Another Seat Rail Bites The Dust

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markz
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Another Seat Rail Bites The Dust

Post by markz » Dec 01, 2017 5:42 pm

Broke my comfy Townie Electra seat rail. LBS sells Townie seats (can order them in for $40cdn) but not parts like the rail or elastromer. Charity LBS sells used, bought 2 old springy for $5 each. Their rails are 14mm flat stock thats 3.5mm wide, requires specific rail clamp.

If you weigh a lot, do you do anything to your seat, maybe a certain placement of the rail clamp, I put mine all the way forward right where the bend is in the rail, so I sit more rearward. Probably a weak placement spot as I still tend seat and use the back of the seat.

Start stiffening up with rails by welding, is the only fix I see. Even cross bracing the rail and permanently welding the clamp.

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Re: Another Seat Rail Bites The Dust

Post by JDMopar » Dec 01, 2017 8:10 pm

Yeah that's a heck of a lever you're making out of the rails. You might consider a setback seatpost. Thomson is perhaps the best seatpost manufacturer or close to it, but you pay for it. Other manufacturers make setback seatposts as well. This may allow you to place the clamp more in the center of the rails. A longer clamp with more length on the rails should also help you.
edit: sorry if you meant you want to keep using those $5 seats you got; that would make my advice fairly moot.


Where are the rails breaking? I really think welding won't help at all.

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Re: Another Seat Rail Bites The Dust

Post by markz » Dec 02, 2017 12:25 am

I cruise, 35kph, no jumps, just on & off curbs taking it easy. Ah thinking about it now, yeah I tend to pick up the bike from the back of the seat. Lots of weight back there with the dd motor, battery. Need to search for a seat post handle. Hmmm wonder if the bar ends would work, hmmmmmmmm

Townie lasted quite awhile, 2 years.
Townie Seat.jpg
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Lasted 2 days
Junk seat.jpg
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Layback seatpost - $5 used pristine condition, 1 maybe 2 months - everyday riding in the summer. I did try to bend it back and fix it after it bent, yeaaaaa no.
layback.jpg
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Found a proper rail clamp - https://www.ebay.ca/itm/Brooks-Leather- ... Swh1haBLNA

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Chalo
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Re: Another Seat Rail Bites The Dust

Post by Chalo » Dec 02, 2017 4:37 am

If you run the seat all the way back on the rails, it will bend. I've demonstrated this over and over. Push it all the way forward, and your problems will go away.

That "proper" seat guts is for a B67 or B130 saddle, with two rails on each side. For a single rail saddle, it won't work even as well as a normal cheap seat guts.

The best I can tell you is to make, or have a machinist make for you, a chunky clamp that attaches to your seat post, that holds another seat post behind it. Or else have someone make you a thick chromoly layback seatpost with a reinforcing gusset.

Don't bother with any seatpost in 22.2mm diameter; none of those will work for you. When I need one that size, I machine it from a solid bar of steel or very high strength aluminum, like 2024-T3 or 7075-T6.

Another thing you can do is to stand up when you know you're going to hit a bump.
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Re: Another Seat Rail Bites The Dust

Post by miro13car » Dec 02, 2017 7:55 am

Any bicycle seat of decent quality would have markings on rails showing how much back or forward you can slide seat.
Last edited by miro13car on Dec 03, 2017 10:07 am, edited 2 times in total.

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Re: Another Seat Rail Bites The Dust

Post by dogman dan » Dec 02, 2017 8:31 am

Move your seat 2 inches or so back, with a thudbuster seatpost.

Then you can put the rail in the middle, or farther back, and still have your seat more to the rear.

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Re: Another Seat Rail Bites The Dust

Post by MadRhino » Dec 02, 2017 11:21 am

The lever effect of setting the mount to the extreme end of the rail, combined to a cheap saddle that has non standard rails... That was calling for troubles.

The best solution is a layback seat post and a saddle that has standard rails. Both are available in cheap to high end components.

Yet, setting a saddle far on the back is not the best way to enlarge your cockpit, unless you like wheelie riding. A wider handlebar and/or longer stem is a much better way to a larger cockpit on your ebike, since it does improve control, aero, and moves some of your weight to the front.
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Chalo
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Re: Another Seat Rail Bites The Dust

Post by Chalo » Dec 02, 2017 3:02 pm

miro13car wrote:
Dec 02, 2017 7:55 am
Any bicycle seat of decent quality would have markings on rails showing how much back or forward you can slide seat.
I'm pretty sure those markings, and the seat rail materials, don't assume a rider could be as heavy as I am (or as heavy as markz is). The remedy is to slide the weight bearing part of the saddle as close as we can to the seat post clamp. That makes for a shorter lever and smaller bending moment.
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Re: Another Seat Rail Bites The Dust

Post by wturber » Dec 02, 2017 11:04 pm

I'm not sure how this will work for a heavy rider, or where you'd even find this adapter these days, but this is what I installed on my road bike about 20 years ago and still use. The adapter lets you clamp the seat in the middle of the rails while shifting the seat backwards. It is machined aluminum and seems pretty strong to me.
IMG_20171202_204948906~2_cr.jpg
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Re: Another Seat Rail Bites The Dust

Post by Chalo » Dec 03, 2017 4:43 am

I used to use one of those in the late '80s/early '90s. It was called Torque Platform, and it was originally intended to place a saddle farther forward than would otherwise be possible, for triathletes who have no clue what they're doing, but know how to follow each other over a cliff. I flipped it around the same way you have yours installed, to help lengthen the cockpit of a commercially available bike, while slackening the effective seat tube angle in the process.

Eventually, the bolt holding everything together broke off. That was when I weighed about 130 pounds less than I do now.
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Re: Another Seat Rail Bites The Dust

Post by wturber » Dec 04, 2017 3:23 am

Chalo wrote:
Dec 03, 2017 4:43 am
I used to use one of those in the late '80s/early '90s. It was called Torque Platform, and it was originally intended to place a saddle farther forward than would otherwise be possible, for triathletes who have no clue what they're doing, but know how to follow each other over a cliff. I flipped it around the same way you have yours installed, to help lengthen the cockpit of a commercially available bike, while slackening the effective seat tube angle in the process.

Eventually, the bolt holding everything together broke off. That was when I weighed about 130 pounds less than I do now.
Yeah. While I like my Trek 1400, I concluded that the seat tube angle was too steep after going through a number of sizing/fit exercises and trying them out. That adapter was my solution. It seems solid. But then I'm not a heavy rider. Wouldn't the better answer overall for a heavy rider be to get a suspension seatpost of some kind? That would tend to reduce peak loading on any component in the chain of seat support.
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markz
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Re: Another Seat Rail Bites The Dust

Post by markz » Dec 04, 2017 2:12 pm

Suspension seat posts probably wouldnt be able to handle us heavy weights. Atleast the cheap ones, wouldnt want to buy an expensive one just for it to break.

My plan is to place the seat in the middle of the rail, and beef it up by welding support brackets, across rail, and maybe even permanently attach to post. Need to weld the Townie seat rail, loved that seat.

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Re: Another Seat Rail Bites The Dust

Post by Chalo » Dec 04, 2017 2:26 pm

markz wrote:
Dec 04, 2017 2:12 pm
Suspension seat posts probably wouldnt be able to handle us heavy weights. Atleast the cheap ones, wouldnt want to buy an expensive one just for it to break.
The SR Suntour NCX post I have was given to me by a customer who bought the heavy spring version and found the spring rate way too stiff for him. It's actually OK for me, and I weigh in the neighborhood of 350 lbs/160 kg. I still have my usual habits, so I don't stay planted in the saddle when I know I'm going to hit bumps. But so far, I have not noticed the thing bottoming out.

That said, it doesn't have a whole lot more setback than a conventional post with some setback. And I would be concerned about bending it if I used most of its available extension. As it is, I have it in a 68cm road bike frame, inserted almost all the way down.
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Re: Another Seat Rail Bites The Dust

Post by Drunkskunk » Dec 04, 2017 5:20 pm

When I topped out at 200lbs, I snapped one of those spring seats going over bump. Ok, it was more of a small cliff. Either way, those things aren't meant for American sized riders. There's just too much torque on too skinny of a rail, and they are usually made of some cheap low strength steel. If you're board and handy, you might be able to make your own rails out of some 4130 steel. it's strong but can take a bend with no more heating needed than a good propane torch.

If that's not what you want, there are some double and tripple rail seats out there, made of better grade parts.
Brooks, for example. https://www.amazon.com/Brooks-Saddles-B ... rooks+seat

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Re: Another Seat Rail Bites The Dust

Post by MadRhino » Dec 04, 2017 10:42 pm

Fine craft saddle, but it is looking like it’s gonna bite your balls when you hit a pothole. :mrgreen:
Make it fool-proof, and I will make a better fool.
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markz
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Re: Another Seat Rail Bites The Dust

Post by markz » Dec 04, 2017 10:48 pm

That'll surely hurt!
How'd you explain it all, not only to the hot er nurse, but your best pals.
MadRhino wrote:
Dec 04, 2017 10:42 pm
Fine craft saddle, but it is looking like it’s gonna bite your balls when you hit a pothole. :mrgreen:

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Re: Another Seat Rail Bites The Dust

Post by MadRhino » Dec 04, 2017 11:59 pm

markz wrote:
Dec 04, 2017 10:48 pm
That'll surely hurt!
How'd you explain it all, not only to the hot er nurse, but your best pals.
MadRhino wrote:
Dec 04, 2017 10:42 pm
Fine craft saddle, but it is looking like it’s gonna bite your balls when you hit a pothole. :mrgreen:
You just tell how you had to find another pothole, to free your balls off the mad saddle. :twisted:
Make it fool-proof, and I will make a better fool.
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