# Issue installing rear rack in threaded hole by rear dropout



## nmum (Oct 10, 2013)

Hi all,

Sorry if this is a seemingly basic question.

I'm having issues in installing a rear Topeak bike rack on my 2009 Hardrock Disc, which looks like it should be a very easy install. The rack is supposed to be disc brakes and I confirmed that it matches the picture.

The issue is that the bolts that came with the rack will not fit in the threaded holes by the rear dropout. I tried putting them on without out the rack and one of them only fit once and would not go more than an 1/8th in.

I tried seeing if the bolt for the water bottle holder would fit in the hole by the rear drop out and it will not go in either.

I'm going to try to test to see if the bolts that came with the bike and used for the upper arms of the rack will fit in those holes later on tonight.

But I found a post online where someone installed the same rack on a 2010 Hardrock Disc and did not mention having issues with this. I'm fairly certain that I am trying to mount it in the correct location as well, where that is the only threaded hole that I can find.

Also when searching online I found an instruction manual for a Specialized bike rack, not sure of the type and for which bike, and it lists the bolts supplied as 2xM5x20mm. In the manual for the rack I have, the bolts are listed as M5xL15mm. So I think they're the same sizes, but maybe different lengths?

So kind of a two part question:

-Is this an issue with the bolts that came with the rack and I should get a different size? The manual says if there are any issues to go back to the bike shop(Performace Bike). This is my first purchase from a bike shop, and I don't know if this means that they'll sell me new bolts or if they will replace them for free. If they're going to charge me, I might as well go to the hardware store. 

-Assuming that the same issue happens when using the bolts from the upper arm, is it normal that the bolts are a tight fit and is it okay to force the bolts in using something like an impact wrench if needed? I'm concerned about possibly damaging the threads or frame.

Thanks in advance!


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## cobba (Apr 5, 2007)

Is there any paint in the threaded holes on the frame?


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## nmum (Oct 10, 2013)

cobba said:


> Is there any paint in the threaded holes on the frame?


It didn't look like it.


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## AndrwSwitch (Nov 8, 2007)

It's not okay to use an impact wrench on an M5 bolt. You can shear an M5 with a socket wrench and a little muscle and your dropouts are aluminum, which doesn't hold threads great, so stripping those holes is easier than one might wish.

I think cobba's question is a great starting point.


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## J.B. Weld (Aug 13, 2012)

Might need to chase it with a tap.


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## nmum (Oct 10, 2013)

Hi all,

Thanks for the replies. So what I gather it's not a simple solution of just muscling it in or getting some new bolts. Wouldn't have minded if it was either one of those too much because it would've been an easier solution.

I'll take a closer look tonight to see if I can tell if there is anything that might be causing issues with the threads like cobba suggested.

When you say chase it with a tap, I assume you mean something like this:
Tool Tips--Taps

And not just putting a wrench or something around it and tapping the handle gently(I'm a newbie, so am still trying to figure out what everything means).

Thanks again!


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## Harold (Dec 23, 2003)

cobba said:


> Is there any paint in the threaded holes on the frame?





J.B. Weld said:


> Might need to chase it with a tap.


This. Just about every rack and fender eyelet on a bike I've seen has been full of paint. Some haven't been too bad and I could thread a bolt in with enough grease and patience (no ham-fisting it in, you have to thread it in gently, then thread it out, and back in and so on to remove the paint - essentially using the bolt as a tap). Others I've had to pull the tap & die kit (and cutting fluid) out because I couldn't even get the bolt started.


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## EABiker (Jun 24, 2004)

To the OP.... The tap is basically a tool used to cut threads in an unthreaded hole of the proper size. When used to "chase" threads, it means that the threads are already cut into the metal, but may be damaged, (crossthreaded), or, in this case, may have paint in them. As suggested, add a drop of oil and turn in the screw until it just gets tight, then back it out. Repeat as needed until the screw cleans the threads.


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## Geralt (Jul 11, 2012)

Didn't read the original post carefully. Nevermind.


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## AndrwSwitch (Nov 8, 2007)

OP - the taps that Sheldon's article refers to are the right thing. Your shop may have them too, which would save you buying something to use once.


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## nmum (Oct 10, 2013)

Success!

Thanks for all the input and the information about tapping.

I was expecting that this was something that I'd have to work on every night for the rest of the week. I was fully expecting needing to get whatever is needed to tap the thread because the bolts would not catch the majority of the times.

But after a couple of tries and lube it eventually caught and once it caught on was pretty easy from there.

I looked at it a little bit more closely before trying and noticed that it looked like the paint on the frame might have been blocking the threads near the beginning, and while working on it noticed pieces falling out. So guess it was due to paint.

I tend to overdo things and started to try to get the bolts in tight as possible but then remembered your warnings about how delicate the threads were. So backed off on that one a bit and tried not to overtighten the other one.

Thanks again!


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## m4xwellmurd3r (Oct 15, 2013)

Heres the issue. An m5 bolt just means its a 5mm diameter bolt, it doesnt tell us the thread pitch.

I think commonly its m5 x 0.8 for the thread pitch, if youre having issues with the bolt, maybe the ones youre using have the wrong pitch?

If not I would get an m5x0.8 thread pitch tap and chase em with wd40 as lube

Edit

Didnt see you got it fixed.


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