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Discussion Starter #1
This possibly applies to Bonnevilles and Scramblers too....

Has anyone experienced a foot peg breaking while riding - i.e. snapped of while standing on them going over a level crossing, stomping on them to get some lean going etc. - NOT breaking due to a drop of fall?

The reason I ask is this: I have just bought a new RH peg as the original had snapped off when the bike toppled over while the previous owner was parking it. These pegs do not look strong at all - they are cast aluminum, and would have expected at least forged and even then, something a little beefier. Now, I have no problem if the peg is designed to break when the bike falls over to prevent further damage to mounting brackets, etc., but I don't think this is the case - it's just a cheaply made part (oh, but it's expensive to buy). My concern is that it up to the job and I just want to have confidence that they are. If no one has had a failure, then all should be well.

For what it's worth, rather than use a rear peg, I adapted a pair of rear pegs from a Yamaha Vigaro which I used while waiting for the replacement Triumph peg. They actually looked pretty good and are definitely stronger than the Triumph pegs - no means of spring loading them though.
 

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Do a search...there are plenty examples of the stock pegs breaking off both while riding and from falling over. Being that you have a Thruxton you should be able to find a set of older Yamaha pegs to replace the stock pegs. The Bonneville/Scram guys only have Oberon or LSL for a replacement peg that bolts on without mods afaik.
 

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Compared to some sport-bikes I think the Bonnie pegs & mounts are pretty stout. Have you seen some of the tiny little aneimic pegs on crotch rockets. I have pencil holders that look beefier. Yes most "Cruisers" have big meaty pegs, but weight is not a factor, and have you seen the size of the guys (and gals) that ride those things.:D
It's been a few years since I have heard of a peg failure while standing on it. I stand on mine all the time up to 50mph or so just to clear the "junk" or to avoid a R/R track cramming the seat up my "arse" as the Brits would say.
Now that I have heard it again I will start thinking about it more before I start playing Bud Ekins.
 

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Discussion Starter #5
The problem is, in my opinion, that the stock pegs are cast, not forged or machined from solid (i.e. "billet"). While casting is a much cheaper manufacturing process and one that can produce complex shapes, the resulting part is weaker and more brittle - not good attributes for a foot peg.

I noticed on the interchangeable parts sticky that there are some Yamaha options and I'll take a look at them. At the end of the day though, as well as being safe, I want it to look right on the bike. If I do find an alternative, I'll let everyone know.
 

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Broken peg

Oh yes, riding along minding my own business went over a speed bump and the peg went clattering down the road, leg was flung back etc. Lucky to stay on. Still love the Bonnie though. I do think the mounting bolts are a tad feeble.
 

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Suffered a right footage snapping off when riding at about 65mph a couple of days ago. Here's the offending foot peg, with the bolt sheared straight off (I should have cleaned it for the photo but understand it was a mess after bouncing down a wet road and then spending 3 days in a wet bag until I got home). The bike has never seen dropped, the peg has never been removed and put back on again (so not overtightened by accident) and the bike has done less than 15k miles. Basically, the item was factory fitted. I serviced the bike only a couple of days before and I know for sure that the peg wasn't loose, nor did I feel that it was loose at any time whilst riding before it sheared off.

I was lucky to have stayed on the bike, if it had been a fast left hand corner with oncoming traffic in the other lane, the chances are I'd have been seriously injured or killed.

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Hmmm, weird. I have been standing on mine (2010) to stretch my legs for 5 years now without issue... You did say the bike went down on the peg so I would think for sure that weakened it....

Now my buddy's Bonne had one snap off just as we were departing our last stop to head home but he has that single bolt attachment setup! :(
 

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Hmmm, weird. I have been standing on mine (2010) to stretch my legs for 5 years now without issue...
The Thruxton and Scrambler have a different design. The clevis bracket is in one-piece with the outrigger, like the vast majority of bikes, not bolted on like the Bonnies.
 

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seen it happen today with my own eyes.

out riding with a pal on his black Bonnie and without warning the right hand peg snaps off. lucky he didn't loose control. the results could have been fatal

it would appear the peg bolt was previously cracked after dropping the bike at low speed some months back and today it decided to let go. examining the broken part on the side of the road you could clearly see it partly fractured half way through, then a clean break the rest of the way

anyone who has laid their bike down on the peg, do yourself a big favour and replace the bolt!
preferably up a size from 8mm to 3/8", that being about 9.5mm in diameter. an 8mm bolt has a cross section of about 50 square mm whereas 3/8" has 70 square mm, a big difference in strength. and use either a grade 8 or DIN 12.9
 

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The outrigger is easily tapped to 3/8'', no drilling required. A 1'' long by 3/8 grade 8 bolt can be torqued to 35 to 40 foot lbs. add a jam nut to the end of the bolt for extra security.
 

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The Thruxton and Scrambler have a different design. The clevis bracket is in one-piece with the outrigger, like the vast majority of bikes, not bolted on like the Bonnies.
Yup, fully aware of that but the OP lists a Thruxton and asks about a Thruxton peg in the post title....
 

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The fact that it DOESN'T happen more often indicates it is likely an assembly/maintenance issue, not a design flaw. The picture looks like it cracked initially, possibly due to vibration under load, then corroded until final catastrophic failure.
 

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Every foot peg ever manufactured doesn't have to fail, to make this the result of a bad design. That is, if indeed it is a bad design.
If it were a bad design then every foot peg could be predictably made to fracture at a load that is in the expected envelope of load cases that the foot peg was design to.

Note that the picture of this particular foot peg shows beach marks (lines with rust) indicating fatigue followed by the final fracture when the cross section of the bolt was only about half that of an undamaged bolt.
 

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My right peg snapped weeks after a lay-down.



I found that the torque specifications for this bolt is critical to it holding together correctly.



I have the "Modre" lowering brackets, so taking them off to check the peg-bolt torque is easy.

 

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If it were a bad design then every foot peg could be predictably made to fracture at a load that is in the expected envelope of load cases that the foot peg was design to.

Note that the picture of this particular foot peg shows beach marks (lines with rust) indicating fatigue followed by the final fracture when the cross section of the bolt was only about half that of an undamaged bolt.
I'm not going to get into another long winded debate about this with you or anyone else. It's been beat to death in too many other threads.

It only took one gusset plate on the I35W Bridge to fail and drop rush hour traffic into the Mississippi for the NTSB to conclude it was a faulty design.

In the end the question may have to be answered by a jury.
 
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