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  1. #1
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    What is the third number in bolt measurement?

    Hello again,

    I just purchased a bolt measuring card from the hardware store and measured all the bolts on my bike. I wrote the sizes down in terms of M5 x 10mm etc. (the M5 being the thread diameter, which takes a 4mm hex, and the 10mm being the thread length, correct?) When I went to Redmist and other sites, they had their bolts listed as M5x8x10mm. What is the middle number (8 in this case), and is it necassary for me to know when I order my new bolts?

    Thanks,

    Stephen

  2. #2
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    What you are probably seeing is the pitch, M5 x 0.8 x 10mm.. This means there is .8mm between threads.. in UN threads you have coarse and fine threads, in in some cases extra fine threads, as in 1/2-13 UNC, 1/2-20 UNF, or 1/2-28 UNEF. Those mean 13, 20, or 28 threads per inch.

  3. #3
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    OK -what is the pitch do most bike bolts?

    Quote Originally Posted by bmadau
    What you are probably seeing is the pitch, M5 x 0.8 x 10mm.. This means there is .8mm between threads.. in UN threads you have coarse and fine threads, in in some cases extra fine threads, as in 1/2-13 UNC, 1/2-20 UNF, or 1/2-28 UNEF. Those mean 13, 20, or 28 threads per inch.


    Thanks! What is the pitch of most bike bolts? Or, do I have to buy a pitch measurer and start measuring my bike bolts all over again? When I called SRP for pricing, they only questioned one M8 bolt I had, and they asked me what the pitch was -course or fine; I had no idea.

    Stephen

  4. #4
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    Good question.. You can get a thread pitch gauge. Looks like a feeler gauge untill you whip out one of the gauges. It has a bunch of little saw teeth on it that fit the threads your are checking and they have the pitch written on the sides of them.

  5. #5
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    Quote Originally Posted by swalters
    Thanks! What is the pitch of most bike bolts?
    Stephen
    Generally, an M5 bolt is .8 thread and M6 is 1.

    M8 bolts are usually 1.25 and M10 1.5 but you should check these two to make sure because they sometimes have a finer thread. ,,,if you don't want to buy a thread pitch guage, you could compare the threads between bolts. For example, if the M10 bolt has a fine thread that is exactly the same as the M6, it should be a 1mm thread pitch. (just make sure the M6 is a 1mm thread first. )

    Cheers,
    Trevor

  6. #6
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    What should be easy seems like a pain in the ass

    Quote Originally Posted by tmaybee
    Generally, an M5 bolt is .8 thread and M6 is 1.

    M8 bolts are usually 1.25 and M10 1.5 but you should check these two to make sure because they sometimes have a finer thread. ,,,if you don't want to buy a thread pitch guage, you could compare the threads between bolts. For example, if the M10 bolt has a fine thread that is exactly the same as the M6, it should be a 1mm thread pitch. (just make sure the M6 is a 1mm thread first. )

    Cheers,
    Trevor
    Hello,

    It's funny that with all the questions about bolts - material, sizes, and such - that pitch is never mentioned. Every manual I have provides bolt info in a different and confusing manner. My Maverick manual has several M5 x .75 or M8 x 1.0 listings, which I believe are probably thread width and pitch, but they never mention the length. My Hope manual never mentions the pitch. The bolt tolerances overall seem terrible, as one rotor bolt will be a 10mm and the other an 11mm or 12 mm (they bolt alll the way through of course, so perhaps a mm or two here and there does not matter). At this point, I would pay someone to do it all for me - unless I'm making a bigger deal than it actually is. Do I really need to measure the pitch on all my bolts? Most of my parts are fairly standard. Will the guys at Redmist, for example, know what I need from dealing with other bikers?

    Also, I've left messages at Redmist all week. Anybody have a number to a place that will call back or answer the phone on the first try?

    Thanks,

    Stephen Frustrated

  7. #7
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    I would say stick with SRP. My experience with both Redmist and Racebolts has been frustrating. Hard to get a response and in the case of Racebolts I placed an order online that was simply ignored and not processed. You might want to check out CBO. They have a decent selection of bolts and they will process your order.

  8. #8
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    From the Machinery's Handbook

    M8 x 1.25
    M8 X 1

  9. #9
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    Which thread is this last post addressing?

    Quote Originally Posted by mtnrider
    From the Machinery's Handbook

    M8 x 1.25
    M8 X 1

    Thanks for the input mtnrider. Are you just saying that M8 bolts come in two pitches? Or, are the measurements you've given specific to one of the part I listed in my previous threads?

    Thanks,

    SDW

  10. #10
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    Quote Originally Posted by swalters
    Hello,

    It's funny that with all the questions about bolts - material, sizes, and such - that pitch is never mentioned. Every manual I have provides bolt info in a different and confusing manner. My Maverick manual has several M5 x .75 or M8 x 1.0 listings, which I believe are probably thread width and pitch, but they never mention the length. My Hope manual never mentions the pitch. The bolt tolerances overall seem terrible, as one rotor bolt will be a 10mm and the other an 11mm or 12 mm (they bolt alll the way through of course, so perhaps a mm or two here and there does not matter). At this point, I would pay someone to do it all for me - unless I'm making a bigger deal than it actually is. Do I really need to measure the pitch on all my bolts? Most of my parts are fairly standard. Will the guys at Redmist, for example, know what I need from dealing with other bikers?

    Also, I've left messages at Redmist all week. Anybody have a number to a place that will call back or answer the phone on the first try?

    Thanks,

    Stephen Frustrated
    Steve you are making it more complicated than it is. Don't worry about bolt pitch. If you need an M6 bolt just order an M6 bolt nearest to the length you need. You will get the correct pitch and the reason its not mentioned in a lot of manuals is that most bolts in applications of a given size are of the same pitch. Hence pitch should be a non issue.

    Also you will likely need only M5 and M6 bolts (there may be a handfull of M4 applications on your bike) for all your bike bolt tuning.
    If in doubt - pedal harder!!!

  11. #11
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    Yeah, I think I get now - Thanks!!

    Quote Originally Posted by Boj
    Steve you are making it more complicated than it is. Don't worry about bolt pitch. If you need an M6 bolt just order an M6 bolt nearest to the length you need. You will get the correct pitch and the reason its not mentioned in a lot of manuals is that most bolts in applications of a given size are of the same pitch. Hence pitch should be a non issue.

    Also you will likely need only M5 and M6 bolts (there may be a handfull of M4 applications on your bike) for all your bike bolt tuning.
    Hello!

    After calling Redmist and SRP, I've figured out that a lot of the bolt tech stuff is not necassary. Imagine when I called them with M5 x 7mm, M5 x 8, and M5 x 6 orders, when they all can actually take 10mm bolts- Who knew?!! (certainly not me!!).

    Thanks again for all the in put.

    Stenphen Less Frustrated Now

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