. In regard to the sandwich combination--is it better to put the smooth 2mm spacer closer to the axle or does it matter. I presume the most sturdy spacer (2.5mm) with the grooves should go on the inside/closest to the axle?

Thanks again.

just realized (what a noob) that my mavic spacer is 2mm not (wishfully thinking) 2.5mm....now gonna sort that out

adamjmeek, It doesen't matter which order the spacers are installed. For sake of OCDness install the Mavic spacer first and then the Shimano spacer(s). My guess is you'll need to obtain another 2 mm spacer to properly tighten the cassette on the freehub, but certainly worth testing before [urchase.

Brad

I think you may need the Mavic spacer plus the 4.5mm 7 speed spacer. Many Mavic wheels require their own spacer with 8/9/10 cassettes.

Thanks guys----the OCD comment had me weak, thanks for that.

I will now have a handful of 2.5mm and 2mm spacers, and the Mavic 2mm.

It sounds like 6.5mm total spacer thickness is the majority recommendation.

Thanks again...

Final Answer: Shimano 7s Cassette + Mavik Aksium = 6mm Spacer

used a total of three 2mm spacers, including the 2mm Mavic spacer, 6.5mm was too thick.

thanks again........... :)

Thanks for the final outcome, it'll help others in the future. :)

Brad