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Deng Bolts...


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Managed to destroy the threads in the maggie mount on my frame a couple of days ago. It happened very unexpectedly as I wasn't using any leverage or force (pretty much just rolling the allen key between my fingers to tighten down the brake finger tight before really tightening the bolts). Been checking the bolt and comparing to other that I know are up to standard. And guess what, the Deng bolt is too small. It's a couple of tenths of millimetres to thin (like 3), and the obvious result when put into soft aluminium is ruined threads... (N)

So my tip, get some proper bolts instead. There are other aftermarket bolts from both cycling specific brands as well as good ones from regular hardware stores. Definately worth it in retrospect I tell you...

Sorry if this is common knowledge or something. But I thought it could be worth posting...

Edited by Marten@ScandinavianTrials
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would deng make these bolts

Nope. He 99.9999% certainly doesn't make his bolts. He'll get them from the cheapest/most reliable source that he can find. That however may mean that the tolerances aren't as tight as they should be but I'd have thought an M5 bolt is pretty much an M5 bolt...

Oh, and Nath- just another reason to run a rear disc :D

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This may sound abit stupid.

But would deng make these bolts to small so products would brake, then we have to buy more...lol ;)

What Bolts should we be using for our 4-bolt mounts?

Nath

It's standard m5, so you should be able to get them everywhere. Approx 25mm length should be perfect. The Deng ones are too short at just 20mm just allowing for 5mm to actually engage the threads making things even worse.

Trialtech has got some sexy titanium bolts (that are up to standard, at least when I measured)... :P

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Approx 25mm length should be perfect. The Deng ones are too short at just 20mm just allowing for 5mm to actually engage the threads making things even worse.

But how many frames have a full 10mm of tapped mounting hole to use? Not many. In which case, if it's 20mm which is about perfect or 25mm which you'll have to cut down, I'd go with the former...

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Dave M, do you know when the Trial-Tech website is going to be up and running probaby, so we can buy his products?

You can buy them from all Trialtech dealers right now (or at least you should be able to). In the UK that would be Tarty (perhaps there are more...).

monkey...: My frame has got 14mm of threads so I guess it differs then...

Edited by Marten@ScandinavianTrials
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I'm pretty sure Deng doesn't get the bolts made bespoke for him. He probably get's them from one of the hundreds of bolt/cold forging manufacturers there are in China which would be rolled off off the production line in huge huge quantities.

I would expect the manufacturer to produce some sort of quality control. I wouldn't be sure if Deng does his own tests, but even if he does, i'd say it was unlikely he would find a bolt out of tolerance, mainly because of the high quantities he must buy and the fact the manufacturer produces their own tests.

So finding one bolt out of tolerance like you have pretty much means you're unlucky, because as a manufacturer it would be daft to check every single bolt, it's likely a guy on the production line will check one every 20-100 who knows, it depends how frequent the bolts tend to go out of tolerance and what sort of quality control measures they have.

Phil.

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Dave M, do you know when the Trial-Tech website is going to be up and running probaby, so we can buy his products?

Big shipment has just been delivered and Tarty should have it up soon. If you know what you want you'll be able to give TB a ring though and they'll sort you out (Y)

monkey...: My frame has got 14mm of threads so I guess it differs then...

Fair enough. Most frames I've had only had roughly 7mm of usable thread before the bolt bottomed out on the tube. As you say though, frames obviously differ :)

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Anyways, now I've forced a stainless proper M5-bolt into the hole (hopefully it friction welded it's ass in there). Weird I had to force it into the damaged hole when it went smoothly into the other holes. Then went out for a small test ride. Seems to work for now. Dunno if I'd trust it for big moves though. Just did some random small gaps and kicked onto some rocks and what not, seems to hold up for that kind of stuff... :ermm:

If it rips out I'm going helicoil, no alternative...

Monkey...: Told you! :P Naah, guess it's pretty odd with this much useable thread. But 7mm of useable thread seems a bit too little to be good. 10mm would seem better to me... The alu is like cheese so any extra threads are most welcome. :P

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Managed to destroy the threads in the maggie mount on my frame a couple of days ago. It happened very unexpectedly as I wasn't using any leverage or force (pretty much just rolling the allen key between my fingers to tighten down the brake finger tight before really tightening the bolts). Been checking the bolt and comparing to other that I know are up to standard. And guess what, the Deng bolt is too small. It's a couple of tenths of millimetres to thin (like 3), and the obvious result when put into soft aluminium is ruined threads... (N)

So my tip, get some proper bolts instead. There are other aftermarket bolts from both cycling specific brands as well as good ones from regular hardware stores. Definately worth it in retrospect I tell you...

Sorry if this is common knowledge or something. But I thought it could be worth posting...

Its happned to me brought new den gbolts other day because mine were f**ked! didnt even do two spins with allen key and the thrads jsut ripped straight out!! definatly changing it tommorow! and to make things worse i dotn have a tapping kit :@ grr

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Whilst were on the intial bolts and threads topic. If threads keep stripping in brake mounts. When don't companys provide them pre-helicoiled ? I.e - Steel threads to begin with ?

It's not cost effective, they will make more money if anyone balls up the helicoiling of their frames, as they then have to buy a new frame.

Edited by Muel
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Heli-coiling can't strip can it ? It's a steel insert right ?

yeah, if it failed, it would just pull the steel insert out, but as the name suggests, its a coil, so when the bolt screws in it exerts a force against the sides of the hole, holding it in tight

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i'm with danny on that one. Heli-coils are much stronger. as it spreads the force of the bolt being put in. seen it on a video make sence on there. But if heli-coils were put in at the factory there would be less chance of them being pulled out. I've personnally never had that trouble!!

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When I read this thread 2 days ago, I posted in my local bike forum where to get my frame heli-coiled in the event I stripped one of the threads.

Today, I stripped the thread off one of the brake mounts. I was about to give it a final tightening and it just stripped. Shame as I only got it barely a month ago! (At least now I know where to go to heli-coil it)

And guess what? I was using Deng bolts! Does that testify that Deng bolts really suck? lol.

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When I read this thread 2 days ago, I posted in my local bike forum where to get my frame heli-coiled in the event I stripped one of the threads.

Today, I stripped the thread off one of the brake mounts. I was about to give it a final tightening and it just stripped. Shame as I only got it barely a month ago! (At least now I know where to go to heli-coil it)

And guess what? I was using Deng bolts! Does that testify that Deng bolts really suck? lol.

Id be tempted to get yourself a heli coil kit, would only be about £30 even if you had to have it shipped from the uk (i payed £21 for mine, with 60 inserts), means you can do yours+ 14 of your mates bikes, then just order another set of inserts for like £5 for 50 posted to japan(approx) and thats coming from the uk,chances are you can get them cheaper than we can from the uk.

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  • 3 months later...

Ripped the threads out of my Echo frame yesterday doing a side hop off something about 4 or 5 foot high... landed with brake on as you do and then had a heatsink adaptor laying by the side of my leg :)

On the way home i popped into my local nuts and bolts store and picked up a 5mm helicoil kit for 21 quid plus vat... i see them on ebay for about 15 quid plus 7 for delivery so not much more to have it when i wanted it. Within 10 minutes i had 4 new steel insert helicoiled maggie mount holes. The same stores can sell single stainless or whatever allen bolts that are much better quality than most standard fit ones.

the same helicoil tool will do up to 8mm so only the tap needed to suit if you need it for 6,7 or 8mm pulled out threads.

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