Been bought a very expensive present I don't want and can't return

Depends how much you value honesty in this relationship
seems that you find the gifts a bit’ingraciating’
is he issue that you don’t want to feel pressured into a closer relationship or that you don’t want to feel pressured into a gift reciprocal situation as a substitute for
closeness maybe rushing things a bit
she is probably reaching out in the only way she operates and maybe trying to buy your love you need to evaluate what you want from the u
and explain where you’re coming from can you put it in a local ad so you can ensure it goes to a good home I think you should separate the two issues
as once the first one is resolved you will know what to do with the second!

Why didn t she speak to you for 25 years and why did you do a go fund me?

YABU for saying you had the money to get yourself an electric bike and felt patronised for the gift directly after saying you have precious little in savings and can’t go wasting a penny on a new saddle.

This has nothing to do with the bike or not getting in with it. You don’t want the connection to her, and that’s okay but be upfront with yourself and then perhaps her.

Take it to a bike shop for a proper bike fit, including getting a new saddle. It might make a world of difference

Considering the speed with which many Mumsnetters usually yell "LTB" or "go NC" at the first hint of trouble in a relationship, not to mention the outrage at gifts deemed unsuitable on the Christmas threads, I'm surprised that there is not more understanding for the OP here. Just because a gift is expensive doesn't mean it has be received with gratitude, or that it is well intended.
My own toxic relative bought me a very expensive pram when I was pregnant with my first. No prior discussion, it just turned up on the doorstep. Everyone was wowed by how kind and generous she was. No, it would have been kind and generous if she had rung me and offered to make a contribution to whatever pram DH and I chose ourselves. I recognised this as the latest in a long line of attempts to control me, a prior notification that she was expecting a significant role in our child's life and something that would I be reminded of every time she wanted something from me for years to come. I didn't even like it. It was ugly, you needed an engineering degree to get it into the car and it just didn't suit my lifestyle. It was her taste, not mine. But it was expensive so I was supposed to be grateful. I allowed myself to be persuaded that it was a kind act, one that I would be a churlish bitch to refuse, she was just trying to nice, oh, and did I mention it was expensive?! But guess what? My first instincts were proved correct by time.
OK, I'm projecting here and the OP's sister may be nothing like my toxic relative. She might be a lovely woman who is just trying to make ammends in the best way she can for whatever the past problems have been. But maybe she isn't. I'd probably give the person who has known her for presumably the vast majority of her life the benefit of the doubt if she's feeling uncomfortable about the gift.

I think that If she knew I'd got rid of it she wouldn't speak to me for another 25 years.

And from your point of view, would that be a good or a bad thing? 😀

You literally need to buy a gel saddle and get on with riding it.

I wear 3 pairs of knickers to pad my arse out. It worked well even when I was over 20 stone.....persevere with the bike. They're great fun, getting fitter is an added bonus.

it must have warranty that starts from
around now? You should sell it asap. It is worth more now than it will be by leaving it in your shed for 6 months.

could you talk to the shop it came from and get another product?

what shines through in your writing is that you don’t want it because it came from your sister. I say this because…. You wanted to try an electric bike and had the money saved but you can’t afford to buy a saddle and you are scared to cycle… even though you are an experienced cyclist.

right now the like is taking up space in your home and symbolically it is annoying you, so get rid of it.

Ah. It’s good you’ve realised it’s not about the bike OP. Don’t do anything hasty with regards to the gift.

Why did she stop speaking to you?

I think if you can get 2/3 of the cost that's better than it going to waste.

I see PPs have said you can change the saddle, which I wasn't aware of, so I'd try that first. Or contact the manufacturer to see if they have any suggestions.

Take a photo of you on it before you send it? Would she really know if you sold it and got a different brand?

New saddle and gel pants will do the trick. Give it another go.

It seemed like you were dropping hints about wanting an electric bike, even though you didn’t want or expect her to buy you one.

If you can, separate the bike from the context. It’s just an object to get from point A to B. The fact it’s new rather than used, means you are likely going to be safer on it.

If you were thinking about buying one second hand would that have cost less than the padded seat or a pair of padded shorts? You might have needed those things as well plus pay to replace any worn out parts to make it road worthy.

Going out a couple of times isn’t a good barometer.

Agree with leave it in the shed though until the weather picks up and you are feeling more motivated.

Sorry your relationship has been difficult. It isn’t helping to read negativity into every gesture she subsequently makes - in the other example you gave, friends could still have contributed if they wanted to, many fundraisers go well over target they are not finite.

@Gresley what was your GFM for?

You get used to the saddle 😁

so ". I wanted to try an electric bike and had the money to buy one myself " but you dont have the money to buy a new saddle?

You seem to be reacting out of resentment and as an ebike rider I feel you could grow to love it.
Get a padded saddle and find some bike lanes, look for a friendly local group that does shorter rides to cafes etc.
I wear padded shorts under my trousers for longer rides and love the freedom that my bike gives me. I’d at least give it until the summer is over before you decide whether to sell it on or not.

You've been given an electric bike worth at least £1K, and you're quibbling about a replacement saddle, which can bought, brand new, for £20 or less? This is what's known as cutting off your nose to spite your face.

the seat on my bike was agony. i have padding everywhere except my bum. then i went on amazon and got a wide saddle. its incredibly comfy and i cycle everywhere. they are about £15. its worth trying before you get rid of something that could be so much fun.

You sound conflicted about your sister. Not being spoken to for 25 years sounds like a serious fall out but then some people are extremely quick to cut off so maybe she has realised she acted hastily but been too stubborn to admit it and the only way she knows how to fix things is with money.

Why did her gfm donation rankle? It didn't stop other people from donating if they wished. I once put in the full amount of a friend's gfm because I knew how badly she was struggling and I wanted her to get what she needed plus whatever anyone else could afford to give. Or was it the first "contact" after years of silence?

Donating to your gfm and buying you a bike are hardly the actions of someone who doesn't want you in their life, or at least she still cares about you, have you been in touch since it arrived?

I felt quite annoyed then because she paid most of what I was asking, so my real friends didn't get the chance
Err it is not really ‘a chance’ to be asked to contribute to a friends go fund me… you seem to want to try to find any excuse to be annoyed at her. She gives you money when you say you need some, and your reaction « she took away the chance for my real friends to give me any ». Sorry but that is self-centered and ridiculous.

What a lovely gift! Get a new saddle and give it a couple of weeks to get used to it.

I have sympathy with you @Gresley
It's not the bike itself I'm sure, it's about your discomfort with the relationship with your sister and your situation resonates with me. There is someone in my family with a long history of controlling behaviour who uses gift giving to try to manipulate people. Sometimes it's a way to try to "buy" herself back into relationships that she has damaged by her behaviour and on other occasions it's a kind of investment. You can guarantee that at some point her "generosity" will be used as a lever, it's all very transactional. So I am always very suspicious of her motives if I receive a gift, especially if it's out of the blue and not a birthday etc. Something will be expected in return at some point. She also always buys things that she likes rather than ever considering the recipient's tastes and reckons she knows what we want better than we do ourselves. It's all about control.
Is it something along the same lines with your sister? If so, you have my sympathy. Not all gifts are given without strings attached or for the best of motives and it is not always ungrateful not to want them. If you're really uncomfortable with keeping the bike why not donate it to charity, either directly or sell it and donate the proceeds?