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Is there a specific kind of bolt used to hold front racks on?

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Is there a specific kind of bolt used to hold front racks on?

Old 07-06-13, 09:29 AM
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3speed
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Is there a specific kind of bolt used to hold front racks on?

Are there specific bolts that are designed for the mid-fork rack mount, or is whatever I find at ACE Hardware good?
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Old 07-06-13, 09:46 AM
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The boss is probably threaded for a metric thread. My Ace does not carry metrics. I order a handful at a time from Peter White Cycles. Just Google them. Delivery takes about a week for me.
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Old 07-06-13, 10:00 AM
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I expected it to be threaded too, but I don't think it is. I took a brush and got some WD-40 on it and tried to scrub inside of the hole to expose some threads in case there was just some crud or rust blocking my view of the threads, but the scrubbing revealed nothing. It just looks like a hole going all the way through.

It's on a 90' Trek 750 if anyone happens to know if those have threaded bosses or not.
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Old 07-06-13, 10:06 AM
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My Ace has a whole metric section, for just about any kind of bolt/screw you would care for.
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Old 07-06-13, 10:08 AM
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^ Yeah, ours has a couple full isles of plastic drawers all full of various kinds of fittings, nuts, bolts, washers, etc, etc. You can find most anything you need in there.
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Old 07-06-13, 10:19 AM
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Originally Posted by 3speed View Post
I expected it to be threaded too, but I don't think it is. I took a brush and got some WD-40 on it and tried to scrub inside of the hole to expose some threads in case there was just some crud or rust blocking my view of the threads, but the scrubbing revealed nothing. It just looks like a hole going all the way through.

It's on a 90' Trek 750 if anyone happens to know if those have threaded bosses or not.
I have a Trek 700 and it is a M5 (same as the water bottle cage mount).
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Old 07-06-13, 11:47 AM
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If you go to the Bike Shop they may have some nice stainless steel bolts ..

and NB, you need length as well as diameter and thread pitch to be right.

Bring the rack and the bike to get the best fit combination.
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Old 07-06-13, 01:56 PM
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Originally Posted by 3speed View Post
I expected it to be threaded too, but I don't think it is. I took a brush and got some WD-40 on it and tried to scrub inside of the hole to expose some threads in case there was just some crud or rust blocking my view of the threads, but the scrubbing revealed nothing. It just looks like a hole going all the way through.

It's on a 90' Trek 750 if anyone happens to know if those have threaded bosses or not.
I have an older Trek 520, and it's unthreaded. Doesn't surprise me one bit.

So just get whatever fits best.

For the record, usually when they're threaded, they're M5 which is probably what your rear bosses are. I thnk I grabbed 6-32 bolts since I couldn't find M5's that were long enough (I'm a purist) ;-)
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Old 07-06-13, 02:00 PM
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Odds are about 99 to 1 you should use a 5mm x 12 or 16 mm SS socket head screw. Just a dab of blue thread locker (don't use red) will keep them from coming loose.
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Old 07-06-13, 02:00 PM
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ACE Hardware for random stainless bolts, it is. Thanks!
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Old 07-06-13, 02:14 PM
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Or NAPA (etc.) auto parts.
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Old 07-06-13, 10:46 PM
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Originally Posted by Wanderer View Post
My Ace has a whole metric section, for just about any kind of bolt/screw you would care for.
Mine too, and it's a pretty small store. Should be an M5 if it's threaded.
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Old 07-07-13, 06:01 AM
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Originally Posted by Western Flyer View Post
Odds are about 99 to 1 you should use a 5mm x 12 or 16 mm SS socket head screw. Just a dab of blue thread locker (don't use red) will keep them from coming loose.
On the front rack, sometimes you need a spacer too, thus might need a longer length. And, maybe a couple washers.

I prefer stainless. There are two hardware stores near me, at one the M5 stainless button head bolts use a 3mm Allen wrench, at the other they use a 4mm. I now go to the hardware store that sells the bolts that use the 4mm wrench.

The blue locktite is a very good recommendation. On my last tour I had to loan a spare bolt to a friend that lost a rack bolt.

If it is unthreaded, I suspect a M5 bolt will work, but it would be best to take the bike to the hardware store to make sure. Nylock nuts would be better than the regular nuts.
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Old 07-07-13, 06:18 AM
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If the bosses are actually un-threaded, now would be the time to learn how to use an M5 tap. Since this is a common thread for drop outs /fender/water bottle, and rack fittings, it is worth having and knowing how to use this tap size. If you think that this is going to be a one-off experience, it's probably better to just pay the LBS to tap the holes and use the right fastener.
I would use stainless steel domed Allen-type fittings. Usually obtainable from your better (i.e., non road racing centric) LBS. Failing that, I use Marine hardware stores like West Marine to find an excellent assortment of stainless fasteners, including the Ny-Lock nuts. Not all local hardware stores have complete offerings in metric sizes. Auto part stores should have metric fasteners, but they may not have the Stainless variety or only hex head versions. YMMV.
Happy Hunting!
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Old 07-07-13, 07:00 AM
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Originally Posted by Pedaleur View Post
I have an older Trek 520, and it's unthreaded. Doesn't surprise me one bit.

So just get whatever fits best.

For the record, usually when they're threaded, they're M5 which is probably what your rear bosses are. I thnk I grabbed 6-32 bolts since I couldn't find M5's that were long enough (I'm a purist) ;-)
If the 520 does not have threaded bosses, are they thru holes (with a matching hole on the inner side of the fork) so that a nut and bolt could be used? If not, I wonder if they were meant to be tapped by the user for a suitable metirc or SAE bolt.
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Old 07-07-13, 09:41 AM
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Originally Posted by ak08820 View Post
If the 520 does not have threaded bosses, are they thru holes (with a matching hole on the inner side of the fork) so that a nut and bolt could be used? If not, I wonder if they were meant to be tapped by the user for a suitable metirc or SAE bolt.
Sorry. Not specific enough. They are unthreaded, through holes meant to take an M5 or smaller without threading. That is, a nut on the backside.

Originally Posted by elcraft View Post
If the bosses are actually un-threaded, now would be the time to learn how to use an M5 tap. Since this is a common thread for drop outs /fender/water bottle, and rack fittings, it is worth having and knowing how to use this tap size. If you think that this is going to be a one-off experience, it's probably better to just pay the LBS to tap the holes and use the right fastener.
Doubtful that will work, since they're most likely bigger than an M5. They probably take a nut on the back side.
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Old 07-07-13, 09:51 AM
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Originally Posted by Western Flyer View Post
Odds are about 99 to 1 you should use a 5mm x 12 or 16 mm SS socket head screw. Just a dab of blue thread locker (don't use red) will keep them from coming loose.
My Ace has these. I also recommend stainless steel. I've had rust problems, though never anything I couldn't crack, so stainless is worth looking for. I concur on the thread locker. The only bolts I can remember vibrating loose were on my rack, and it happened a couple of times when I was younger. I put blue Loctite on all my rack bolts and none have come loose.
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Old 07-07-13, 10:55 AM
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I have read of forks that have a through hole on each fork blade. The tubes duo only works with forks that have this feature.

I think that any M5 bolt that is long enough should work, but I would also recommend stainless steel.
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Old 07-07-13, 01:56 PM
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It not only has holes on the other side, but seems like there was a hole drilled in the fork, and then a small tube brazed into the fork that goes all the way through. So it's one solid hole that goes all the way through the fork. I fully plan on going stainless. I've got some blue lock tight in the tool box too. Thanks for the suggestions.
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Old 07-07-13, 02:11 PM
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Yeah - from the date you've got a non-threaded brazeon that goes right through the fork. If you can, better to get a shouldered bolt. Stainless isn't essential if its got some kind of anti corrosion coating and gets oiled or greased ocassionally. Stainless in contact with aluminum (your rack) will just force galvanic corrosion of the rack itself instead.
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Old 07-08-13, 12:50 PM
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I wonder how many forks have that through hole. I`ve never seen one in person, but knew that they existed. Since the Tubus racks are actually meant for that style mounting, could it be a European standard?

Also a little surprised that so many here are using stainless bolts. I like them too, but don`t carry huge weight, and since there`s always so much discusion here about bombproofing, I would have figured at least half would go for grade 5 or 8 bolts, which would be much stronger than most stainless. And my Ace doesn`t have a good bolt selection either, so I go to Tru Value for hardware
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Old 07-08-13, 02:02 PM
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Just remember to use lock washers when attaching racks, especially if the holes are not threaded. They are cheap insurance. So is including a couple of spares of any small hardware in your repair kit!
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Old 07-08-13, 02:35 PM
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Thanks again, guys! I'll see if I can find some sort of coated bolt and make sure I get some lock washers and an extra couple bolts and washers for the tool bag.
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Old 07-08-13, 03:18 PM
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It not only has holes on the other side, but seems like there was a hole drilled in the fork, and then a small tube brazed into the fork that goes all the way through. So it's one solid hole that goes all the way through the fork. I fully plan on going stainless. I've got some blue lock tight in the tool box too. Thanks for the suggestions.

If its the Through the fork type ... a bolt long enough to go straight Through

and then you fix a Nylon Insert locking nut on the opposite side ..

Ask for a Ny-lock nut in the appropriate size. and number..

there are some racks that are 2 pieces, without a connecting hoop
that utilize both ends of that through Bolt.

Last edited by fietsbob; 07-08-13 at 03:21 PM.
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Old 07-08-13, 03:42 PM
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Originally Posted by fietsbob View Post
... and then you fix a Nylon Insert locking nut on the opposite side ..

Ask for a Ny-lock nut in the appropriate size. and number..
While ny-lock nuts are great, I would still use a metal locking washer as well. For those of us in the hot climates (temperatures above 100 degrees) those nylock inserts can soften (or even melt) and the metal locking washer adds a nice redundancy. Temperatures on pavement in the American southwest can be as high as 140 degrees in the foot or so above the pavement. The paved area around the Pheonix Airport has surface temperatures of 160+ degrees in the summer.
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