Streetmachine GT - seat touching frame and other problems

[TPMB12]

I have a secondhand SMGT with a large, rigid seat. I've noticed a knocking sound that I put down to b the seat flexing and knocking against the frame when I go over bumps the knocking is only over bumps. Before every ride I lift the seat up as far as it will go and tighten the QRs. They still slip which is a concern, but only halfway down the slots.

First question is to any streetmachine owner with a hard seat, does yours ever contact the frame if the seat is right down?

Second, why could it be slipping? The QRs are very tight. I have washers between the seat slots and the frame bolt holes because iirc that's how it came.

Third, if I can't fix it properly, would it be good enough with ba thin strip of foam stuck to the seat with superglue where it contacts the frame? Bodge it.

Fourth, if replacement is needed (all other bodges I mean solutions aren't good) what seat is best? I assume the new GTe two part seat won't fit. So I also assume a mesh seat or a rigid seat made by iirc novosport are my options. The mesh seat being ventiseat I think? Any views?

I'm sure someone on here will have a good answer for me, you people always do.

[ElyDave]

The seat touching the frame in and of itself I'd not be worried about, that's happened due to seat flex on both my M5 and Cruzbike.  I've used some frame protection tape on the Cruzbike.

Personally I'd focus more on the slipping QR's - definitely tight enough, engaging properly etc

[TPMB12]

Yes, so tight I have trouble closing and opening them. They only slip a bit but it's resulting in the contact.

The washer location isn't the cause I think, you wouldn't put a washer against the QR clamp. I'm wondering if the gap between the frame and the seat slots is too great. Is that even going to be an issue? I'm thinking the QRs work best clamping against a rigid slot so filling the gap between slots and frame might give it a better surface to clamp against.

Just trying to think of reasons and solutions. Four more penny washers is a cheap solution of it's that easy.

[Mr Larrington]

I replaced the seat q/rs on my Speedmachine - which uses the same old-skool one-piece seat - with nuts and bolts, the better to do them up Bastard Tight.

[DTEK HPVS]

I have a secondhand SMGT with a large, rigid seat. I've noticed a knocking sound that I put down to b the seat flexing and knocking against the frame when I go over bumps the knocking is only over bumps. Before every ride I lift the seat up as far as it will go and tighten the QRs. They still slip which is a concern, but only halfway down the slots.

First question is to any streetmachine owner with a hard seat, does yours ever contact the frame if the seat is right down?

Second, why could it be slipping? The QRs are very tight. I have washers between the seat slots and the frame bolt holes because iirc that's how it came.

Third, if I can't fix it properly, would it be good enough with ba thin strip of foam stuck to the seat with superglue where it contacts the frame? Bodge it.

Fourth, if replacement is needed (all other bodges I mean solutions aren't good) what seat is best? I assume the new GTe two part seat won't fit. So I also assume a mesh seat or a rigid seat made by iirc novosport are my options. The mesh seat being ventiseat I think? Any views?

I'm sure someone on here will have a good answer for me, you people always do.

Suggest you apply seatpost "grip" paste to increase the surface tension (as used on ICE trike handlebars by the works in Falmouth . Weldtite and others make it .
TF2 Carbon Gripper Paste is specifically designed for use in assembling carbon components
Reduces required tightening torque on handlebars, stems and seatposts
Increases surface friction to reduce slippage and prevent seizing
10g tube

[TPMB12]

Thanks for that, I'll give it a try.

[Kim]

I replaced the seat q/rs on my Speedmachine - which uses the same old-skool one-piece seat - with nuts and bolts, the better to do them up Bastard Tight.

Me TTAW.  It's pretty much a design flaw.  The QRs are external cam (or at least mine were) which means they're rubbish by default.  Some decent bolts and nylocks will sort it, unless you're in the habit of changing the seat angle for different riding conditions (to their credit, the seat bracket design means you can do that without adjusting the boom length, but once I became confident with the bike I just kept it in the fully reclined position the whole time).

The bolts securing the seat brackets to the fibreglass of the seat also benefit from being Bastard Tight, else there are creaking noises as you sit back and forward in the seat.

I'm not sure about the seat touching the frame.  I don't think mine does that.  But it's a Medium so maybe it simply doesn't reach?

[TPMB12]

I take the seat off to put it on the roof occasionally to take it away with us. I'm thinking of getting a decent qr like a hope one with brass washer to it (instead of the plastic bit that is curved to take the external cam lever).

I know internal cam action is best but a good external cam with the brass is actually very secure. I replaced the original QRs on my upright with ones by hope after I had a few cases of the qr coming undone. I couldn't be sure whether or was a practical joke at work or the cam action but I replaced them and put it around I suspected a joke and wouldn't take too kindly to it happening again. Don't know whether the better qr or my implied threat solved the problem but they've not worked loose in over a year without me checking them.

[Kim]

I take the seat off to put it on the roof occasionally to take it away with us. I'm thinking of getting a decent qr like a hope one with brass washer to it (instead of the plastic bit that is curved to take the external cam lever).

Ah, putting a Streetmachine on the roof of anything is classic #TallPeopleProblems material.  I count myself lucky that I can get it in a dangly bike space. 

But yes, that's a good reason.  I suppose an allen key skewer doesn't have much going for it over a nut and bolt, other than being much more expensive and only needing one tool.

[Tigerbiten]

Would a clamp around the seat stays placed so it holds the seat stay at the correct position before the QR is tight help.

[fd3]

I have a speedmachine, not a streetmachine, but I would have thought that if your seat is hitting the frame it's more likely a rear suspension issue?

[TPMB12]

It's hitting it in the middle between the front and rear fixing points. It's where the seat curves away from the part I sit on and the part my back contacts. This part rests on the diagonal frame part that is rigidly attached to the main boom in front of the front connection point of the rear suspension damping unit. The other end of this unit attaches to the  seat stay part of the pivoting rear triangle. The chainstay part is attached to the back of the main boom with a pivot.

Basically the seat is attached to the rigid part of the frame which doesn't move. It's almost like the seat isn't right for the frame or the fitting brackets that's clamped to the frame aren't bolted to the seat in the right position. I doubt that's the case but it's touching when I go over moderate to bad potholes. Plus the clamps are slipping.

I've got some carbon grip paste. I'll give that a go but my bottom line bodge job option is to put a bit of camping mat CCF and glue it to the underside if the seat so its not getting damaged and isn't damaging the frame. Can't afford a new seat with the cost of the bike and necessary bits for it to become my summer touring holiday bike. So I need the paste to work or a basic bodge job.

[Tigerrr]

On my speed machine I never rode with the seat raised at all - let it sit on the bottom and set the suspension hard.