jefnvk

So one of the takeaways from a recent tour was that I was less than impressed with my rear rack. I started at about 8-9kg, and had about 13kg of weight at the end as my beer and souvenir collection expanded, and it just never felt that stable. It was carried in two equally loaded panniers. While I am looking for another rack, I am curious if anyone has an opinion on whether threaded eyelets are more secure than a thru bolt. My front eyelets are threaded, but the rear are is not, and I was attaching the rack with a 5mm bolt. All the mounting hardware I had for the frame and fenders seemed to be a regular threaded 6mm, is this a fairly common size? Any reason I shouldn't just drill and tap the eyelets to that spec?

Alternatively, is there a preferred mounting position if you are running both rack and fenders on the same eyelet? I didn't notice a change between not having the fenders and having them, but the fender mounts were between the rack and the frame.

EDIT: Rack was an Axiom Journey adjustable for reference. Supposedly holds 50kg, I don't believe it.

Tourist in MSN

An M5 bolt is pretty strong. Thorn rates their expedition rack as having a capacity of 40 kg, but they rate that same rack as 60 kg capacity with 6mm bolts. (They also say cut those in half for South American Ripio.) I interpret that to mean that the M5 bolts are good enough for 40 kg on normal roads.

I assume you have a derailleur bike with rim brakes. On the drive side, use a long enough bolt that you can go through the fender mount (maybe a few washers too) and then the rack, then thread that into the frame. And make sure that the bolt is not too long to cause chain problems on the smallest sprocket. You might need to shorten the bolt with a hacksaw.

On the other side, you can mount it the same way - or since on the non-drive side you have more room inside the dropouts you could mount the rack on the outside of the dropout and the fender on the inside of the dropout and use a nut (nylock is best) on the inside to hold the fender bracket in place.

fietsbob

There are stronger Heat Treated bolts, too ..

I bought 2, 8.8 marked on the head Steel Bolts , for My bottom support into the dropout eyelet fastener ..

Not stainless, so once tight I put touch up paint on the head. .... 5mm , 8mm hex head.

jefnvk

I guess maybe I didn't describe that well. I'm asking specifically about having the eyelet threaded, versus just using a bolt with a nut. Is there any sort of advantage to threading specifically, holding the bolt more securely than just a putting it through the hole and tightening it down with lock washers (other than IMO being easier to install things)? The only reason I mention a 6mm is that is what I'd need to go to to thread, as a 5mm fits through the non-threaded hole cleanly.

Not worried about the bolt itself breaking, just the fact that it has room to move around in a thru hole more than if it were threaded in, although not enough to go up to a 6mm.

RichSPK

So, you could feel the rack moving a bit on the bolt? I don't remember if my rear eyelets are threaded or not, but I've never felt like the rack was moving around, neither on my '85 Raleigh Alyeska nor on my '88 Klein Performance.

jefnvk

Yeah. I guess the best description as it felt as if it was swaying just a bit side to side, which is where I thought about that extra room in the bolt hole allowing some movement. My thought was if it was actually threaded into the frame, that movement would be much harder to achieve, the bolt would be fixed more in one place than tightened through a hole slightly larger than itself.

There are a few variables I'm trying to work through to pinpoint the issues exactly, it may well just be the rack design itself. Mostly just curious on people's opinions of thru-bolt v threaded for mounting, and if there is any harm or benefit to doing so on a bike that wasn't originally equipped with it before breaking out the drill and tap. The girlfriend's had a threaded eyelet, it made installing things much easier anyhow.

MixedRider

Have you tried a 6mm bolt? Does the eyelet look like it has a worn spot (ie. not circular anymore but more oval)?

If you can't find something that fits just right, this may be all you can do. Maybe try some putty or something around the bolt to limit movement. If you try and thread the eyelet now, if it is pretty worn from years of use with bolt movement, you may risk compromising the eyelet itself.

jefnvk

Nah, hole isn't worn, I think I'm the first to ever put a rack on the thing. Paint was almost perfect inside the hole. I did try a 6mm, it was too big (that is what came with the rack, and what worked on the girlfriend's bike). The only thing I could think of there is I sprayed the frame with a clear enamel, maybe that is restricting the hole a bit too much, but I think the bolt in general looks too big to fit.

Its a 1982 Miyata 610, is it possible it was originally bored for a SAE size bolt? I just assumed it would be metric. I just went out and measured it, the bolt it is indeed 5mm, and when I grab the rack and give it a good tug back and forth, I can see the bolt moving around.

Tourist in MSN

I do not think I have ever seen an unthreaded rear fender or rear rack mount on a modern frame, and the ones I have seen were always M5 thread, except some older Raleigh Nottingham frames that I think were number 12 fine thread.

If it is steel, I see no reason that you can't tap it. If Aluminum, it can be tapped, but the metal is softer and maybe there was a reason it was not threaded in the first place.

jefnvk

Cr-Mo steel, so no worries about Aluminum. Is an 82, so a bit older, but my fronts were threaded which is why I was confused when I get to the back. Think I'm just gonna do it when I get the new rack figured out, guess the worst case is I have exactly what I have now but with a 6mm bolt holding it on :/

79pmooney

Rack and fenders. I run the rack next to the dropout and the fenders outside. That way the bolt doesn't (and cannot) flex as long as it is snugged up tight. I put a washer under the bolt head outside the fenders so the bolt has no tendency to spread the fender stay eyes.

Done this way, there should be no noticeable flex until the bolt breaks. Threading for 6 m,m will raise that level, but with good bolts snugged properly, 5 mm bolts should do. An even better way to do this would be to run the bolts from the inside, ie heads toward the wheel. You could then snug the nut against the rack so you have a minimally short bolt holding the rack in place. But do this with a bolt with cm of extra length. Now fit the fenders on the bolt and use an second nut. I've done this in the past and it works very well. Use lock nut or lockwashers. You don't want the bolt loosening into your chain or cog. Plus is the ease of removing fenders while leaving the rack on.

Ben

CliffordK

You certainly don't want your rack to be wobbling. That puts stress on everything, and you'll end up with broken bolts or a broken rack.

Get it TIGHT. And, properly tightened, it won't make any difference if the bolt goes through to a nut, vs threaded (assuming a tight fitting and possibly hardened bolt too).

I never liked the feeling of standing and pedalling with a heavy load on my rack, but I always considered it was due to flex with the road bike, wheels, and tires.

jefnvk

Yeah, I should mention my bolt head is on the inside. Didn't have any room to do it the other way, at least on the drive side.

elpy zee

My mid-1980s Miyata 610 is the same, with no threads on the rear eyelets. I used some stainless bolts and nylock nuts I had lying around, and no wobble whatsoever after 5,000+ miles, many with heavy loads in the rear panniers. Rack is a Blackburn EX-1, I think. The rear fender has 2 stays on each side, and the attachment sandwich has the rack between the two fender stays.

BigAura

It's your rack. Get a tubus and report back

Happy Feet

If the hole is between a 5-6mm can you not just drill it out to 6mm and use that bolt? I think I've read of people doing that intentionally to have a stronger bolt (6mm).

tortron

is the paint worn off around the hole?
I ask because it may not be moving at all, and the sway the rack, or frame, or both flexing

Miele Man

You want as snug a tolerance between the bolt and the hole as you can get. otherwise you might have movement. You also need everything to be tight. Something that can make any rack sway is long arms between the rack and the mounting holes on the bike.

Can you post an image of your rack without the saddlebags?

Cheers

RichSPK

I'm pretty sure that any play in the bolt hole would allow the rack to move up and down or fore and aft, but not side to side.

bradtx

jefnvk, A threaded eyelet could be better if you wanted to use a lock nut in conjunction. Otherwise, tight is tight. If I had only one eyelet for both fenders and a rack, I'd place the rack's vertical stay next to the eyelet with the fender stay outboard of that, or place the fender stay inside of the eyelet.

If I had a rack that was swaying / flexing, I'd look at the rack's horizontal stays. There maybe a better way to secure the rack? While I doubt it, don't rule out the possibility of frame flex.

Brad

Trevtassie

If a 5mm bolt is a loose fit then tap it to 6mm, since it's already about the right size for a 6mm tap. That'll help a bit. Is there any play in the adjustable legs where the lock screws fit? Maybe also check the holes where the lock screws go through to the bottom legs to see if they aren't flogged out too. The other thing that might be worth trying is some different top struts. To me, from an engineering perspective, the top struts look pretty close together where they mount on the rack. It might be possible reverse the mounting clamps on the struts so they're further apart and then straighten the struts to fit on the mounts on the bike.

saddlesores

how is the rack attached at the top?

one version has two struts. if this type,
are they bolted inside or outside the seatstays?

other version has a single flat bar that bolts
to the brake bridge.

gauvins

(Major) bummer...

Threaded eyelets (+locktite blue) is certainly more convenient. But not more secure. I often saw suggestions to back up threaded brackets with nylocks to positively eliminate the risk of a bolt coming loose.

Philly Tandem

I agree that it sounds more like a rack issue than a bolt issue. Assuming that the bolts are tight-tight at the eyelets. Double-check all mounting bolts all-around. The Axiom looks pretty well-braced, otherwise I'd say it could be a lack of triangulation on the rack that allows it to flex under load.

If you want the most secure bolt attachment, go with threaded eyelets backed up by a nylock nut on the bolt for redundancy, or at least some Loctite blue on the bolt itself into the threads. But I really doubt that's your issue here. Threaded eyelets are more for convenience and looks (IMO), negating the need to back up with a nut. Plus, there might not be enough room for a nut on the drive-side.

jefnvk

Mounting up top is two P-clips. They are far more solid than the lower mounts, grabbing and shaking doesn't budge them. Arms are mounted on the inside side of the seatstays, I couldn't get them on the outside. Adjustment bolts on the rack are all solid and secured.

Thanks for all the input! I'm also leaning more towards the rack itself, but the loose bolts do cause me concern that I want to sort out. Maybe I'll try looking at some SAE bolts, seeing if any of them fit a bit better, but otherwise I think I'll tap it. I'm also thinking that a front rack will be added, just to get some weight off the back to help with handling, that was always in the plans anyways.

Any advice on a bit sturdier rack? Also, is it wrong to think that anything marketed for a 700 would also fit a 27"? Can't imagine there is enough of a difference in tire size to run into any fit issues.